اثر ارتفاعات در ايجاد بيابان هاي بادپناهي (شبيه سازي اثر كوه هاي كرمان در ايجاد بيابان لوت)

The Effects of elevation on creation of leeward deserts: Simulation of the effect of Kerman Mountains on creating the Loot desert)

در توزيع مكاني ناهمگون ريزش هاي جوي و شكل گيري بيابان ها، شرايط جغرافيايي و به خصوص عامل ارتفاعات، نقش موثري دارند. بيابان لوت، يكي از خشك ترين مناطق زمين در كمربند بياباني جهان است كه در ايامي از سال تحت سيطره پرفشار جنب حاره اي قرار داشته و علاوه بر آن، در سايه باران كوه هاي استان كرمان نيز واقع شده است. بر اين اساس در اين پژوهش تلاش شده است ميزان اثرگذاري ارتفاعات در ايجاد بيابان لوت با استفاده از داده هاي مشاهدات ايستگاهي و شبكه بندي شده (ERA-Interim/ECMWF) بارش و داده هاي مورد نياز جهت اجراي مدل اقليم منطقه اي (RegCM4.1) از ICTP، شناسايي گردد، از اين رو به اين منظور با حذف توپوگرافي در مدل اقليمي منطقه اي RegCM4.1، اثرات اين سد كوهستاني بر ميزان بارش منطقه بررسي گرديد. شبيه سازي در دو حالت مرجع و حذف توپوگرافي براي سال آبي 2006- 2007 انجام گرفت.

In heterogeneous spatial distribution of rainfalls and the formation of deserts, geographical conditions and, especially, elevation have an influential role. The Loot desert, as one of the driest areas of the Earth on the global desert belt, is dominated by the subtropical high pressure for some time in a year and is located in the rain shadow of Kerman province mountains. Accordingly, in this study, using station and networked (ERA-Interim/ECMWF) precipitation data and the required data for running the regional climate model (RegCM4.1) from ICTP, attempt is made to detect the effectiveness of heights in formation of the Loot leeward desert. So, in order to detect the effect that mountainous dams on the rainfall of the region, topography was removed from the RegCM4 climate model. Simulation was performed in the original state, and topography was removed for the farming years of 2006-2007. The results showed that the model rainfall estimation is 151 mm, which is close to the observed average of the area. In the removed topography simulation, the precipitation of the eastern and central-western smoothed heights is reduced from 177 to 157 and from 244 to 144 mm respectively. However, in the Loot area, the precipitation shows an increase of more than 100% (i.e. 67 to 148 mm). It is to be noted that, in the absence of the mountainous mass, the spatial distribution of precipitation becomes more uniform and the precipitation significantly increases in the Loot region. Therefore, it can be concluded that the Loot region is inherently a desert resulting from the general circulation of the atmosphere, and the Kerman province mountains have intensified the arid conditions into hyper arid conditions.