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A weak‐constraint four‐dimensional variational analysis system in the stratosphere
Author(s) -
Lindskog Magnus,
Dee Dick,
Trémolet Yannick,
Andersson Erik,
Radnóti Gabor,
Fisher Mike
Publication year - 2009
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.392
Subject(s) - radiosonde , stratosphere , constraint (computer aided design) , radiance , depth sounding , covariance , error analysis , meteorology , environmental science , mathematics , atmospheric sciences , statistics , remote sensing , physics , geology , oceanography , geometry
A weak‐constraint four‐dimensional variational (4D‐Var) analysis system designed to correct stratospheric model errors has been evaluated. Verifications against upper‐level radiosonde temperature observations and Stratospheric Sounding Unit (SSU) radiance data show that the addition of a weak constraint in the stratosphere can greatly reduce analysis bias. Both single‐observation analysis experiments and extended assimilations have been performed to help us understand the impact of the model error covariance specifications required for the weak‐constraint formulation. It is found that the use of multivariate balance constraints similar to those implemented in background‐error covariances can be problematic. Copyright © 2009 Royal Meteorological Society