# Hybridization of static and ensemble B in JEDI EnVar

**URL:** <https://forums.jcsda.org/t/hybridization-of-static-and-ensemble-b-in-jedi-envar/213>\
**Category:** JEDI\
**Created:** [October 19, 2021, 5:10pm UTC](https://forums.jcsda.org/t/hybridization-of-static-and-ensemble-b-in-jedi-envar/213 "2021-10-19T17:10:13Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![hbo9955](https://yyz1.discourse-cdn.com/flex031/user_avatar/forums.jcsda.org/hbo9955/32/47_2.png) [@hbo9955](https://forums.jcsda.org/u/hbo9955)\
**Post date:** [October 19, 2021, 5:10pm UTC](https://forums.jcsda.org/t/hybridization-of-static-and-ensemble-b-in-jedi-envar/213/1 "2021-10-19T17:10:13Z")

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Hello,

I would like to know how the ensemble covariances are blended into the variational framework in JEDI EnVar application. Is it achieved by explicitly replacing the static B with a weighted sum of static and ensemble B (Hamill and Snyder 2000), or through augmented control variables (Lorenc 2003) as in GSI?

Thanks,  
Bo

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**Author:** ![benjaminmenetrier](https://yyz1.discourse-cdn.com/flex031/user_avatar/forums.jcsda.org/benjaminmenetrier/32/9_2.png) [@benjaminmenetrier](https://forums.jcsda.org/u/benjaminmenetrier)\
**Post date:** [November 3, 2021, 7:48am UTC](https://forums.jcsda.org/t/hybridization-of-static-and-ensemble-b-in-jedi-envar/213/2 "2021-11-03T07:48:53Z")

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Hi @hbo9955, sorry for this late reply. The EnVar in JEDI-OOPS uses [Buehner (2005)](https://rmets.onlinelibrary.wiley.com/doi/abs/10.1256/qj.04.15) implementation, which [Wang et al. (2007)](https://journals.ametsoc.org/view/journals/mwre/135/1/mwr3282.1.xml) showed to be equivalent to [Lorenc (2003)](https://rmets.onlinelibrary.wiley.com/doi/10.1256/qj.02.132).