百叶箱与通风辐射罩的气温日最值差异

Comparative Analysis of Maximum and Minimum Temperatures of LTS and ASPTS

利用2009年8月—2010年7月的平行观测资料,对新型自动气象站中百叶箱和通风辐射罩气温观测系统气温日最值对比差的分布、粗差率、一致率以及平均值等进行统计,对日最值的出现时间进行对比,对日最值对比差与环境风速的关系进行分析,建立并验证了百叶箱气温日最值的订正方法。结果表明:百叶箱和通风辐射罩气温日最值对比差的分布均呈右偏态,且偏斜程度较大,不服从正态分布;日最高气温与最低气温的一致率分别为90.0%和81.5%,两者存在较大差异,但其粗差率基本一致,均略高于3.0%;与通风辐射罩气温观测系统相比,百叶箱的日最值数据总体偏高0.2℃左右,同时其出现时间也存在不同程度的滞后;气温日最值的差异会随着环境风速的增强而减小,特别是当风速大于4.5 m·s^(-1)时,其差异可缩小到0.1℃以内;以环境风速为主要参数的气温订正方法将最高气温的差异缩小到0.03℃,一致率提高到95.2%,将最低气温的差异缩小到0.01℃,一致率提高到94.1%。

In order to meet demands of comprehensive weather observation in modern meteorological service, a development and assessment program of new automatic weather station （NAWS） is sponsored and launched by Meteorological Observation Center of China Meteorological Administration. Besides the traditional louver temperature observation system （LTS）, NAWS can also be equipped with aspirated radiation shield temperature observation system （ASPTS）, which borrows the design experience of US Climate Reference Network, for the purpose of achieving future long term homogeneous temperature observations. NAWS has been employed in the surface meteorological station in some provinces of China. Differences between LTS and ASPTS results, influencing factors and the correction method all need investigation, therefore, a parallel experimental measurements consists of LTS and ASPTS is conducted. The experiment is carried out in Nanjing University of Information Science ＆ Technology （32°12′N, 118°42′E, elevation is 32 m） from August 2009 to July 2010. Maximum and minimum temperature measurements derived from LTS and ASPTS are compared, and biases of extreme values and difference of the occurrence times are examined under different regimes of ambience wind speeds. A correction model based on ambient wind speed is developed and checked. Results indicate that differences of daily extreme temperature between LTS and ASPTS are not subject to the normal distributions, while they demonstrate a right skewed state and a great degree of deflection. The concordance rate of maximum temperature between LTS and ASPTS is 90.0%, while that of minimum temperature is 81.5%. The gross error rate of maximum temperatures between LTS and ASPTS is almost the same as that of minimum temperature, both of which are about 3.0%. Compared with ASPTS measurements, the extreme values derived from LTS have a positive deviation of 0.2℃ and a lag of 2.5 minutes and 3.2 minutes for maximum temperature and minimum temperature, respectively. Differences of extreme values would be reduced with the enhancement of ambience wind speeds, even reduced to 0.1℃ when the speed is stronger than 4.5 m·s-1. The deviation correction, which is developed mainly based on wind speed, reduces the difference to 0.03℃ and 0.01℃, and increases the consistent rate to 95.2% and 94.1% for the maximum temperature and minimum temperature, respectively.