Assimilation of Doppler weather radar observations in a mesoscale model for the prediction of rainfall associated with mesoscale convective systems

Abstract

Obtaining an accurate initial state is recognized as one of the biggest challenges in accurate model prediction of convective events. This work is the first attempt in utilizing the India Meteorological Department (IMD) Doppler radar data in a numerical model for the prediction of mesoscale convective complexes around Chennai and Kolkata. Three strong convective events both over Chennai and Kolkata have been considered for the present study. The simulation experiments have been carried out using fifth-generation Pennsylvania State University-National Center for Atmospheric Research (PSU-NCAR) mesoscale model (MM5) version 3.5.6. The variational data assimilation approach is one of the most promising tools available for directly assimilating the mesoscale observations in order to improve the initial state. The horizontal wind derived from the DWR has been used alongwith other conventional and non-conventional data in the assimilation system. The preliminary results from the three dimensional variational (3DVAR) experiments are encouraging. The simulated rainfall has also been compared with that derived from the Tropical Rainfall Measuring Mission (TRMM) satellite. The encouraging result from this study can be the basis for further investigation of the direct assimilation of radar reflectivity data in 3DVAR system. The present study indicates that Doppler radar data assimilation improves the initial field and enhances the Quantitative Precipitation Forecasting (QPF) skill.

The SAARC STORM: A Coordinated Field Experiment on Severe Thunderstorm Observations and Regional Modeling over the South Asian Region

“…-24-mar-2013). Many studies have been carried out using the pilot field experiment datasets (Abhilash et al 2007(Abhilash et al , 2008Das et al 2009b;Litta and Mohanty 2008;Joseph 2009;Rao 2009;Litta et al 2012a;Gopalakrishnan et al 2011;A. Tyagi et al , 2012B.…”

“…It shows some fidelity (nearly correct genesis and intensification), but the time of occurrence is still not very good. Detailed model evaluation results based on the pilot data are discussed in Abhilash et al (2007), Das et al (2009b), Litta and Mohanty (2008), Litta et al (2012a), A. Tyagi et al (2011Tyagi et al ( , 2012, and B.…”

“…Thus, overall the SAARC STORM program will collect massive observations to investigate the life cycle of the storms and utilize them for modeling and forecasting including nowcasting of severe convective weather in the premonsoon season over South Asia. The results based on the pilot experiments conducted so far (which are described in many papers; e.g., Abhilash et al 2007Abhilash et al , 2008Das et al 2009b;Litta and Mohanty 2008;Joseph 2009;Rao 2009;Litta et al 2012a;Gopalakrishnan et al 2011;A. Tyagi et al , 2012B.…”

Skills of different mesoscale models over Indian region during monsoon season: Forecast errors

“…The global models do not have such privileges and, they are very expensive to run at high resolutions. Moreover, at finer resolution the mesoscale models are also capable of assimilating large amounts of high resolution observations available from present day satellites and Doppler radars (Abhilash et al 2007). The mesoscale models can be configured to run from global to cloud resolving scale for simulation of thunderstorms and cloud cluster properties.…”

Assimilation of Indian radar data with ADAS and 3DVAR techniques for simulation of a small-scale tropical cyclone using ARPS model

“…It has been a challenging task to ingest radial wind and reflectivity observations of Indian DWR in the assimilation cycle of a numerical model. Realizing the importance of DWR data in mesoscale NWP modeling, Abhilash et al (2007) attempted to study the impact of retrieved wind fields from single Indian Doppler radar (Kolkata) for simulation of pre-monsoon convective events over India by MM5 model using 3DVAR data assimilation technique. Wind fields derived from DWR radial wind applying Uniform Wind Technique (UWT) are used in the assimilation cycle of MM5 model.…”