Simulation of heavy rainfall event along east coast of India using WRF modeling system: impact of 3DVAR data assimilation

The study is evaluated the impact of WRF three dimensional Variational (3DVAR) data assimilation for simulation of a heavy rainfall event due to the presence of the monsoon depression (MD) along the east coast of India. In this purpose, two numerical experiments are carried out such as CNTL (without data assimilation) and 3DV (with assimilation of observations from Global Telecommunication System) for simulation of the heavy rainfall event occurred during 16–21 August 2016 over Indian region. The model is integrated upto 120 h starting at 00 UTC of 16th August 2016 in both the experiments. The results demonstrate that the model with resulting high-resolution reanalyses from 3DV produced reasonably well simulated the location and intensity of rainfall due to the presence of the MD. The model simulated mean sea level pressure (MSLP), vertical structure, track and direct position errors (DPEs) of the MD reasonably well represented in the assimilation experiment (3DV). The statistical skill scores viz. Equitable Thereat Score (ETS) and bias with various thresholds of the rainfall are improved in the 3DV experiment as compared to the CNTL experiment. The present study clearly suggested that the data assimilation (3DVAR) has a positive impact on the simulation of the heavy rainfall event.