پایش تغییرات طوفان های گرد و غبار و ارتباط آن ها با شاخص نوسان اطلس شمالی (NAO) در ایستگاه های منتخب غرب و جنوب غرب ایران (مقاله علمی وزارت علوم)
درجه علمی: نشریه علمی (وزارت علوم)
آرشیو
چکیده
هدف این پژوهش بررسی ارتباط بین رخداد طوفان های گرد و غبار با شاخص نوسان اطلس شمالی (NAO) در ایستگاه های منتخب غرب و جنوب غرب ایران (آبادان، بستان، ایلام، دهلران، کرمانشاه و سرپل ذهاب) است. برای این منظور، از کدهای سینوپ روزهای توأم با طوفان گرد و غبار، دید افقی کمتر از ۱ کیلومتر، داده های مربوط به مقادیر شاخص (NAO) طی دوره آماری ۲۰۲۲-۱۹۸۷ و داده های ماهواره ای شامل شاخص عمق نوری هواویز (AOD) حاصل از تولیدات سنجنده های دوره های ۲۰۱۷-۲۰۰۰ MISR و ۲۰۲۲-۲۰۰۲ MODIS استفاده شد. نتایج ضرایب همبستگی نشان داد که ارتباط نسبتاً قوی و معکوس بین شاخص NAO در فاز منفی و ارتباط مستقیم ضعیف در فاز مثبت با گرد و غبار وجود دارد و بین ۵۱ تا ۷۰ درصد رخدادهای گرد و غبار با فاز مثبت هم زمان بوده است. نمودار تغییرات سری زمانی شاخص ها در دو فاز منفی و مثبت نشان داد از سمت غرب به سمت جنوب غرب مقدار شاخص AOD افزایش یافته که این افزایش در ایستگاه آبادان مشهود است. مطابق با شاخص حاصل از تولید سنجنده MISR سال های ۲۰۱۱ و ۲۰۱۵ در فاز مثبت و سال ۲۰۰۸ در فاز منفی اوج فعالیت طوفان گرد و غبار در تمامی ایستگاه ها بوده و کمترین مقدار آن نیز مربوط به ایستگاه های سرپل ذهاب و کرمانشاه به ترتیب در سال های ۲۰۰۲ و ۲۰۰۴ است. مطابق با شاخص دیپ بلو حاصل از سنجنده MODIS در فاز مثبت سال ۲۰۲۲ و در فاز منفی سال ۲۰۰۹ را می توان به عنوان اوج طوفان های گرد و غبار تفکیک کرد.Monitoring the changes in dust storms and their relationship with the North Atlantic Oscillation index (NAO) in selected stations in the west and southwest of Iran
1. IntroductionDust storms play a crucial role in the Earth’s atmospheric cycle. In arid and semi-arid regions, the rapid change in air temperature causes the formation of pressure differences in different parts of the region and the creation of strong and permanent winds. Deserts and dry regions and strong winds are the two causes of the dust phenomenon. One of the most effective ways to identify dust source areas is by using remote sensing techniques. The AOD (Aerosol Optical Depth) index provides the possibility of temporal and spatial monitoring of dust over a wide area in terms of detection accuracy and temporal and spatial extent.2. Research MethodologyIn this research, we investigated the relationship between the North Atlantic Oscillation index (NAO) and the occurrence of dust storms from the data related to the horizontal visibility of less than 1000 m and the current weather code expressing the dust storm (codes 6 to 9 and 30 to 35) 6 The synoptic station located in the west and southwest of Iran (Abadan, Bostan, Ilam, Dehloran, Kermanshah and Sarpol-E-Zahab) was used for some time (1987-2022) and the values related to the index (NAO) were also obtained from www.cdc.noaa .gov.htm was removed. To control the quality of the data, correlation coefficients were calculated along with the negative and positive phases of the North Atlantic oscillations and the frequency of dust storms. To check the temporal distribution of dust, satellite data of the AOD index produced by MODIS and MISR measurements obtained from Giovanni’s website at http://gdata1.sci.gsfc.nasa.gov were used, and the graph of the index changes in time scale Annually, the North Atlantic Oscillation Index was examined in two positive and negative phases. Due to the high ratio of the number of days in the positive phase compared to the negative phase in the years when the positive phase prevailed, dust storm routing was conducted with the HYSPLIT model for 6 h and at three altitude levels of 200, 1000 and 1500 m from the ground for the period Statistics were made for 2011-2022 and wind direction was assessed using WRPLOT software.3. Results and discussionThe results of examining the relationship between the North Atlantic Oscillation and dust storms at selected stations showed that in all stations, between 51% and 70% of dust storms occurred in the positive phase. In general, it seems that the conditions for the occurrence of dust storms show more compliance with the positive phase. The number of correlation coefficients between the North Atlantic Oscillation index and the annual dust storms in the desired stations is inversely and significantly correlated with the NAO index in the negative phase, and it is insignificant and insignificant in the negative phase. The results of the study of the graphs of the changes in the AOD index produced by the MISR sensor at the same time as the positive phase in the stations of Ilam, Kermanshah, and Sarpol-E-Zahab show low amounts of aerosols and significant amounts in the three stations of Abadan, Bostan, and Dehloran. In the negative phase of the NAO index, changes in the amount of suspended particles in the atmosphere from years 2001 to 2006 and 2010 decreased at all stations. While it has increased in year 2008. Along with the predominance of the positive phase according to the AOD index obtained from the MODIS sensor, there has been an increasing trend in the annual average slope of the AOD index at all stations. Along with the dominance of the negative phase, AOD values showed that from 2002 to 2006, the average trend of the AOD index was decreasing, and from 2008 to 2016, the index value increased in all stations. The routing of dust particle transport during the positive phase of the North Atlantic Oscillation Index in the stations investigated with the HYSPLIT model shows the western and southwestern part of the region where dust enters these stations. In other words, the dust originated from eastern Syria, Iraq, and Saudi Arabia and entered Iran and reached these stations. The results of the annual Wind Rose show that in Abadan and Bostan stations, the most erosive winds were from the northwest direction, in Ilam from the southwest direction, and in the rest of the stations, they were from the west side.4. ConclusionThe results of dust storm monitoring using satellite data showed that these techniques can play a major role in dust monitoring because of their wide coverage. The study of the results of the correlation coefficient between the positive phase of the North Atlantic Oscillation Index and the occurrence of dust storms indicates that there is a direct relationship between the occurrence of dust storms and the positive phase at the same time. in the negative phase, the opposite relationship is established. analysis of annual average dust change graphs concerning the positive and negative phases of the North Atlantic Oscillation Index showed that the largest annual changes in the AOD index produced by MISR and MODIS sensors in the positive and negative phases are related to the Abadan, Bostan, and Ilam stations, respectively. Tracking the paths of dust entry has shown the entry of dust from neighboring western countries and western Chenob to these areas.
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