INVESTIGATION ON THE URMIA LAKE DROUGHT USING SATELLITE ALTIMETRY AND WEATHER REANALYSIS PRODUCTS

Abstract. The Urmia Lake is located in northwestern Iran. It is the sixth largest salt lake in the world. In the past 14 years, this lake strongly faced to the water level decrease and surface water reduction. Several space-borne techniques have been employed for detecting the hydrological cycle and its inter-annual changes.

The goal of this paper is to investigate weather reanalysis products such as specific humidity of NCEP model and a total column water vapor extracted from ECMWF model and other techniques such as satellite altimetry that have been powerful for the identification of some drought factors of the Urmia Lake.

In this study, we used satellite altimetry data from ENVISAT and CryoSat-2 to monitor the Lake water level and optical satellite imagery to determine the surface water extent of the lake during 2002 to 2014. Our altimetry and satellite imagery results reveal decrease in height and area of Urmia Lake over the last 14 years. The lake surface area and the water level decreased continuously at approximately 2666 km² and 3.5 m respectively.

Moreover, we employed the monthly 0.125°×0.125° datasets of the ECMWF data and 2.5°×2.5° datasets of the NCEP data to demonstrate amount of water vapor in the atmosphere over the lake. The total column water vapor extracted from ECMWF data and specific humidity of NCEP data show similar behavior. Results indicate that no meaningful correlation between the altimetry data and weather reanalysis models exists. The weather reanalysis models do not indicate descending variations during 2000 until 2014. For interpreting the situation and studying the climate change and man-made impacts on the drought in this region, we need to use ground-based data such as wind speed, precipitation, barometric pressure and temperature.