有限区域变分四维同化系统的设计和试验

Schemes and Experiments of Regional Four-Dimensional Variational Data Assimilation Systems

使用共轭码技术 ,构造了中尺度模式的伴随模式 ,研究了模式侧边界条件。基于伴随模式技术的原理 ,设计了伴随同化和 Derber同化方法两套方案 ;下降算法采用共轭梯度法 ,使用准真实资料 ,进行了同化数值试验和预报试验。结果表明 ,两套同化方案都取得了一定的同化效果 ,Derber同化方法比伴随同化更令人满意。证明了变分同化是提高预报准确率的一种非常有效的手段。

Based on the conjugate code technique,a meso scale adjoint model is constructed,and the lateral boundary conditions of the model is discussed.Then assimilation and prediction experiments are performed by adopting the adjoint and Derber's assimilation schemes,and using the quasi real data and the descent algorithm of conjugate gradient method in assimilation.The results show that the both schemes achieve fine assimilation effect with Derber's scheme better than conjugate one.It is suggested that the variational assimilation is an effective skill to improve the prediction accuracy.