mahdi frotan

In order to monitor dust storms in Khuzestan province, statistical data were first obtained from the General Meteorological Department, and the days with dust reports with minimum horizontal visibility of less than 10 km were selected as free days. The results of zoning and the average dust concentration map by calling MODIS satellite data in Google Earth Engine revealed that the density of this phenomenon was in the western, southwestern and central regions of the province. For the synoptic investigation of this phenomenon, the most intense dust storms were selected for 9 synoptic stations and these days were analyzed by drawing synoptic maps; And the movement path and origin of this phenomenon and its density were displayed through the HYSPLIT model. The results indicated that in the majority of dust storms in the south of Iran, thermal low-pressure systems were active, and in Europe, high-pressure systems prevailed, and the slope of the pressure gradient between these two systems led to the direction of westerly currents with high wind speed at high altitudes towards the study area. And the prevailing rotating situation in the region has added to the instability of the air. The western winds have also passed through the deserts of North Africa, the north of the Arabian Peninsula, Iraq and Syria, parallel to the Nave canal in the west of Iran, and have led the hot and dry air of these regions to the atmosphere of the region.

Flood as a natural disaster with the highest relative frequency of occurrence has always threatened human life. The purpose of this study was discovering the relationship between atmospheric circulation patterns and floods in the Balikhlochai watershed of Ardabil in order to prevent its dangers with an environmental approach to circulation. For this purpose, discharge data for three stations of Almas, Nir, and Gilandeh from the period 2009-2017 were obtained from the regional water department of Ardabil province. Using the ward hierarchical clustering method, two floods occurred on March 7, 2010 and December 8, 2010 were selected and analyzed. The data related to the upper levels of the atmosphere were obtained from the National Center for Environmental Prediction (NCEP-NCAR) website and combined maps of sea level pressure with geopotential height of 500 hectopascals, wind vector with precipitable water, omega with tawai and half-molar specific humidity in Gardes software were drawn. The results of the synoptic analysis showed that the dominance of the Mediterranean thermal low pressure system and the Chinese thermal high pressure system were important factors in the atmospheric disturbance, and besides that, the location of the studied area in front of the landing axis of the Eastern Mediterranean fleet resulted in rotating air movements. And the vertical air velocity of the studied area showed an unstable atmosphere. The specific humidity has also increased since the day before the flood in the lower layers of the atmosphere, and the flow of moisture from the Mediterranean Sea through the western subtropical winds on the atmosphere of the studied area has played an important role in causing torrential rains.

In order to carry out this research, the daily and three-hourly data of precipitation parameters and wind speed and direction were used for a period of 13 years (2009-2021) for 11 Ardabil synoptic stations. Percentile 95% free days were obtained for each station. For statistical analysis and consensus, the condition of choosing a representative day for each station was the simultaneous occurrence of rain and wind as a criterion, and for the sake of brevity, an event was analyzed at Meshkinshahr station. Using TRMM satellite NETCDF data, precipitation density was displayed in GIS software, and wind direction was shown using Golbad software, and synoptic maps were drawn using NCEP data. The statistical results for Meshkinshahr station showed the maximum wind frequency with 56% in the winter season. And the month of March occurred, which often entered the city from the south, but most of the rain was in spring with (41%) and May was the rainiest month. The results of synoptic analysis showed that the prevailing system over the studied area was low pressure over the Aral Lake and the rotating conditions of the air ascent followed. In the east of the Mediterranean Sea and the north of the Black Sea, high-pressure systems have formed, and with their outward movement, they have led the western currents towards the region. Also, the studied area is located in front of the descent axis in the west of Iran, and the positive rotation of the air has led to the strengthening of the divergence in the vorticosphere. The speed of the horizontal movement of the air has reached the speed of the wind and by containing the moisture of the Mediterranean Sea, it has injected 1.2 grams per kilogram of moisture into the atmosphere of the region.

To check the consensus, the average temperature data was obtained from the Meteorological Department of Ardabil Province and the days with temperature below -10°C during the statistical period (1355-1400) were selected as cold days, then the trend of the time series of the frequency of freezing days with the least square error method in the model Linear regression was determined and its results showed a decreasing trend from 2010 onwards. Finally, for the simultaneous analysis of atmospheric factors, 25 January 2016 was selected as a representative through the ward hierarchical clustering method. Next, the data of the upper levels of the atmosphere were received from the website (NCEP/NCAR) and synoptic maps were drawn in Gardes. The results of the analysis of these maps showed that the Siberian thermal high pressure system played an effective role in transferring cold air from northern latitudes to the studied area. In addition to this phenomenon, the location of the study area in front of the European Ridge has resulted in negative air circulation conditions, which resulted in the strengthening of downward currents and a decrease in air temperature. Hyfran-plus statistical model was used to estimate the return periods of cold waves, and the result showed that the stationarity test (Wald-Wolfowitz) and the normal statistical distribution were more accurate in determining the return periods of cold waves. And the results of the Chi-Squared test also showed that it is possible to ensure the extraction of the results at a significant level of 5%. Finally, in order to predict changes in the temperature parameter, using the CanESM2 general circulation model, under three scenarios RCP2.6, RCP4.5, and RCP8.5, the future perspective of the period (2020-2050) was examined. Its results showed that the model had the necessary ability to simulate the average temperature.

The type and intensity of soil erosion in a region depends on climatic conditions, lowland and elevation of the land, soil and land use, among which the importance of land use is greater than other factors due to the effective role of humans on it. The purpose of this research is to evaluate and analyze the amount of soil erosion in the Balikhlochai watershed using the RUSLE experimental model in Ardabil province. In order to carry out this research, first, the satellite image of the studied area from the year 1400 and the month of June was obtained from the US Geological Survey Center, and after atmospheric and radiometric corrections, a land use map was prepared using the supervised classification method using support vector machine. Then the RUSLE model was used to estimate the erosion rate. SPSS 21, Excel, ArcGIS 5.4, Archydro and ENVI 5.3 software were used to analyze and produce maps in this research. RUSLE model parameter layer including rain erosion layer, soil layer, topography layer, vegetation layer and soil protection factor as well as various statistics related to rain gauge stations, hydrometry, topographic maps 1:50000, geology 1:100000 as well as DEM (20 meters area) and GIS geographic information system and remote sensing have been used. The results of this study showed that the average amount of annual soil erosion for the whole basin ranges from -6.65 to 14.75 tons per hectare per year. Also, the investigation of regression relationships between the factors of RUSLE model and the amount of annual soil erosion showed that the topography factor (LS) with the highest coefficient of determination R^2=0.95 is the most important in the estimation of annual soil erosion using the RUSLE model.

Frost is one of the natural events whose early and late occurrence can affect different aspects of human life. Therefore, this research has been carried out with the aim of predicting the atmospheric factors of this phenomenon with an environmental approach. For this purpose, the environmental data related to the daily minimum temperature of 2001-2017 for 9 synoptic stations located in Ardabil, Urmia and Tabriz provinces were obtained from the Meteorological Organization of the whole country and the days with temperature below 0 degrees Celsius that cover 40% of the studied area in were selected and using the ward hierarchical clustering method that was applied on the average sea level pressure maps related to ice days, the classification of the free days was done. In order to determine the representative of each class using scripting in the MATLAB environment, Lund's correlation was calculated between the maps of different days of each class of 2 to 5 groups with a coefficient of 0.5; And the days that had a correlation coefficient of 0.5 and the most similarity with the majority of days of that class were introduced as the representative of the group. After determining the representative day, atmospheric data was prepared from the Nova site and maps of sea level pressure, geopotential height, wind vector, temperature of 500 hPa and atmospheric thickness were drawn in Gurdes software. The results of the 4 patterns for ice days showed that the most effective systems on the northwest of Iran were high pressure systems in Siberia, low pressure systems near the Arctic and high pressure systems in Northern Europe, and the studied areas were located in the front of Faraz and the negative circulation of air brought stable conditions. In most of these patterns, the western winds that have moved in the polar ice channel have brought cold air from the northern latitudes into the atmosphere of the study areas and caused low air temperatures.

Climatic zoning and knowledge of effective climatic factors and elements can be very effective in determining climatic potentials. The purpose of this research is to pay attention to this principle in order to know the environmental capabilities and limitations and to deal with natural disasters. In this regard, the climatic zoning of Ardabil province was discussed using modern methods. First, for 11 synoptic stations of this province, 22 important meteorological parameters for the 12-year statistical period (2009-2021) were received from the General Meteorological Department. In the next step, the annual average of these variables was obtained for each station, and since their measurement scale was different, they were standardized in the Spss software environment. Then, in the same software, factor analysis was performed on these data and the output results were 5 main factors, which are: the first thermal factor with 31.89% variance, the second pressure-steam factor with 21.08% variance, the third moisture factor with 18.61 variance, the fourth precipitation factor with 14.05 percent variance and the fifth wind-radiation factor with 7.48 percent variance, which in total explained 93.12 percent of the climatic behavior of the region. In the next step, according to the output of the 5 factors, three similar climatic regions were distinguished from each other using Ward's hierarchical cluster analysis method. Also, to show the scope of activity of each of these factors, climate zoning was done in Gis software environment and using Idw interpolation method. According to the final map obtained, most of these factors were concentrated in the cities of Parsabad, Beilesawar, Nemin, Serain and Givi. According to Dumarten's climate classification, it was also recognized that the climate of Ardabil province is part of the semi-arid climate.

Coordination between the temporal changes of two distant points, which is mainly used for pressure changes, is called remote connection. The purpose of this study is to investigate the variability of temperature and precipitation parameters of Ardabil, Meshginshahr, Sarab and Harris stations from two remote connection models of North Atlantic Oscillation Index and Pacific Decades Index using Pearson torque correlation method and synoptic analysis. For this purpose, data related to the two mentioned indicators were prepared from the Nova site for the period 2009-2018. Also, for this statistical period, data related to temperature and precipitation parameters were obtained from Ardabil Meteorological Department. Then, after standardization of temperature and precipitation, using Pearson correlation method for NAO index, it was found that the temperature of all stations in June, October and February precipitation of Ardabil station had the highest significant direct correlation with 99 and 95% confidence level with this index. The AMO index also showed a direct relationship with the January temperature of Harris station with only 5% probability of error. In order to investigate the effect of these patterns on the studied parameters of NETCDF data, monthly mean sea level pressure, geopotential level of 500 hPa, temperature and rainfall water were obtained from Nova site and synoptic maps were drawn in Gardes software environment. The results showed that when NAO index is in negative phase and AMO index is in hot phase, the dominant system in the studied areas is low thermal pressure and rotational conditions prevail and temperature and rainfall increase and wetting occurs, unlike when NAO index is in phase. The AMO index is positive in the cold phase, with the dominance of high-pressure systems and rotation conditions in the study areas, the temperature and rainfall have decreased and the drought conditions have been determined.

Heavy rain resulting from atmospheric patterns, depending on the extent of activity and the time period of its occurrence, has adverse events and consequences such as floods. The present study was conducted in order to synoptic analysis of 171.5 mm heavy rainfall (March 19, 2017) leading to flood in Minoodasht city. The view of this study is a circular to environmental and first, the amount of rainfall at Minoodasht station was determined and by receiving upper atmosphere data from the website of the National Center for Environmental Prediction (NCEP / NCAR) and analyzing them, the causes of heavy rainfall was revealed. In order to study the synoptic conditions, using the Gardes software, sea level pressure maps were drawn, and in the upper atmosphere, geopotential height, wind vector, vorticity, omega, thickness, eddy and humidity (500 hPa level) were studied. The results of map analysis showed that during heavy rains, high pressure systems were formed in Mongolia and southern China and were caused a pressure gradient & strong front with prevailing low pressure system in Minoodasht. In the upper atmosphere, the presence of cut-off low-pressure blocking has been placed as a barrier to the west winds and has caused the flow of west winds to the study area. In addition, the high thickness of the atmosphere in the study area and the dominance of the amount of negative eddy, led to air instability and the presence of positive virtuosity cores and negative omega, indicates an unstable atmosphere on the days in the study area. Also, the inflow of moisture from moisture sources such as the Caspian Sea, the Aral Sea, the Black Sea and the Mediterranean Sea has provided special conditions for severe rainfall.