The intensity of the interannual variability (IIV) of the mean tropical cyclone (TC) genesis latitude over the western North Pacific (WNP) has been weakening significantly since the late 1990s. It is found that the IIV of the mean TC genesis latitude depends largely on the strength of the out-of-phase relationship between TC genesis numbers in the north (north of 15°N) and south (south of 15°N) of the WNP. A weaker (stronger) north–south TC see-saw has led to a smaller (larger) IIV of the mean TC genesis latitude after (before) the late 1990s. Different configurations of sea surface temperature (SST) anomalies are found to be responsible for the decadal changes in the north–south TC see-saw and dipole structure. Before the late 1990s, the joint effect of SST anomalies over the tropical Pacific and tropical North Indian Ocean dominated, rendering the obvious north–south TC see-saw and larger IIV of the mean TC genesis latitude. After the late 1990s, however, the dominant SST anomalies associated with TC genesis shift to the tropical central Pacific (CP) and tropical North Atlantic Ocean, which have weakened the north–south TC seesaw and reduced the IIV of the mean TC genesis latitude. These observed decadal changes in the configuration of SST anomalies are considered to be closely associated with the shift of the El Niño–Southern Oscillation (ENSO) from eastern Pacific (EP) type to the CP type during the recent decades. The results suggest that the increased influences from the tropical Atlantic Ocean have become more important to the variations of TC activity in the WNP during the recent decades. These results may have important implications for assessing the latitudinal distributions of TC-induced hazards.

自1990年代后期以来，北太平洋西部（WNP）的平均热带气旋（TC）发生纬度的年际变化强度（IIV）一直在明显减弱。发现平均TC成因纬度的IIV很大程度上取决于北半球（北纬15°）和南侧（南纬15°）TC起源数之间的异相关系的强度。 WNP。1990年代后期之后（之前），南北向TC跷跷板减弱（较强）导致平均TC产生纬度的IIV较小（较大）。发现海平面温度（SST）异常的不同配置是南北TC跷跷板和偶极子结构年代际变化的原因。在1990年代后期之前，海温异常在热带太平洋和热带北印度洋上的共同影响占主导地位，呈现明显的南北向TC跷跷板和更大的平均TC产生纬度IIV。但是，在1990年代后期之后，与TC成因有关的主要SST异常转移到了热带中部太平洋（CP）和热带北大西洋，这削弱了南北TC跷跷板并降低了平均TC成因纬度的IIV。近几十年来，这些观测到的海温异常构造年代际变化被认为与厄尔尼诺-南方涛动（ENSO）从东太平洋（EP）型向CP型的转变密切相关。结果表明，近几十年来，来自热带大西洋的影响的增加对于WNP中TC活性的变化变得越来越重要。