Local Changes in Meteorological Parameters Caused by Desiccation of the Lake Urmia

Abstract

Changes in land cover have significant impacts on meteorological parameters of the area. The water level of the Lake Urmia has reduced considerably in recent years. Due to the very different characteristics of water and land, the desiccation of the Lake has a significant impact on atmospheric parameters close to the lake basin. In this study, four synoptic stations around the lake were investigated to study the anomalous changes of the meteorological parameters in a 33-year period from 1985 to 2017. Then, using the WRF-Lake model, the lake in two scenarios of high water (1998) and low water condition (2017) was simulated. The changes in the mean monthly temperature anomalies in all studied stations indicate an increase in period of sharp decrease in lake water depth compared to the average long-term regional temperature. The results also show that the average monthly wind speed at stations near the shore has decreased over the mentioned 33-year period. The anomaly study of the average monthly relative humidity shows its increase in waterlogged years and its decrease in years the water depth in the lake has decreased sharply. From 2006 onwards, despite the approximate decrease of two thirds of the lake water, the relative humidity is not affected by the continuous decrease of the lake depth. Small changes were observed in cumulative precipitation anomalies with changes in the lake water depth. The simulation results performed by the WRF-Lake model also show that in these two scenarios, the temperature of the cold season of the year (from December to February) on Lake Urmia and its shore decreased by 2.6 and 1.86°, respectively. In the warm season of the year (from June to August), it is increased by 1.20 and 1.40°. Also, the average wind speed on the lake in the cold and warm season of the year from 1998 to 2017 has decreased by 1.14 and 0.35 m/s, respectively. Simulation results for relative humidity and precipitation also show that these parameters are less affected by local climate conditions than temperature and wind speed parameters.