پديد آورندگان :
ميري، پروين دانشگاه فردوسي مشهد، مشهد، ايران , راشكي، عليرضا دانشگاه فردوسي مشهد - بيابان زدايي، مشهد، ايران , سپهر، عادل دانشگاه فردوسي مشهد - ژئومورفولوژي، مشهد، ايران
كليدواژه :
شاخصهاي گردوغبار , شرق خراسان , سنجندۀ TOMS , سنجندۀ OMI
چكيده فارسي :
ذرات معلق در هوا نقش مهمي در توازن انرژي زمين و جو ايفا مي‌كنند و به عنوان يك عامل مهم در تعيين تغييرات آب‌وهوايي شناخته مي‌شوند. هرساله طوفان‌هاي گردوغبار اثرات مخربي بر روي سلامت، مزارع، تأسيسات و اكوسيستم‌ها مي‌گذارند. خراسان ازجمله مناطقي است كه به‌شدت تحت تأثير اين پديده قرار دارد و بادهاي 120 روزه سيستان از عوامل تشديد‌‌كننده اين پديده بخصوص در مناطق شرقي است. يكي از راه‌هاي مطالعۀ اين پديده روش‌هاي سنجش‌ازدوري است. اين تحقيق با هدف بررسي تغييرات زماني و مكاني شاخصهاي گردوغبار بر پايه داده‌هاي ماهواره‌اي در منطقۀ شرق خراسان انجام پذيرفته است. در اين پژوهش جهت مطالعۀ ذرات معلق جو، از شاخصهاي UVAI،AAOD و AOD استفاده شده است. براي اين منظور از داده‌هاي سنجندۀ TOMS بر روي ماهوارۀ Nimbus 7 در سال‌هاي 1978 تا 1993 و بر روي ماهوارۀ Earth probe در سال‌هاي 1996 تا 2005 و از داده‌هاي سنجنده OMI بر روي ماهوارۀ Aura از سال 2004 تا 2014 استفاده شده است. نتايج اين پژوهش روند صعودي اين شاخص‌ها را در طي سال‌هاي 2014-1978 نشان مي‌دهد. همين‌طور شاخص UVAI بيشترين ميزان ذرات معلق را در سال‌هاي 2002، 2008 و 2014 و شاخصهاي AAOD و AOD بيشترين ميزان ذرات معلق را در سال‌هاي 2008 و 2014 نشان مي‌دهند.
چكيده لاتين :
Introduction Satellite remote sensing provides an undoubtedly unique opportunity to extract spatial patterns of regional, international and seasonal aerosol properties. In order to understand the effects of air particles on climate and human health over the lands, it’s necessary to have spatial and temporal distribution of aerosol. Ground-based measurement data do not provide the spatial pattern of particles and therefore, satellite data are used. Aerosol indices such as Aerosol Index (AI) and Aerosol Optical Depth (AOD) are commonly used to identify the amount of atmospheric particles. East Khorasan is under the influence of dust emission since the strong Levar winds (120-day wind) blow over the region. The aim of this study was to investigate the temporal and spatial variability of aerosol in the East Khorasan, Iran based on satellite data. 2. Study Area East Khorasan with an area of 100,161 km2 is limited from the north and east to Turkmenistan and Afghanistan and from south to Sistan and Baluchistan Province. There are 11 meteorological stations at this region including Sarakhs, Mashhad, Torbat-e-Heydarieh, Torbat-e-Jam, Taybad, Khaaf, Gonabad, Qaen, Birjand, Sarbishe and Nehbandan. 3. Material and Methods The Aerosol indices were obtained from TOMS sensors with a spatial resolution (1^°×〖1.25〗^°) and OMI sensors with a spatial resolution (〖0.25〗^° 〖×0.25〗^°) from http://disc.sci.gsfc.nasa.gov/giovanni. The monthly, seasonal and yearly mean values of the data sets were calculated from all available data. To study atmospheric aerosols, UVAI, AOD and AAOD indices were used. For this purpose, TOMS sensor data from the satellite Nimbus 7 satellite in 1978 and 1993 and in 1996 and 2005 and the Earth probe OMI on Aura satellite were used from 2004 to 2014. 4. Results and Discussion The results indicated that the amount of particulate matter obtained using UVAI/OMI is highest in all cities in June, July and April and lowest in December, November, and October. The AAOD related to each city was quite different from other cities and there was no specific month which showed the highest or the lowest concentration of absorbing particles; it seems that the UVAI index does not follow a specific pattern while the UV index has the highest amount in Mashhad. Therefore, UV seems to be associated with air pollution. AOD index also had the highest value in the city of Mashhad in May and the lowest value occurred in Tayabad and then in Khaaf in December. Maximum UVAI/TOMS index occurred in June. The OMI sensor has the same monthly pattern as the TOMS data. Tayabad had the highest aerosol (UVAI) and Mashhad had the lowest. From 2004 to 2014, the amount of aerosol increased in the region. The concept of AAOD is close to UV-absorbing aerosols such as smoke, dust and minerals in all cities increased in the period of 11 years. 5. Conclusion According to the results, spatial and temporal variabilities of indices are more associated with climate processes and then topography. Low attitude areas have the highest UVAI aerosol value while mountainous areas have the lowest amount of UVAI inde
