Simulating Daily Soil Temperature in Egypt Using a High-Resolution Regional Climate Model: Sensitivity to Soil Moisture and Temperature Initial Conditions

Abstract

In this study, a high-resolution regional climate model (RegCM4) was used to forecast the daily soil temperature at a depth of 40 cm (hereafter ST40). The RegCM4 was downscaled by the Global Forecast System (GFS of one degree horizontal resolution) to 25 km grid spacing. To examine the sensitivity of the ST40 to different initial conditions of the soil moisture and temperature, four experiments were conducted and grouped into two cases. The first case considered the comparison between initialing the RegCM4 from bare soil and from the global satellite soil moisture product (ESACCI). On the other hand, the second case examined the influence of initializing the soil temperature from the Century reanalysis product (Century) versus initializing from zero values. The results showed that initializing the RegCM4 with the ESACCI has a notable impact on the simulated ST40 with respect to the bare soil. Additionally, when the RegCM4 is initialized with the Century product, the simulated ST40 is improved in the sense that the ST40 trend becomes smoother than when the RegCM4 is initialized with zero values. In comparison with the Century reanalysis product, the RegCM4 shows good performance when it is initialized with the ESACCI and Century products. In conclusion, the RegCM4 can give a reliable forecast of the ST40 when it is initialized with the ESACCI satellite soil moisture and Century reanalysis soil temperature products especially in data-scarce regions.

Keywords

• Egypt
• ESACCI
• RegCM4
• satellite
• soil moisture