School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China; Guangdong-Hongkong-Macao Greater Bay Area Weather Research Center for Monitoring Warning and Forecasting (Shenzhen Institute of Meteorological Innovation), Shenzhen 518040, China.
Institute for Environmental and Climate Research, Jinan University, Guangzhou 510632, China; Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou 510632, China.
Sci Total Environ. 2020 Jun 1;719:137430. doi: 10.1016/j.scitotenv.2020.137430. Epub 2020 Feb 19.
A new aerosol optical depth (AOD) data assimilation (DA) module was developed in Gridpoint Statistical Interpolation (GSI) 3-dimensional variational (3DVAR) system, named FastJ/CRTM-AOD DA module. And applied to the Modal Aerosol Dynamics Model for Europe with the Secondary Organic Aerosol Model (MADE/SORGAM) in the Weather Research and Forecasting/Chemistry model (WRF/Chem). The Fast-J optical module in WRF/Chem was used as the observation operator of AOD. The corresponding Jacobian code was modified from the one of CRTM-AOD in GSI. This way obviated the need for the Jacobian code's generation, which was complex and difficult for the highly nonlinear observation operator. During the studying period (January and April of 2014), compared to the ground AOD observations, AOD DA reduced about 20% fractional error (FE) with MADE/SORGAM. The original DA framework, which applied to the Goddard Chemistry Aerosol Radiation and Transport (GOCART) mechanism, performed slightly better than the new assimilation scheme for the low-value AOD situations (value < 0.4). However, compared to the original DA framework, the new DA scheme show a notable improvement for the high-value (0.4 < value ≤ 1.2) and extreme-high-value (value > 1.2) AOD situations. FE can be reduced by 48% and 64%, respectively. It indicates that the AOD DA impacts on AOD forecasts vary significant between different aerosol mechanisms. Moreover, FastJ/CRTM-AOD DA module can be easily and efficiently applied to the other aerosol schemes and the other optical modules, which is important to the development on AOD assimilation.
一个新的气溶胶光学厚度（AOD）数据同化（DA）模块是在格点统计插值（GSI）三维变分（3DVAR）系统中开发的，名为 FastJ/CRTM-AOD DA 模块。并应用于欧洲模态气溶胶动力学模型与二次有机气溶胶模型（MADE/SORGAM）在天气研究与预报/化学模型（WRF/Chem）中。WRF/Chem 中的 Fast-J 光学模块被用作 AOD 的观测算子。相应的雅可比代码是从 GSI 中的 CRTM-AOD 一个修改而来的。这样就避免了生成雅可比代码的需要，对于高度非线性的观测算子来说，这是复杂和困难的。在研究期间（2014 年 1 月和 4 月），与地面 AOD 观测相比，AOD DA 降低了 MADE/SORGAM 约 20%的分数误差（FE）。原始的 DA 框架，应用于戈达德化学气溶胶辐射和传输（GOCART）机制，在低值 AOD 情况下（<0.4），比新的同化方案略好。然而，与原始的 DA 框架相比，新的 DA 方案在高值（0.4<值≤1.2）和极高值（值>1.2）AOD 情况下有显著的改进。FE 可以分别减少 48%和 64%。这表明 AOD DA 对 AOD 预测的影响在不同的气溶胶机制之间有很大的差异。此外，FastJ/CRTM-AOD DA 模块可以很容易和有效地应用于其他气溶胶方案和其他光学模块，这对 AOD 同化的发展是重要的。
