摘要
運用1979-1993年歐洲中長期預報中心的季節系集模擬結果，本研究嘗試探討季節氣候的潛在可預報度，同時評估目前模式的預報技術。季節時間尺度氣候年際變化的潛在可預報度主要是比較邊界驅力與內部動力的影響強弱而來，利用「變異數分析」方法可以將此外在邊界驅力所造成的訊號從系統內部的雜訊中分離出來，邊界驅力而來的變異量和總變異量的比值可以用來呈現潛在可預報度，最大潛在可預報度出現在受海水表面溫度影響最大的熱帶地區，熱帶以外的地區幾乎沒有潛在可預報度，但某些參數場會在特定季節（例如冬季的高度場）的中緯度地區製造出與遙相關型態相關的較大潛在可預報度中心。重力位高度場和溫度場較其他參數有潛在可預報度，而降水場則是研究參數中最小的，一般而言，潛在可預報度的大小和範圍由低層往高層增大，以重力位高度場最明顯，但對於亞洲季風區的夏季而言，850hPa緯向風場的潛在可預報度比200hPa大。印度季風區因緯度較低，所以各參數的潛在可預報度通常較東亞季風區高，且不同參數間的季節變化不一致，而東亞季風區各參數的潛在可預報度則會較一致地在夏季和冬季較高，秋季較小。夏季季風區的潛在可預報度一般較中緯度地區大。利用四個夏季季風指標進行潛在可預報度分析，其中偏東亞附近地區的季風指標（包括對流與環流指標）潛在可預報度比偏南亞附近地區的季風指標大。
由距平型態相關校驗歐洲中長期預報中心模式的預報技術得知，系集平均預報一般而言會讓模式模擬呈現出比任意單一模擬較佳的預報結果，除東亞季風區的冬季降水外，亞洲季風區季節降水預報技術和Nino3.4地區海溫距平大小的相關性不高，即使在海溫距平很大的年份，模式也可能因為無法模擬出正確的觀測型態分布，而呈現出較差的預報技術。東亞季風區、太平洋-北美地區的冬季和南亞季風區的夏季平均降水預報可能性較高，這結果和潛在可預報度分析一致。東亞季風區在反聖嬰年期間進行降水短期氣候預報技術得分最高，東亞和南亞季風區都出現模式在聖嬰年春季有較高的預報能力，而在反聖嬰年春季預報技術卻迅速減低的情形，這可能和反聖嬰年春季比聖嬰年春季產生較多的氣候雜訊卻伴有較少的氣候訊號有關。太平洋-北美地區的季節降水預報技術在聖嬰年期間最佳，特別是冬季，其夏季降水預報技術得分在反聖嬰年期間最低，但亞洲季風區夏季降水預報技術得分在反聖嬰年期間則較其他年份高。

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