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Effects of the wind–mass balance constraint on ensemble forecasts in the hybrid‐4DEnVar
Author(s) -
Song HyoJong,
Kang JeonHo
Publication year - 2019
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.3440
Subject(s) - covariance , environmental science , perturbation (astronomy) , meteorology , nonlinear system , wind speed , ensemble forecasting , mathematics , atmospheric sciences , statistics , physics , quantum mechanics
Ensemble forecast covariance plays an important role in the hybridized background error covariance framework to improve the resultant analysis quality. However, a localization of ensemble samples is needed to fully take advantage of flow‐dependent error modes. In this regard, it is an interesting and practical issue as to which variables, composing the ensemble perturbation, the localization should be applied to. This study examines this issue in a boreal‐summer month by comparing two experimental sets: (a) a set of model variables, and (b) another set of model wind variables and unbalanced dry mass (temperature and surface pressure) used for the control variables. In the comparison, it is shown that imposing the wind–mass balance on the ensemble perturbation improves the Antarctic lower‐stratospheric temperature and tropical mid‐/lower‐tropospheric humidity. The nonlinear wind–mass balance relationship smooths an evolution of humidity forecast forced by the resultant analysis increments.