Time-space characteristics of diurnal rainfall over Borneo and surrounding oceans as observed by TRMM-PR
Time-space characteristics of diurnal rainfall over Borneo and surrounding oceans as observed by TRMM-PR
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DOI：
10.1175/jcli3714.1
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发表时间：
2006-04-01
影响因子：
4.9
通讯作者：
Yasunari, T
中科院分区：
文献类型：
--
作者：
Ichikawa, H;Yasunari, T
利用5年的热带降雨测量使命（TRMM）降水雷达（PR）资料，研究了婆罗洲及其周边地区降雨日变化的时空特征。的日变化周期显示出系统的调制，与季节内变化的大尺度环流模式，与低级别的卡斯特或西风带在岛上的制度。低对流层西风（东风）分量对应于活跃（不活跃）对流的岛屿，与有关的马登-朱利安振荡的季节内大气扰动的通道。一个显著的特点是，降雨活动在午夜至早晨之间传播到该岛的背风面。在东风区，传播的相速度约为3 in s（-1），在西风区，传播的相速度约为7 m s（-1）。整个岛屿上空都有传播，导致背风面的降雨量增加。两种制度之间发达的对流/降雨系统的垂直结构显着不同。在东风制度，层状降雨在岛上广泛的午夜，而在西风制度，当地对流降雨占主导地位。在近海地区，对流性降水在两个区域都占主导地位，然后逐渐减少，而风暴在东风区域发展为更深的对流系统。除了背风面的降雨传播外，在西风带期间，南海地区还发展了浅风暴，导致从午夜到早晨的强降水。
Five years of Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) data were used to investigate the time and space characteristics of the diurnal cycle of rainfall over and around Borneo, an island in the Maritime Continent. The diurnal cycle shows a systematic modulation that is associated with intraseasonal variability in the large-scale circulation pattern, with regimes associated with low-level casterlies or westerlies over the island. The lower-tropospheric westerly (easterly) components correspond to periods of active (inactive) convection over the island that are associated with the passage of intraseasonal atmospheric disturbances related to the Madden-Julian oscillation. A striking feature is that rainfall activity propagates to the leeward side of the island between midnight and morning. The inferred phase speed of the propagation is about 3 in s(-1) in the easterly regime and 7 m s(-1) in the westerly regime. Propagation occurs over the entire island, causing a leeward enhancement of rainfall. The vertical structure of the developed convection/rainfall system differs remarkably between the two regimes. In the easterly regime, stratiform rains are widespread over the island at midnight, whereas in the westerly regime, local convective rainfall dominates. Over offshore regions, convective rainfall initially dominates then gradually decreases in both regimes, while the storms develop into deeper convective systems in the easterly regime. Aside from leeward rainfall propagation, shallow storms develop over the South China Sea region during the westerly regime, resulting in heavy precipitation from midnight through morning.