應用福衛三號掩星觀測資料於亞澳季風區重力波活動之分析 ; An analysis of gravity wave activity in the Asia- Australian monsoon region observed by FORMOSAT-3/COSMIC radio occultation technique.

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Title:	應用福衛三號掩星觀測資料於亞澳季風區重力波活動之分析;An analysis of gravity wave activity in the Asia- Australian monsoon region observed by FORMOSAT-3/COSMIC radio occultation technique.
Authors:	陳坤新;Kun-Hsin Chen
Contributors:	太空科學研究所
Keywords:	重力波;GPS 掩星觀測;FORMOSAT-3/COSMIC;radio occultation technique;FORMOSAT-3/COSMIC;Gravity wave
Date:	2010-07-24
Issue Date:	2010-12-09 10:50:33 (UTC+8)
Publisher:	國立中央大學
Abstract:	重力波一直以來都是研究大氣動力理論值得探討的一環，因觀測技術進步及理論發展，才開始對重力波有了進一步的了解。在觀測技術方面，像過去在極地或海洋地區取得大氣參數並非容易及充足的區域，研究這些資料不易取得地區的重力波活動情形，便往往產生了侷限，福爾摩沙三號於2006年四月發射，由六顆低軌微衛星組成，每天提供在全球約2000~2500個大氣剖面參數，它的主要科學目標是利用掩星觀測信號，推斷大氣參數，包括折射率、溫度、壓力和相對濕度場，為我們在研究重力波時，提供了一個很有利的資料平台。本論文利用福爾摩沙三號掩星觀測的大氣溫度剖面資料，從2006年九月到2009年十二月，選取高度從20公里至40公里，分析亞洲與澳洲季風區（45°N~45°S, 60°E~160°E）重力波活動之季節變化，計算重力波平均位能能量(AveEp)值，來探討重力波活動在不同季節的變化，以及地域性重力波活動情形，將研究區域以每緯度15度及經度20度為間隔，劃分成三十個不重疊區域，並比較各區間的差異。季節變化中發現在15°N~30°N與15°S~30°S區域，分別在北半球夏季(JJA)與南半球夏季(DJF)有較大的AveEp值，在30°N~45°N與30°S~45°S區域，則分別在北半球冬季(DJF)與南半球冬季(JJA)有較大的AveEp值，地域性的分析觀察到北半球夏季(JJA)與南半球夏季(DJF)時，分別在印度半島與澳洲北部有較大的AveEp值，另外在2007年十二月到2008年二月觀察到AveEp值高出許多，推測很有可能的原因，在於當時反聖嬰現象造成沃克環流增強而產生了影響。With the improvement of observation techniques and physical theories, scientists became more familiar with the gravity waves, a key factor of the atmospheric dynamics. In the past, atmospheric profiles were not supportive enough for us to conduct research on some hard-to-reach areas, such as the oceans and the Polar regions. Data shortage has caused many difficulties in climate studies until the launch of Formosat-3 in April, 2006. The constellation consists of six Low Earth Orbit (LEO) satellites at the height of 800 km, providing 2000 to 2500 soundings per day. The main scientific goal is to utilize the radio occultation (RO) signals to infer the atmospheric parameters, including refractivity, temperature, pressure, and relative humidity fields. The FORMOSAT-3/COSMIC has provided a very favorable data platform to perform the investigation of the gravity wave activities. This paper is focused on the studies of the seasonal variations of gravity wave activities using the temperature profiles obtained by the FORMOSAT-3/COSMIC RO technique at height of 20~40 km, from September 2006 to December 2009. The average potential energy (AveEp) of the gravity waves was estimated to quantify the seasonal variations and compare those between Asian and Australian Monsoon regions（45°N~45°S, 60°E~160°E）. The study area was divided into 30 non-overlapped regions, each representing a 15 by 20 degree grid, in latitude and longitude, respectively. We compared those grids in different latitudinal intervals over different geographic locations. The result showed that the larger AveEp values of the 15°N~30°N and 15°S~30°S intervals occurred in summer - JJA for the northern hemisphere and DJF for the southern hemisphere. However, for 30°N~45°N and 30°S~45°S intervals, larger AveEp values appeared in winter - DJF for the northern hemisphere and JJA for the southern hemisphere. Furthermore, the spatial analysis of gravity wave activities indicated that within the higher AveEp value latitudinal intervals, the largest AveEp value located at the Indian Peninsula in the northern hemisphere summer (JJA) and Northern Australia in the southern hemisphere summer (DJF). In this study, we also found that the AveEp values were much higher than those in 07/08DJF and 08MAM. We believed the gravity anomalies were attributed to the strengthening of the Walker Circulation, which was caused by the La Nina phenomenon.
Appears in Collections:	[Graduate Institute of Space Science] Department of Earth Sciences

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