地基微波辐射计和FY-3D微波探测仪联合同化试验研究

【作者】 王冰力；

【导师】 鲍艳松； 成巍； 刘娟娟；

【作者基本信息】 南京信息工程大学 ， 大气遥感与大气探测， 2024， 硕士

【摘要】 地基微波辐射计(Ground-Based Microwave Radiometer,MWR)具有连续观测、可无人值守工作等优势,卫星微波探测仪具有时空分辨率高、覆盖面积广等的特点。这两种探测仪器都具有对云雨一定的穿透性,为云天条件的探测提供了更多的可能。天气系统的发生发展往往与大气水汽的变化紧密相关,尤其是强对流天气,为使数值模式预报更准确,微波资料不可或缺。资料同化通过融合观测资料和模式来改善模式初始场,进而提高预报准确性。联合同化地基-星载微波资料,对数值预报的发展具有一定意义。为了探究这两种微波资料的联合同化对区域数值模式的影响,利用北京地区MWR和FY-3D微波垂直探测仪(Microwave Temperature Sounder-2/Microwave Humidity Sounder-2,MWTS-2/MWHS-2)资料,开展个例和批量试验。主要结论如下:(1)经过质量控制之后的MWR二级产品,各站点平均偏差趋于0,均方根误差得到有效降低,温湿廓线与探空数据较为一致;质控和偏差订正之后的MWTS-2/MWHS-2晴空观测资料,其偏差和均方根误差均显著改善,有效剔除质量较差的数据,保证了同化的有效性。MWTS-2/MWHS-2云天条件下观测数据采用间接同化,经过反演并质控之后的陆地地区温度和湿度均方根误差分别为1.080K、0.845g/kg,平均偏差分别为0.002K、0.003g/kg;海洋地区温湿度均方根误差分别为1.063K、0.869k/kg,平均偏差分别为-0.001K、0.006k/kg。(2)短时强降水个例表明,MWR和MWTS-2/MWHS-2观测资料都能够对模式初始场进行调整;单独同化常规加MWR主要影响北京区域以内的温湿要素,改进了该区域内的温湿度预报;单独同化常规加MWTS-2/MWHS-2对整个模式场都有调整,对温湿度的分析场和预报场改进程度较大,且效果较MWR显著;而联合同化进一步提高了温湿度预报场的准确性,能够更好的预测降水时大气的热力结构,有效减小了降水的虚报,提高了降水预报评分。(3)批量试验结果显示,MWR和MWTS-2/MWHS-2观测资料能够很好地改进温湿度预报,其中MWTS-2/MWHS-2资料的改善幅度更大些,联合同化结合了两者的优势,进一步的改善了温湿度预报场,尤其是在近地面高度层;对于降水预报,MWR主要改进了暴雨和大暴雨预测,MWTS-2/MWHS-2对中雨量级以上的降水都有较好的改进作用,联合同化在0-12h的降水预报相比单独同化的改进效果好,但是在24h的降水预报中对暴雨和大暴雨量级的预测比单独同化常规加MWTS-2/MWHS-2的预测略差。更多还原

【Abstract】 The Ground-Based Microwave Radiometer(MWR)has the advantages of continuous observation and unattended operation,while the satellite microwave sounder has the characteristics of high spatial and temporal resolution and wide coverage area.These two kinds of detection instruments have certain penetrability to clouds and rain,which provides more possibilities for the detection of cloud and sky conditions.The occurrence and development of weather systems are often closely related to the changes of atmospheric water vapour,especially strong convective weather,and microwave data are indispensable to make numerical model forecasts more accurate.Data assimilation improves the initial field of the model by fusing observations and the model,thus improving the forecast accuracy.The joint assimilation of ground-based and satellite-based microwave data is of great significance to the development of numerical forecasting.In order to investigate the effect of the joint assimilation of these two microwave data on the regional numerical model,both individual and batch experiments are carried out using the data from the MWR and the FY-3D microwave vertical sounder(Microwave Temperature Sounder-2/Microwave Humidity Sounder-2,MWTS-2/MWHS-2)in the Beijing area.batch tests.The main conclusions are as follows:(1)Following quality control measures,the secondary products derived from the Microwave Radiometer(MWR)exhibit a mean deviation that approaches zero across each station,showcasing an effective reduction in root mean square error.Moreover,the temperature and humidity profiles derived from these products display remarkable consistency with data obtained from radiosondes.Similarly,after undergoing quality control and deviation correction,the clear-sky observation data from the MWTS-2/MWHS-2instruments demonstrate substantial improvements in terms of deviation and root-meansquare error reduction.Additionally,this process effectively filters out data of inferior quality,thereby ensuring the assimilation process’ s effectiveness and reliability.The root mean square errors of temperature and humidity over land area after inversion and quality control were1.080 K and 0.845g/kg,respectively,and the average deviations were 0.002 K and 0.003g/kg,respectively.The root-mean-square errors of temperature and humidity in the ocean area are1.063 K and 0.869k/kg,respectively,and the mean deviations are-0.001 K and 0.006k/kg,respectively.(2)The short-duration heavy precipitation case study indicated that both MWR and MWTS-2/MWHS-2 observations could adjust the model’s initial conditions.Assimilating conventional plus MWR data significantly improved the temperature and humidity fields within the Beijing area covered by the observation stations,with impacts on precipitation forecasts primarily reflected in the magnitude of predicted rainfall.Assimilating conventional plus MWTS-2/MWHS-2 data adjusted the entire model field,showing more significant improvements in temperature and humidity analysis and forecasts compared to MWR alone.Joint assimilation further enhanced the accuracy of temperature and humidity forecast fields,better predicting the atmospheric thermodynamic structure at the time of precipitation,effectively reducing false precipitation reports,and improving precipitation forecast scores.(4)Batch test results show that MWR and MWTS-2/MWHS-2 observations can improve the temperature and humidity field prediction,and MWTS-2/MWHS-2 observations can improve the temperature and humidity prediction field,especially in the near-surface elevation layer.MWR mainly improved the precipitation forecast of rainstorms and heavy rainstorms.MWTS-2/MWHS-2 had a better effect on the precipitation above the moderate rainfall level.The combined assimilation had a better effect on the precipitation forecast of 0-12 h than that of single assimilation.However,the prediction of rainstorms and heavy rainstorm magnitude in the 24-hour precipitation forecast is slightly worse than that of assimilated MTS-2 /MWHS-2 alone.更多还原