Using time‐slice experiments performed with version 4 of the Whole Atmosphere Community Climate Model (WACCM4) and satellite observations, we investigate hemispheric differences in, and the seasonal dependence of, water vapor transport into the stratosphere in response to Indo‐Pacific warm pool (IPWP) sea‐surface temperature (SST) variations. Specifically, the amplitude of the lower stratospheric water vapor (SWV) response to a warmer (cooler) IPWP (i.e., IPWP Niño [Niña]) occurs mainly in boreal winter when the IPWP SST forcing is identical for different seasons, and the response in the northern tropics (NT) is greater than that in the southern tropics (ST). The seasonality in and hemispheric contrasts of the SWV response to IPWP Niño and IPWP Niña are traced to the tropical cold point temperature, including its zonally symmetric pattern associated with tropical upwelling and its zonally asymmetric features that manifest as the morphology of the coldest point region. Together with the seasonal variations in topical upwelling response, the morphology of the coldest point region, which is affected by equatorial planetary waves and the summer monsoon, determines the seasonality and NT‐ST contrasts in the SWV response to IPWP SST forcing. Among these factors, the importance of the climatological displacement of convective activity from the equator to NT associated with the summer monsoon is highlighted.

中文翻译：

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印度洋-太平洋暖池对平流层下部水汽的影响：季节性和半球对比

使用对整个大气层社区气候模型（WACCM4）第4版进行的时间片实验和卫星观测，我们调查了响应印度洋太平洋暖池而进入平流层的水汽输送的半球差异和季节依赖性（ IPWP）海表温度（SST）的变化。具体而言，较低平流层水汽（SWV）对较暖（较冷）的IPWP（即IPWPNiño[Niña]）的响应幅度主要发生在北方冬季，当不同季节的IPWP SST强迫相同时，北部热带地区（NT）大于南部热带地区（ST）。SWV对IPWPNiño和IPWPNiña的响应的季节性和半球对比可追溯到热带冷点温度，包括与热带上升相关的纬向对称模式，以及表现为最冷点区域形态的纬向不对称特征。加上局部上升响应的季节变化，受赤道行星波和夏季风影响的最冷点区域的形态决定了SWV对IPWP SST强迫的响应中的季节性和NT-ST对比。在这些因素中，突出强调了与夏季风有关的对流活动从赤道到北半球气候转移的重要性。受到赤道行星波和夏季风的影响，决定了S​​WV对IPWP SST强迫的响应中的季节性和NT-ST对比。在这些因素中，突出强调了与夏季风有关的对流活动从赤道到北半球气候转移的重要性。受到赤道行星波和夏季风的影响，决定了S​​WV对IPWP SST强迫的响应中的季节性和NT-ST对比。在这些因素中，突出强调了与夏季风有关的对流活动从赤道到北半球气候转移的重要性。