黄河上游玛曲地区1971—2010年云量的变化特征

Analysis on Changes of Cloud Coverage in the Maqu Area of the Upper Reaches of Yellow River in the Recent 40 Years

利用玛曲国家基本气象观测站1971—2010年的总云量、低云量等观测数据,用线性趋势分析、小波分析等方法对玛曲地区近40 a总云量、低云量的月、季、年际、年代际变化和周期性变化特征进行分析。研究表明,近40 a来,平均总云量距平在-0.1%～0.1%之间,保持了很好的稳定性,平均低云量以4.0%/10 a的速率递增;春、夏、秋季低云量呈现出不同程度的增多趋势,夏季增加趋势非常明显达7.3%/10 a。平均总云量周期变化不明显,平均低云量有明显的6～7 a的周期。玛曲地区在总云量保持稳定的情况下低云量不断增多,夏季低云量的增多趋势非常明显,且积雨云的增多是主要特征,是对玛曲草原气候变化的一种响应机制,反映出在气候变暖的大背景下,玛曲草原对流性天气活动频繁。

Using the data of total cloud coverage and low cloud coverage from the national basic meteorological stations in Maqu during 1971-2010, with a linear trend analysis and wavelet analysis methods, characteristics of monthly, quarterly, annual, inter-decadal and peridical change of the total cloud coverage and low cloud in recent 40 years were analyzed. The studies have shown that over the past 40 years, the average total cloud amount anomaly is between-0.1% ～0.1%,maintaining a good stability, the average low cloud coverage increases at the rate of 4.0%/10 a; low cloud coverage in spring, summer and autumn show varying degrees of increase trends, obviously up to 7.3%/10 a in the summer; the periodic changes of mean total cloud coverage are not obvious; the average cycle of low cloud coverage is clear which is 6 ～7 a; in the Maqu region the total cloud amount remains stable increasing while the low cloud coverage increases, particularly during the summer with the main feature, the cumulonimbus clouds, indicating a response mechanism of climate change which reflected the convective weather occurs frequently in the context of climate warming in the Maqu grassland.