Prediction of extreme rainfall associated with monsoon depressions over Odisha: an assessment of coastal zone vulnerability at district level

Abstract

The present study investigates the climatological rainfall vulnerability districts associated with monsoon depressions (MDs) over Odisha using both observational and modeling perspectives for a period of 34�years (1980�2013). Four heavy rainfall cases associated with MDs crossed Odisha are simulated with the help of high-resolution advanced research weather research forecasting system, and the rainfall vulnerability mapping for more than 1-mm rainfall values at district level are evaluated. The observational analyses on the frequency of MDs for the study period exhibit a decreasing trend. It is noticed that the rainfall vulnerability districts are present to the left side of the track of the MDs. The model simulation result depicts that the location of formation of MDs is always behind the actual position of the system and also do the landfall after the actual time. The model has a positive bias in the prediction of the intensity of rainfall and a spatial shift in the distribution of rainfall. The model is showing higher Heidke skill for less intensity rainfall threshold values. The analysis also suggests that the maximum rainfall vulnerable districts are present 150�200�km away from the original position, still these districts are present to the left side of the MDs. Analysis on the horizontal and vertical structure of MD suggests that the presence of relative humidity is less in WRF and the distribution of relative vorticity is not same as the observation, which may be the major causes of having such error in predicting heavy rainfall. � 2019, Springer Nature B.V.