中国区域积雪多源融合实况分析产品研制

Development of a real-time analysis product for multi-source fusion of regional snow cover in China

  • 摘要: 准确、及时掌握积雪的时、空变化对于数值预报、气候变化、灾害天气分析等至关重要。本文充分利用中国气象局陆面数据同化系统(CLDAS v2.0)大气驱动数据、风云四号气象卫星(FY-4)积雪覆盖、积雪深度站点观测、地表参数等数据,采用CLM、Noah和Noah-MP陆面模式积雪模拟,“Ensemble Square Root Kalman Filter+Direct Insertion”(EnSRF+DI)积雪同化,Triple Collocation (TC)协方差多模式集成以及考虑高程的多重网格变分分析方法,研制了中国区域6.25 km、1 h分辨率积雪多源融合实况分析产品。采用站点观测数据评估表明,该产品质量总体优于国际同类产品GLDAS和ERA5_Land积雪数据,且较积雪模式模拟而言,同化FY-4积雪覆盖后积雪深度的均方根误差(RMSE)能够降低10%。该产品数据格式为netcdf,序列长度为2021年11月—实时,数据大小为45 MB/h,产品要素包括积雪深度、积雪覆盖率、积雪深度变化。已通过中国气象局高价值气象数据产品准入,在中央气象台天气会商、灾害天气监测、融雪性灾害分析等方面得到应用。

     

    Abstract: Accurate and timely monitoring of spatiotemporal variations in snow is crucial for numerical weather prediction, climate change studies, and disaster weather forecasting. This study leverages multiple datasets, including the atmospheric forcing data for China Meteorological Administration (CMA) Land Surface Data Assimilation system (CLDAS v2.0), Fengyun-4 snow cover data, in-situ snow depth observations, and land surface parameters. Snow simulations of CLM (Community Land Model), Noah (the Cmomunity Noah Land Surface Model), and Noah-MP (Noah with Muti-Parameterization Options) land surface models, the "Ensemble Square Root Kalman Filter+Direct Insertion"(EnSRF+DI) snow assimilation technique, the TC (Triple Collocation) covariance-based multi-model integration, and a multi-grid variational analysis method accounting for elevation are employed in the present study to develop a multi-source merged snow analysis product over China at the spatial and temporal resolutions of 6.25 km and 1 h respectively. Evaluation based on in-situ observations demonstrates that the quality of this product is generally superior to that of international counterparts, such as GLDAS and ERA5_Land snow depth products. Compared to snow depth simulations solely from land surface models, the assimilation of Fengyun-4 satellite snow cover data reduces the Root Mean Square Error (RMSE) of snow depth estimates by 10%. The product is provided in netcdf format, with temporal coverage beginning in November 2021 and continuing in near real-time, and an approximate data volume of 45 MB/h. It includes key variables such as snow depth, snow cover fraction, and snow depth change. This product has been recognized as a high-value meteorological dataset by the CMA and has been operationally applied in weather briefings, disaster weather monitoring, and snowmelt flood risk analysis.

     

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