Diurnal cycle of the Intertropical Convergence Zone in the east Pacific
Diurnal cycle of the Intertropical Convergence Zone in the east Pacific
复制标题
东太平洋热带辐合带的日循环
DOI：
10.1029/2010jd014835
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发表时间：
2010
影响因子：
--
通讯作者：
H. Stern
中科院分区：
文献类型：
--
作者：
C. Bain;G. Magnusdottir;Padhraic Smyth;H. Stern
[1]利用东太平洋90°W-180°W，0°N-25°N的热带辐合带（ITCZ）范围和位置资料，研究了海洋云量的日变化。该数据集是使用统计模型生成的，该模型利用了1980年至2009年的30年每3小时红外（IR）卫星数据。对流的ITCZ包络线在整个区域有一个明显的日变化周期，云量的范围在下午达到峰值。ITCZ内亮温的日变化是由东向西变化的，但平均IR有两个极小值，表明冷云的日变化有一个高峰，一个出现在上午0600-0900，另一个出现在下午1300-1600。对云顶温度的分解表明，高云在清晨达到最大值，中层云在下午达到最大值。低云在傍晚（2200-0000 LST）达到最大值，紧接着是高云的增加，这表明最深的对流系统在几个小时内迅速增长。云顶温度的日变化存在季节性变化，表明当ITCZ较宽时，下午平均温度较低的可能性较大。这是通过季节变化和比较厄尔尼诺年，当ITCZ是更存在，拉尼娜年。
[1] A data set of Intertropical Convergence Zone (ITCZ) extent and location in the eastern Pacific, 90°W–180°W, 0°N–25°N, is used to examine the diurnal cycle of cloudiness over the ocean. The data set was generated using a statistical model which utilizes 30 year, 3‐hourly infrared (IR) satellite data from 1980 to 2009. The ITCZ envelope of convection has a significant diurnal cycle across the whole domain, and the area of cloudiness “pulses” in extent, peaking in the afternoon. The diurnal cycle of brightness temperatures within the ITCZ changes from east to west, but generally there are two minima in mean IR, implying cold cloud is at a peak: one in the morning, 0600–0900 LST, and another in the afternoon, 1300–1600 LST. Decomposition of cloud top temperatures show that high cloud is at a maximum in the early morning and midlevel cloud peaks in the afternoon. Low cloud is at a maximum in the late evening (2200–0000 LST) and is immediately followed by increases in high cloud, suggesting that the deepest convective systems grow rapidly, within a few hours overnight. There are seasonal changes in the diurnal cycle of cloud top temperature, and it is suggested that colder mean temperatures are more likely in the afternoon when the ITCZ is more extensive. This is shown via seasonal changes and also by comparing El Nino years, when ITCZ is more present, to La Nina years.