中国近地表气温直减率及其季节和类型差异

近地表气温直减率是推测近地表气温空间分布的重要参数。中国幅员辽阔,气候和地形地貌条件复杂,直接使用反映对流层平均状况的单一气温直减率(0.65℃/100 m)很难表征中国近地表气温直减率的季节和类型差异。本文利用中国839个国家气象站点2000-2013年的近地表气温数据,分别在国家尺度和综合自然区划尺度上使用多元回归分析方法计算各个季节的平均气温直减率(lr_meanT)、平均最低气温直减率(lr_minT)和平均最高气温直减率(lr_maxT),并借助空间插值算法对气温直减率的可靠性进行了验证,最后分析了其季节和类型的差异。结果表明：①在国家尺度上,3种气温直减率均小于0.65℃/100 m;lr_minT、lr_meanT和lr_maxT的季节差异分别为0.05、0.13和0.24℃/100 m,且一般有夏季最大、冬季最小的季节规律;春、夏、秋、冬季气温直减率的类型差异分别为0.12、0.05、0.11和0.26℃/100m,且有lr_minT>lr_meanT>lr_maxT的规律。②在综合自然区划尺度上,气温直减率大多低于0.65℃/100 m,且存在明显的地域差异;夏季气温直减率一般大于冬季气温直减率,季节差异大多超过0.10℃/100 m;气温直减率类型差异半数区域超过或等于0.10℃/100 m,在春、夏、秋季,半数左右的区域lr_maxT >lr_minT,在冬季,多数区域的lr_minT >lr_maxT,lr_meanT一般处于lr_maxT和lr_minT之间。

Near-surface air temperature lapse rates and seasonal and type differences in China

The lapse rate of near-surface air temperature is a critical parameter for obtaining high-precision air temperature products, especially in mountainous areas. The average lapse rate for the troposphere is 0.65℃/100 m, which cannot depict the seasonal and type differences in near-surface air temperature. This study used data from 839 Chinese national-level meteorological stations in 2000-2013 to calculate the lapse rates of seasonal mean air temperature (lr_meanT), seasonal mean minimum air temperature (lr_minT), and seasonal mean maximum air temperature (lr_maxT) based on a multiple regression method at the national and regional scales, respectively. A spatial interpolation algorithm was used to validate the reliability of these lapse rates, and the seasonal and type differences were analyzed. The following results were obtained: (1) At the national scale, all the lapse rates are smaller than 0.65℃/100 m. The seasonal differences of lr_minT, lr_meanT, and lr_maxT are 0.05, 0.13, and 0.24℃/100 m, respectively. Generally, the lapse rates of the summer are greater than those of the winter. The differences among the three types of lapse rates of air temperature are 0.12, 0.05, 0.11, and 0.26℃/100 m, respectively, in spring, summer, fall and winter. Generally, lr_minT is the largest, while lr_maxT is the smallest. (2) At the regional scale by the comprehensive physical geographical regionalization, the lapse rates are also mostly smaller than 0.65℃/100 m. There are spatial differences for each type of lapse rate—the spatial ranges of annual lr_minT, lr_meanT, and lr_maxT are 0.27-1.66℃/100 m, 0.22-1.03℃/100 m, and-0.10-0.83℃/100 m, respectively. The seasonal differences of lapse rates are mostly greater than or equal to 0.10℃/100 m, and the lapse rates of the summer are mostly greater than those of the winter. The differences among the three types of lapse rates in half of the regions are greater than 0.10℃/100 m. lr_maxT is larger than lr_minT and lr_meanT for half of the regions in spring, summer, and fall, while lr_minT is usually the largest in winter. Because of the seasonal differences, spatial differences, and differences among the three types of temperature lapse rates, temperature lapse rate should be determined for each season, region, and temperature type.