تحلیل الگوهای همدیدی و نقش گردش منطقه‌ای جو در تولید گردوغبار محلی و منطقه‌ای بر روی استان قزوین

طی سال های اخیر پدیده گردوغبار در پی رخداد دوره های خشک و افزایش متوسط دمای جهانی در سراسر دنیا رشد چشمگیری داشته است. از این رو مناطق واقع در کمربند خشک دنیا تاثیر بیشتری نسبت به سایر مناطق از این پدیده حدی داشته اند به همین منظور برای بررسی رخداد دوره های گردوغباری در استان قزوین از داده های 5 ایستگاه واقع در منطقه طی بازه زمانی 2002 تا 2021 و برای بررسی گردش جو نیز از داده های era5 با توان تفکیک 0.125 درجه جغرافیایی و برای پایش و ردیابی گردوغبار از مدل hysplit و مقادیر aod سنجنده modis استفاده شد. نتایج حاکی از آن بود که دوره های گردوغباری شدید در استان معطوف به فصل گرم سال و به خصوص تابستان منطقه بوده و از سویی کمترین درصد رخداد این پدیده نیز در دوره زمستانه منطقه می باشد. بررسی گردش جو منطقه ای نیز نشان داد 4 الگوی جوی بصورت منطقه ای و فرا منطقه ای در رخداد گردوغبارهای شدید و فراگیر منطقه نقش دارند که می توان به ترتیب به پرارتفاع جنب حاره و گسترش پایین سوی تاوه قطبی اشاره نمود. مسیریابی ذرات نشان داد که کانون های واقع بر روی عراق کنترل کننده دوره های گردوغباری منطقه می باشند و از سویی گردوغبارهای محلی متاثر از کانون های داخلی کشور بوده که عمده آن بر روی استان خوزستان شکل می گیرند. وجود کانون های خارجی از جمله ترکمنستان نیز به عنوان عامل تشدید کننده گردوغبارهای استان قزوین شناسایی شد. از نظر شدت گردوغبار و حجم انتقالی گردش پرارتفاع جنب حاره دارای بیشترین تاثیر بر روی منطقه بوده که بر اساس تحقیق حاضر می توان با استفاده از داده های با توان تفکیک بالا مقادیر ارتفاع ژئوپتانسیل و تاوایی نسبی را شاخصی مناسب برای پیش بینی این پدیده در دوره گرم سال در نظر گرفت.

analysis of synoptic patterns and the role of regional atmospheric circulation in local and regional dust production over qazvin province.

during the recent years, the dust phenomenon has grown significantly around the world following the occurrence of dry periods and the average increase in global temperature. therefore, the regions located in the dry belt of the world have been more affected by this extreme phenomenon than other regions.the main goal of this research is to investigate the synoptic patterns and the role of regional circulation of the atmosphere in the production of local and regional dust in qazvin province. it is internal and external, and in this research, it has been tried to investigate and analyze the different dimensions of regional and extra regional dusts using methods and data with high resolution.in order to analyze dusty days in qazvin province, two environmental and circulation databases were used. in this way, first, according to the meteorological data recorded in the ground level stations, the number of dust days was determined and then the circulation patterns that generated them were identified. the formation of environmental databases was done in such a way that the number of dusty days in the province in a 20 year period (2002 to 2021) for 5 hamdid stations using the code of current weather phenomena (ww) of the country’s meteorological organization (codes 6 and 30 to 35, which are related to dusty days) ) was determined in matlab software.in order to analyze synoptic patterns and the role of regional atmospheric circulation in local and regional dust production over qazvin province in a 20 year period, the following results were obtained. station surveys during the statistical period showed that the majority of local and regional dust occurrences in the province are related to the hot period of the year and especially the summer season, which accounts for the largest amount of dust transmission in the region. on the other hand, the cold period of the year, especially winter, has the lowest percentage of dusty days in the province. the results of the investigation of atmospheric circulation in the region for periods of intense and pervasive dust showed that 4 circulation patterns are the main cause of this phenomenon in qazvin province. the mentioned patterns have a regional and extra regional nature, and in this category, we can mention the high altitude formation of a tropical front with a strong descent of air and an increase in negative relative humidity as a regional factor. among the extra regional factors, we can mention the downward expansion of the polar ice cap and the formation of deep troughs on the main sources of dust in the middle east, which have created periods of intense and pervasive dust in the region. the circulation of the lower level also showed that for the formation of dust in the region, southern currents were the main ones, although in some patterns, northern currents also carried dust particles. the increase in wind speed over the main sources of dust and on the other hand the increase in wind speed over qazvin province also showed the interaction of sub level pseudo jets in the formation and transfer of dust particles. the results of tracking dust particles indicated that the main source of dust in the region is iraq and other dust producing sources in the region have a reinforcing effect. in such a way that the transport of particles with the monitoring of more than 48 hours in the region showed the existence of local currents which were at the heart of the circulation of the regional scale and caused the rise of dust from the country of iraq. it is necessary to explain that sources such as the country of turkmenistan have also played a role in the occurrence of intense and pervasive dust periods in the region, which aggravate the conditions during the combined process with the flow to the region.