Lagged Responses of the Tropical Pacific to the 11-yr Solar Cycle Forcing and Possible Mechanisms

• 作者: Wenjuan HUO Ziniu XIAO Xin WANG Liang ZHAO
• 来源期刊: 气象学报（英文版）
• 年，卷（期）: 2021,（3）
• 所属期刊栏目: ORIGINAL PAPER
• 页码范围: 444-459
• 页数: 16页
• 语种: 英文

摘要

This paper uses two subsets of ensemble historical-Nat simulations and pi-Control simulations from CMIP5 as well as observational/reanalysis datasets to investigate responses of the tropical Pacific to the 11-yr solar cycle. A statistic-ally significant 11-yr solar signal is found in the upper-ocean layers above the thermocline and tropospheric circula-tions. A warming response initially appears in the upper layers of the central equatorial Pacific in the solar maximum years in observations, then increases and shifts into the eastern Pacific at lagged 1–3 yr. Meanwhile, an anomalous updraft arises over the western equatorial Pacific and shifts eastwards in the following years with anomalous subsid-ence over the Maritime Continent. These lagged responses are confirmed by the historical-Nat simulations, except that the initial signal is located more to the west and all the responses are weaker than the observed. A simplified mixed-layer heat budget analysis based on the historical-Nat simulations suggests that the atmospheric forcing, espe-cially the shortwave radiation, is the major contributor to the initial warming response, and the ocean heat transport effect is responsible for the eastward displacement of the lagged warming responses. In the solar maximum years, the zonal ocean temperature gradient in the western–central Pacific is reduced by the initial warming, and anomalous westerly winds appear over the western equatorial Pacific and extend into the eastern Pacific during the lagged years. These anomalous westerly winds reduce the wind-driven ocean dynamical transport, resulting in the initial warming in the central equatorial Pacific being amplified and the surface warming shifting eastward during the lagged 1–3 yr.