Seasonal Rainfall Forecasts for the Yangtze River Basin of China in Summer 2019 from an Improved Climate Service

• Published in: Journal of Meteorological Research Vol. 34; no. 5; pp. 904 - 916
• Main Authors: Bett, Philip E., Martin, Nicola, Scaife, Adam A., Dunstone, Nick, Martin, Gill M., Golding, Nicola, Camp, Joanne, Zhang, Peiqun, Hewitt, Chris D., Hermanson, Leon, Li, Chaofan, Ren, Hong-Li, Liu, Ying, Liu, Min
• Format: Journal Article
• Language: English
• Published: Beijing The Chinese Meteorological Society 01-10-2020; Met Office Hadley Centre, Exeter EX13PB, UK%Met Office Hadley Centre, Exeter EX13PB, UK; College of Engineering, Mathematics and Physical Sciences, University of Exeter, Devon EX44QF, UK%Laboratory for Climate Studies, National Climate Center, China Meteorological Administration, Beijing 100081, China%Met Office Hadley Centre, Exeter EX13PB, UK; Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science &Technology, Nanjing 210044, China%Wuhan Regional Climate Center, Wuhan 430074, China; Plymouth Marine Laboratory, Plymouth PL13DH, UK%Met Office Hadley Centre, Exeter EX13PB, UK; University of Southern Queensland, Toowoomba QLD 4350, Australia%Center for Monsoon System Research, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China%Laboratory for Climate Studies, National Climate Center, China Meteorological Administration, Beijing 100081, China
• Subjects: Atmospheric Protection/Air Quality Control/Air Pollution; Atmospheric Sciences; Climate Science for Services Partnership (CSSP) China; Earth and Environmental Science; Earth Sciences; Geophysics and Environmental Physics; Meteorology; East Asian summer monsoon (EASM); Yangtze River basin (YRB); climate service; seasonal rainfall forecasts
• ISSN: 2095-6037; 2198-0934
• DOI: 10.1007/s13351-020-0049-z

Rainfall forecasts for the summer monsoon season in the Yangtze River basin (YRB) allow decision-makers to plan for possible flooding, which can affect the lives and livelihoods of millions of people. A trial climate service was developed in 2016, producing a prototype seasonal forecast product for use by stakeholders in the region, based on rainfall forecasts directly from a dynamical model. Here, we describe an improved service based on a simple statistical downscaling approach. Through using dynamical forecast of an East Asian summer monsoon (EASM) index, seasonal mean rainfall for the upper and middle/lower reaches of YRB can be forecast separately by use of the statistical downscaling, with significant skills for lead times of up to at least three months. The skill in different sub-basin regions of YRB varies with the target season. The rainfall forecast skill in the middle/lower reaches of YRB is significant in May–June–July (MJJ), and the forecast skill for rainfall in the upper reaches of YRB is significant in June–July–August (JJA). The mean rainfall for the basin as a whole can be skillfully forecast in both MJJ and JJA. The forecasts issued in 2019 gave good guidance for the enhanced rainfall in the MJJ period and the near-average conditions in JJA. Initial feedback from users in the basin suggests that the improved forecasts better meet their needs and will enable more robust decision-making.