Southeast China Rainfall Variability and its Relationship with the Large-Scale Circulation Over the Indo-Pacific Region and East Asia
Monday, June 15, 2015
Chi-shing Calvin Cheung, The Chinese University of Hong Kong, Institute of Environment, Energy and Sustainability, Hong Kong, Hong Kong, Chi-Yung Francis Tam, The Chinese University of Hong Kong, Earth System Science (ESSC), Hong Kong, Hong Kong and Sai-ming Lee, Hong Kong Observatory, Hong Kong, Hong Kong
Abstract:
In this study, the ability of five different general circulation model (GCM)-based dynamical seasonal forecasting systems in reproducing southeastern China (SEC) seasonal rainfall variability, as well as the latter’s covariability with the large-scale atmospheric circulation, was assessed by comparing simulations from the corresponding model hindcast experiments and NCEP/NCAR Reanalysis (NNR), covering the period of 1983 – 2008. Using singular value decomposition analysis (SVDA), it was found that SEC rainfall has strong covariability with the large-scale sea level pressure (SLP) over the Indo-Pacific to continental East Asian region on the inter-annual timescale. Building on such a strong relationship between SLP and SEC rainfall anomalies, a statistical downscaling scheme was further formulated in order to improve the performance of GCMs in the local SEC rainfall prediction. Cross-validated results show that such a scheme based on rainfall-SLP relationship can lead to improvements in seasonal forecasts of rainfall of some of the models. The potential use of such a scheme for studying the impact of climate change on the SEC regional rainfall variability will be discussed.
