Use of Incremental Analysis Updates in 4D-Var Data Assimilation  

作　　者：Banglin ZHANG Vijay TALLAPRAGADA Fuzhong WENG Jason SIPPEL Zaizhong MA 

机构地区：[1]I.M.System Group,Inc.,College Park [2]NOAA NCEP Environmental Modeling Center,College Park [3]NOAA Center for Satellite Applications and Research,College Park [4]Joint Center for Satellite Data Assimilation,College Park

出　　处：《Advances in Atmospheric Sciences》2015年第12期1575-1582,共8页大气科学进展（英文版）

基　　金：supported by NOAA’s Hurricane Forecast Improvement Project

摘　　要：The four-dimensional variational （4D-Var） data assimilation systems used in most operational and research centers use initial condition increments as control variables and adjust initial increments to find optimal analysis solutions. This approach may sometimes create discontinuities in analysis fields and produce undesirable spin ups and spin downs. This study explores using incremental analysis updates （IAU） in 4D-Var to reduce the analysis discontinuities. IAU-based 4D-Var has almost the same mathematical formula as conventional 4D-Var if the initial condition increments are replaced with time-integrated increments as control variables. The IAU technique was implemented in the NASA/GSFC 4D-Var prototype and compared against a control run without IAU. The results showed that the initial precipitation spikes were removed and that other discontinuities were also reduced, especially for the analysis of surface temperature.The four-dimensional variational （4D-Var） data assimilation systems used in most operational and research centers use initial condition increments as control variables and adjust initial increments to find optimal analysis solutions. This approach may sometimes create discontinuities in analysis fields and produce undesirable spin ups and spin downs. This study explores using incremental analysis updates （IAU） in 4D-Var to reduce the analysis discontinuities. IAU-based 4D-Var has almost the same mathematical formula as conventional 4D-Var if the initial condition increments are replaced with time-integrated increments as control variables. The IAU technique was implemented in the NASA/GSFC 4D-Var prototype and compared against a control run without IAU. The results showed that the initial precipitation spikes were removed and that other discontinuities were also reduced, especially for the analysis of surface temperature.

关 键 词：data assimilation incremental analysis updates 4D-Vat convergence 

分 类 号：P435[天文地球—大气科学及气象学]