بررسی اثر تغییر پوشش سطحی بر تغییرات رژیم دما، بارش و رطوبت در بخش‌های شرقی و غربی دریاچه ارومیه

Introduction Many factors controlling atmospheric parameters, includes lake and seas, mountains, urban areas and etc. One of this factors is land cover. If the land cover is changing, then the nature of climate will change. One of the important part of land cove are aquatic bodies. Lakes are considered as natural controls on temperature, rain fall and moisture regime in interior continents. Due to climatic changes such as reduced rainfall, increased temperature and also uncontrolled use of surface water resources in watershed areas, distinguished changes are exposed. Monitoring such changes and consequences should be considered as an important issue in the national and regional development and natural resource management. Any change in hydro climatic conditions of lakes such as increase or decrease of their levels is reflected into climatic conditions of lake surroundings. Future more lakes or other aquatic bodies need a minimum amount of fresh water inflow, called environmental flows, to meet specific ecosystem requirements. Among the most obvious examples of changes in the land cover, is the change in water level of the Urmia Lake and ultimately drying water of the lake in recent years. Urmia Lake with its previous lake area of approximately 5000–6000km 2, had a crucial socio- economic and ecological role in the Northwestern part of Iran. During the past decades, Lake Urmia has been strained by a number of concurrent anthropogenic and natural causes.  The aim of current study are numerical simulation of the role of Urmia Lake in climatic elements in surrounding areas of this lake. For this aim the TAPM mode was used. The Study Area Urmia lake basin is located in northwest of Iran limited in 44°07´ E to 47° 53´ E longitude and 35° 40´N to 38° 30´N latitude with total area of about 52,679km2.Urmia lake is the largest lake in Iran and one of the world’s salt-saturated lakes that has significant role in moderating the climate of a vast area containing East and west Azerbaijan provinces. According to 39-year period of daily precipitation data (1973 to 2011) the annual mean precipitation over the basin is 352 mm (farajzade et al, 2014). Material and Methods For analysis of climatic role of Urmia lake in Northwestern Iran the synoptic data in station of Urmia and Bonab Cities in respectively in west and east of lake were analyzed. For simulation of the role of Urmia Lake in climatic elements (min, max and mean temperature, monthly precipitation and relative humidity) in surrounding areas the TAPM mode was used. Then by using TAPM model outputs and observed data performance of the model calibrated. TAPM model is a model for air pollution simulation that made by CSIRO in format comprehensive software. This software had been used and recommended by more than 190 users in 25 countries in different parts of world. In this research for purposes of simulation and evaluation the monthly data of two years; 2003 and 2006 were used. For computing the occurred changes and as such as estimating the errors the observed and simulated data were compared with together. For analyzing the role of Urmia Lake in climatic elements in surrounding areas, two scenarios were considered. First: Existence of the lake at it’s the maximum extent; two: Aquatic body of Urmia lake removed and substituted by an area having coverage of gravel and sand with a texture of loam (fig 1).