Performance of Noah land surface model over the tropical semi-arid conditions in western India

The land surface parameters are simulated with a Noah-LSM (NCEP, OSU, Air Force and Office of Hydrology Land Surface Model) version 2.7.1 for the tropical conditions using the surface and subsurface observations over a semi-arid region of Gujarat, India from the Land Surface Processes Experiment (LASPEX) data sets. The surface forcings are air temperature, air humidity, surface pressure, wind speed, and surface downward short wave and long wave radiations. The model simulations were carried out for two cases viz one in using soil moisture dependent soil thermal conductivity and the other by using a fixed site specific soil thermal conductivity. Simulated surface parameters are compared with observations obtained in the LASPEX to validate the Noah-LSM performance. Simulated skin temperature and net radiation are in agreement with observed results for dry surface conditions. However, simulated soil temperatures at different depths are deviating from observations particularly for wet period. Simulation of soil hydrology related parameters is very sensitive to the use of soil thermal conductivity. Based on the evaluations of model and observed results, we propose the improvement of Noah-LSM taking into consideration the site specific soil thermal conductivities and surface parameters for tropical conditions.