北京1960—2008年气候变暖及极端气温指数变化特征

应用均一化逐日气象观测资料，分析了北京地区1960—2008年气候变暖及主要极端气温指数的统计特征。结果表明：近49年来北京年平均气温增温速率约为0.39℃/10a,最高、最低气温变化具有明显的非对称性。霜冻日数和气温年较差呈现下降趋势,暖夜指数及热浪指数呈现上升趋势，除气温年较差外，其他极端气温指数的气候变率均在加大。北京年平均气温及极端气温指数主要存在21年、15～17年及准10年周期特征。年平均气温与极端气温指数之间存在较强相关性，气候变暖突变发生前后某些极端气温指数发生频率表现出明显差异。自1980年起，北京市区极端最高气温及其增温率明显高于近郊和远郊，高温日数市区多于近郊，近郊多于远郊；近、远郊极端最低气温温差高于城、近郊温差。

Characteristics of Climate Warming and Extreme Temperature Indices in Beijing over 1960-2008

Using the homogenized temperature data series in the period 1960-2008, the characteristics of climate warming and variations of extreme temperature indices in Beijing were analyzed. Results indicate that the increase rate of annual mean temperature were 0.39℃/10a, and the mean maximum and minimum temperatures changed asymmetrically, indicating that the climate warming were mainly caused by minimum temperature increasing. The climate base state indices of frost days (FD) and extreme temperature range (ETR) declined, warm nights (TN90) and heat wave duration index (HWDI) increased, and most of extreme temperature indices exhibited high variability except for the ETR index. Morlet wavelet transform shows that the main periods for mean annual temperature and extreme temperature indices were about 21, 15-17, and 10 years. There were a close correlation between annual mean temperature and extreme temperature indices. Since 1980, extreme high temperature, and high temperature days have increased more in urban areas than in suburbs and exurbs, while extreme low temperature and low temperature days have decreased more in urban areas and suburbs than in exurbs. The above results suggest that the variations in extreme temperatures in Beijing have been obviously affected by its urbanization process.