利用衛星遙測海面高度及海面溫度估算熱帶太平洋上層海洋熱含量異常及混合層厚度

A Study of Upper Layer Heat Storage Anomaly in Tropical Pacific Using Satellite Altimetry and Thermometry

粘慶熙(Ching-Hsi Nan) ； 劉倬騰(Cho-Teng Liu)

《航測及遙測學刊》 9卷1期 (2004/03) Pp. 1-12

https://doi.org/10.6574/JPRS.2004.9(1).1

摘要

上層海洋的熱含量異常主要是海洋溫度異常對上層海水的積分，海水溫度升高時，其熱膨脹效應會提高海水比容，而造成海面升高，所以海面高度異常值可用來反推上層海洋的熱含量變動值。從過去的研究可以發現兩者問有很高的線性相關，這表示可以從高度計資料估計上層海洋熱含量的變動量。而對上層海洋的熱含量而言，從高度計資料可以得知整個溫度剖面的變動量，從長期平均值可以估計斜溫層下方的溫度分佈，再加上海面溫度的量測，我們可以估計整個上層海洋溫度的剖面變化。在熱帶東太平洋海域，熱含量異常可由 Tropical Atmosphere Ocean(TAO)陣列的海水溫度剖面量測值估算，其誤差約為23xl0^7J/m^2, 海面高度異常可由 TOPEX/POSEIDON(TP)高度計量測，由此海面高度異常估計的熱含量異常誤差約為20~30xl0^7J/m^2。由於上層海洋熱含量主要是決定海面溫度及混合層厚度，所以本研究使用TP海面高度計資料、地球同步衛星海面溫資料(GOES)、以及TAO錨確溫度計串的資料，研究熱帶東太平洋上層海洋熱含量的變化及混合層厚度。結果顯示，用本方法估計的混合層厚度，比用長期平均值準確，但因GOES海面溫資料的品質隨海域而不同，本方法的準確度亦隨海域而不同。

關鍵字

上層海洋熱含量 ； 海面高度 ； 海面溫度 ； 衛星遙測

並列摘要

The heat content (H)of the ocean upper layer may be calculated directly by integrating the water temperature over depth. Its anomaly may be estimated by the sea surface height anomaly (SSHA) that is associated with the thermal expansion effect of the water column. In the tropical eastern Pacific Ocean, we may use the Tropical Atmosphere and Ocean (TAO) temperature array to estimate the heat content anomaly with root-mean-square deviation (RMSD)of 23x10^7(J/m^2), or use the SSHA of TOPEX/POSEIDON (TP)to estimate with RMSD of 20 x10^7~30 x10^7 (J/m^2). High correlation between these estimates was found in the earlier studies. This assures that we may estimate the heat content anomaly of the ocean upper layer with altimeter data. Because the mixed layer and thermocline dominate the temperature profile, H is mostly determined by the sea surface temperature (SST) and the mixed layer depth (Ii) if the shape of temperature profile in the thermocline does not change much. With this assumption, we use the estimated SST from Geostationary Operational Environmental Satellite (GOES) and the computed SSHA from TP to derive the temporal change of mixed layer depth h. The quality of this method in estimating h is assessed with the in situ measured h by the TAO array of temperature sensors. It was found that using GOES SST and TP’ SSHA to estimate h is much better than nocast data, i.e. the long term mean h. It is also found that the accuracy of GOES SST varies with region, therefore the RMSD of h has regional dependence.

並列關鍵字

Heat Contents ； Sea Surface Anomaly ； Sea Surface Temperature ； Remote Sensing