نوع مقاله : مقاله پژوهشی
1 گروه جغرافیا.دانشکده ادبیات و علوم انسانی.دانشگاه ازاد اسلامی.واحد اسلامشهر. تهران. ایران
2 دانشجوی دکتری آبوهواشناسی، گروه جغرافیای طبیعی، دانشکده علوم انسانی، دانشگاه آزاد اسلامی، واحد علوم و تحقیقات. تهران، ایران
3 استاد گروه جغرافیا. دانشگاه تهران
عنوان مقاله [English]
This climatehascharacteristics and behaviors that distinguish it from the surrounding areas.Gradually, living and inanimateelements adapt to those conditions.As a result, any sudden change beyond the normal range and its normalbehaviorcauses theclimateof biologicalelements tobe stressedand stressed. These abnormalities maybe caused by climatechangeorlocal or human factors.In this study, we have tried to first examine the fluctuationsor changesin the temperature of the region in each of its parts in the last three decades.Temperature anomalies were alsoassessed for sea level in the same three decades. Synoptic patterns lead to anomalies in the temperature (hot and cold advection) are in cold season. In this study, atmospheric data of 31 stations from northwestern to western synoptic stations of Iran were used. To create a database with the same statistical database, statistical periods from 1989 to 2018 are arranged. To detect climate change, the software for detecting climate change, provided by the (Meteorological Organization), has been used. The statistical period studied is divided into three ten-year statistical periods and the changes in these three statistical periods were calculated for all cold months. In another part of the work for the colder months of the year in three decades, the status of sea level temperature anomalies was also examined using NCEP / NCAR site maps.The standardized Z index was used to identify the predominant synoptic pattern.The final selectioncriteria anomalies station high frequencyof 50% of the stations has been studied.So if the abnormalities are more frequent in the 15 stationandwas elected as a representative on the end of 202 days in the cold period has had this feature. Also,sea level data were extracted in the same range for 202 days during a script.The data of sea level equationwas converted to numerical data by scripting in Grads software environment, amatrix with dimensions of 203* 253 was analyzed by rotation with array in SPSS environment by factor analysis method, and by quarry ax method.Eleven factorsjustify 95.40percent of climate behavior in the cold months. Finally, after examining 11 factors, 4 dominant patterns were identified in this region.The results of this study showed that the temperature difference in northwestern Iran with southwesternand Middle Western is decreasing. The temperature difference betweenthe southandthe north in thefirst decade (1989-1989) was between 7 and 9 degreesCelsius, dependingon the month.in the second decade (1999-2008)this difference decreased to 5.5to 6.5 degreesCelsiusand in thethird decade(2009-2018) it decreased to 5 to 6 degrees Celsius.This means that the temperaturerangebetween the north and south of the country is declining.This means that the temperature range between the north and south of the country is declining. Among the colder months,January had the highest temperature fluctuations and April had the lowest temperature fluctuations.If we exclude January, in other months, a total of three decades in the northern part of the study area, especially in Ardabil province, the trend of increasing temperature changes and vice versa in the southern part of this increasing trend has had a slight slope. But in January, the phenomenon fluctuated sharply. In the second decade, compared to the first decade, there was an increase in both the northern and southern regions, while in the third decade, compared to the second decade, there was a decrease in both regions. Temperature anomaly maps prepared for the colder months of the year showed that from January 4 to April in thefirst decade we saw negative anomaliesthroughout the region.So in the first decade, compared to the previous decade, we have faced a negative anomaly throughout the region. But in the second and third decades, anomalies have been positive inalmost the entire region. This phenomenon has accelerated in the third decade.In November and December, the anomalies fluctuated sharply.In the first decade, the northwest was negative in both months, but the south had a positive anomaly.In the second decade, the situation was completely reversed and the northwestern region was associated with a positive anomaly and the southern part with a negative anomaly. But in the third decade, anomalies in almost the entire region tended to be positive and harmonized with other months.The results of visual examination and factor analysis on abnormal temperature days showed that four consecutive patterns of temperature abnormalities in the western and northwestern regions of Iran during the cold period.
Therefore, four patterns are the cause of temperature changes and the general temperature of the region is outof its normal conditions in the cold period. As can be seen in the two models,the air temperature in the region is warmer than usual during this season of the year. This means that the temperature in the region is rising unusually and the general trend of the region is disrupted.In both cases, in addition to warming or rising temperatures, precipitation has also occurred. It is emphasized that not every precipitation system is associated with a warming. As can be seen, in both models, along with the warm rise of Saudi anticyclone, it plays a key role in hot advection. Two consecutive patterns have also been associated with cold weather, causing temperatures in the region to drop significantly. So the abnormal days that accompanied the cold. Or the temperature in the area has dropped unusually. Siberian high-pressure systems and Saudi and immigrant anticyclones have played a major role. In other words, the combined pattern of these three anticyclone systems has played a major role in cold advection and air stability in the region. In general, the temperature in the region is rising, and this upward trend is more intense in the northwest than in the south.The main systems that create abnormal days in the high-pressure Siberian and immigrant areas for cold advection and the Saudianticyclonehaveplayed arole in perpetuating these cold eruptions.Inother words,thecold weather has been advection to the region by two Siberian and migratory systems, and the anticyclone of Saudi Arabia in the higher layers has caused the reliability of this cold wave.On hot days, during the cold period of the year, Saudi Arabia's cyclone and Sudan's low pressure haveplayed a majorroleinhotadvection