Using observational data and model simulations, the author find that the North Indian Ocean (NIO) sea surface temperature (SST) anomalies can trigger an eastward atmospheric Kelvin wave propagating into the equatorial western Pacific, inducing an anomalous anticyclone over the subtropical Northwest Pacific (NWP) and resulting in prominent summer climate anomalies in the East Asia-Northwest Pacific (EANWP) region. However, the response of tropospheric temperatures and atmospheric Kelvin waves to the South Indian Ocean (SIO) SST anomalies is weak; as a result, the impact of the SIO SST anomalies on the EANWP summer climate is weak. The contrasting impacts of NIO and SIO SST anomalies on the EANWP summer climate is possibly due to the mean state of SSTs in the two regions. In summer, the climatological SSTs in the NIO are higher than in the SIO, leading to a stronger response of atmospheric convection to the NIO SST anomalies than to the SIO SST anomalies. Thus, compared with the SIO SST anomalies, the NIO SST anomalies can lead to stronger tropospheric air temperature anomalies and atmospheric Kelvin waves to affect the EANWP summer climate.
利用观测资料和数值模拟，本文发现北印度洋海温异常比南印度洋海温异常对东亚夏季气候有更显著的影响。北印度洋海温异常能激发东传的开尔文波动，造成副热带西北太平洋反气旋异常，从而导致东亚夏季气候异常。而南印度洋上空大气气温对南印度洋海温异常的响应较小，不能造成显著的大气开尔文波动，从而对东亚和副热带西北太平洋夏季气候影响较小。这种差异可能归因于南北印度洋不同的气候态海温。夏季，北印度洋气候态海温显著高于南印度洋，导致大气对流活动对北印度洋海温异常的响应更强。从而和南印度洋相比，北半球海温异常能激发更强的大气开尔文波动来影响东亚夏季气候。