Preprints
https://doi.org/10.5194/egusphere-2022-434
https://doi.org/10.5194/egusphere-2022-434
 
09 Jun 2022
09 Jun 2022

Guidance on how to improve vertical covariance localization based on a 1000-member ensemble

Tobias Necker1, David Hinger1, Philipp Johannes Griewank1, Takemasa Miyoshi2, and Martin Weissmann1 Tobias Necker et al.
  • 1Institut für Meteorologie und Geophysik, Universität Wien, Vienna, Austria
  • 2RIKEN Center for Computational Science, Kobe, Japan

Abstract. The success of ensemble data assimilation systems substantially depends on localization, which is required to mitigate sampling errors caused by modeling background error covariances with undersized ensembles. However, finding an optimal localization is highly challenging as covariances, sampling errors, and appropriate localization depend on various factors. Our study investigates vertical localization based on a unique convection-permitting 1000-member ensemble simulation. 1000-member ensemble correlations serve as truth for examining vertical correlations and their sampling error. We discuss requirements for vertical localization by deriving an empirical optimal localization (EOL) that minimizes the sampling error in 40-member sub-sample correlations with respect to the 1000-member reference. Our analysis covers temperature, specific humidity, and wind correlations on various pressure levels. Results suggest that vertical localization should depend on several aspects, such as the respective variable, vertical level, or correlation type (self- or cross-correlations). Comparing the empirical optimal localization with common distance-dependent localization approaches highlights that finding suitable localization functions bears substantial room for improvement. Furthermore, we discuss the gain of combining different localization approaches with an adaptive statistical sampling error correction.

Journal article(s) based on this preprint

09 Jan 2023
Guidance on how to improve vertical covariance localization based on a 1000-member ensemble
Tobias Necker, David Hinger, Philipp Johannes Griewank, Takemasa Miyoshi, and Martin Weissmann
Nonlin. Processes Geophys., 30, 13–29, https://doi.org/10.5194/npg-30-13-2023,https://doi.org/10.5194/npg-30-13-2023, 2023
Short summary

Tobias Necker et al.

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-434', Lili Lei, 04 Jul 2022
    • AC1: 'Reply on RC1', Tobias Necker, 23 Jul 2022
  • RC2: 'Comment on egusphere-2022-434', Pavel Sakov, 08 Aug 2022
    • AC2: 'Reply on RC2', Tobias Necker, 14 Sep 2022
  • EC1: 'Comment on egusphere-2022-434', Olivier Talagrand, 17 Aug 2022
    • AC3: 'Reply on EC1', Tobias Necker, 14 Sep 2022

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-434', Lili Lei, 04 Jul 2022
    • AC1: 'Reply on RC1', Tobias Necker, 23 Jul 2022
  • RC2: 'Comment on egusphere-2022-434', Pavel Sakov, 08 Aug 2022
    • AC2: 'Reply on RC2', Tobias Necker, 14 Sep 2022
  • EC1: 'Comment on egusphere-2022-434', Olivier Talagrand, 17 Aug 2022
    • AC3: 'Reply on EC1', Tobias Necker, 14 Sep 2022

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision
AR by Tobias Necker on behalf of the Authors (15 Sep 2022)  Author's response    Author's tracked changes    Manuscript
ED: Reconsider after major revisions (further review by editor and referees) (19 Sep 2022) by Olivier Talagrand
AR by Tobias Necker on behalf of the Authors (26 Oct 2022)  Author's response    Author's tracked changes    Manuscript
ED: Referee Nomination & Report Request started (31 Oct 2022) by Olivier Talagrand
RR by Anonymous Referee #1 (11 Nov 2022)
ED: Publish subject to minor revisions (review by editor) (12 Dec 2022) by Olivier Talagrand
AR by Tobias Necker on behalf of the Authors (14 Dec 2022)  Author's response    Author's tracked changes    Manuscript
ED: Publish subject to technical corrections (14 Dec 2022) by Olivier Talagrand
AR by Tobias Necker on behalf of the Authors (15 Dec 2022)  Author's response    Manuscript

Journal article(s) based on this preprint

09 Jan 2023
Guidance on how to improve vertical covariance localization based on a 1000-member ensemble
Tobias Necker, David Hinger, Philipp Johannes Griewank, Takemasa Miyoshi, and Martin Weissmann
Nonlin. Processes Geophys., 30, 13–29, https://doi.org/10.5194/npg-30-13-2023,https://doi.org/10.5194/npg-30-13-2023, 2023
Short summary

Tobias Necker et al.

Tobias Necker et al.

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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

Short summary
This study investigates vertical localization based on a unique convection-permitting 1000-member ensemble simulation. We discuss requirements for vertical localization by deriving an empirical optimal localization (EOL) that minimizes the sampling error in 40-member sub-sample correlations assuming 1000-member correlations as truth. Results suggest that vertical localization should depend on different aspects that can help to improve vertical localization in future data assimilation systems.