SS01 – The Asian Monsoon in a Changing Climate
|
Thu-02 Jul 2020 | 13:30 – 15:30 | Tower B, Lavender II Chih-Pei CHANGNational Taiwan University “Boreal Winter Seasonal Prediction of Western Maritime Continent Rainfall During ENSO” |
Chih-Pei CHANG1,2#+, Tim LI3, Song YANG4
1National Taiwan Universit, 2Naval Postgraduate School, 3University of Hawaii, 4Sun Yat-sen University
Since the beginning of the Association of Southeast Asian Nations Climate Outlook Forum (ASEANCOF) in 2013, the most difficult challenge has been the rainfall forecast in boreal winter. This is the Maritime Continent monsoon season during which rainfall reaches maximum in the annual cycle. This forecast difficulty arises in spite of the general notion that seasonal predictability of the Maritime Continent rainfall may be higher than most places because of the strong and robust influences of ENSO. The lower predictability is consistent with the lower correlation between ENSO and western Maritime Continent rainfall that reaches minimum during the boreal winter monsoon. Various theories have been proposed to explain this low correlation. In this paper we review the relevant research and show that the main cause of the forecast difficulty is the wind-terrain interaction involving the Sumatran and Malay Peninsula mountains, rather than the effect of sea-surface temperature (SST). The wind-terrain interaction due to the low-level regional scale anomalous horizontal circulation offsets the anomalous Walker circulation during both El Nino and La Nina. The net result of these two opposing responses to ENSO is a lower local predictability. We propose to call this low-predictability region the WIMP (western Indonesia-Malay Peninsula) region both for its geographical location and its special characteristic of causing difficulties for forecasters to make a confident forecast during the boreal winter. Our result suggests climate models lack skills in forecasting rainfall in this region because their predictability depends strongly on SST. The predictability may increase if a warming climate in the future affects the Walker circulation and the horizontal circulation in a significantly different way, but proper treatment of the terrain effect remains important...
Biography
Chih-Pei Chang is Distinguished Chair Professor of Atmospheric Sciences at National Taiwan University and Distinguished Professor Emeritus at Naval Postgraduate School. He received his B.S. from National Taiwan University in 1966 and Ph.D. from University of Washington in 1972. His research interest includes dynamic meteorology, tropical meteorology, monsoons, and climate dynamics. He has edited/co-edited 11 books published by Oxford University Press, World Meteorological Organization, and World Scientific Publishing Company. He received the Sigma Xi Monterey Chapter Menneken Research Award in 1980, was elected a Fellow of the American Meteorological Society in 1982, received the AMS Meisinger Award in 1983, Papers in Meteorological Research Best Paper Award in 1989, and Naval Postgraduate School Distinguished Professor Medal in 2003, He was elected a Fellow of the Meteorological Society of Republic of China in 2007, and received US Navy Superior Civilian Service Award in 2013. He was Lead Advisor for the Central Weather Bureau Modernization Project from 1984 to 1999, and has served as a member of scientific advisory committees of Hong Kong Observatory, APEC Climate Center, Beijing Climate Center, and Center for Climate Research Singapore. In 2013 he was named an Honorary Member of the Hong Kong Meteorological Society for his role in founding the HKMS. In 2017 he received a Certificate of Appreciation from WMO Commission of Atmospheric Sciences for his leadership over a decade as Chair of the WMO Monsoon Panel. He has been Chair of the Editorial Committee and Editor-in-Chief for World Scientific Series on Asia-Pacific Weather and Climate since 2000.