基于中尺度模式的星载高光谱红外辐射资料直接同化及应用研究

Highspectral infrared remote sensing can provide the information about temperature and humidity of the atmosphere at high vertical resolution and high accuracy. However, due to the constraints of assimilation technique and only using the clear data, the impact is limited after assimilating observations into mesoscale model. The project based on coupling the mesoscale numerical model WRF (Weather Research and Forecast) and GSI (Gridpoint Statistical Interpolation) assimilation system, through the improvement of the accuracy of observation-error for cloud contaminated data and bias correction method, improves the potential application value of assimilating radiances into mesoscale model. The research includes three aspects: (1) Taking the climate of China into account, the simulated radiances are calculated based on the radiative transfer model in the region of clear and cloud, respectively, which can improve the regional accuracy of satellite observation-error. Thus the cloud contaminated channel can be used effectively; (2) Based on a scheme of VarBC (Variational Bias Correction), a combined method is proposed using the online and offline VarBC, which can improve the stability of correction when assimilating the radiances data into mesoscale model; (3) The influence and forecast accuracy of assimilating radiances into mesoscale are verified in the typhoon forecast experiments. This research aims to improve the forecast and early warning capability for typhoon and other mesoscale disasters in the regional model, and provide the scientific reference for China to carry out the radiances assimilation of first hyperspectral infrared sensor in future.

星载高光谱红外资料具有高垂直分辨率和高精度的大气温湿度廓线信息。然而，由于同化技术和仅使用晴空资料的限制，致使其在中尺度区域预报中的同化应用效果有限。本项目基于中尺度数值预报模式WRF 和GSI同化系统耦合，通过改进云污染资料观测误差描述和偏差订正技术，提高高光谱红外辐射资料在中尺度模式中的直接同化应用能力。具体研究内容涵括三个方面：（1）结合中国区域气候特征，基于通用辐射传输模式全空间模拟，提高资料观测误差描述，实现受云污染影响较小通道资料的应用；（2）采用变分偏差订正方案，利用在线与离线相结合的手段，提高辐射资料在中尺度模式中的偏差订正稳定性；（3）检验高光谱红外资料同化在台风预报中的应用效果。以期改善区域模式对台风等中尺度灾害天气的预测预警能力，为我国将要发射的首颗星载高光谱红外传感器开展资料同化应用提供科学参考。

项目通过耦合中尺度天气预报模式和区域同化系统，综合利用高光谱红外资料高分辨率垂直观测信息和区域大气数值模式高分辨率的优点，深入研究卫星高光谱红外资料直接同化的关键技术难点。围绕研究目标，完成以下研究内容：（1）量化了高光谱红外资料观测误差特征，提出了基于数据驱动的观测误差协方差构建技术，奠定了有云区域产品的同化基础；（2）提出在线和离线相结合的动态偏差订正方案，提高区域模式偏差订正效果和稳定性；（3）实现星载高光谱红外资料在区域模式中的直接同化应用，显著改善区域模式对台风路径和强度预报的精度水平。研究为高光谱红外资料同化的业务化应用提供技术参考。