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三峡地基遥感垂直观测系统温湿廓线的误差分析与订正方法探讨

Error analysis and correction method of temperature and humidity profiles in the Three Gorges ground-based remote sensing vertical observation system

  • 摘要: 三峡地基遥感垂直观测系统是中国气象局“补短板工程”的先行试点,用于监测三峡库区大气垂直廓线的精细结构及演变,其中大气温湿廓线通过微波辐射计反演得到,评估大气温湿廓线的反演偏差并提高其精度对发挥好垂直观测系统在三峡库区的精密监测作用具有重要意义。利用2022年11月—2023年6月三峡微波辐射计和同址探空、自动气象站、毫米波测云仪等探测资料,评估了三种天气条件下(晴天、云天、雨天)微波辐射计83个探测高度层温湿度的反演偏差,提出对83个高度层重新分组与探空建立线性回归的微波辐射计温湿度订正方法;评估了订正前后的精度变化并以一次雨雪天气过程的探测结果讨论了订正方法的适用性。结果表明:(1) 三种天气条件下微波辐射计和探空温度一致性均较好,多数高度层平均偏差在2 ℃以内。(2) 晴天所有高度层微波辐射计探测湿度均高于探空探测;云天和雨天6 km以上高度层探测湿度均方根误差达30%。(3) 高度层重新分组后建立的订正关系能明显提升微波辐射计探测的温湿廓线精度。(4) 以一次雨雪天气过程探测为例,订正后的微波辐射计探测的温湿廓线与实况更接近。

     

    Abstract: The Three Gorges ground-based remote sensing vertical observation system, as the first pilot project of the "short board repair project" by the China Meteorological Administration, can monitor the fine structure and evolution of the atmospheric vertical profile in the Three Gorges Reservoir Region. The atmospheric temperature and humidity profiles are retrieved from the microwave radiometer in the Three Gorges ground-based remote sensing vertical observation system. Evaluating their retrieval bias and improving their accuracy is of great significance for precision monitoring of the vertical observation system in the Three Gorges Reservoir Region. By using microwave radiometer data, radiosonde data, automatic weather station data, and millimeter wave cloud gauge data of Three Gorges from November 2022 to June 2023, this study evaluates the bias of temperature and humidity at 83 height layers retrieved from microwave radiometer under sunny, cloudy, and rainy days. Then a linear regression correction method based on radiosonde data after the regrouping of the 83 height layers for temperature and humidity profile of the microwave radiometer was proposed. Finally, the applicability of the correction method by using the accuracy changes before and after the correction was evaluated using the observation from a rainy and snowy weather process. The results are as follows: (1) The temperature of the microwave radiometer has good consistency with radiosonde temperature under three weather conditions, and the bias of most height layers is less than 2 ℃. (2) On sunny days, the humidity of the microwave radiometer is higher than that of the radiosonde at all height layers. Above 6 km, the root mean square error (RMSE) of the humidity can reach 30% on cloudy and rainy days. (3) The correction method established after the regrouping of the 83 height layers can improve the temperature and humidity profile accuracy of the microwave radiometer. (4) The corrected temperature and humidity profiles of the microwave radiometer are closer to the reality in the case of a rain and snow event.

     

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