Predictability of the Western North Pacific Subtropical High Associated with Different ENSO Phases in GloSea5

• 作者: Daquan ZHANG Gill M. MARTIN José M. RODRíGUEZ Lijuan CHEN Zongjian KE
• 来源期刊: 气象学报（英文版）
• 年，卷（期）: 2020,（5）
• 所属期刊栏目: SPECIAL COLLECTION ON CLIMATE SCIENCE FOR SERVICE PARTNERSHIP (CSSP) CHINA
• 页码范围: 926-940
• 页数: 15页
• 语种: 英文

摘要

The western North Pacific subtropical high (WNPSH) dominates the summer climate over East Asia. The intensity, position, and shape of WNPSH influence the spatiotemporal distributions of precipitation, temperature, and tropical cyclone activities in this region. This paper intends to investigate the performance of the UK Met Office Global Sea-sonal forecast system version 5 (GloSea5) in simulation/prediction of the WNPSH based on a hindcast dataset. Ana-lyses of the hindcast data show a systematic bias in the mean circulation over West Pacific, with negative geopoten-tial height anomalies over the western North Pacific (WNP) and cyclonic anomalies in the 850-hPa winds and water vapor transport, indicating a weakening and eastward shift of the WNPSH. Despite the model's bias in the climato-logy, it well captured the interannual variability of the monthly and seasonal-mean intensity of the WNPSH and the position of its ridge line in boreal summer from 1993 to 2015. The seasonal hindcasts indicate that there is signific-ant prediction skill at up to three-month lead time for both the intensity and position of the WNPSH ridge line. The relationship between the WNPSH and different phases of the El Ni?o–Southern Oscillation (ENSO) in both the ob-servational data and GloSea5 hindcasts was then investigated. The model captured the summer WNPSH anomalies well during most of the ENSO phases, except in the La Ni?a decaying and neutral summers. The intensity of the anti-cyclone in the WNP is weak in the decaying phase of El Ni?o in the GloSea5 hindcasts compared with the reanalysis data. GloSea5 is capable of representing the lagged teleconnection between El Ni?o events in the previous winter and the intensity of the WNPSH in the following summer. Regression analysis reveals weakened negative sea surface temperature anomalies (SSTAs) over the WNP in GloSea5, which reduced the gradient between the tropical western Pacific and the tropical Indian Ocean, resulting in a weaker easterly anomaly and stronger westerly anomaly, contrib-uting to the weak anomalous anticyclone over the WNP and the weakened WNPSH relative to the reanalysis data.