Abstract: The authors use the detrended fluctuations analysis (DFA) to analyze the ISCCP cloud amount data at four locations: Beijing, Shanghai, Western Pacific, and Eastern Pacific. It is found that cloud amount indeed has power-law correlation in large time scales, which indicates that the cloud amount has strong long-term correlation in the locations studied. The crossover over the ocean appears later than that over the continent.The long-term correlation of the the cloud amount over the Western Pacific is stronger than the Eastern Pacific’s.

Key words: ISCCP, long-term correlation, cloud amount, DFA

摘要： 为了探索云量的变化规律, 利用去趋势波动分析(DFA)方法, 选取北京、上海、太平洋西部和太平洋东部等4个区域, 对ISCCP每3小时的云量时间序列进行了分析, 发现: 这4个区域的云量在大的时间尺度上存在幂律相关性, 即云量具有较强的长程相关性(或持续性); 西太平洋上空云量的长程相关性强于东太平洋上空和其他两个地区。还发现海洋上折点出现的时间迟于陆地上。

关键词: ISCCP, 长程相关性, 云量, DFA