Identifying the Best Microphysics Option to Improve Accuracy of Medium Range Rainfall Forecast for Tamil Nadu
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Author:Mehala, M1, Dheebakaran, Ga, Panneerselvam, S, Patil Santosh Ganapati*, and Kokilavani, S.
Page No:1
DOI : https://doi.org/:10.29321/MAJ 2019.000267
Abstract
Weather Research and Forecasting (WRF) model is a numerical weather
prediction system and having wide range of applications.It offers multiple
physics options that could be combined in any way to improve the accuracy
of forecast suitable to particular region.Each physics option has it’s own
individuality and no single scheme could perform better in all locations. In this
context, a study was carried out to identify the best WRF microphysics scheme
for improvingmedium range rainfallforecastissued by Tami Nadu Agricultural
University at block levelforTamil Nadu. Based on the review of previous
studies, the present study was restricted to three microphysics options which
are suitable for tropical conditions viz. Kessler scheme, WSM3 and WSM6
class schemes. Forecast wasdeveloped daily at 3 km resolution with a lead
time of six days for 32 locations of Tamil Nadu and for the first fortnight
of November 2017. The simulated forecast values were verified with the
observed data collected from the Automatic Weather Stations of TamilNadu
Agricultural Weather Network (TAWN) using skill score and root mean square
error verification methods. Input data resolution and microphysics option
had huge impact on model performance. Data resolution of 0.25 degree
performed better than 0.50 degree in all microphysics schemes considered
for the study. Among the three microphysics options, the Kessler scheme
had higher rainfall forecast accuracy than WSM 3 class scheme and WSM
6 class scheme. Root mean square error was also low in Kessler scheme
compared to other two schemes. Kessler scheme produced highly usable
forecast than WSM 3 and 6 class schemes. Hence, it is concluded that the
Kessler scheme with 0.25o
input data resolution produced higher rainfall
forecast accuracy for Tamil Nadu region
Key words : :Weatherforecast, WRF, Microphysics,Accuracy, Verification
