This study examines the potential impact of subsurface potential temperature and current conditions on the sea surface temperature (SST) and rainfall over the tropical region using Climate Forecast System Version 2 (CFSv2) ensemble seasonal reforecasts for 1958–2014. The climatological difference of earlier period (1958–78; P58‐78) and later period (1994–2014; P94‐14) in January initialized reforecasts (JIR) depicts mild‐warm SST over the equatorial eastern Pacific in January, but its magnitude becomes larger over there from May to August. The difference between JIR P58‐78 and P94‐14 depicts warm potential temperature (PT) up to 3°C over the equatorial central and eastern Pacific at depth from 155 to 70 m in January therefore 20°C isotherm of JIR P58‐78 in January tends to be deeper in the equatorial eastern Pacific than JIR P94‐14. The magnitude of equatorial undercurrent (EUC) in JIR P58‐78 is larger in the eastern Pacific at depth from 125 to 35 m from January to February than JIR P94‐14. Therefore, water upwelled to the surface through EUC was usually warm in January of JIR P58‐78. As lead months increase, the center of warm PT gradually moves upward in the eastern Pacific than its location in January, resulting in development of warm SST in the eastern Pacific in March. The difference between April initialized reforecasts P58‐78 and P94‐14 depicts warm PT up to 1.5°C in the eastern Pacific at depth from 135 to 35 m in April but as lead months increase, magnitude of warm PT gradually decreases, resulting in negligible difference SST over the eastern Pacific.

中文翻译：

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CFSv2预报中地下条件对热带SST时空变化和降雨的影响

这项研究使用1958–2014年气候预报系统第2版（CFSv2）总体季节性预报，研究了热带地区海表温度和当前条件对海表温度（SST）和降雨的潜在影响。一月的初始预报（JIR）在较早时期（1958-78； P58-78）和较晚时期（1994-2014； P94-14）的气候差异描述了1月赤道东太平洋的温和暖SST，但其幅值从五月到八月，那里变得更大。JIR P58-78和P94-14之间的差异描述了1月赤道中太平洋和东太平洋从155到70 m深度处最高3°C的暖势温度（PT），因此JIR P58-78在20°C等温线一月在赤道东太平洋比JIR P94-14更深。东太平洋JIR P58-78的赤道暗流（EUC）的强度在1月至2月的125至35 m深度比JIR P94-14大。因此，通过EUC上升到地表的水通常在JIR P58-78的一月变暖。随着铅月份的增加，东太平洋暖PT中心比1月份的位置逐渐向上移动，导致3月份东太平洋暖SST的发展。4月初始化的重预报P58-78和P94-14之间的差异描述了东太平洋4月从135到35 m深度处高达1.5°C的温暖PT，但随着铅月份的增加，温暖PT的幅度逐渐减小，因此可以忽略不计东太平洋的海温差异。