بررسی دقت مدل wrf و تصاویر ماهواره‌ای در شبیه سازی گرد‌و‌خاک جنوب شرق ایران: مطالعه موردی آوریل 2017

امروزه وقوع توفان‌های گردوخاک یکی از معضلات مهم بسیاری از مردم جهان است و هر ساله سبب بروز خسارات فراوان در بخش‏های مختلف زندگی انسان‏ها می‌شود. کشورهایی که در کمربند گردوخاک قرار دارند بیشتر از این معضل زیست محیطی آسیب می‏بینند. ایران نیز به عنوان کشوری در غرب آسیا، همواره از توفان‏های گرد‌و‌خاک آسیب دیده است، توفان‏هایی که عمدتا منشا خارجی دارند. هدف از این مطالعه، بررسی پدیده گرد‌و‌خاک در جنوب‏شرق ایران و منطقه هامون است. به این منظور، مورد مطالعاتی 26 تا 28 آوریل در منطقه هامون مورد بررسی قرار گرفت. گرد‌و‌خاک 26 تا 28 آوریل نشان داد که در برخی از ایستگاه‏های منطقه دید افقی به کمتر از 1000 متر رسیده است و تصاویر رنگ حقیقی سنجنده مودیس و rgb ماهوارهmsg به خوبی توده‌ی گرد‌و‌خاک در منطقه را نشان می‏دهند. همچنین تصویر بازتابی تصحیح شده سنجنده مودیس توده گرد‌و‌خاک را واضح‏تر نشان داده‏اند. به نظر می‏رسد عمق نوری ذرات با استفاده از الگوریتم dt و db با قدرت تفکیک 10 کیلومتر، غلظت ذرات را بیشتر از مقدار واقعی نشان می‌دهد. مقایسه خروجی مدل wrf-chem با مدل merra2 حاکی از آن است که هر دو مدل شدت غلظت سطحی گرد‌و‌خاک را در منطقه هامون به خوبی نشان می‏دهند، هر چند مقادیر خروجی مدل wrf-chem بیشتر از مقادیر غلظت سطحی خروجی مدل merra2 است. مقایسه خروجی غلظت سطحی گرد‌و‌خاک این دو مدل با غلظت pm10 گزارش شده در ایستگاه زابل، نشان‏دهنده آن است که داده‏های خروجی هر دو مدل بسیار بیشتر از داده‏های گزارش شده ایستگاهی است. همچنین در این مورد مطالعاتی، میانگین مربعات خطا مدل merra2در ایستگاه زاهدان کم بوده که نشان دهنده عملکرد قابل قبول این مدل در این ایستگاه در مورد مطالعاتی مذکور است. همچنین خطای mse مدل wrf-chem در ایستگاه زاهدان بالا بوده که نشان‏دهنده عملکرد ضعیف این مدل در ایستگاه زابل است.

investigating the accuracy of wrf model and satellite imagery in dust simulation in southeastern iran: a case study april 2017

dust storm is one of the natural phenomena that has a great impact on human life and the environment. every year, some countries in the world where dust sources are located are affected by soil storms. also, many more countries that do not have sources of dust particles are affected by the transfer of dust particles. dust storms damage human health and respiratory system, disrupt power lines, disrupt road and air transportation, and agricultural sector severely affected. the most important sources of dust production are deserts. after that, dried lakes can be named as the second source of dust production in the world. glaciers and altered agricultural lands are other sources of dust in the world the largest source of dust in the world is in the africa that imports large amounts of dust particles into the earth’s atmosphere each year. the sahara desert is the largest desert in the world with an area of 9 million square kilometers and is located in 10 countries in north africa. kok et al showed that sub-saharan africa emits about half of the world’s dust. then, the dust sources in the middle east and central asia are in the second place and 30% of the production sources of global dust storms are located in them. one of the most important dust regions is the east asian deserts, which emit 11% of the world’s dust particles. therefore, the middle east is one of the most important regions in the world where many soil sources are located. in the middle east, most of the sources of dust are located in iraq, syria and saudi arabia, but some of these sources are located in iran, although the sources of production in iraq and syria are less active, however, these springs affect different parts of iran by producing dust storms. in addition to scattered domestic springs, the main springs producing dust in iran include the dried parts of the lake and hamoon wetland in the southeast, the dried parts of the horalhvizeh wetland (hur al-azim) in the southwest and part of dried urmia lake in northwestern iran. sistan and baluchestan province, which is located in southeastern iran, in addition to high temperatures and low rainfall, is affected by 120-day winds. today, the occurrence of dust storms is one of the most important problems of many people in the world and every year it causes a lot of damage in various aspect of human life. countries in the dust belt are most affected by this environmental problem. as a country in the middle east, iran has always been affected by dust storms, which mainly originated from dust sources in other countries. the purpose of this study is to investigate the dust phenomenon in southeastern iran and the hamoon region. for this purpose a severe dust case was examined on april 26-28 in the hamoon lake region. the investigation from april 26 to 28 showed that in some stations in the region, the horizontal visibility has reached less than 1 kilometer, and the true color images of the modis sensor and the rgb of the msg satellite shows well the dust mass in this area. also, the corrected reflection image of the modis sensor has shown the dust mass more clearly. it seems that the optical depth of the particles by using the dt and db algorithm with a resolution of 10 km overestimated the concentration of dust particles in the study area. comparing the output of the wrf-chem model with the merra2 model shows that both models show the intensity of dust concentration in the hamoon area, although the output values of the wrf-chem model are higher than the output surface concentration values of merra2 model. comparing the output of surface dust concentration of these two models with the pm10 concentration measured in zabol station, shows that the two models overestimated dust concentration in comparison with the reported station data. also, in this case study, the mean square error (msrt) of merra2 model in zahedan station was low, which indicates the acceptable performance of this model in this station in this dust case. furthermore, the mse of wrf-chem model in zahedan station is high, which indicates the poor performance of this model in zabol station.