Indian monsoon data assimilation and analysis regional reanalysis: Configuration and performance

A high resolution, long-term regional reanalysis over the Indian subcontinent has been developed and is currently in production. The regional reanalysis has been produced as part of the Indian Monsoon Data Assimilation and Analysis (IMDAA) project and is the outcome of a collaboration between the Met Office (MO), the National Centre for Medium Range Weather Forecasting (NCMRWF) and the India Meteorological Department (IMD). The reanalysis will produce a consistent data set of high-resolution fields for a wide range of atmospheric variables available from 1979 to 2016. Production runs started in 2017, and computations for 10 years have been completed as of May 2017. The entire production will be completed in early 2018. This article introduces the IMDAA regional reanalysis, describes the forecast model, data assimilation method, and input data sets used to produce the reanalysis. The performance of the system from a pilot study run for 2008-2009 are presented indicating that the regional reanalysis is able to capture major monsoon featuresa key phenomenon in the Indian subcontinent.