Verification and usability of medium range weather forecast for north bank plain zone of Assam, India

摘要

Location specific multi-model ensemble (MME) weather forecast issued by IMD for Sonitpur, representing district of north bank plain zone of Assam during March, 2009 to February, 2014 has been analyzed and verified for its accuracy. Analysis of the verification of the forecast data, were carried on seasonal and annual (March-February) basis using various verification techniques, viz., ratio score, Hanssen and Kuipers (H.K) Score, probability of detection (POD), Heidke skill score (HSS), false alarm ratio (FAR), critical success index (CSI) and RMSE for rainfall, and RMSE for other parameters (viz., maximum and minimum temperature, wind speed, morning and afternoon relative humidity), usability analysis and correlation approach during March, 2009 - February, 2014. The ratio score of rainfall was higher during post monsoon and winter seasons as compared to pre-monsoon and monsoon seasons, indicating the performance of multi-model ensemble under Sonitpur worked better in post-monsoon and winter seasons than in the other two seasons. Very good performance was observed for rainfall and wind speed during pre-monsoon season. During monsoon season, performance of rainfall was found poor and other parameters were found excellent. During post-monsoon excellent performance was observed for rainfall and wind speed but poor performance was observed for minimum temperature forecast. In winter, the forecasting performance of rainfall was excellent during all years. Correlation-coefficients were derived between the forecasted and observed values during different seasons. Rainfall was highly correlated during all seasons except monsoon and annual basis. Hence, the forecast was found widely applicable among different user groups.