模式和SSM/I客觀潛力指數在中尺度對流系統預報上之應用

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Title:	模式和SSM/I客觀潛力指數在中尺度對流系統預報上之應用
Authors:	戴世杰;Shih-Chieh Tai
Contributors:	大氣物理研究所
Keywords:	客觀潛力指數;SSM/I;WRF;Objective Potential Index;SSM/I;WRF
Date:	2006-07-07
Issue Date:	2009-09-22 09:42:50 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	台灣附近海域每年在五、六月梅雨季節期間經常伴隨中尺度對流系統（Mesoscale Convective System, MCS）的發生，而根據許多前人研究顯示，海氣交互作用與中尺度對流系統之間有密切的關聯性，本研究之目的即在於運用客觀潛力指數（Objective Potential Index, OPI）分析此類中尺度對流系統。OPI具有描述海氣交互作用強弱的空間分布及其變化趨勢的能力，在MCS生成、發展及消散的先期預警上有不錯的表現。本研究針對2005年5、6月梅雨季期間的對流個案，使用WRF（Weather Research and Forecasting）模式在水平網格解析度30公里的設定下，模擬1至3天的相關海氣參數場並計算OPI空間分布的情形，之後將其結果與SSM/I資料的實際反演結果進行比較分析。研究結果顯示，WRF及SSM/I OPI在空間分布型態上大致相同，但局部區域仍有差異，較為明顯的是WRF OPI相對於SSM/I OPI高值區的相同位置，其數值會有顯著偏低的情況。就個案的時序分析方面，IR亮度溫度的最低值（即對流最大強度）大約出現在SSM/I OPI極大值的時間點之後一天到二天左右。此外，對流達最大強度前，WRF及SSM/I OPI皆有相對極大值出現，但兩者在時間上並不一致，而且WRF OPI指數也有低估的情形。 Each year mesoscale convective systems (MCSs) usually occur in May and June, Mei-Yu season, over the ocean around Taiwan. Many previous studies exhibited that there is a close relationship between air-sea interaction and MCSs. The purpose of this research is to analyze such MCSs by the Objective Potential Index (OPI). The OPI has the capability to describe the spatial distribution of the intensity of air-sea interaction and its tendency for variation, and it can serve as an indicator for arising, development, and dissipation of MCSs. In this investigation, the convection cases in May and June 2005 are simulated by the Weather Research and Forecasting (WRF) model with a horizontal resolution of 30 km in the simulated domain. After the WRF model integrates for 72 hours, compute the WRF-derived OPI with the simulated air-sea parameters, and then compare the results with the SSM/I-derived OPI. The results indicated that the distributions of WRF-derived OPI and SSM/I-derived OPI are similar roughly, but many differences still exist in local areas. It was seen that underestimations from the WRF-derived OPI occurred in regions, where the higher values of the SSM/I-derived OPI existed in a spatial distribution. In terms of the time series analysis, the minimum of infrared brightness temperature (also denotes the strongest convection) appeared about 1 to 2 days after the maximum of SSM/I-derived OPI. In addition, it was seen that before the convection reached its highest intensity, the WRF and SSM/I OPI both showed a relative extreme value. However, the time point was not consistent with each other. Furthermore, the WRF-derived OPI index also seemed to underestimate the values.
Appears in Collections:	[Department of Atmospheric Sciences and Graduate Institute of Atmospheric Physics ] Department of Earth Sciences

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