Integrating remote sensing data with WRF for improved simulations of oasis effects on local weather processes over an arid region in northwestern China

Land use/cover types derived by satellite remote sensing data from the Earth Observing System Moderate Resolution Imaging Spectroradiometer (MODIS) were used to replace the U.S. Survey (USGS) data in the Weather Research and Forecasting (WRF) model. Simulations in this study were further improved by modifying the initial fields of WRF with soil temperature and moisture observations, because these two variables are important to producing "cold-wet island" effects. These improvements enabled the WRF model to reproduce the observed "cold and wet island" effects of the oasis.; Location and landscape map of the Jinta oasis. Jinta oasis is an inverse triangle situated between 98°39‧E and 99°08‧E and 39°56‧N and 40°17‧N in the north-central Heihe River Basin in northwestern China (Fig. 1). The average annual total precipitation is about 59.5 mm and the annual potential evapotranspiration is about 2538.6 mm (Meng et al. 2009). The total area is about 1652 km2. Jinta oasis is a typical irrigated area in arid northwestern China. It has an undulating topography and varies in elevation by only 80 m. ; In the field, there were 4 automatic weather stations (AWSs) and 1 oasis meteorological tower station in the vegetated areas, and 1 Gobi meteorological tower station was located in the nonvegetated area. The four AWSs were at 2 m height, and the two tower stations were at 4 heights (1.8, 5.8, 13, and 18.9 m). This figure shows the comparison of land use/vegetation maps between the default (USGS) and modified MODIS data for the 1 km-resolution domain. Most of the oasis is irrigated cropland, with grassland decreasing rapidly in the interior and outer edges of the Jinta oasis and degrading to desert (Fig. 2b). With population growth, more and more grassland is used to plant crops, which results in the reduction of shrubland and grassland.