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防辐射罩区域自动气象站气温观测偏差分析及其订正方法

Analysis and correction method of temperature observation deviation in the radiation shield of regional automatic meteorological stations

  • 摘要: 分析防辐射罩区域自动气象站气温值偏差变化特征,有助于自动站气温资料质量的订正,进而提高自动站气温资料的可用性。因此,基于2019年6月—2022年5月湖北省防辐射罩区域自动气象站及与其邻近的百叶箱站观测的逐小时气温资料,首先分析两类站点间小时气温偏差( T_bs )的季节变化和日变化特征,并探讨降水、相对湿度、日照、风等气象要素对 T_bs 的影响;然后,基于多元线性回归和随机森林方法,分别建立两种防辐射罩站观测气温订正模型,评估两种模型对防辐射罩站气温观测偏差的订正效果。结果表明:(1) 总体上,白天时段防辐射罩站小时观测气温较其邻近百叶箱站加权平均小时观测气温要高,防辐射罩站年均高温日数较其邻近百叶箱站偏高20.0 d;(2) T_bs 存在明显季节变化和日变化规律,总体呈现夏季高、冬季低;日间高、夜间和清晨低的特点,平均 T_bs 在晴天13:00(北京时,下同)最高,可达到1.0 ℃以上;(3) T_bs 会随站点气象条件的变化而变化,在无降水现象时较大,而有降水时接近0 ℃; T_bs 与相对湿度负相关,而与日照时数正相关,与风速则是先呈现正相关,随着风速增大至临界值以后呈现负相关;(4) 多元线性回归和随机森林模型对防辐射罩站气温观测偏差均有较好的订正效果,使平均 T_bs 由0.72 ℃分别降至0.17 ℃和0.16 ℃。随机森林模型的订正效果总体优于多元线性回归模型,且对超过35 ℃的高温订正效果更佳,订正后防辐射罩站总高温日数下降比例超过55%。

     

    Abstract: Analyzing the variation pattern of temperature observation deviation in the radiation shield of regional automatic meteorological stations can help to correct the quality of temperature data, thereby improving the usability of temperature data. Therefore, based on the hourly temperature data observed by the radiation shield of regional automatic meteorological stations and its neighboring station with thermometer screen at the Hubei Province from June 2019 to May 2022, this study first analyzes the seasonal and daily variation characteristics of the hourly temperature deviation ( T_bs ) between the two types of stations, and explores the influence of meteorological factors such as precipitation, relative humidity, sunlight, and wind on T_bs . Then, multiple linear regression and random forest methods were used to establish two temperature correction models for radiation shield stations respectively, and the correction effects of the two models on the temperature observation deviation at the radiation shield stations were analyzed. The results are as follows. (1) Overall, the observed temperature at the radiation shield stations during the day is higher than that of its neighboring stations with thermometer screen . The average annual number of high temperature days at the radiation shield station is 20.0 days higher than that of its neighboring stations with thermometer screen. (2) There are obvious seasonal and daily variations in T_bs between the two types of stations, with an overall trend of high in summer and low in winter, high during the day, and low at night and early morning. The average T_bs is highest at 13:00 BT on a clear day, reaching over 1.0 ℃. (3) T_bs will vary with changes in meteorological conditions at the station, with a greater value in the absence of precipitation and approaching 0 ℃ in the presence of precipitation. The T_bs has a negative correlation with relative humidity, a positive correlation with sunshine hours, and a positive correlation with wind speed at first, followed by a negative correlation as the wind speed increases to the critical value. (4) Multiple linear regression and random forest models have good correction effects on temperature deviation at radiation shield stations, reducing the average T_bs from 0.72 ℃ to 0.17 ℃ and 0.16 ℃, respectively. The correction effect of the random forest model is slightly better than that of the multiple linear regression model, and the random forest model has better correction effect for high temperatures exceeding 35 ℃. After correction, the total number of high temperature days at the radiation shield station has decreased by more than 55%.

     

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