A four-dimensional variational chemistry data assimilation scheme for Eulerian chemistry transport modeling
A four-dimensional variational chemistry data assimilation scheme for Eulerian chemistry transport modeling
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DOI：
10.1029/1999jd900280
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发表时间：
1999-08
影响因子：
--
通讯作者：
Hendrik Eibern;H. Schmidt
中科院分区：
文献类型：
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作者：
Hendrik Eibern;H. Schmidt
利用化学反应、输运和扩散的四维变分技术，解决了对流层微量气体观测资料同化成欧拉化学输运模型的反问题。以科隆大学欧洲空气污染扩散化学输送模型2和区域酸沉积模型2气相机制为基础，在伴随模型版本的基础上，开发了一个完整的四维变分数据同化包，其中包括水平和垂直平流、隐式垂直扩散和伴随气相机制的伴随算子。为了评估该技术的潜力和局限性，而不降低不完善的气象分析和统计上未建立的误差协方差估计的影响，使用了人工气象数据和观测。结果是在一套实验的基础上提出的，其中人工“观察”的简化记录提供给同化程序，而其他“数据”被保留用于分析的性能控制。从计算和存储要求两方面论证了四维变分技术适用于先进并行平台上的综合化学输运模型。进一步表明，即使“测量”具有无偏随机误差，观察到的物种通常也可以被分析。提出了更具挑战性的实验，旨在提高方法的技能(1)通过将可用的观测主要限制为地表臭氧观测，有限的同化间隔为6小时；(2)从选择不佳的初始猜测值开始。在三维化学输运模型的首次应用中，不仅成功地分析了观察到的成分，还分析了化学上密切相关的未观察到的成分。
The inverse problem of data assimilation of tropospheric trace gas observations into an Eulerian chemistry transport model has been solved by the four-dimensional variational technique including chemical reactions, transport, and diffusion. The University of Cologne European Air Pollution Dispersion Chemistry Transport Model 2 with the Regional Acid Deposition Model 2 gas phase mechanism is taken as the basis for developing a full four-dimensional variational data assimilation package, on the basis of the adjoint model version, which includes the adjoint operators of horizontal and vertical advection, implicit vertical diffusion, and the adjoint gas phase mechanism. To assess the potential and limitations of the technique without degrading the impact of nonperfect meteorological analyses and statistically not established error covariance estimates, artificial meteorological data and observations are used. The results are presented on the basis of a suite of experiments, where reduced records of artificial “observations” are provided to the assimilation procedure, while other “data” is retained for performance control of the analysis. The paper demonstrates that the four-dimensional variational technique is applicable for a comprehensive chemistry transport model in terms of computational and storage requirements on advanced parallel platforms. It is further shown that observed species can generally be analyzed, even if the “measurements” have unbiased random errors. More challenging experiments are presented, aiming to tax the skill of the method (1) by restricting available observations mostly to surface ozone observations for a limited assimilation interval of 6 hours and (2) by starting with poorly chosen first guess values. In this first such application to a three-dimensional chemistry transport model, success was also achieved in analyzing not only observed but also chemically closely related unobserved constituents.