Application of WRF weather model to forecast precipitation in Nilwala river basin

Abstract

The Weather Research and Forecasting (WRF) model is a numerical weather prediction and atmospheric simulation system designed for both research and operational applications. It was fine tuned to forecast precipitation over Nilwala river basin in Sri Lanka by investigating the impacts of its physics options on precipitation forecasting. In model fine tuning, impacts of microphyics schemes, cumulus schemes, land surface schemes, boundary layer schemes and long/shortwave schemes were investigated. Model predictions were compared with observed point rainfall data for three rainfall events to find reasonably good physics combinations. It was seen that the model combination, Ferrier microphysics scheme, Kain-Fritsch cumulus scheme, Rapid Update Curve land surface scheme, Yonsei boundary layer scheme, Rapid Radiative Transfer model longwave radiation scheme and Dudhia shortwave scheme yields good precipitation predictions over the basin when compared with the other physics combinations tested.

Analysis of Statistical Downscaling Model (SDSM) projected future rainfall in Northwestern, Western and Southern provinces of Sri Lanka

“…Although extensive research has been carried out with downscaling of GCMs using the SDSM model for climate change studies in the rest of the world, a few research could be found within Sri Lanka. According to the best understanding of the authors' of this paper, Dorji et al (2017), Imbulana et al (2018), Bandara and Weerakoon (2020), Khalid et al (2017), Muhinadeen et al (2016), De Silva (2006, Shantha and Jayasundara (2005), De Silva (2007), Herath et al (2016), Nandalal et al (2012), and have projected future rainfall in different regions of Sri Lanka based on climate models (i.e. using GCMs, RCMs and Weather Research Forecasting (WRF) and SDSM).…”

Dynamic Downscaling of Rainfall Data for Deduru Oya River Basin using WRF Weather Model

“…Forecast Weather The WRF model has been used to model the weather over Nilwala river basin [8]. It was configured to predict rainfall for 24 h into future over the domain.…”

“…Physics Scheme Parameters Microphysics and the cumulus physics parameters are sensitive to the numerical weather prediction over tropical areas [8]. Therefore, before operational purposes, the model output should be evaluated for multiple microphysics and cumulus physics parameters to find the optimum physics parameters [10].…”

“…Microphysics includes certain water vapour, cloud and precipitation processes. There are a number of microphysics such as Kessler scheme, Lin et al scheme, WRF Single Moment 3-class (WSM3) scheme, WSM5 scheme, WSM6 scheme, and Ferrier scheme [8].…”

“…The WRF model contains a number of different physics parameterizations, allowing to include the effects of significant weather processes such as microphysics, cumulus physics, surface layer physics, planetary boundary layer physics, land surface physics and radiation physics. The physics parameters were varied during model calibration [8]. Accordingly, the most effective set of physics parameters were chosen before the model was applied for any operational purposes.…”