Synoptic conditions and potential causes of the extreme heavy rainfall event of January 2009 over Mindanao Island, Philippines
Synoptic conditions and potential causes of the extreme heavy rainfall event of January 2009 over Mindanao Island, Philippines
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2009年1月菲律宾棉兰老岛特大暴雨天气条件及潜在原因
DOI：
10.1007/s11069-021-04934-z
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
J. Matsumoto and H. Kubota
中科院分区：
文献类型：
--
作者：
Olaguera;L. M.;M. E. Caballar;J. C. de Mata;L. A. T. Dagami;J. Matsumoto and H. Kubota
本文研究了2009年1月菲律宾棉兰老岛（122 - 127°E; 5 - 10°N）暴雨/洪水（HRF）事件的天气条件，这在以前的研究中较少被强调。棉兰老岛北方的卡加延德奥罗市（Cagayan de Oro City）发生了大范围的洪水，2009年1月10日、11日和13日的降雨量超过了该市1979年至2017年1月所有日降雨量记录的第99百分位数近两倍。2009年1月15日，棉兰老岛东海岸的希纳端站也感受到了类似的波动。棉兰老岛北方冷锋切变线和热带东风的相互作用增强了水汽辐合。较暖的空气团被前进的较冷的空气团迫使上升，因为它的密度比较冷的空气团低。增强的水汽辐合和浮力差的空气质量导致了增强的上升，从而导致降水沿着冷涌切变线。进一步的分析表明，在925 hPa的异常东风和偏北风增强明显的菲律宾。异常的东风维持了温暖的东风的供应，并与北风相互作用，提供了较冷的温度气团。这次HRF事件的气候学研究了1979年至2017年1月。作者确定了其他15例与2009年1月HRF事件相似的病例，并进行了滞后复合分析。结果表明，菲律宾北部高压系统向南扩展，冷暖平流加强，以及沿着冷锋切变线水汽辐合加强，是造成这两次HRF事件的主要原因。这项研究的结果有重要的影响，减灾在东北季风季节降雨活动时，在一般情况下，在这一地区的强度较低。
This study investigates the synoptic conditions that led to the heavy rainfall/flood (HRF) event in Mindanao Island, Philippines (122 −127°E; 5 −10°N), on January 2009 (JAN2009 HRF) that are less emphasized in previous works. Extensive flooding was reported over Cagayan de Oro City in the northern part of Mindanao, where the rainfall on January 10, 11, and 13, 2009, exceeded the 99th percentile of daily rainfall records of all January of the city from 1979 to 2017 by almost two times. A similar exceedance was also felt in Hinatuan station over the eastern coast of Mindanao Island on January 15, 2009. The interaction of a cold surge shearline over the northern Mindanao Island and the warm tropical easterlies led to enhanced moisture convergence. The warmer air mass is forced to ascend by the advancing colder air mass because it has lower density than the colder air mass. The enhanced moisture convergence and buoyancy difference by the air masses led to enhanced ascent and consequently rainfall along the cold surge shearline. Further analysis shows that enhanced anomalous easterly and northerly winds at 925 hPa are apparent over the Philippines. The anomalous easterly winds sustained the supply of warmer easterlies and collaboratively interacted with the northerly winds that supplied colder temperature air mass.The climatology of this HRF event was examined for all January from 1979 to 2017. The authors identified 15 other cases that are similar to the JAN2009 HRF event and performed lag composite analyses. The results show that the occurrence of these HRF events is facilitated by the southward expansion of the high-pressure system to the north of the Philippines, enhanced cold and warm temperature advections, and enhanced moisture convergence along the cold surge shearline. The results of this study have important implications for disaster mitigation during the northeast monsoon season when rainfall activities are, in general, less intensive over this region.