ANNOUNCEMENTS
Carrying out weather and climate prediction for longer than 15 days, especially for tropical regions like India, is mainly based on how well anomalous features are captured by the models. Coupled models incorporating various stand-alone atmosphere, land, sea-ice, ocean models have been observed to capture such anomalies well. NCMRWF uses a fully coupled global model (NCUM-G) having a resolution of 60 km to produce such extended range prediction (ERP) products wherein the forecasts are valid for up to four weeks. Although the products have a coarser resolution, it has been observed that the forecast accuracy is generally higher for the first week and well captured through to the second week. The forecast accuracy, however, has been observed to deteriorate after the second week. NCMRWF’s own developed regional model (NCUM-Reg) of 4 km resolution issues forecasts valid for 3 days which are dynamically downscaled from the NCUM-G model, and it has been observed to produce well-defined forecast products with greater accuracy. Indian Summer Monsoon Rainfall (ISMR) has a number of active and break phases within a season. An active phase was selected and NCUM-G ERP products, NCUM-Reg products were observed for the selected ISMR active phase. All the comparisons have been done against observed data for the JJAS 2021 season and the selected active phase within the same season. The predictability skills of the dynamically downscaled NCUM-Reg model has also been studied.
Keywords: NCUM-G, Coupled modelling, ERP, Dynamical Downscaling, NCUM-Reg, ISMR, Active Phase.
