Cloud Episode Propagation over the Indonesian Maritime Continent from 10 Years of Infrared Brightness Temperature Observations
Cloud Episode Propagation over the Indonesian Maritime Continent from 10 Years of Infrared Brightness Temperature Observations
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根据 10 年红外亮度温度观测，印度尼西亚海洋大陆上空的云层传播
DOI：
10.1016/j.atmosres.2012.09.004
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发表时间：
2013
影响因子：
5.5
通讯作者：
and J.D. Tuttle
中科院分区：
文献类型：
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作者：
Marzuki;H. Hashiguchi;M.K. Yamamoto;M. Yamamoto;S. Mori;M.D. Yamanaka;R.E. Caibone;and J.D. Tuttle
利用2001 - 2010年的云顶亮温资料，分析了印度尼西亚海洋大陆（10°S-10°N，80°E-160°E）深对流的持续时间、跨度和传播速度。整个研究区域分为北方（0°-10 ° N）和南方（0°-10 ° S）两个区域，以研究云条纹的季节和纬度变化。向西传播的云条纹与向东传播的云条纹之比约为3：1。向西移动的条纹通常比向东移动的系统具有更长的跨度和更快的速度。向西（向东）传播系统的相干事件的持续时间为9.5（7.5）h，平均跨度为519（378）km;大多数事件的纬向相速度为6- 30 ms −1。对于跨度> 1000 km、持续时间> 20小时的事件，纬向相速度中值为14.2 ms − 1（向西）和13.5 ms −1（向东）。还讨论了复发频率，从每天1起事件到每月1起事件。统计特性的纬度和季节依赖性受到热带辐合带年周期的强烈影响。西移系统的数量在每个月都很显著，而东移系统则随季节和纬度变化很大。在南部地区，6月、7月和8月（牙买加）和北方地区，12月、1月和2月（斐济），向东迁移的频率较低。在北方地区，西向传播事件的平均跨度在JJA，9月，10月和11月（SON）比其他时期长得多，这种影响部分是由于有利的环境剪切条件，以维持一个长寿命的系统。在日循环位相的短波加热和耗散模态中，存在向东和向西传播的事件。因此，热力强迫，这是与发现在岛屿和陆地-海洋界面的高地，每天占主导地位。除了环境条件的几个可能的原因，目前的结果进行了讨论。结果表明，低空风场对降水传播速度有一定的支持作用，其支持作用与MJO位相有关。然而，如我们的结果所示，单独的风平流可能不足以迅速传播降水。降水迁移的速度，特别是苏门答腊岛周围的传播重力波和湿开尔文波的框架中报告的值是相似的。
The cloud-top brightness temperature data from 2001 to 2010 are used to derive a climatology of deep convection duration, span, and propagation speed over the Indonesian Maritime Continent (10°S–10°N, 80°E–160°E). The full domain of study is divided into northern (0°–10°N) and southern (0°–10°S) regions to investigate the seasonal and latitudinal variabilities of cloud streaks. The ratio of westward- to eastward-propagating cloud streaks is found to be approximately 3:1. Westward-moving streaks generally have longer spans and faster speeds than eastward-moving systems. Coherent episodes of westward- (eastward-) propagating systems have 9.5 (7.5) h durations and 519 (378) km spans on average; most episodes have zonal phase speeds of 6–30ms−1. Median zonal phase speeds of 14.2 (westward) and 13.5ms−1(eastward) are found for events with >1000km spans and >20h durations. The recurrence frequency, which is categorized from 1 event per day to 1 event per month, is also discussed. The latitudinal and seasonal dependences of statistical properties are strongly influenced by the Inter-Tropical Convergence Zone annual cycle. The number of westward-migrating systems is significant every month, while eastward-migrating systems strongly vary by season and latitude. Eastward migration is less frequent in the southern region during June, July and August (JJA) and in the northern region during December, January and February (DJF). In the northern region, the westward-propagating events' mean span is much longer during JJA, September, October, and November (SON) than the other periods; this effect is partially due to the favorable environmental shear conditions necessary to sustain a long-lived system. Eastward- and westward-propagating events are found during the shortwave heating and dissipation modes of diurnal cycle phase. Thus, thermal forcing, which is associated with the elevated terrain found over the islands and the land–sea interface, is dominant on a daily basis. Several possible reasons behind the present results besides the environmental conditions are discussed. It is found that low-level wind may support the precipitation propagation speed, and its support may depend on the Madden–Julian Oscillation (MJO) phase. However, advection by wind alone is likely insufficient to propagate the precipitation as quickly, as our results show. The speed of precipitation migration particularly around Sumatra is similar to the values reported in the framework of propagating gravity waves and moist Kelvin waves.