Diurnal Cycle of the ITCZ in DYNAMO
Diurnal Cycle of the ITCZ in DYNAMO
复制标题
DYNAMO 中 ITCZ 的昼夜周期
DOI：
10.1175/jcli-d-17-0670.1
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发表时间：
2018
影响因子：
4.9
通讯作者：
Ruppert, James H.
中科院分区：
文献类型：
--
作者：
Ciesielski, Paul E.;Johnson, Richard H.;Schubert, Wayne H.;Ruppert, James H.
在2011年马登-朱利安振荡动力学(迪纳摩)野外实验的特别观测期间，在印度洋中部建立了两个探测阵列，一个在赤道以北，一个在赤道以南，在这里分别称为NSA和SSA。利用这些阵列每三小时一次的辐射和降雨观测资料，研究了MJO抑制阶段ITCZ对流的日循环。在10月上半月，当对流在国家气象局上空被抑制，而在SSA上空显著时，探空阵列上的环流可以被描述为局部哈德利环流。在ITCZ内存在着强烈的上升运动，延伸到整个SSA，并在NSA上方补偿下沉。观测到了一个显著的日脉动，影响了赤道两侧的条件，它在清晨(0500-0800 LT)运行最强，在当天晚些时候(1700-2000 LT)显著减弱。在MJO爆发前阶段，国安局日间下降的下沉可能有助于那里对流层低层到中层的增湿。ITCZ内的表观加热Q1表现出从清晨底层重廓线到白天弱顶重廓线的日演变，表明从对流到层状降水的发展。利用弱温度梯度近似，结果表明，水平辐射加热梯度和直接云辐射强迫对ITCZ内垂直运动和对流的日变化有重要影响。
During the 2011 special observing period of the Dynamics of the Madden–Julian Oscillation (DYNAMO) field experiment, two sounding arrays were established over the central Indian Ocean, one north and one south of the equator, referred to here as the NSA and SSA, respectively. Three-hourly soundings from these arrays augmented by observations of radiation and rainfall are used to investigate the diurnal cycle of ITCZ convection during the MJO suppressed phase. During the first half of October, when convection was suppressed over the NSA but prominent over the SSA, the circulation over the sounding arrays could be characterized as a local Hadley cell. Strong rising motion was present within the ITCZ extending across the SSA with compensating subsidence over the NSA. A prominent diurnal pulsing of this cell was observed, impacting conditions on both sides of the equator, with the cell running strongest in the early morning hours (0500–0800 LT) and notably weakening later in the day (1700–2000 LT). The declining daytime subsidence over the NSA may have assisted the moistening of the low to midtroposphere there during the pre-onset stage of the MJO. Apparent heatingQ1within the ITCZ exhibited a diurnal evolution from early morning bottom-heavy profiles to weaker daytime top-heavy profiles, indicating a progression from convective to stratiform precipitation. Making use of the weak temperature gradient approximation, results suggest that both horizontal radiative heating gradients and direct cloud radiative forcing have an important influence on diurnal variations of vertical motion and convection within the ITCZ.
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影响因子：
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作者：
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发表时间：
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发表时间：
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影响因子：
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