بررسي تشكيل و انتشار طوفان‌هاي گرد و خاك ورودي به غرب و جنوب‌غرب ايران با استفاده از مدل پخش لاگرانژي ذرات HYSPLIT

Investigation of Formation and Propagation of Dust Storms Entering to the West and Southwest of Iran Using Lagrangian Particle Diffusion Model, HYSPLIT

امروزه معضل افزايش فرسايش بادي و طوفان‌هاي گردوخاك بعلت تغيرات اقليمي و خشكسالي‌هاي متوالي به بحراني منطقه‌اي جهاني تبديل شده است. براي منشأيابي، پيش‌بيني شدت و گستردگي و سرعت انتقال اين طوفان‌ها از روش‌هاي مختلفي همچون مدل‌هاي عددي، تصاوير ماهواره‌اي و تحليل‌هاي همديدي استفاده مي‌شود. در اين مطالعه با بررسي و تحليل نقشه‌هاي فشاري سطوح مختلف جوي، به اثر پارامترهاي دما، فشار و سرعت باد در سطوح مختلف جو مؤثر بر انتشار طوفان‌هاي گردوخاك پرداخته شده است. در اين مطالعه در مرحله اول به بررسي عوامل همديدي موثر بر رخداد طوفان‌هاي گردوغباري ورودي از غرب و جنوب غرب به ايران پرداخته شده، در مرحله دوم براي مشخص كردن منشأ شكل گيري اين طوفان‌ها از مدل پخش لاگرانژي HYSPLIT با استفاده از روش رديابي پس‌رو استفاده شد. براي تاييد خروجي اين مدل عددي، از بررسي همديدي استفاده گرديد. خروجي‌هاي مدل نشان مي‌دهد كه به طور كلي منابع اصلي غبار براي طوفان‌هاي گردوغباري جنوب غرب ايران محدوده‎‌اي در حد فاصل مركز تا شمال عراق، شرق سوريه تا شمال عربستان مي‌باشد. براي مطالعه، يك دوره آماري 5 ساله از سال 1385 تا 1389 و 10 موج گردوغباري مهم در اين دوره انتخاب و مورد مطالعه قرار گرفت. در اين مطالعه براي ترسيم نقشه‌هاي همديدي از داده‌هاي باز تحليل NCEP/NCARبا دقت فضايي 2/5×2/5 درجه در راستاهاي طول و عرض جغرافيايي استفاده شد.بنابراهميت موج فراگيروگسترده گردوغباري روزهاي سيزدهم تاشانزدهم تيرماه 1388،الگوهاي همديد ومكانيسم تشكيل، انتقال وانتشار گردوغباردرآن به تفصيل مطالعه شد درتمام موارد،استقراريك سامانه كم فشاربرمنطقه خاورميانه وتقويت شرايط ناپايداري در سطح بيابان‌هاوهم چنين تاثيرهماهنگ يك موج كم فشار ديناميكي برفراز جو منطقه،زمينه مناسب رابراي انتقال ريزگردهابه جومنطقه فراهم ميآورد. در انتها نتايج با تصاوير ماهواره METEOSAT8 موجود در مركز باروري ابرهاي يزد مقايسه گرديد كه همخواني بسيار زيادي مشاهده گرديد.

Introduction More than half of our land area is desert or semidesert areas constitute onefifth of the total area of the country. The phenomenon of wind erosion and dust storms are with the onset of wilderness areas and expand into adjacent areas, causing many problems for health, transportation, economic, activities and …. . Wind erosion is a serious problem in many parts of the world, especially in arid and semiarid regions prone to wind erosion in North Africa, Middle East, parts of south, central and East Asia, Siberia and scattered. Climate scientists are convinced that a strong high pressure process large volumes of the vast wilderness of the west and southwest Asia fine dusts and will be transferred to the layer above the troposphere. Afterwards a lot of other strong currents fine dusts will move to higher latitudes. Materials and Methods In this study the synoptical weather maps were received from I. R. of Iran Meteorological Organization, and data of the National Centers for Environmental Prediction/National center for Atmospheric Research NCEP/NCAR and synoptic for the region were plotted to obtain the particle trajectory using a numerical modal of particle diffusion Lagrangian model. HYSPLIT was used to obtain the region of the storm and its path to check the information of the satellite images and satellite center in Yazd METEOASAT8 cloud seeding was used. 10 Dust storms events in the south west were selected. The list is given in table 2 HYSPLIT model was run for all selected output produced by synoptic maps and satellite images were compared with the model in all cases. The high resolution model stream utput to predict the formation and distribution of storms because of the importance of learning to storm Persian on June 2009 storm was fully investigated and stated synoptic maps were analyzed with the model output. Abadan weather station in the south west of the country was selected for review. Results and discussion The dust is not an unknown phenomenon especially in the central and western parts of Iran. But the frequency of occurrence and concentration which sometimes causing loss of visibility below 50 meters in recent years is considered as new phenomenon. The upper levels of the Iranian plateau in summer are dominated by tropical pleural pressure. The low pressure at the surface temperate increases. Low pressure depends on the Arabian Peninsula in northern Iraq Syria and create the right conditions for the rise of large amounts of dust into the air 1 A critical region in northwestern Iraq as a new center is formed dust storm that previously have been treated. 2 Depending on Iraq and northern Saudi Arabia causing low pressure conditions to climb the huge amount of dust in the air is Conclusion HYSPLIT model can predict the storm path. Airlines and warnings can use this model to identify sources of storm formation in Iran and surrounding countries. This model also has the high ability to predict the direction of dust particles or dimensional model is applicable along with that particular satellite images.