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題 名 | 利用ECMWF資料估算熱帶海洋大氣邊界層之渦流熱量通量=An Estimate of Boundary Layer Surface Heat Fluxes Over the Tropical Ocean by the Use of ECMWF Data |
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作 者 | 王溫和; 林松錦; | 書刊名 | 大氣科學 |
卷 期 | 24:3/4 民85.09-12 |
頁 次 | 頁211-232 |
分類號 | 328.822 |
關鍵詞 | 渦流通量; Bulk formula; Surface fluxes; |
語 文 | 中文(Chinese) |
中文摘要 | 本研究主要目的在於探討西太平洋熱帶地區海氣之間渦流通量對時空特徵,及其所造成大氣邊界層擾動對東亞梅雨期大氣環流之影響。本文首先利用1982~1993十二年的ECMWF同化資料,並採用bulk formula方法來估算渦流熱量通量,探討春季期間(二~五月)熱帶地區海氣之間滑流通量的特徵,藉以作為後續研究梅雨期天氣型態變化因素的參考。 利用ECMWF同化資料及TOGA實際船舶觀測資料分別估算渦流熱量通量,比較分析結果發現在定性上兩者的分佈型態是相似的,而定量上兩者的差異並不會太大。通常在赤道暖水區的渦流熱量通量值較小,副熱帶的北半球太平洋地區、南半球印度洋地區及澳洲東方海面的值較大。而以經向觀點來看東西向不均勻象是存在的,印度洋地區的海溫與潛熱通量皆高於太平洋地區,由於海溫的不同造成兩地海氣交互作用有著不同的特性。在印度洋地區,潛熱通量的大小主要由風場所決定。而在太平洋赤道地區,風場與海氣間水汽差對潛熱通量的影響則相當。基本上,在印度洋地區與太平洋地區海溫較高的地方會有較大的海氣水汽差值存在,但其伴隨的風場卻較微弱,因而造成海溫高的地方通常有較小的潛熱通量。由於潛熱通量小,相對而言其蒸發冷卻作用對較小,此或許是暖水區能維持海溫較高的原因之一。整體而言,在熱帶地區渦流通量的強弱是由地面風速大小所控制,然而對通量的變化,海氣間的溫濕差似乎又較風場的影響明顯。渦流交換係數的選擇對通量值大渦流熱量通量的變化趨勢亦受到ENSO事件的影響。在ENSO年相對有較大的渦流熱量係數的選擇對通量值大小的影並不如預期的敏感。由EOF分析顯示在此期間海溫的變化,以ENSO為主,渦流熱量通量的變化趨勢亦受到ENSO事件的影響。在ENSO年相對有較大的渦流熱量通量,而anti-ENSO年的渦流熱量通量相對有較小值。海溫、渦流熱量通量變化在赤道地區的太平洋與印度洋之間似乎存在有同相位變化的關係。 |
英文摘要 | The purpose of this research is to understand the temporal and spatial characteristics of the surface fluxes between the ocean and the atmosphere in the tropical western Pacific area, and to investigate the consequent influence of such air-sea interaction on the atmospheric circulation over the East Asia during the Mei-Yu season. By the use of 1982~1993 ECMWF data, this study first computed and analyzed the surface fluxes with the bulk formula. Comparisons of surface fluxes computed from ECMWF data and ship observations obtained during TOGA experiment show that the spatial distribution and magnitude of surface fluxes are quite consistent. Small fluxes are usually found in the tropical warm pool with large fluxes in the subtropical northern Pacific Ocean, southern Indian Ocean and sea surface to the east of Australia. In the warm pool area, though there appears higher air-sea moisture gradient, but surface wind is usually lighter, and in a consequence, surface heat fluxes are relatively smaller. This could be one of the reasons that keep sea surface temperature warmerdue to less evaporation effect. Results also real different features in the distribution of heat fluxes between the Indian Ocean and the Pacific Ocean. Generally, surface heat fluxes are somewhat larger in the Indian Ocean than in the Pacific Ocean. In the Indian Ocean, the magnitude of surface fluxes is mainly determined by surface wind. But, in the Pacific Ocean, surface fluxes are determined by both surface wind and air-sea moisture gradient. Overall, the magnitude of surface fluxes is dominantly controlled by the surface wind, and the variation of surface fluxes is majorly influenced by the differences of temperature and humidity between the atmosphere and the ocean. The choice of transfer coefficients is not so sensitive on the estimations of surface fluxes as expected. The EOF analyses of sea surface temperature and surface heat fluxes both reveal characteristics of ENSO events. The surface heat fluxes appear to be larger during the ENSO years and smaller during the anti-ENSO years. Variations of sea surface temperature and surface heat fluxes are also found to be positively correlated between tropical pacific Ocean and Indian Ocean. |
本系統中英文摘要資訊取自各篇刊載內容。