Performance of NCUM global weather modeling system in predicting the extreme rainfall events over the central India during the Indian summer monsoon 2016
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Indian summer monsoon rainfall shows predominant intraseasonal variability with extremes such as droughts and floods being a part of its natural variability. In this aspect, forecast from the National Centre for Medium Range Weather Forecasting based global model (NCUM) with 17 km horizontal resolution is examined for the synoptic features associated with the heavy rainfall events during 2016 summer monsoon over central India. As 2016 monsoon brought anomalous rainfall over central India resulting in flood in many parts of east and west Madhya Pradesh, the analyses concentrate on two active phases of summer monsoon, i.e., 2nd July 2016–13th July 2016 (phase 1) and 2nd August 2016–7th August 2016 (phase 2). The details during said two phases of extreme events are compared with the observations. It is found that the model has a reasonable skill in large-scale features in simulating these extreme events with reasonable bias and a good correlation. NCUM could forecast these extreme rainfall events with a lead time of 5 days (up to Day-5 forecast) and the spatial correlation indicate that the forecast skill of the NCUM is reasonable for Day-1, and the skill decreases by Day-5. Analysis and model forecast at 850 and 500 hPa level for wind and moisture transport are used in this study. It is seen that the stronger winds and associated moisture transport from Arabian Sea and Bay of Bengal to the Indian land region leading to the extreme rainfall events.
KeywordsExtreme rainfall Indian monsoon NCUM Bias RMSE
The authors are thankful to Head NCMRWF, Noida for his encouragement for this work. Comments from anonymous reviewers helped to improve the quality of this study.
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