Preprints
https://doi.org/10.5194/gmd-2021-394
https://doi.org/10.5194/gmd-2021-394
Submitted as: model experiment description paper
04 Jan 2022
Submitted as: model experiment description paper | 04 Jan 2022
Status: a revised version of this preprint was accepted for the journal GMD and is expected to appear here in due course.

Stratospheric Nudging And Predictable Surface Impacts (SNAPSI): A Protocol for Investigating the Role of the Stratospheric Polar Vortex in Subseasonal to Seasonal Forecasts

Peter Hitchcock1, Amy Butler2, Andrew Charlton-Perez3, Chaim Garfinkel4, Tim Stockdale5, James Anstey6, Dann Mitchell7, Daniela I. V. Domeisen8,9, Tongwen Wu10, Yixiong Lu10, Daniele Mastrangelo11, Piero Malguzzi11, Hai Lin12, Ryan Muncaster12, Bill Merryfield6, Michael Sigmond6, Baoqiang Xiang13,14, Liwei Jia13, Yu-Kyung Hyun15, Jiyong Oh16, Damien Specq17, Isla R. Simpson18, Jadwiga H. Richter18, Cory Barton19, Jeff Knight20, Eun-Pa Lim21, and Harry Hendon21 Peter Hitchcock et al.
  • 1Dept. Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA
  • 2NOAA Chemical Sciences Laboratory, Boulder, CO, USA
  • 3Department of Meteorology, University of Reading, UK
  • 4Fredy and Nadine Herrmann Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
  • 5European Centre for Medium-range Weather Forecasts, Reading, UK
  • 6Canadian Centre for Climate Modelling and Analysis, Environment and Climate Change Canada, Victoria, BC, Canada
  • 7School of Geographical Sciences, University of Bristol, Bristol, United Kingdom
  • 8University of Lausanne, Lausanne, Switzerland
  • 9ETH Zürich, Zürich, Switzerland
  • 10Beijing Climate Center, China Meteorological Administration, Beijing, China
  • 11CNR-ISAC, Bologna, Italy
  • 12Recherche en prévision numérique atmosphérique, Environment and Climate Change Canada, Dorval, QC, Canada
  • 13Geophysical Fluid Dynamics Laboratory, NOAA, Princeton, NJ, USA
  • 14University Corporation for Atmospheric Research, Boulder, CO, USA
  • 15National Institute of Meteorological Sciences, Korea Meteorological Administration, Jeju, Korea
  • 16School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea
  • 17Centre National de Recherches Météorologiques, Université de Toulouse, Météo-France, CNRS, Toulouse, France
  • 18Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder, CO, USA
  • 19Space Science Division, US Naval Research Laboratory, Washington, DC, USA
  • 20Hadley Centre, Met Office, Exeter, United Kingdom
  • 21Bureau of Meteorology, Melbourne, Victoria, Australia

Abstract. Major disruptions of the winter season, high-latitude, stratospheric polar vortices can result in stratospheric anomalies that persist for months. These sudden stratospheric warming events are recognized as an important potential source of forecast skill for surface climate on subseasonal to seasonal timescales. Realizing this skill in operational subseasonal forecast models remains a challenge, as models must capture both the evolution of the stratospheric polar vortices in addition to their coupling to the troposphere. The processes involved in this coupling remain a topic of open research.

We present here the Stratospheric Nudging And Predictable Surface Impacts (SNAPSI) project. SNAPSI is a new model intercomparison protocol designed to study the role of the Arctic and Antarctic stratospheric polar vortices in sub-seasonal to seasonal forecast models. Based on a set of controlled, subseasonal, ensemble forecasts of three recent events, the protocol aims to address four main scientific goals. First, to quantify the impact of improved stratospheric forecasts on near-surface forecast skill. Second, to attribute specific extreme events to stratospheric variability. Third, to assess the mechanisms by which the stratosphere influences the troposphere in the forecast models, and fourth, to investigate the wave processes that lead to the stratospheric anomalies themselves. Although not a primary focus, the experiments are furthermore expected to shed light on coupling between the tropical stratosphere and troposphere. The output requested will allow for a more detailed, process-based community analysis than has been possible with existing databases of subseasonal forecasts.

Peter Hitchcock et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on gmd-2021-394', Anonymous Referee #1, 25 Jan 2022
    • AC1: 'Reply on RC1', Peter Hitchcock, 14 Apr 2022
  • RC2: 'Comment on gmd-2021-394', Anonymous Referee #2, 22 Feb 2022
    • AC3: 'Reply on RC2', Peter Hitchcock, 14 Apr 2022
  • EC1: 'Comment on gmd-2021-394', Juan Antonio Añel, 22 Feb 2022
    • AC2: 'Reply on EC1', Peter Hitchcock, 14 Apr 2022
  • EC2: 'Comment on gmd-2021-394', Juan Antonio Añel, 22 Feb 2022
    • AC2: 'Reply on EC1', Peter Hitchcock, 14 Apr 2022
  • EC3: 'Comment on gmd-2021-394', Juan Antonio Añel, 22 Feb 2022
    • AC2: 'Reply on EC1', Peter Hitchcock, 14 Apr 2022

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on gmd-2021-394', Anonymous Referee #1, 25 Jan 2022
    • AC1: 'Reply on RC1', Peter Hitchcock, 14 Apr 2022
  • RC2: 'Comment on gmd-2021-394', Anonymous Referee #2, 22 Feb 2022
    • AC3: 'Reply on RC2', Peter Hitchcock, 14 Apr 2022
  • EC1: 'Comment on gmd-2021-394', Juan Antonio Añel, 22 Feb 2022
    • AC2: 'Reply on EC1', Peter Hitchcock, 14 Apr 2022
  • EC2: 'Comment on gmd-2021-394', Juan Antonio Añel, 22 Feb 2022
    • AC2: 'Reply on EC1', Peter Hitchcock, 14 Apr 2022
  • EC3: 'Comment on gmd-2021-394', Juan Antonio Añel, 22 Feb 2022
    • AC2: 'Reply on EC1', Peter Hitchcock, 14 Apr 2022

Peter Hitchcock et al.

Peter Hitchcock et al.

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Short summary
This paper describes an experimental protocol focused on sudden stratospheric warmings to be carried out by subseasonal forecast modeling centers. These will allow for inter-model comparisons of these major disruptions to the stratospheric polar vortex, and of their impacts on the near surface flow. The protocol will lead to new insights into the contribution of the stratosphere to subseasonal forecast skill, and to new approaches to the dynamical attribution of extreme events.