یوسف قویدل

Climate change is likely to intensify hydrological cycles and affect the intensity and frequency of extreme rainfall.An increase in extreme rainfall in recent years has led to the assumption that climate change has made extreme rainfall non-stationary. Nonstationarity is defined as a change in the parameters of the probability distribution function due to the influence of time variables or other physical variables .The purpose of this study was to investigate the effect of temperature on the non-stationarity of extreme rainfall in Iran.The AIC value was calculated to determine whether the extreme rainfall follows the stationary or non-stationary model. The non-stationary GEV distribution was used to analyze the frequency of extreme rainfall. The return period of extreme rainfall was calculated based on the maximum temperature and the average annual temperature. It was observed that the intensity and frequency of extreme rainfall were non-stationarity due to an increase in the temperature and no spatially uniform pattern was observed in non-stationarity across the country. Related to the maximum temperature variable, the intensity of extreme rainfall was significantly decreased in 6 stations, including Hamedan, Shiraz, Shahr-e Kord, Zahedan, Iranshahr, and Shahroud. On the other hand, the trend of nonstationarity in Kerman has been significantly increasing with increasing maximum temperatures. Only two stations, Zahedan and Arak, were found to be significantly non-stationary concerning the annual mean temperature, and both stations showed a decreasing trend.

This paper intends to identify and statistically analyze monthly changes in the lethal temperature above 50 degrees Celsius (TU50c) in the Northern Hemisphere. For this purpose, the reanalyzed data related to the maximum temperature up to two meters of the earth's surface was used during the period of 73 years from 1948 to 2020, and after adjustment, analyzed on a monthly basis. Descriptive statistics analysis methods, linear trend analysis and non-parametric Mann-Kendall test are used for evaluating the frequency of such occurrences. During the 73-year study period, 9553 days with minimum temperature of 50 degrees Celsius were identified and their coordinates were extracted. Examining the daily frequency of TU50c in the Northern Hemisphere showed that the months of May and January have had the highest frequency, respectively. Also, the highest increasing trend in the number of fatal temperatures was observed in the months of March, April, July and August. In terms of location, the region that could record the highest frequency and the most intense TU50c was related to Africa especially Sudan, West Asia (between Iraq, Southwest of Iran, Kuwait and Saudi Arabia) and India in the Indian subcontinent. Moreover, these temperatures are not rare in America either; but TU50c has not been reported in Europe and East Asia. The highest and most intense temperatures occurred in the fifth decade, between 1988 and 1998.

Drought is one of the most catastrophic environmental hazards in West Asia, and severe droughts throughout history have destroyed many ancient civilizations. The persistence and severity of damaging droughts has made drought an important research topic in the West Asian region, which is very important due to the arid climate, the importance of rainfall and water. In this study, using SPEI method and accurate networked data, critical areas caused by extensive and severe droughts of 1 to 12 months in West Asia in the long-term 118 years of 1901 2018 have been studied. The results of spatial analysis of accumulation index or ASPEI showed that in different time periods, the most affected areas of severe drought or the critical drought centers of the West Asian region are located in Yemen, southern Iran and western Saudi Arabia. The southern and western regions of Turkey, northwestern Turkmenistan, western Pakistan and Afghanistan, western Oman and Azerbaijan were also less important areas of severe and widespread droughts in West Asia. The lowest incidence of severe drought was observed in Armenia. The trend of temporal changes in the critical points extracted from the intensity and extent of droughts of 1 to 12 months indicates a significant downward trend in the critical centers of droughts in West Asia, and therefore severe and widespread droughts of 1 to 12 months will continue in the future and possibly Their intensity will increase. In other words, in the future we will see wider and more severe droughts in the West Asian region, especially in Yemen, Iran, Saudi Arabia and Iraq.

Today, climate change has become a major challenge for human societies. The widespread concern of environmental scientists and researchers about global warming has prompted them to study the time series of climatic parameters, especially temperature to reveal the trends of these parameters over the past few decades. Due to the importance of this issue, the present study was conducted to investigate the trend of spatial changes in the minimum temperature of Iran. In this regard, V20CR networked minimum temperature data with daily time resolution and 1 in 1 degree spatial resolution during the period 2019-1836 have been used. First, the trend of minimum temperature changes was calculated using Mann-Kendall test. Then, using spatial statistical methods such as global and local Moran index and hot spot analysis, the patterns governing Iran's minimum temperature and their dispersion were identified. The results of this study showed that in the cold months of the year the zone is trendless, while the decreasing trend is dominant in Iran in the warm months of the zone. An increasing trend has been observed in the southern regions and to some extent in the southeast of Iran. A declining trend occurred in northwestern Iran in January and is gradually spreading throughout Iran in other months. In May, it reaches its maximum expansion in Iran. According to the World Moran Index, the minimum temperature in Iran has a pleasant pattern. The local Moran index also showed that the northwest of Iran follows the pattern of low cluster and the southern regions of Iran follow the pattern of high cluster. The findings from hot spots indicate that the northwestern regions have cold-temperature spots (negative spatial autocorrelation) and the southern regions have hot-temperature spots (positive spatial autocorrelation).

 Greenhouse warming poses the main cause of atmospheric hazards’ exacerbation and emergence in recent years. Earth planet has been witnessing frequent and severe natural hazards from the distant past; however, global warming has strongly influenced the occurrence of some atmospheric hazards, especially the ones induced by temperature and has increased the frequency and severity of those risks. Such extreme risks arising from temperature element and being affected by global warming could be referred to hot days and their frequency more than one day which undergo heat waves. Of the studies conducted worldwide in conjunction with the phenomenon of heat waves, the following can be pointed out; Schär (2015) has focused his studies on the Persian Gulf and the worst heat waves expected in this area. The recent work revealed an upper limit of stability which enables the adaptability of human body with heat stress and humidity. If people are exposed to a combination of temperature and humidity over long periods higher than this level, they will lead to hyperthermia and death, because heat dissipation from the body is physically impossible. Paul and al-Tahrir (2015) using a high-resolution regional climate model demonstrated that such a situation can occur much earlier. In Iran, in relation to heat waves, Ghavidel (2013) analyzed climatic risk of Khuzestan province in 2000 regarding super heat waves using the clustering approach. The obtained results unveiled the establishment of a low pressure at ground level and high pressure dominance at mid-altitudes up to 500 hp as well as the increase in atmosphere thickness having led to the ground overheating. Added to that, the source of heat entering into Khuzestan is advective and hot and dry air transport through Arabian Peninsula, Iraq and Africa. Ghavidel and Rezai (2014) addressed in a study to determine the temperature-related threshold and analyze the synoptic patterns of super heat temperatures in southeast region of Iran; the results of study approved that the only pattern effective on the occurrence of super heat days in Iran’s southeast is the establishment of the Grange’s heat low-pressure at ground level and subtropical Azores high elevation dominance at 500 hPa level. In this study, absolute statistical indicators, also recognized as above-threshold values approach, were used in order to identify, classify and heat waves synoptic analysis in the warm period of the year in the southern half of Iran. To use above-mentioned indicators, firstly daily maximum temperature statistics of studied stations with the highest periods were averaged every day once in June to September and once for the months of July and September. Using statistical indicators of long-term mean and standard deviation or base period, indicators would be defined for the classification of heat waves and days with peak extreme temperatures. In such classifications, usually long-term average or base period is multiplied by 1 to 3 to 4 times standard deviation and each time is account for the factor of each class. To select the days for synoptic analysis, averaging was performed of all classified waves into four heat wave categories of low, intermediate, strong and super heat; accordingly based on the maximum blocks in each class of heat waves, days that had the highest temperature values were selected as the class representative for mapping and synoptic analysis. This study dealt with investigating heat waves synoptic during the year’s warm period in the southern half of Iran. Studies showed that a variety of synoptic systems in the year’s warm period affect the study area. As well as, synoptic analyses concluded that in the southern half of Iran over the year’s warm period when occurring heat waves, low-pressure status dominates the ground level (caused by Gang’s low-pressure and local radiant mode); thus high-pressure status with closed curves is prevailing in atmosphere’s upper levels that gives rise to the divergence, air fall and Earth's surface heating. Studying the status of the atmosphere thickness in the days with the heat wave in the study area indicates its high altitude and thickness that this itself implies the existence of very hot air and susceptibility of the conditions for the occurrence of heat waves. In addition, wind maps at atmosphere’s different levels well illustrate the wind of very warm and hot air masses from the surrounding areas to the southern part of Iran; therefore it can be noted that aforementioned hot air masses mainly wind from places like different regions of the Arabian Peninsula, Iraq, North Africa and the low latitudes to the study area.

In this study, the daily Total Ozone Column (TOC) measured by the instruments of TOMS (2001) and OMI (2005-2011) satellites and Brewer ground station (2002-2004) is used to investigate the extreme ozone mini-holes over Esfahan. Based on previous reports on validation of the TOC data products, it is found that there is no problem with homogenization of data records, which was provided by the above measuring instruments. Firstly, it is shown that the TOC monthly mean and standard deviation over central Iran depend on the seasonal cycle with maximum values of 298 and 27 DU in winter and minimum values of 270 and 8 DU in summer, respectively. The difference between the maximum and minimum climatological monthly means is 53 DU. Regarding the absolute values of TOC, the maximum (minimum) amplitude is related to the winter season with 169 DU in Feb (summer with 39 DU in Aug). Due to the minus twice standard deviation of the monthly average which is known as the threshold chosen to identify the possible ozone mini-holes, 25 events are detected during the study period with maximum concentrations, of which 16 and 7 cases occurred in autumn and winter seasons, respectively. The most occurrences of ozone mini-hole are seen in 2005 and 2011 with 7 and 6 events, respectively. It is worthwhile to mention that the lowest levels of ozone in Arctic were also seen during the two mentioned years from 2001 to 2011. Nevertheless, no mini-holes were detected for three years 2003, 2004 and 2009. The range of ozone negative anomalies is confined from around 24% in winter (Jan) to 6% in summer (Aug). However, it was reported that ozone mini-holes in some regions have reduced the TOC up to 40% of climatology mean of mid and high latitudes over the northern hemisphere. It is found that during ozone mini-hole events, the Tropopause Height (TH) tends to move upwards (with a maximum of 5.5 km higher than monthly average on 10 March 2008) which in turn leads to decrease in the temperature and pressure of TH. Similar to its seasonal cycle, the low observed values of the tropopause temperature and pressure in summer is stronger than winter season. In general, the ranges of temperature (pressure) in the thermal tropopause during low ozone events becomes from -2.3°C (-27 hPa) in February 2006 to -15.5°C (-115 hPa) in March 2008. However, the mentioned above pattern almost explains the maximum events, the observed ozone mini-holes in January 2002 don not show similar anomalies in TH. It is more probably that low ozone events during the January of 2002 are more related to the meridional transport of air masses with climatology low ozone from the subtropical latitude which is poleward near the tropopause. Backward trajectory analysis also showed that the origins of poor ozone air masses in the spring/summer (autumn/winter) seasons are related to the eastern areas (western areas) of Iran. On 7 Jan 2002 at 16 km altitude (on 16 Oct 2011 at 22km altitude), the lower part of trajectory analysis, is more characterized by horizontal movement of poor ozone air mass from lower latitude (higher latitude). During the two extreme low ozone events over Esfahan which approximately correspond to the deepest events and eventful periods, two broad ridges are seen over coastal line of North-West Europe along with two deep troughs in the eastern-central Mediterranean Sea. The blocking ozone mini-holes over North-West Europe are related to the upward movement of geopotential height in the upper troposphere and lower stratosphere (UTLS) region which is in agreement with both the advection of poor ozone air from the sub-tropical (7 Jan 2002) and the higher latitudes (16 Oct 2011) toward the mid latitudes over central Iran.

In the 6 to 8 June 2007 occurrence of the Gonu tropical storm caused heavy rainfall in the South East region was Iran and after heavy rainfall the severe floods occurred in South East Iran. In effects of Gonu super Cyclone in the 3-day period from 6 to 8 June 2007 of the South East region saw rain was showery precipitation. The total rainfalls in the study area to the number 503. 5 mm were mature. Using various data related to atmospheric moisture in different levels، and low moisture supply source and quality and qualities in the event of rain caused by Gonu storm in 2007 was studied. studding of the atmospheric Moisture Flux Convergence (MFC) during Gonu storm in 6 to 8 June 2007، using the physical equations of related to the MFC in the atmosphere، map atmospheric MFC map''s at levels 1000، 850، 700 and 500 hpa for 00z، 06z، 12z and 18z times have been illustrated and analyzed. The achieved results showed that the maximum convergence has taken place in 1000 and 850 hpa levels، and the other atmospheric levels had Lesser role in a rain storm days occurred in June 2007 Gonu. Also the results showed that moisture origin of precipitation in 6 June at 1000 and 850 hpa levels are the Indian Ocean، Gulf of Aden، and Arabian Sea and at other levels، are the Arabian Sea and Gulf of Oman. in June 8th the most effective moisture are related to the Gulf of Oman and Arabian Sea. Attention to the time of year and considering the moisture transfer path of from the warm seas، the South East meteorological stations of Iran، and with attention to convectional rainfall maps we can be note to this important point that and flooding rainfall caused by Gonu storm have occurred due to pass and dominance of a warm and humid air mass by the convection and convergence mechanism.

Identity is an index of superior quality that appears the nature of a phenomenon. It is obvious that a subject، in the ratio of its needs and desires، determines the objectivity of a phenomenon. Place identity is a kind of human epistemology about surrounded environmental patterns. It has helped him/her to choose suitable place as habitant during the history. Thus، with evolution of his/her experiences has been selected the best suitable places. Place identity، indeed، is a part of substructures of individual identity of human being، and it is also، as the result of general knowledge of men about the physical world that he/she live in it. Geosystems present patterns according to spatial components relationship. Therefore، they could act as a guide for human activities. In this study، we used geography phenomenological approach and geosystem analysis to understand the nature of genesis and historical evolution of place، as bases of social and historical identity. Therefore، perception subjectivity of place has replaced with objectivity perception of the same place. For the purpose of accessing to the goal، we have defined identity، place identity، geosystems and their general characters. Then، on the base of these definitions، we have studied place identity according to geosystems approach to recognize them for description civil and social identity. Understanding the nature of place in the context of geomorphic systems for land use planning، especially habitants are the final goal of the research. Research results shows that every place، in geosystem approach، has a unique identity that it''s structure and function perception can determine land use planning. Therefore، every place has a spatial legislations، and capability. Following the legislations and capability is caused sustainability development.

Ozone is a very small part of earth atmosphere, but its presence is nevertheless vital to human well-being. Most ozone resides in the upper part of the atmosphere. This region called the stratosphere is more than 10 kilometers above earth's surface. About 90 percent atmospheric ozone is contained in the ozone layer or ozonosphere which shields every living thing from ultraviolet light from the sun. Total ozone is all the ozone in the atmosphere. Total ozone values often report in Dobson units. Typical values vary between 200 to 500 Dobson over the globe. Total ozone varies strongly with spatial (latitude) and temporal over the planet. This paper with using different statistical as regression analysis, variance analysis and Student- Newman-Keuls (SNK) methods tried to discover the relationship between total ozone and time variation in monthly, seasonal and annual time scale in Isfahan ozone metric station. Analysis of variance shows significant different between time series means p<0.01. The best series agreement with the among of ozone is seasonal series so that average of among of ozone shows a significant in each season with S.N.K test but monthly and yearly mean of ozone dont show significant difference in all of months and years. Spring has the maximum of seasonal mean of ozone and fall has the minimum of it. Results of study on trend indicate a no significant trend in the annual mean in the time series.