مهری اکبری

The present study investigated the impacts of NAO and ENSO on the precipitation in the southern shores of Caspian Sea. The accumulated monthly and annual rainfalls from 5 synoptic stations during the years (1956-2017) were taken through Islamic Republic of Iran Meteorology Organization (IRIMO) and the Multivariate Enso Indices (MEI) and NAO activity years are obtained from National Oceanic Atmospheric Administration. Pearson correlation was used to investigate the relationship between indices and precipitation amounts of selected stations. The results showed that there was a significant relationship between precipitation and NAO index in some months in all stations but this correlation was not following a particular pattern in all the stations. The maximum correlations were observed at Babolsar and   Anzali station and the least correlation was found at  Gorgan stations. The correlation between precipitation and different phases of NAO showed that there was a positive correlation between precipitation and negative phase of the index in Ramsar station and a negative correlation between precipitation and positive phase in the Gorgan station.The results of the Pearson correlation show a significant correlation between the MEI and rainfall amounts in the autumn in some stations in the early winter. In Review drought and wet periods with both Indicator it was observed that the behavior of the stations in the El Niño period, which was with different phases of the NAO was not entirely harmonious but the coefficient of 89% of rainfall in normal and more than normal during the period of El Niño showed that Elnino is better fitted to normal and more than normal rainfall in these stations also coefficient of 60%  of weak to severe droughts in the Lanina period in the selected stations Indicates that the LaNina phase was more related with severe droughts in the under studied period.

This study was aimed at examining the types of inversion and their severity using the thermodynamic indices of the atmosphere such as SI, LI, KI and TT at Bandar Abbas Station for 2010-2020. In this study, Radioosvand data at the Bandar Abbas Station was obtained and used from the University of Wioming for the last 11 years (3.5 local) during the last 11 years (2010 to 2020). The results of the analysis showed that the average number of inversion phenomenon in Bandar Abbas was 501 cases per year, as in some days several types of inversion were observed at different altitude. Of these inversion, about 31.6 % are related to radiation temperature inversion, 4.3 % front, and another 64.1 % for subsidence inversion. Due to the air session underneath, the share of subsidence inversions is more than other types of inversion. In the meantime, the most severe inversion of subsidence was 1354 and the weakest inversions were with 29 cases and fronts. In general, the long -term average intensity coefficient of inversion of Bandar Abbas station with a coefficient of 0.062 indicates that the intensity of the city's inversion is mostly extremely severe, which can be very destructive effects both environmentally and physical health in the city's residents. Bandar Abbas follow. The correlation between the inversion elements also showed that by reducing the thickness of the inversion layer, the intensity of temperature inversion also increased.

This study has analyzed dating methods used in paleoclimatological studies. The method was review, document, and library. The statistical complex under study was among 2579 valid scientific works, between 1974-2023 in a period of 49 years, of which 108 scientific sources related to age measurement methods in Iran and internationally have been identified and analyzed. The articles have been received from domestic databases (Irandoc, Noormags, Elmnet, Magiran, Ensani, SID) and international databases (Google Scholar, Semantic Scholar). The keywords searched in these databases included climatic reconstruction, dating, and Quaternary. The results of this research showed that the most dating methods in paleoclimatology studies are carbon-14, oxygen isotope, tree chronology, and luminescence, respectively, and most dating studies have been done with the carbon-14 method. In terms of the spatial distribution of the conducted studies; In Iran, most of the studies have focused on the level fluctuations of Lake Urmia, and at the international level in China (Tibetan Plateau). Based on the review of sources, the first study area of paleoclimate in Iran was Zaribar Lake and it was done in 1961. Focusing more thematic studies on the topics of climate change, droughts, and droughts; in terms of time scale, it is Holocene and Quaternary. Based on the studies reviewed in this research, Iran's climate has changed from a hot and humid climate to a temperate climate since the Cretaceous period and experienced dry periods in the Central Plateau during the Pleistocene. Since the climate change caused by global warming has intensified since the Quaternary period, therefore, the use of dating methods for paleoclimate studies can be somewhat appropriate in terms of planning and risk management with regard to the new and advancing climate of the world.

in this research, their effects on the flight of airplanes were investigated. The study area is the country of Iran, and the flight routes of Kermanshah, Ahvaz and BandarAbbas to Tehran. The research data includes maps of the Vertical Transect (profile) of the jet stream, the daily average of the Zonal wind (U-Wind) and meridional wind (V-Wind) components for the winter period of 2018 through NOAA/NCEP environmental databases. Also, flight route information was received from FlightRadar24 and Flightaware systems. First, by using Vertical Transect maps, the days containing strong U-Wind were extracted, and the average position of the core of the Jet Streams in the Zonal and meridional wind components, the Tropospheric level of 200 HP was detected. The list of flights was prepared, and the Zonal Wind maps were produced. Finally, the height of the flights was compared with the level of the currents of the Jet Streams, and the influence or lack of influence of the Jet Streams on the flights was studied. According to the results of the research, all the Jet Streams caused turbulence for all flights, and they caused a decrease in the speed of flights between Ahvaz and BandarAbbas to Tehran and an increase in the speed of flights between Kermanshah and Tehran according to the direction and type of Jet Streams. It was also found that all the Jet Streams had a speed of more than 90 knots, so the capacity to create tension and turbulence such as CAT was seen in them

The ambient air temperature in the troposphere usually decreases with increased altitude (per 1000 meters increases the height of 5 to 6 degrees Celsius), but sometimes with increased air temperature, which is called temperature or inversion inversion. Temperature inversion occurs when a layer of hot air is above cold air adjacent to the Earth. In this case, air stability is created and instead of increasing temperature height to a few hundred meters above Earth with increased height. We will increase temperature. The importance of temperature inversion phenomenon is doubled when examining the effects of temperature inversion phenomenon. The phenomenon of temperature inversion is important because it causes fumation. This phenomenon occurs when the sun's radiation is unstable in the vicinity of the surface for a short time after sunrise, then combined with the scattered material in the nightly layer, causing the scattered material to return to the surface. . As a result, the concentration of pollutants increases sharply and the phenomenon of fiomia is created.

In this study, the daily data of the radio atmosphere above the Birjand Synoptic Station (Table 1) for 00 Greenwich (3.5 local) over the last 11 years (2010 to 2020) to 11 km high from Earth from Vioming University He got. Indicators used include thermodynamic indices such as SI, LI, KI and TT and potential temperature. Also of other data used in this study, radiosvand transmitted information including inversion height from ground to meter (ZBASE), inversion height from ground to meter (ZTOP), base temperature in base and inversion layer to degree Selicius (TBASE), the temperature difference between the base and the top of the inversion layer to the grade of silicius (DTINV) is the height difference between the base and the apex of inversion to meter (DZINV) and the pressure in the base (PBSE) and the inversion layer (PTOP) from Relationships (1 and 2) are calculated First calculated using the relationship (1) the potential of the ceiling and the floor of the inversion layer of the relationship (1)Θ: Potential temperature to Kelvin grade T: Temperature to Kelvin P: Air pressure to hectopaskal After calculating the potential temperature of the ceiling and floor of the inversion layer using the relationship (1), we have calculated the intensity of temperature inversion using relationship (2) on a monthly, seasonal and annual time scale. Relationship (2):Δθ Difference of the temperature potential and the base of inversion to the grade of Kelvin Δz thick layer of inversion to meter Z station height to hectometry

The results showed that the average annual temperature inversion phenomenon at Birjand Station was about 90 cases per year, as it may not occur in different heights in some days, about 11.1 % of the radiation temperature inversion, front. A 12.4 %, and the other 76.5 % is related to temperature inversion of subsidence. Due to the air session underneath, the share of subsidence inversions is more than other types of inversion. The results showed that the highest average inversion layer in Birjand was formed in 2010 and 2015 at 9 ° C. The highest annual temperature of the inversion is related to the inversion of subsidence, which is due to the subsidence of the air subcutaneous air subcutaneous in the upper layers of the atmosphere and the high temperature on the ground. In terms of annual altitude, the highest height of the inversion layer occurred in 2019 with 4490 meters. In terms of thickness of the inversion, the inversion of the type of subsidence with 207 and the radiation with 145 meters form the thickest and the thinnest layer of inversion. Results of the average inversion layer pressure in Birjand showed that 2014 and 2015 were formed with about 870 miles and 2019 with 592 milligrams. Among the types of inversion, the most severe inversion of the front was 0.044 % and then subsidence with 0.030 %. In terms of the intensity of severe inversion with 0.7 % and poor inversions with 0.92 % were the lowest and the highest in Birjand. In fact, the inversions of the city of Birjand are poor because of their physiographical and geographical properties.

The correlation results also showed that there was a direct and significant relationship between the intensity of inversion and the inversion layer temperature at 99 %. That is, the higher the temperature of the inversion layer, the greater the inversion of inversion and vice versa. But there is a significant relationship between the inversion intensity and the height of the layer at 95 % probability level. This reverse relationship indicates that whenever the inversion layer occurred at the lower altitude, the inversion of inversion has also increased; But the relationship between the thickness and intensity of the inversion layer showed that with the increase in the thickness of the inversion layer, the inversion of inversion in Birjand also increased as the layer temperature was higher as the inversion was more severe. There is also a direct and significant relationship between the intensity and pressure of the inversion layer at 95 % so that with increased pressure, the inversion will increase. In general, the city of Birjand is under the tranquility of the tropical climate because of its specific location, which is also on the roads of 120 -day Sistan, so it will be weak if inversion occurs.

In recent years, dust has been Iran's most important environmental crisis. On 25 February 1396, there was heavy dust in Iran which was important for research in two aspects: spatial extent and time of occurrence (winter). The purpose of this research is to analyze the synoptic conditions and to trace the phenomenon. For this purpose, satellite and re-analyzed data were used. Modis data showed that more than 60 percent of Iran's area to this day was affected by dusty airwaves, indicating that this phenomenon is widespread. The maximum optical depth of aerospace was observed in the northeast of Yazd province with a mean of 2.03. The results of the synoptic analysis of this phenomenon showed that at sea level a low-lying core comprises northeast and central parts of Iran. At a level of 850 hPa, a low altitude north of Lake Baikal and a high altitude over southern Pakistan and their resulting cyclonic and anticyclonic movements have led to the convergence of airflow in central Iran. The thermal contrast caused by the cold air of the upper latitudes and the warm air of the lower latitudes have resulted in the formation of a core of the hornbeam at a level of 500 hPa in central Iran. Minimum moisture content in all levels as well as rising air (based on equilibrium values) have provided the conditions for the rise of sweeping dust in Iran. Analysis of air mass routing 48 hours before the dust peak in three parts of southwest, central and northeast of Iran showed that air mass transfer route was in all parts of western Iran. However, even in the center of Iran, even at a height of 500 meters, the air mass has shifted from the Arabian deserts to Iran, resulting in heavy winter dust transfer to central Iran.

Although the air layer adjacent to the earth's surface - the boundary layer - is a small fraction of the entire atmosphere, the processes that take place on a small scale are very important to human life and activites. Among living organisms, plants and especially trees have undeniable effects on surface temperature and especially in urban environments have several balancing effects. This research was carried out using Landsat 8 satellite imagery and with      Arc GIS software to compare the surface temperature of the earth in two areas with vegetation of coniferous trees (Chitgar Park) and broadleaf trees (Shahid Chamran Park).The values ​​of Radiance, Reflectance, Brightness Temperature, Normalized Difference Vegetation Index, Proportion of Vegetation and Emissivity and then Land Surface Temperature were calculated and generated. A total of 1700 points were harvested from Chitgar Park and 800 points from Chamran Park. In SPSS software, Leven test (F) statistics was used to prove the homogeneity of variances of the samples and parametric tests (T with two independent samples) were used to prove the significant difference between the surface temperature of the earth in the mentioned areas. According to Leven test, the value was Sig = 0.409 (P_value), which confirms the homogeneity and equality of variance of the studied samples. Also, in the T test, the value was Sig = 0.000, which is less than 0.05, which means a significant difference. Therefore, the difference between the surface temperature data of the two parks was proved. Also, by comparing the graphs of LST values ​​in the two groups, we found that Chitgar Park has a higher surface temperature than Chamran Park. In the current dilemma of the century, global warming, knowing these local realities and providing logical solutions to reduce surface temperature at the regional and regional scales as a whole can effectively solve the problem of global warming on a global scale.

 The data used in this study is a Landsat 8 satellite imagery with the acronym: 8 (LC08_L1TP_165035_20190706) is LANDSAT. Retrieved July 6, 2019 from the USGS website. Production of component images for Shahid Chamran Parks in Karaj and Chitgar in Tehran:     The surface temperature image was generated step by step using the Landsat 8 satellite image using the Raster Calculator command in the ArcMap software environment. First, relevant and effective indicators in calculating the surface temperature of the earth, Top of atmospheric radiance, reflectance, Brightness Temperature, normalized difference vegetation index, proportion of vegetation, emission coefficient (emissivity), calculation and their images are produced and then the land surface temperature, It was calculated and produced according to the following mathematical formulas.Step 1: Produce a spectral radius image from above the atmosphereTo obtain the brightness temperature, the image must first be converted to radius. Therefore, the gray DN values of bands 10 and 11 of the Landsat 8 satellite TIRS sensor should be converted to high atmospheric radius separately with the help of the MTL file, which is an extension of the Landsat image (Tables 1, 2 and 3). Formula (1)  Calculate the radius of the upper atmosphere  TOA (Lλ) = ML * Qcal + AL Lλ = (Watts / (m2 * srad * μm)) The radius of the atmosphere in terms of ML = Multi-band radius_ 10 band Step 2: Produce an image of the light temperature above the atmosphere After converting the DN values of bands 10 and 11 to high atmospheric radii, we converted these two corrected bands to Brightness Temperature. BT = (K2 / (ln (K1 / L) + 1)) - 273.15     Formula (2): Calculation of Brightness Temperature BT  Atmospheric Brightness Temperature (° C) Lλ = (Watts / (m2 * srad * μm)) Radius of the atmosphere in terms of BT = (1321.0789 / Ln ((774.8853 / “% TOA%”) + 1)) - 273.15 K1 = K1 Constant Band (No.), K2 = K2 Constant Band (No.) Step 3: Produce vegetation index image formula (3): normalized difference vegetation index image was generated using NDVI = (Band 5 - Band 4) / (Band 5 + Band 4) Step 4: Produce a proportion of vegetation image The proportion of vegetation image was generated using normalized difference vegetation index. formulas (4):Calculate the proportion of vegetation PV = (NDVI - NDVImin / NDVImax- NDVImin) 2 PV = Square (("NDVI" - 0.216901) / (0.632267 - 0.216901)) Step 5: Produce the Emissivity image  Emissivity image was generated using formula (5) ε = 0.004 * PV + 0.986  Formula (5): Calculate the Emissivity coefficienStep 6: Produce an image of the earth's surface temperature  Land surface temperature image was generated using formula (6). Formula (6) :Calculate ground land surface temperature LST = (BT / (1 + (0.00115 * BT / 1.4388) * Ln (e)))

 Text Comparison of surface temperature phenomena (LST) According to Table (6), the highest land surface temperature with 44.42 ° C belongs to Chitgar Park, which is covered with coniferous trees, and the lowest in Shahid Chamran Park, in Karaj with 28.09 ° C with broadleaf trees. Has been. According to Tables (7) and (8), the lowest temperature of Chamran Park is 28.09 ° C and the highest is 36.51 ° C and the lowest temperature of Chitgar Park is 34.74 ° C and the highest is 44.42 ° C. . According to Figure (22), Chitgar Park with an average surface temperature of 38.92 ° C is warmer than Shahid Chamran Park with an average land surface temperature of 31.39 ° C. Figure (23) shows a red graphic showing the surface temperature of the ground in Chitgar Park with coniferous species (pine) and the blue diagram shows the surface temperature of Shahid Chamran Park in Karaj with broadleaf species. It is clear that the temperature is significantly higher in Chitgarh Park. The range of temperature fluctuations in Shahid Chamran Park is between 36.51 - 28.09 ° C and in Chitgar Park is between 42 / 44-74 / 34 which is exactly shown in the diagram. The fact that the red chart is higher than the blue chart explains this correctly. This is due to the lower density of trees in Chitgarh Park as well as the predominant tree species (needle-shaped) due to less shading and more input radiation. T test with two independent samples:   This test, which is a parametric test, was used to prove a significant difference between the earth's surface temperature in areas with coniferous and deciduous trees. Leven test (F) was used to prove the homogeneity of sample variances and t-test with two independent samples was used to examine the homogeneity of the means of the two statistical populations, which resulted in the following results. As can be seen in Table (12), the value = 0.409 Sig, which is the same value as P_value, is greater than 0.05, ie the variance of the communities is homogeneous and equal. 0.05 is less, which means that the difference is significant. Due to religion, the difference between the land surface temperature data of Shahid Chamran and Chitgar parks is proved.

According to all the findings, Chitgar Park has a higher land surface temperature than Chamran Park, which is due to the lower density of trees and also the type of dominant tree species (needle-shaped). Coniferous species that take up less space than broadleaf species and have less shading. They also make it possible for the sun to collide with the ground due to the fact that the leaves of the adjacent trees do not meet, and this is an important factor in raising the surface temperature in the mentioned park. Species compatible with the climate of the study areas are broadleaf species because they have more leaves shading and care than coniferous species and ultimately cause more climate adjustment. The difference in temperature between the two parks confirms this fact. In the current dilemma of the century, global warming, knowing these local realities and providing logical solutions to reduce surface temperature at the regional and regional scales as a whole can effectively solve the problem of global warming on a global scale.

Using statistical downscaling methods has been increased because the dynamic models are time-consuming and not cost-effective. This study has compared the results of two downscaling models i.e. CCT and SDSM in simulating the daily climatic parameters including precipitation, maximum, minimum and mean temperature in the Karganrood basin in Guilan province, Iran. The meteorological data of Bandar Anzali synoptic station during 1975-2018 was used as the observation period. Then, using the CCT downscaling model, MIROC climate model, SDSM downscaling model, CanESM2 climate model, daily precipitation, maximum, mean and minimum temperature of basin were simulated and compared with RCP2.6, RCP4.5, and RCP8.5 scenarios in 2025-2050, 2051-2075 and 2076-2100, respectively. NS, R2 and RMSE were used to study the robustness of downscaling indices. Based on NS, R² and RMSE criteria, SDSM model in the exponential microscale of maximum, mean and minimum temperature and in precipitation except RMSE factor value of RCP2.6 scenario and in the next period 2076-2051 in all cases compared to CCT model with error. The results of the Mann-Kendall test showed that the changes of precipitation and temperature simulated in future periods in the CCT model were significant with the highest significance relating to RCP8.5. The results of Mann-Kendall test also showed that in precipitation and temperature in future periods in the CCT model was more significant than the SDSM model and the highest significance was related to the maximum temperature (Z = 3.22), respectively and the minimum temperature (Z = 4.14) at 95% confidence level is related to RCP8.5.

IntroductionPrecipitation is considered to be one of the most important elements of climate. It affects the distribution of other climate elements and thus, has played a prominent and significant role in recent studies especially those focusing on global climate change. Due to its geographical location, Iran climate is affected by various climate elements. As one of the most important components of general atmospheric circulation, jet streams affect the quality of precipitation (amount, intensity, temporal and spatial distribution, etc.). Jet streams are relatively narrow bands of strong wind traveling across very long distances at high altitudes of the troposphere (tropopause) forming a hypothetical wind tunnel. Materials & MethodsThe study area surrounds southwestern Iran including provinces of Khuzestan, Ilam, Chaharmahal and Bakhtiari, Kohkiluyeh and Boyer Ahmad, Bushehr and Fars. The present study applies statistical methods and synoptic climatology. Based on the library research, representative days were selected in accordance with the following conditions: 1. Precipitation must have occurred in cold season, since cold season events generally show various patterns due to multiple weather systems affecting precipitation in Iran. 2. A significant percentage of the total annual precipitation must have occurred on the specified day (for example, a precipitation in the 90th percentile in each station). 3. Precipitation must be pervasive (i.e. recorded in more than 70% of the stations in the study area). Three representative days, December 17th 2006, November 25th 2014, and January 17th 1996 were thus selected with the highest precipitation volume over a 30-year statistical period (1989-2018). Two climate databases (precipitation data collected from meteorological stations in the capital city of the previously mentioned provinces and NCEP/NCAR climate data separated based on a 2.5 degree pattern) were used for synoptic analysis of these precipitation events. First, daily precipitation recorded by synoptic stations of southwestern Iran on each of these days was obtained. Then, climatic parameters such as geopotential altitudes of 500 and 850 hPa, jet streams occurring at an altitude of 300 hPa, specific humidity at the 1000 hPa level and values of omega component (measuring upward and downward movement of air flow) at the 500 and 850 hPa levels have been used to explore the relationship between these precipitations and jet streams in troposphere. Finally, GrADS was used to map the previously mentioned parameters. The relationship between precipitation occurrences across different stations of southwestern Iran and troposphere jet streams was exhibited based on an analysis of jet stream maps, moisture flows and other climatic parameters at various atmospheric levels. Results & DiscussionThe relationship found between previously mentioned precipitation events and tropospheric jet streams shows that in each of these events, the jet stream is a westerly wind meandering toward southwest or northeast in the study area and extending throughout North Africa and the Middle East. Central core of the jet stream was traveling above the study area with a speed of 35 to 60 meters per second. The present study indicates that in these three days of heavy precipitation, the jet stream axis has affected the study area in a southwest-northeast direction. Moreover, a cyclone is located at the 850 and 500 hPa levels approximately over eastern Mediterranean whose eastern side extends across southwestern Iran. Southwest-northeast direction of jet stream axis and eastern side of the Mediterranean Sea cyclone being extended toward the study area intensified instability in the lower atmospheric levels of the study area. Negative omega values at the 850 and 500 hPa levels (from -0.15 to -0.8 Pascal-second) indicates severe atmospheric instability in the study area. ConclusionEvery year, southwestern regions of Iran face intensive, and pervasive rainfalls resulting in severe floods and damaging agricultural products, gardens, roads, facilities, industries, etc. The present study indicates that Mediterranean cyclones, westerly winds across the lower atmospheric levels, and the subtropical jet stream meandering in the southwest-northeast (in the meridian direction) direction across the upper atmospheric levels affects the study area. Precipitation in this region is mainly supplied by the moisture coming from warm southern seas (Red Sea, Arabian Sea, Sea of Oman, Persian Gulf, etc).

The phenomenon of climate change and global warming is one of the biggest challenges of the present age, which has affected the hydrological cycle on a global and regional scale. The purpose of this study is to investigate the effects of climate change on torrential rains And Temprature, Rainfall, Run off  in Tehran province. In this study, changes in torrential rainfall in Tehran and the frequency and intensity of torrential rainfall in the future and climate change and the rate of increase of floods on periodic floods have been investigated.

This research has been done in two study discussions (meteorological, hydrological). First, parameters (temperature and precipitation) for synoptic stations (Abali, Shemiran, Mehrabad) for the period (1988-2020) were received from the Meteorological Organization and rainfall and runoff data from hydrometric stations were received from the Tehran Regional Water Authority. Down Scaling model and methods in this research SDSM-DC, Mann-Kendall, Rclimdex, XLSTAT, to simulate future floods and SMADA, HEC-HMS model to simulate floods in current and future periods have been used.

The results showed that the temperature extreme indices in all stations had an increasing trend and the precipitation indices had an increasing trend only in Abali station. But rainfall in Shemiran and Mehrabad stations had a decreasing trend. Examination of rainfall changes using Mann-Kendall test in most months of the year shows a stable trend and jumps are observed in the rainy months, which can be justified by the increase in rainfall frequency. In the CanESM Model 2 simulation, emphasizing the RCP8.5 release scenario, an increasing temperature trend was observed for the coming decades. The highest temperature increase belongs to Mehrabad station with an average temperature increase of 5.1 percent for the period 2021-2083. The highest rainfall for all three stations is estimated in March next year. Therefore, with the increase of temperature trend, changes in the type of precipitation have occurred, which can be affected by urban microclimate. Simulation of the rainfall-runoff model of the basin with the HEC-HMS model showed that the volume of discharge in the future will be reduced by 5 percent and for return periods, the maximum discharge is estimated at 1501.7 cubic meters.

Due to Rainfall behavior is expected to increase in the coming decades, while reducing its fluctuations. It is predicted that the climate of Tehran in the future will have more fluctuations in precipitation and warmer than the current situation, and this increase and frequency of precipitation is likely to increase flood frequency and reinforce its occurrence, while rainfall will occur more accidentally but with greater intensity, leading to environmental and urban hazards.

The main purpose of this study is to investigate changes in atmospheric thickness and its relationship with temperature changes during the cold period of the year. To achieve this goal, data on geopotential elevation and temperature of 1000 hPa for the years 1960 to 2020 have been extracted from the NCEP NCAR site. In the next step, using the programming capabilities of Gardes, numerical extraction of atmospheric thickness between the levels of 1000 to 5000 hPa per meter and temperature data of the level of 1000 hPa in degrees Celsius was performed. Four 15-year periods are divided. The spatial distribution of the 15-year average and the 60-year long-term average, as well as the positive anomalies showed that the thickness of the atmosphere increased significantly during the first to the fourth period, and this increase reached its maximum in the fourth period. The study of the trend in the first period has shown a decrease in the thickness of the atmosphere for the whole of Iran, but with the beginning of 1976 (beginning of the second period) we have witnessed a sharp increase in the thickness of the atmosphere, which continued until the fourth period. The results of Pearson correlation coefficient showed that there is a significant relationship between changes in atmospheric thickness and temperature changes in the cold period of Iran at the 95% confidence level. Spatially, this correlation reaches its highest level in the west, northwest and southwest of the country. As a result, it can be said that the thickness of Iran's atmosphere has increased significantly in recent years, and one of the reasons is the change in the nature of inflows to Iran and, of course, global warming.

Having sustainable human capital leads to the adoption of strategies which make rural families resilient to risks, especially drought. The purpose of this study is to investigate the role of human capital in climate drought management in rural areas of Kermanshah. The present study is an applied research in terms of purpose (type of use), and the method used in this research is a descriptive-analytical method. The statistical population of the study, including all experts related to the subject of research in Kermanshah, is made of 120 people. The sample size was selected for 120 experts based on the total census. Data collection tools include two questionnaires of human capital and drought management. Moreover, the human capital index has sub-indicators that include (expertise, skills and knowledge). The validity of the questionnaire was formal, which was confirmed by university professors, and the total reliability of the questionnaire, based on Cronbach's alpha, was 0.84 and was proven. The collected data were analyzed based on the path analysis of structural equations. The results showed that human capital in general is effective in drought management. Among these, human capital sub-variables, which include knowledge, skills and expertise have also affected drought management, so that knowledge on drought management with an impact factor of 0/26 and a significant value of 0/002, drought management skills with an impact factor of 0/34 and a significance of 0/000, and specialization with an impact factor of 0/49 and a significance of 0/000, have affected drought management. Among these, expertise had the highest impact, while knowledge had the least impact.

Sistan and Baluchestan Province, in southeast of Iran, is covering about 11 percent of the whole space of the country but is one of the driest provinces in Iran and its average annual rainfall is about 110 mm. The purpose of this study was to identify large-scale atmospheric circulation patterns causing extreme and widespread rainfalls during the warm seasons (spring and summer) in southeast of Iran (Sistan and Baluchestan province).Data and Precipitation data of 6 synoptic stations of Sistan and Baluchestan province during a 30-year statistical period (1979-1998) were obtained from Meteorological Organization of Iran (IRIMO). The intensity of precipitation based on 90th percentile threshold and widespread precipitation index of at least ≥50% of the studied area were calculated. To identify the synoptic patterns of the upper atmosphere, the ERA5 data of the ECMWF European Center of Med-Latitude Weather Forecast with spatial resolution of 0.25° × 0.25° were obtained. The collected atmospheric parameters included mean sea level pressure (mslp), geopotential height (z), specific humidity (q), zonal (U) and meridional (V) wind components, relative vorticity (rv) and omega (w) and maps of the upper atmosphere were drawn at different levels using Gards software in the domain of 10 to 70E and 10 to 90N. Regarding the two selected characteristics, three events of heavy and widespread precipitation were determined. By analyzing the daily rainfall data over a period of 30 years (2018-1988) during the warm months of the year, the number of days with torrential and widespread rainfall in Sistan and Baluchestan province were determined. According to the index the previously defined floods and mudslides were obtained for 3 days with torrential and widespread floods that often occur in the spring, which are categorized to three main patterns including: 1- Gono Tropical Storm 2- Omega Blocking and 3 – 500 hpa trough system. The results showed that during the maximum 24-hour precipitation, in the first synoptic pattern, the southern cities of the province received the maximum precipitation due to the proximity of the storm’s core, but gradually from southern to northern latitudes, the rainfall declined considerably so that Chahbahar station had the maximum rainfall and Zabol station recorded zero rainfall. The storm is expected to move eastward as it moves to higher latitudes, but the high pressure formed on the Indian subcontinent acted as a barrier and directed the storm to the west, thus affecting the southern regions of Iran. In the second and third pattern, the location of Sistan and Baluchestan province in front of the trough axis and advection of cold weather of the northern latitudes were the main causes of instability that lead to heavy rainfall. The moisture of these rainfalls was obtained from Oman, Arabian Sea and Indian Ocean respectively. In the second pattern, the anticyclonic clockwise motions of the Arabian Sea has provided the moisture for extreme precipitation events. Common points of all three precipitation patterns are atmospheric moisture reduction in all three levels of the earth, 850 and 700 hectopascals from south to north of the province. This is mainly due to the distance from moisture sources as well as the arrangement and height of the roughness of Sistan and Baluchestan province, which has caused moisture trapping and prevented the transfer of sufficient moisture for the occurrence of torrential rains. In the second model, the amount of moisture reduction from south to north is less, which indicates the activity of the Arabian Sea high pressure and the power of this high pressure in moisture transfer. In general, with increasing altitude towards the northern regions, mainly rainfall systems have lost their moisture and unevenness has prevented the proper distribution of moisture in the province. In southeastern Iran, the spatial distribution of precipitation is strongly influenced by the proximity to the sea and the location of the topographic features. Upper air levels turbulences are the most common cause of air mass rise. The main factor in reducing heavy rainfalls in northern areas of Sistan and Baluchestan is the lack of sufficient water vapor to reach these areas. Extreme rainfall is more likely to occur in spring than in summer due to the appropriate thermal gradient in southeastern Iran. Finally, the results of the study showed that the possibility of precipitation in spring compared to summer due to the appropriate temperature gradient in southeastern Iran and the activity of Siberian and Northern European high pressure, the conditions for fronting in these areas are provided. Since the humidity of the southern oceans through atmospheric rivers has been effective in the occurrence of heavy rainfall in southeastern Iran, rising temperatures in the southern oceans due to global warming can strengthen moisture flows in the future and from this route to affect the intensity of rainfall in southeastern Iran.

Climate geomorphology examines the effects of climate on earth surface processes and forms. Current landforms are shaped by different natural processes. External processes under the influence of climatic conditions of each region cause changes in the primary forms and create certain shapes. Morpho-climatic regions are the areas of the planet in which certain shapes and special patterns are formed under the influence of climate condition.Climate change is one of the main factors in shifting the boundaries of morpho-climatic areas. In recent decades, as a result of the increase in greenhouse gas emissions, it has affected different parts of the natural environment and made drastic changes in climatic conditions. These trends can lead to changes in morpho-climatic zones, including glacial areas, adjacent glaciers, temperate, arid, and semi-arid regions.In this study, the effect of climate change for the year 2100 in Alborz province has been investigated. This province is very important in terms of nature as well as social and economic conditions. Naturally, it has a high morphological diversity. four morpho-climatic regions including the semi-glacier, temperate, semi-arid, and arid areas are developed in the province. These morpho-climatic regions depend on climatic conditions, and climate change can alter these territories. Therefore, it is assumed that the morphological conditions and geomorphic processes prevailing in the study area until 2100 due to climate change will change the boundary of morpho-climatic areas. As the result of the changes, arid and semi-arid morpho-climatic areas would be replaced by semi-glacial and temperate morpho-climatic areas.

In this study, meteorological data of 8 synoptic stations around Alborz province have been selected as study area. They have been used in different scenarios to reconstruct these parameters. Other information and maps have been extracted and prepared from topographic maps, satellite images, and Digital Elevation Model (DEM) of the study area. Morpho-climatic zoning is based on the Peltier method using average annual temperature and precipitation. In order to reconstruct the temperature and rainfall values of these areas and estimate them for the year 2100, we have used CanESM2 model. The information has been reconstructed as a raster layer based on correlation relations with DEM. One of the most widely used micro-scale models based on multiple regressions is the SDSM model for creating conditional data. In this model, regression predictor variables are initially selected as independent variables. Then, after calibrating the model, the model is evaluated to predict future scenarios. The morpho-climatic zones are determined according to the Peltier model using the average temperature and annual precipitation layers with the help of Python scripting based on a spatial application in ArcGIS10.7.1 software. Finally, precipitation and temperature data have been prepared for the period 2070 to 2100, and based on these data, a morpho-climatic zoning map have been prepared for 2100 in the study area.

Using total annual rainfall maps and average annual temperature, we initially developed the current state of the morpho-climatic areas, based on this map in Alborz province. Then, in the next step, the distribution maps of the total annual rainfall and the average annual temperature were prepared based on the climatic data reconstructed in the SDSM model for the year 2100 and based on three scenarios. Finally, we have made a zoning according to Peltier diagram based on spatial conditions in the region. The method helped determine the boundary of arid, semi-arid, temperate, semi-glacial and glacial morpho-climatic regions. In the three scenarios, in 2100, the area semi-arid and arid regions will be increased. The areas semi-glacier and temperate regions will be reduced respectively, in favor of expansion of the arid and semiarid areas. In three optimistic, moderate and pessimistic scenarios, 36, 47 and 49% of the area of the semi-glacier mopho-climatic zone and 2, 25 and 30% of the area of the moderate mopho-climatic zone have been reduced, respectively. In contrast, according to the optimistic, moderate and pessimistic scenarios, 1, 5 and 5% of the area of semi-arid mopho-climatic zone and 2, 5 and 7% of the area of arid mopho-climatic zone increased, respectively.In the current situation, the area of the morpho-climatic zone of the glacier is less than one percent of the total area in the moderate and pessimistic scenarios have significantly decreased. The largest change in the province is related to the temperate morpho-climatic zone, which is mainly accompanied by an increase in arid and semi-arid regions. According to the presented results, it is possible to predict the reduction of the morpho-climatic areas of the glacier and adjacent glaciers in favor of temperate areas for the desired time. In particular, it should be noted that the occurrence of scenario 8.5 is more likely. Therefore, the continuation of the existing conditions can cause remarkable natural damages.

In this study, using a microscale model, it has been determined that the annual temperature and precipitation trends will be more developed towards drought and decrease in rainfall and change in the zones. Based on two moderate and pessimistic scenarios, three morphoclimatic zones of semi-glacier, glacier, and temperate regions are mainly located in the Alborz highlands. The areas will be reduced by 2010 in favor of arid and semi-arid zones. Found. Therefore, in general, it can be stated that in Alborz province, arid and semi-arid areas are increasing and glacial areas and adjacent glaciers and temperate areas are decreasing. This trend could change the shape of the effective morpho-climatic zones in this province until 2100, according to the current trend. The findings of this study show that the climatic conditions of the natural environment of Alborz province in the next hundred years will be accompanied by further expansion of arid and semi-arid regions. These changes will lead to changes in the surface conditions of the earth, including the intensity and weakness of vegetation and erosion. This will be a factor in the need for change in human activities in agriculture and industry.

Economic uncertainty and foreign investment have always been the focus of researchers, policymakers and investors, but what has been overlooked is the measurement of economic uncertainty with a focus on foreign investment. Therefor the purpose of this study is to design an investment conditions uncertainty index by identifying the economic factors affecting FDI inflows in the largest owners of gas reserves including. For this purpose, first the economic variables affecting foreign direct investment are modeled and identified using annual data from 1997 to 2017 of Russia, Iran and Qatar and the Feasible Generalized Least Squares method in the data panel. According to the results, GDP growth, inflation, real interest rate, stock market capitalization and trade openness have significant effect on foreign direct investment. After identifying influential variables, using monthly and seasonal data for the maximum available time period, after estimating the types of GARCH models and determining the optimal model for each variable, the optimal criterion of their fluctuations is calculated. Finally, using the obtained criteria and weighting based on the results of the panel model, Investment conditions uncertainty index for each country is constructed. According to the results, Trend of mentioned index clearly shows the fluctuations due to economic changes in different countries and its compliance with macroeconomic, monetary and fiscal policies adopted by governments, so that, it can be a useful guide for our country's policymakers, It also provides an appropriate scale for assessing the uncertainty of countries by policymakers, investors and researchers at macro and micro level.

Cyclonic systems are generally unstable conditions messenger that result from the spread of significant disturbances that occur in atmospheric currents. In this study, daily rainfall data of 4 catchments and gridded data (ECMWF) with 6-hour time steps and spatial separation of 0.25 * 0.25 from 1979 to 2004 were used. using with the cluster analysis method 3 atmospheric patterns were extracted. where the center of the trough in 500 and 700 hPa Stacking on top of each other, the geopotential height is the minimum and the geopotential gradient will be the maximum and will lead to the occurrence of the most cyclogenesis, Which occurred in the first pattern these conditions and resulted in average heavy rainfall of 38.6 mm. In the second pattern, none of the conditions of stacking on top of each other and deeping of the trough, and this has led to the lowest average heavy rainfall of 32.7 mm. In the third pattern, the condition of matching of the two centers of the troughs is established, but they do not condition of deeping trough And have led to heavy rainfall of 36/1 mm which is less than the first pattern. Also, the most cyclogeneses location in the eastern Mediterranean to Iraq, heavy rains caused by cyclones are born in this region. The results also showed that most of the moisture comes from the Red Sea. the subtropical jet stream plays a role in strengthening and ascending, in the north of Saudi Arabia and the Persian Gulf.

Due to the time consuming and uneconomical use of dynamic models, the use of downscaling climatic exponential methods has increased. In this study, the results of HadGEM2-ES, MIROC and NoerESM1-M climatic models that were calibrated by CCT toolbox after simulating daily climatic parameters of daily precipitation, maximum and minimum temperature in the Karganrood basin in Gilan province, Iran. The meteorological data of Bandar Anzali synoptic station during 1975-2018 was used as the observation period. Daily parameters of precipitation, maximum and minimum temperature of Karganrood watershed were simulated under RCP4.5 and RCP8.5 scenarios in the next three periods of 2050-2025, 2051-2075 and 2100-2076, respectively, and compared with the observation period. NS, R2 and RMSE evaluation indices were used to evaluate the climate models HadGEM2-ES, MIROC and NoerESM1-M. The results of this study showed that the comparison of changes in future temperature data of the region using climatic models used with the observation period according to Mann-Kendall test is not random and under the influence of factors, in addition to correlation, a significant trend showed that the highest levels of significance were related to maximum temperature (Z = 4.04) and minimum temperature (Z = 4.6) at 95% confidence level in NoerESM1-M climate model and in the next period of 2051- 2075, respectively is under RCP8.5 scenario and its rate is increasing.

Global warming and climate change are very important issues of the last century, which have been considered by scientists in various fields of science. The Hyrcanian forest is one of the oldest and most historic habitats of the world's deciduous trees. Beech trees are one of the valuable industrial species with a lifespan of 200 to 300 years. The science of tree chronology can show past weather events. The diameter of the annual growth rings of the trees forms a time series. With this method, a time series of 202 (1816-2017) years was obtained from the diameter of the growth rings of beech trees.Researchers are always thinking about the future. This study uses time series of growth rings of forest beech trees and analyzes it.And the use of modeling based on the Box-Jenkins method with emphasis on ARIMA models were examined. The results showed, Time series with ARIMA model (1,1,1) had the best fit, at the 95% level, it is significant and the trend forecast has a negative and decreasing slope. Climatic factor of annual precipitation in the regional station and neighboring stations with a decreasing and negative trend The average minimum, middle and maximum average temperatures are increasing. Climate change is reducing growth for Hyrcanian forest trees. It was registered as the second natural heritage of Iran in UNESCO. It will pose a threat to plant and animal communities.

Heavy rains are among the natural hazards that knowledge of their temporal and spatial distribution helps to reduce potential damage. For this purpose, the existence of a significant relationship between widespread precipitation and topographic indices of Alborz mountainous region has been investigated. In this study, Pearson correlation test was used and in this model, the dependent variable of total daily precipitation of the study area (precipitation occurred in more than 70% of synoptic stations in the area) and the independent variable of data related to topographic indicators of the study area (station height Synoptic, station slope and direction, longitude and latitude of the station, distance from the northern baseline, distance from the ridge, average height of the station in a radius of 2.5 km, average height of eight blocks fifty km in eight geographical directions to the center of the synoptic station, height difference Its average is eight blocks from the average height of the station in a radius of 2.5 km). First, the correlation between precipitation (129 days) and topographic indices based on common synoptic stations in three seasons of winter, spring and autumn was identified and then the correlation coefficients with 95% confidence interval at a significance level less than 0.05 were investigated. Each season, a sample day with the highest correlation coefficients in the majority of topographic indices was selected as the representative of that season. The study area, which is the vast Alborz mountain range, has been divided into areas with topographic and climatic similarities due to the complexity of topography and the diversity of its climatic conditions in each area. The highest number of significant statistics in terms of temporal and spatial scale between widespread precipitation with topographic indices is related to widespread precipitation in spring with 18 cases and the lowest is related to widespread precipitation in winter with 9 cases in autumn 14 cases of significant linear relationship have been identified. Among the topographic indices, the strongest index is related to the difference between the average height of blocks 50 km from the average height of the station in a radius of 2.5 km in different directions according to different seasons of the year and Evidence of the effect of direction on inclusive rainfall in the study area and that the area is in a certain direction to receive more rain , meaning that the mass of humid air entering from the northern parts of the country, including Siberian high pressure (Babaei Fini, 1393) due to low altitude and proximity to the ground is affected The surface roughness is located and the mass of moist air entering from the northwestern and western parts of the country, including the western migratory high pressures (Qashqaei, 1375), (Moradi, 1385)) due to higher altitude and more power is less affected by surface roughness. And the region's precipitation is affected by these high-level atmospheric systems. On the other hand, widespread precipitation in the northwestern and south-central Alborz region has the highest and the lowest south-western Alborz region has a significant linear relationship with the values of topographic indices. The results of this study have a significant linear relationship with most topographic indices (22 indices out of 24 Index) with widespread precipitation to be able to estimate and predict the most effective indices affecting precipitation in the region. The two topographic indices for the station and the distance from the ridge did not enter the correlation model on any day and in any area of the study area and did not establish any significant linear relationship, albeit weakly, with the total precipitation of the area.

Climate change refers to changes in the direction of the mean of climatic parameters over a long period of time. Changes in the limit values and averages of climatic parameters are important consequences of climate change. This is scientifically different from climate fluctuations. Climate fluctuations are periodic and the deviations of the climatic parameters indicate the average and can occur in different time periods, but climate change is a general and widespread fluctuation in the climate of a region; currently, global warming is seen as part of climate change. Attention to climate change in recent years has become increasingly important due to the economic, social, and financial consequences of weather events. According to the Intergovernmental Panel on Climate Change, human intervention in global climate change is undeniable, although some researchers still believe that some climate change is unknown and that the mere human impact of climate change should not be confirmed. But the challenge of climate change in recent decades is very different from climate change in recent decades, one is that human intervention in nature has increased and the other is the rapid pace of climate change that has made it difficult to adapt.Given that none of the research on climate change has comprehensively addressed this issue in Iran, it was necessary to conduct a comprehensive study of the available resources, including the effect of climate change on hazards, hydrology, agriculture, urban and so on. Its effect is on the social and economic consequences that have taken place in Iran so far.This study was conducted using the library method and searching in authoritative scientific and research sources in relation to research on climate change in Iran and no data has been processed in it, so that the temporal and spatial changes of climate change over several The year has been studied and analyzed in Iran. It has also divided it into sub-sectors of agricultural climate, hydrology, urban, social and economic climate, and hazards based on studies conducted in various fields of climate change. First, keywords such as climate change and global warming were searched in reputable scientific databases such as Google Scholar, Science Direct, Magiran, SID, and the University of Tehran Library. In the next step, resources were categorized into separate study sections and different definitions of climate change. A variety of methods used to study climate change and the area under study were discussed, and finally the various conclusions were summarized and analyzed.Today, the phenomenon of climate change has attracted the attention of all researchers. Iran, as a region in the dry desert belt, has been strongly affected by the effects of climate change and therefore many studies have been conducted in various fields of climate change in Iran. The sequence is divided.The rise in border incidents in recent years has become a major concern for climatologists in recent years. The first effect of climate change is on atmospheric elements, especially temperature and precipitation. Therefore, it is important to investigate the changes in these variables in order to moderate the damage or adapt to the phenomenon of climate change.The World Water Organization emphasizes the need to research water resources, upsetting the balance of the climate system caused by rising greenhouse gases, and emphasizes the importance of studying the impact of climate change on hydrological parameters such as evaporation and transpiration. The country seems essential.One of the most important issues in the agricultural sector in recent decades, which has limited the production of crops, is climate change. This phenomenon changes the water resources of each region over time. It is essential to know the temporal and spatial fluctuations of meteorological parameters (such as temperature, precipitation, relative humidity, etc.) and its effect on the agricultural sector to manage water and agricultural resources and adopt appropriate strategies.Urbanization and urban development, along with population growth and the development of industrial activities and the wasteful consumption of fossil fuels, have greatly increased air pollution, with short-term and long-term disease exacerbating some climate fluctuations and environmental impacts, including changing time periods. Suitable in terms of comfort climate.In recent decades, the process of industrialization has accelerated dramatically. Population growth and the growing need for food have made the development of industries and factories inevitable, and this has made the phenomenon of climate change from a luxury issue a very serious one, at the forefront of negotiations between the leaders of large and small countries Is located.According to research conducted in Iran since the beginning of the global warming phenomenon, in general, the temperature is increasing and rainfall is decreasing despite high time and space variability. The temporal and spatial intervals of climate patterns have changed or their occurrence has been more or less than average. But extreme phenomena, such as drought, are more affected by climate change than others. This has weakened the Siberian low-pressure low and intensified the high-pressure side of the tropics. Although some studies have shown that rainfall increases in some areas, rising temperatures will increase evaporation and transpiration, and we will continue to face shortages of water resources in the future. As surface water levels drop and groundwater levels drop, dams will gradually lose their function, and the status of aquifers will shift from a critical state to a supercritical state, followed by the number and severity of events. Floods and droughts will increase. Increased evapotranspiration has increased the water needs of agricultural products. Although the length of the growing season has increased and the time of cultivation has changed, the effects of global warming and global warming have reduced crop yields. It has become a product, and food security, human health, and macroeconomics have been severely affected by water scarcity. In cities, too, climate change has increased air pollution, created a thermal island, and ultimately wiped out climate comfort. Climate change has also led to security and political disputes, mostly over water disputes. Regardless of the effects of climate on various projects, designers and experts are less successful in planning. A direct way to slow down global warming and climate change is to significantly reduce the use of fossil fuels and try to adapt to the effects of climate change, including increasing the intensity and frequency of droughts. Also, having knowledge and information plays an important role in the occurrence of protective and preventive behaviors against climate change. Finally, the results of evaluating climate change adaptation strategies based on social, economic and environmental indicators of water security show that in order to reduce system vulnerability in the coming period, while increasing economic water productivity in agriculture by increasing irrigation efficiency, agricultural activity will be reduced and compensated. Increase economic and social damage, service and industry activity.

Impacts of Global Warming on Humidity Amounts of Precipitation SystemsAbstract:To conduct this research, in first step the precipitation data of four synoptic stations (Kermanshah, Khorram Abad , Sanandaj and Hamedan) in the western Iran during the period 1979-1979 in cold months of January, February, March, October, November and December were obtained from the Meteorological Organization of Republic of Islamic Iran (IRIMO) and based on the ninety-fifth percentile threshold,, the heaviest 24-hour rainfall of each station in each month was identified. Further for the days when heavy rains occurred, the specific humidity cell data and the daily temperature for four times (18-12-06-00) from the reanalysis ERA5 data over a period of 30 years ( 1979-1979) European Center of Mid-Latitude Weather Forecast (ECMWF) with spatial resolution of 0.25 * ° 0.25 ° arc were received . Non-parametric Mann-Kendall and age Sen’s Slope Estimator Nonparametric tests were used to analyze the trend and Pearson correlation coefficient and linear parametric regression methods were used to analyze the relationships. The results show that the specific humidity trend of rainfall systems in western Iran (except March at 700 hPa) in January, February, March, October, November and December at both 850 and 700 hPa levels was positive and incremental, although it was not significant at the 95% confidence level. There is a positive linear relationship between the temperature trend of precipitation systems and their specific humidity (except October at 850 hPa) from January to March and November to December at 850 and 700 hPa, which Can affect the intensity of rainfalls, type and speed of horizontal movement of precipitation systems in the future.Abstract:To conduct this research, in first step the precipitation data of four synoptic stations (Kermanshah, Khorram Abad , Sanandaj and Hamedan) in the western Iran during the period 1979-1979 in cold months of January, February, March, October, November and December were obtained from the Meteorological Organization of Republic of Islamic Iran (IRIMO) and based on the ninety-fifth percentile threshold,, the heaviest 24-hour rainfall of each station in each month was identified. Further for the days when heavy rains occurred, the specific humidity cell data and the daily temperature for four times (18-12-06-00) from the reanalysis ERA5 data over a period of 30 years ( 1979-1979) European Center of Mid-Latitude Weather Forecast (ECMWF) with spatial resolution of 0.25 * ° 0.25 ° arc were received . Non-parametric Mann-Kendall and age Sen’s Slope Estimator Nonparametric tests were used to analyze the trend and Pearson correlation coefficient and linear parametric regression methods were used to analyze the relationships. The results show that the specific humidity trend of rainfall systems in western Iran (except March at 700 hPa) in January, February, March, October, November and December at both 850 and 700 hPa levels was positive and incremental, although it was not significant at the 95% confidence level. There is a positive linear relationship between the temperature trend of precipitation systems and their specific humidity (except October at 850 hPa) from January to March and November to December at 850 and 700 hPa, which Can affect the intensity of rainfalls, type and speed of horizontal movement of precipitation systems in the future.

Urbanization represents the most dramatic human alteration of the land surface, typically resulting in the formation of urban heat islands . Land surface temperature (LST) is a key parameter for surface energy balance and urban climatology studies. Understanding the spatial distribution of temperature is the basis for proper planning and environmental policy making. In this study, using Landsat 7 satellite imagery in two time periods of base year (2017-2010) and second interval (2000-2005) were used on average in three warm months of the year Then these images were first geometrically corrected; then these images were used to calculate temperature-related parameters using a single-window method in Gorgan. It was then used to improve the accuracy of the work using the hourly temperature data of the thermal islands analyzed. The results show that temporal and spatial variations of thermal islands in Gorgan have a high cluster pattern. However, the local Moran index and hot spots in the north, northwest and east and downtown have a positive spatial correlation (hot spots). However, there are cold spots in the southern areas of the city. However, many parts of the city of Gorgan have no significant patterns or spatial autocorrelation during the study period. It can be said that the thermal islands of Gorgan depend on two factors: one is the prevailing climatic conditions in the period under study and the second is the prevailing humanitarian conditions in the city. climatic conditions in the period under study and the second is the prevailing humanitarian conditions in the city.

The present study aims to investigate the changes in atmospheric conditions causing a hazardous climatic phenomenon known as hailstorm. These changes are classified and related to thermal and dynamic changes. In order to study the dynamics and synoptic of hail phenomenon in Mashhad, daily hail rainfall data were used during the 1980-2010 period. Then, one heavy rainfall specimen was identified and selected during the statistical period. The results of the hail analysis indicate that the highest frequency of hail occurrences were from 9 to 13 (UTC) in Mashhad city. Moreover, the highest frequency was from March to May months. In atmospheric predictions, there are different indicators for assessing the instability of atmosphere which lead to hail occurrence. The parameters and indicators under investigation in this study for 28 July 2009 include SHOW, TT, K, BI, RI, JEFF, Boyden, DCI, KO and SOI. According to the results of this research, when hail occurred in Mashhad, instability indices increased meaningfully, In addition, all instability indicators showed severe instable conditions (thunderstorm) during hailstone occurrence. Analyzing the weather charts indicated the changes of climatic parameters on the days of hailstorm and the days before them. Charts showed that the temperature and air pressure decreased while the relative humidity and dew point temperature increased on the days of hail in comparison with the earlier day.

The aim of this study is to identify the spatial distribution of Vertically Integrated Moisture Flux Convergence (Vertically Integrated) Moisture Flux Convergence) on Iran’s atmosphere. To achieve this aim, the monthly ECMWF gridded data used during the period from 1/1979-12/2013. First, based on the specific humidity content in the atmosphere, troposphere divided into three layers (850-1000hPa), mid (700-775hPa) and upper (500-600hPa). In order to achieve VIMFC spatial variations on Iran, spatial self-correlation methods   of globular moron and hot spots used at 90, 95, 99 and 99/99 percent significance levels. The results of this study showed that the spatial distribution of VIMFC in Iran during the first layer of troposphere and especially during warm months of year has a high cluster pattern and in cold months of the year and in the third layer of troposphere cluster pattern decrease. Based on the hot spots index in the first layer of troposphere low height regions, in the second layer of troposphere the  high regions of the Alborz, zagros and central mountains and in the third layer of troposphere alpine regions of central and eastern Iranchr('39')s mountains has positive spatial self-correlation (hot spots). The results show that in winter and autumn during the second period (1999-2013), the range of hot spots of the VIMFC show a significant reduction compared to the first period (1979-1998) on Iran.