The intertropical convergence zone (ITCZ) accounts for more than 30% of the global precipitation and its variability has a great effect on the people living in the tropical area. It is the manifestation of the Hadley circulation, tropical dynamic and thermodynamic coupling and the air-sea interaction. Therefore, it is essential to understand the changes and variability of the ITCZ, including its position and intensity. Using observed precipitation from GPCP and TRMM 3B43, as well as the ERA5 reanalysis data, we examine the ITCZ variations over the global and seven regions from 1998-2018. These data sets show consistent ITCZ climatology and inter-annual variability. Except over Atlantic and eastern Pacific where ITCZ stays in the northern hemisphere, the ITCZ crosses the equator after equinoxes over other sections. There is no overall significant shift of annual mean ITCZ position over the globe and seven regions, except over the America section where the GPCP data show a significant increase trend of 0.8°decade-1 and over the western Pacific section where ERA5 data show a significant decrease trend of -1.2°decade-1. The ITCZ positions over the globe and Africa are related to both ENSO and NAO, while ITCZ position over eastern Pacific is significantly affected by ENSO and the Atlantic ITCZ is mainly related to NAO. Except for the western Pacific, all other sections are significantly related to local meridional surface temperature gradient, particularly over America, Atlantic and eastern Pacific. The meridional gradient variation of the vertically integrated moist static energy has generally good agreement with the shift of the intertropical convergence zone, particularly for the seasonal climatology over the Africa region. The relationship between ITCZ position and intensity shows complicated patterns, with positive correlation over the globe, but different correlations over different sections. The two observed data sets are more or less consistent, but ERA5 shows discrepancies over some sections. It is also found that the local meridional temperature gradient has more influences on the ITCZ positions than the global one

中文翻译：

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1998-2018年间观测到的热带辐合带的变化

热带辐合带（ITCZ）占全球降水量的30%以上，其变异性对热带地区的居民影响很大。它是哈德利环流、热带动力和热力耦合以及海气相互作用的体现。因此，必须了解 ITCZ 的变化和可变性，包括其位置和强度。使用 GPCP 和 TRMM 3B43 观测到的降水，以及 ERA5 再分析数据，我们检查了 1998-2018 年全球和七个地区的 ITCZ 变化。这些数据集显示了一致的 ITCZ 气候学和年际变化。除了 ITCZ 位于北半球的大西洋和东太平洋，ITCZ 在其他部分的春分点之后穿过赤道。全球和七个地区的年平均 ITCZ 位置没有整体显着变化，除了美洲段 GPCP 数据显示 0.8°decade-1 的显着增加趋势和西太平洋段 ERA5 数据显示显着增加趋势-1.2°decade-1 的下降趋势。全球和非洲的 ITCZ 位置与 ENSO 和 NAO 均有关，而东太平洋 ITCZ 位置受 ENSO 影响显着，大西洋 ITCZ 位置主要与 NAO 相关。除西太平洋外，所有其他剖面都与局地经向表面温度梯度显着相关，尤其是在美洲、大西洋和东太平洋。垂直积分湿静能的经向梯度变化与热带辐合带的移动总体吻合较好，特别是对于非洲地区的季节性气候学。ITCZ位置与强度的关系呈现复杂的格局，在全球范围内呈正相关，但在不同区间呈不同的相关性。两个观察到的数据集或多或少是一致的，但 ERA5 在某些部分显示出差异。还发现局部经向温度梯度对 ITCZ 位置的影响大于全球经向温度梯度