The WRF model performance for the simulation of heavy precipitating events over Ahmedabad during August 2006
The summer monsoon season of the year 2006 was highlighted by an unprecedented number of monsoon lows over the central and the western parts of India, particularly giving widespread rainfall over Gujarat and Rajasthan. Ahmedabad had received 540.2mm of rainfall in the month of August 2006 against the climatological mean of 219.8mm. The two spells of very heavy rainfall of 108.4mm and 97.7mm were recorded on 8 and 12 August 2006 respectively. Due to meteorological complexities involved in replicating the rainfall occurrences over a region, the Weather Research and Forecast (WRF-ARW version) modeling system with two different cumulus schemes in a nested configuration is chosen for simulating these events. The spatial distributions of large-scale circulation and moisture fields have been simulated reasonably well in this model, though there are some spatial biases in the simulated rainfall pattern. The rainfall amount over Ahmedabad has been underestimated by both the cumulus parameterization schemes. The quantitative validation of the simulated rainfall is done by calculating the categorical skill scores like frequency bias, threat scores (TS) and equitable threat scores (ETS). In this case the KF scheme has outperformed the GD scheme for the low precipitation threshold.
KeywordsRainfall TRMM inner and outer domains
- Chang H I, Kumar A, Niyogi D, Mohanty U C, Chen F and Dudhia J 2007 The Role of Land Surface Processes on the Mesoscale Simulation of the July 26, 2005 Heavy Rain Event over Mumbai, India; Global Planet. Change, submitted.Google Scholar
- Ching F C, Jou B J D, Lin P-L and Hong J S 2005 A real-time MM5/WRF forecasting system in Taiwan, www.mmm.ucar.edu/MM5/workshops/ws04/PosterSession/Chien.Fang-Ching.pdf.
- Deb S K, Kishtawal C M, Pal P K and Joshi P C 2008 Impact of TMI SST for the simulation of heavy rainfall episode over Mumbai on 26th July 2005; Mon. Wea. Rev. (doi: 10.1175/2008MWR2291.1), in press.Google Scholar
- Dorita R-E, Lui L, Ge M, Warner T and Swaerdlin S 2006 Simulation of high impact weather event over Isreal with WRF-RTFDDA System — A Case Study, www.ucar.edu/wrf/users/workshops/WS2006/abstracts/psession/P8_09_Rostkier_Edestien.pdf.
- Kain J S and Fritsch J M 1993 Convective parameterisation of mesoscale models: The Kain-Fritsch scheme; In: The Represenation of Cumulus Convection in Numerical Models (eds) Emanuel K A and Raymonds D J, Amer. Meteor. Soc., Boston, pp. 165–170.Google Scholar
- Mazarakis N, Kotroni V, Lagouvardos K and Music Nickovic S 2006 Impact of the assimilation of conventional data on the quantitative precipitation forecasts in the Eastern Mediterranean; Adv. Geo. Sci. 7 237–242.Google Scholar
- Mesinger F 1996 Improvements in Quantitative Precipitation Forecasts with the ETA Regional Model at National Centers for Environmental Prediction: The 48-km Upgrade; Bull. Amer. Meteorol. Soc. 2637–2649.Google Scholar
- Skamarock W C, Klemp J B, Dudhia J, Gill D O, Barker D M, Wang W and Powers J G 2005 A description of the Advanced Research WRF Version 2; NCAR Tech Note, NCAR/TN-468+STR, 88 pp. (Available from UCAR Communications, P. O. Box 3000, Boulder, CO 80307).Google Scholar