T Ensafi Moghaddam,; F. Khoshakhlagh; A.A Shamsipour; R Akhavan; T Safarrad; F Amiraslani
Volume 9, Issue 2 , December 2017, , Pages 79-98
Abstract
Dust in the atmosphere and their interactions with precipitation have great impacts on regional climate where there are large arid and semiarid regions. Dust is one of the factors affecting precipitation. There are many ambiguities about the cause of the difference between amount of rainfall from an ...
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Dust in the atmosphere and their interactions with precipitation have great impacts on regional climate where there are large arid and semiarid regions. Dust is one of the factors affecting precipitation. There are many ambiguities about the cause of the difference between amount of rainfall from an area to another area and from time to time. So that even with the spread of knowledge and technology yet still there is not completely specified the cause of these fluctuations. Nowadays, satellite images are broadly used for monitoring the effects of dust variations on the precipitation changes. Nowadays, satellite images are broadly used for monitoring the effects of dust variations on the precipitation changes. The aim of this study was to investigate the relationship between dust dynamic and precipitation variations. This research can be help to find the impact of dust occuarrances on precipitation changes in the South-West parts of Iran during thirty years by cluster analysis, remote sensing, and aridity zoning in GIS software. In this investigation, we analyzed data sets of daily average visibility(a proxy for surface aerosol concentration), daily No of reports frequency of dust occurance and daily precipitation at 45 meteorological stations during past 30 years(1986-2016)were obtained from the Iran Meteorological Organization. The consistent trends in observed changes in visibility, precipitation, and daily No of reports frequency of dust occurance appear to be a testimony to the effects of dust. In present study, we tried to determine the relationship between dust events data and measured precipitation changes in a ground stations. Therefore frequency of dust occurrence from 1986 to 2016 at 30 stations, compared with rainfall anomalies for South-West of Iran as a whole. Rainfall is expressed as a regionally averaged, standardized departure (departure from the long-term mean divided by the standard departure), but the axis of the rainfall graph is inverted to facilitate comparison with dust occurrence. Dust is represented by the number of days with dust haze. Then‚ dust days ratios which measured by number of days with dust in month and horizontal viewing which measured by number of days with visibility min < 2000 were compared by map of mean annual rainfall of stations in South-West of Iran. Precipitation maps were created using the inverse distance weighting interpolation (IDW). Too, In this study, (MODIS) Aerosols Optical Thickness(AOD)product is applied in order to estimate dust intensity. AOD images and MODIS/Terra Calibrated Radiances 5-Min L1B Swath 1km (MOD021KM) were utilized to assessment of move pattern of the dusts in the study area. Our results indicated that MODIS products could be a reliable tool to assess dust events patterns and to survey the concentration of particulate matter .So AOD images and MODIS/Terra Calibrated Radiances 5-Min L1B Swath 10km were utilized to assessment of special move pattern of the dusts frequency in the study area‚and indicated the opposite response of light rain to the increase in dust, have seen in mountainous and plain areas.
