Impact of the moisture and land surface processes on the sustenance of the cyclonic storm Yemyin over land using the WRF-ARW model

In this study, an attempt is made to analyze the sensitivity of land surface process and the associated moisture budget characteristics of the cyclonic storm Yemyin (2007), which originated over the Bay of Bengal, crossed the entire Indian subcontinent, entered into the Arabian Sea and made a 2nd landfall at the Pakistan Coast. Sensitivity of land surface processes is carried using the WRF-ARW model with a focus on the sustainability and re-intensification of the system over land along with the available observations. Our results suggest that the transport of moisture and soil moisture played a major role in the maintenance and re-intensification of the system over land. Transport of the strong moisture by the monsoon currents from the Arabian Sea to land furnished the energy required for the system. The transport of the vertically integrated moisture helped to increase the moisture convergence over the Indian landmass which gave the energy to sustain the system on land. An early period of rainfall before reaching the system helped to increase the soil moisture which releases the latent heat over land. Evaporation over land played an important role in amplifying the mid-tropospheric moisture, which contributed to the precipitation along with moisture flux convergence. The Noah and RUC land surface physics produced the least errors in the movement of the system while the RUC scheme gives significant results for intensification. The soil moisture zero experiment failed to provide the good results for movement and intensity of the system compared to other experiments. The soil moisture zero experiment did not yield give good results due to lack of sufficient soil moisture.