Evaluation of WRF-simulated multilevel soil moisture, 2-m air temperature, and 2-m relative humidity against in situ observations in India

The ability of the Weather Research and Forecasting (WRF) model to simulate multilevel soil moisture (SM), 2-m air temperature (T-2m), and 2-m relative humidity (RH2m) was evaluated for five different locations in India. WRF model simulations were carried out for 30 cases during different seasons with two different land surface schemes, viz. Noah and Rapid Update Cycle (RUC). The simulations were compared with insitu observations taken routinely at 30-min time intervals at the five selected locations. Statistical evaluation showed that, although the model could simulate SM reasonably well [with the majority of cases falling in the < 25% relative error (RE) category] at different depths for Delhi (DLH) and Gulbarga (GLB), the model errors were high (with most cases falling in the > 50% RE category) for Almora (ALR), Hyderabad (HYD), and Cochin (CHN). In case of T-2m, model errors were high (RE > 15%) over hilly terrain, e.g., at ALR, while errors were relatively lower (RE < 10%) for plane areas such as HYD, GLB, DLH, and CHN. In general, the diurnal variation showed that the model underestimated (overestimated) afternoon temperatures during nonrainy (rainy) days. RH2m was also well simulated by the model at the locations HYD, GLB, and CHN, although it underestimated RH2m during morning hours at the locations ALR and DLH. Overall, the comparison showed that the WRF model could reproduce the near-surface temperature and humidity for plane areas such as HYD, GLB, and CHN reasonably well, but has limitations for complex terrains, e.g., at ALR, and highly polluted cities such as DLH.