%0 Journal Article
%T A Comparative Study on Performance of Analysis Nudging and 3DVAR in Simulation of a Heavy Rainfall Event Using WRF Modeling System
%A Ashish Routray
%A Krishna K. Osuri
%A Makarand A. Kulkarni
%J ISRN Meteorology
%D 2012
%R 10.5402/2012/523942
%X The present study focuses on the performance-based comparison of simulations carried out using nudging (NUD) technique and three-dimensional variational (3DVAR) data assimilation system (3DV) of a heavy rainfall event occurred during 25¨C28 June 2005 along the west coast of India. The Indian conventional and nonconventional observations are used in the 3DV experiment. Three numerical experiments are conducted using WRF modeling system, the model is integrated upto 54 hours from the initial time 0000 UTC of 25 June 2005. It is noticed that the meteorological parameters are improved in the resulting high-resolution analyses prepared by NUD and 3DV compared to without data assimilation experiment (i.e., called CNTL experiment). However, after the successful inclusion of observations using the 3DVAR data assimilation technique, the model is able to simulate better structure of the convective organization as well as prominent synoptic features associated with the mid-tropospheric cyclones (MTC) than the NUD experiment and well correlated with the observations. The simulated location and intensity of rainfall is also improved in 3DV simulation as compared with other experiments. Similar results are noticed in the root mean squar errors, correlation coefficients, and Equitable Threat Scores between TRMM and model simulated rainfall for all the three experiments. 1. Introduction Most of the rainfall along the Indian Peninsula during the southwest monsoon (SWM) occurs in association with convective activity over the Arabian Sea (AS) and the Bay of Bengal (BOB) that propagates into the peninsular India. These rainfall activities are usually associated with mesoscale convective systems (MCSs) embedded in large-scale synoptic system. Several investigators have also studied the interaction of the low-level jet with Western Ghats which lead to substantial rainfall during SWM along the west coast of India. The analysis by the authors in [1] shows that the maximum rainfall rate along the west coast of India could be as high as about 20£¿cm per day. Previous studies on heavy rainfall [2, 3] identified numerous patterns and mechanisms in the synoptic scale and mesoscale that promote heavy rainfall developments and established linkage between heavy rainfall events along with wide variety of synoptic features. There have been considerable improvements in high-resolution mesoscale models over the past few decades. The mesoscale models have shown increased skill in producing not only the correct rainfall intensity and location but also the timing of evolution of the convection
%U http://www.hindawi.com/journals/isrn.meteorology/2012/523942/