On the sensitivity of the daily maximum and minimum air temperature of Egypt to soil moisture status and land surface parameterization using the RegCM4

Daily maximum (T_max) and minimum air temperature (T_min) are sensitive to the soil moisture status and land surface parameterization. However, this topic has not been investigated in arid regions (e.g., Egypt). To address this issue, four 13-year experiments were conducted using a regional climate model (RegCM4). The first two considered the soil moisture status (bare soil versus global satellite soil moisture product; ESACCI). The other two considered the sensitivity to the two land surface schemes coupled to the RegCM4: Biosphere Atmosphere Transfer System (BATS) and version 4.5 of the community land model (CLM45). In all simulations, the RegCM4 was downscaled by the Era-Interim reanalysis with 25 km grid spacing. The simulated T_max and T_min were evaluated with respect to the Climate Research Unit (CRU) and station data.

Results showed that switching from bare soil to ESACCI has a considerable influence on the simulated T_max and T_min. Furthermore, the CLM45 outperforms the BATS with respect to the CRU. Concerning T_max, such behavior is obviously noted in the coasts of the Mediterranean and Red Sea. Overall of Egypt, the CLM45 has potential skills more than the BATS particularly in the inland regions. In comparison with the observed data, behavior of the BATS/CLM45 varies with the location and month. Despite of the noted biases, the RegCM4 can be recommended for future studies concerning the seasonal prediction or climate change of Egypt as long as it is configured with the CLM45 land surface model and initialized with the ESACCI satellite moisture product.