Linking rapid forecast error growth to diabatic processes
Abstract The predictability of high‐impact weather events over the North Atlantic is controlled by synoptic‐scale systems and the mesoscale structures embedded within them. Despite forecast uncertainty being greatest at small scales at the initial time, forecast error projects strongly onto synoptic...
Published in: | Quarterly Journal of the Royal Meteorological Society |
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crwiley:10.1002/qj.3861 2024-06-02T08:11:14+00:00 Linking rapid forecast error growth to diabatic processes Sánchez, Claudio Methven, John Gray, Suzanne Cullen, Mike Met Office Academic Partnership 2020 http://dx.doi.org/10.1002/qj.3861 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fqj.3861 https://onlinelibrary.wiley.com/doi/pdf/10.1002/qj.3861 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/qj.3861 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.3861 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Quarterly Journal of the Royal Meteorological Society volume 146, issue 732, page 3548-3569 ISSN 0035-9009 1477-870X journal-article 2020 crwiley https://doi.org/10.1002/qj.3861 2024-05-03T10:55:01Z Abstract The predictability of high‐impact weather events over the North Atlantic is controlled by synoptic‐scale systems and the mesoscale structures embedded within them. Despite forecast uncertainty being greatest at small scales at the initial time, forecast error projects strongly onto synoptic and larger scales within days. Different stages of error growth have previously been identified including: convective instability, baroclinic instability and the influence of divergent outflow on the tropopause position, and interactions between disturbances at tropopause level. Evidence is presented for "predictability barriers" (PBs) identified with events on certain validation dates during the North Atlantic Waveguide and Downstream impact Experiment (NAWDEX) where ensemble spread grows more quickly than usual, but ensemble‐mean forecast error grows even faster. An advective mechanism for diabatic influence on the development of tropopause ridges is hypothesised to be linked to the PB events. A semi‐geostrophic balance tool is used to attribute the response of the 3D ageostrophic flow to geostrophic and diabatic forcing, enabling a novel diagnostic for Diabatically Induced Ageostrophic Advection (DIAA) of potential vorticity. It is shown that predictability barriers are linked to events with strong diabatic influence on tropopause advection during the NAWDEX period. Error growth exceeds ensemble spread rate by approximately 4/3 during strong DIAA events, showing that predictive skill is considerably lower in these situations. Article in Journal/Newspaper North Atlantic Wiley Online Library Quarterly Journal of the Royal Meteorological Society 146 732 3548 3569 |
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English |
description |
Abstract The predictability of high‐impact weather events over the North Atlantic is controlled by synoptic‐scale systems and the mesoscale structures embedded within them. Despite forecast uncertainty being greatest at small scales at the initial time, forecast error projects strongly onto synoptic and larger scales within days. Different stages of error growth have previously been identified including: convective instability, baroclinic instability and the influence of divergent outflow on the tropopause position, and interactions between disturbances at tropopause level. Evidence is presented for "predictability barriers" (PBs) identified with events on certain validation dates during the North Atlantic Waveguide and Downstream impact Experiment (NAWDEX) where ensemble spread grows more quickly than usual, but ensemble‐mean forecast error grows even faster. An advective mechanism for diabatic influence on the development of tropopause ridges is hypothesised to be linked to the PB events. A semi‐geostrophic balance tool is used to attribute the response of the 3D ageostrophic flow to geostrophic and diabatic forcing, enabling a novel diagnostic for Diabatically Induced Ageostrophic Advection (DIAA) of potential vorticity. It is shown that predictability barriers are linked to events with strong diabatic influence on tropopause advection during the NAWDEX period. Error growth exceeds ensemble spread rate by approximately 4/3 during strong DIAA events, showing that predictive skill is considerably lower in these situations. |
author2 |
Met Office Academic Partnership |
format |
Article in Journal/Newspaper |
author |
Sánchez, Claudio Methven, John Gray, Suzanne Cullen, Mike |
spellingShingle |
Sánchez, Claudio Methven, John Gray, Suzanne Cullen, Mike Linking rapid forecast error growth to diabatic processes |
author_facet |
Sánchez, Claudio Methven, John Gray, Suzanne Cullen, Mike |
author_sort |
Sánchez, Claudio |
title |
Linking rapid forecast error growth to diabatic processes |
title_short |
Linking rapid forecast error growth to diabatic processes |
title_full |
Linking rapid forecast error growth to diabatic processes |
title_fullStr |
Linking rapid forecast error growth to diabatic processes |
title_full_unstemmed |
Linking rapid forecast error growth to diabatic processes |
title_sort |
linking rapid forecast error growth to diabatic processes |
publisher |
Wiley |
publishDate |
2020 |
url |
http://dx.doi.org/10.1002/qj.3861 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fqj.3861 https://onlinelibrary.wiley.com/doi/pdf/10.1002/qj.3861 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/qj.3861 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.3861 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Quarterly Journal of the Royal Meteorological Society volume 146, issue 732, page 3548-3569 ISSN 0035-9009 1477-870X |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/qj.3861 |
container_title |
Quarterly Journal of the Royal Meteorological Society |
container_volume |
146 |
container_issue |
732 |
container_start_page |
3548 |
op_container_end_page |
3569 |
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1800757299925483520 |