Skill of short- to medium-range monsoon rainfall forecasts from two global models over India for hydro-meteorological applications

Meteorological applications

article

Satya Prakash¹  Ashis K. Mitra¹  I. M. Momin¹  E. N. Rajagopal¹  Sean F. Milton²  Gill M. Martin² 

[1] National Centre for Medium Range Weather Forecasting (NCMRWF), Earth System Science Organization (ESSO), Ministry of Earth Sciences;Global Modelling Division, Met Office

关键词: Indian summer monsoon rainfall;    medium-range weather forecast;    numerical weather prediction models;    skill metrics;    hydro-meteorological applications;    flood forecast;   

DOI  :  10.1002/met.1579

学科分类：社会科学、人文和艺术（综合）

来源: Wiley

【 摘 要 】

The South Asian region is dominated by summer monsoon rainfall which, in many years, is associated with severe floods leading to socio-economic losses. In India, areas with high population are exposed to heavy rainfall events and their associated risks. Indian monsoon rainfall simulation and prediction at various spatial and temporal scales are challenging scientific tasks for the weather/climate modelling community. Skilful short- and medium-range predictions of rainfall from global numerical models during monsoons are highly desirable for various hydro-meteorological applications, including flood forecasting. For recent years (e.g. 2000–2016) higher resolution global advanced assimilation-forecast systems have resulted in improved medium-range rainfall forecasts. These model rainfall forecasts potentially could be used in hydro-meteorological applications including water-related disaster management/planning. In this study, deterministic rainfall forecasts from two state-of-the-art global models (from the National Centers for Environmental Prediction and the Met Office) were evaluated against observed rainfall for the Indian summer monsoon season. Objective skill scores such as mean, bias, correlation co-efficient, mean absolute error and root-mean-square error from Day 1 to Day 5 were examined for the monsoon season over India and at seven major river basins within India for 2013. It was seen that both of the models had useful skill for different regions and basins. For the Indus and Krishna basins, even the Day 5 forecasts were seen to be skilful. In general, the Met Office Day 5 forecasts were more skilful at all seven river basins. Finally, rainfall forecasts from the latest higher resolution Met Office Global Unified Model (implemented in July 2014) were compared with its immediate predecessor to document any further improvement during the monsoon period over India. It was seen that, at the medium range, the newer version of the Met Office model simulated Indian monsoon rainfall more realistically than the previous versions, with much reduced biases in the core monsoon trough region.

【 授权许可】

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