How grid‐spacing and convection representation affected the wind speed forecasts of four polar lows
Abstract The horizontal resolution in numerical weather prediction models can have a large impact on the quality of polar low forecasts. However, there are few studies on the effect of the horizontal grid spacings which are currently in operational use at the European Centre for Medium‐Range Weather...
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crwiley:10.1002/qj.3911 2024-06-02T08:01:59+00:00 How grid‐spacing and convection representation affected the wind speed forecasts of four polar lows Hallerstig, Matilda Magnusson, Linus Kolstad, Erik W. Mayer, Stephanie Research Council of Norway 2020 http://dx.doi.org/10.1002/qj.3911 https://onlinelibrary.wiley.com/doi/pdf/10.1002/qj.3911 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/qj.3911 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.3911 en eng Wiley http://creativecommons.org/licenses/by/4.0/ Quarterly Journal of the Royal Meteorological Society volume 147, issue 734, page 150-165 ISSN 0035-9009 1477-870X journal-article 2020 crwiley https://doi.org/10.1002/qj.3911 2024-05-03T11:19:38Z Abstract The horizontal resolution in numerical weather prediction models can have a large impact on the quality of polar low forecasts. However, there are few studies on the effect of the horizontal grid spacings which are currently in operational use at the European Centre for Medium‐Range Weather Forecasts (ECMWF). Here, we evaluate the 10 m wind speed forecasts for four polar lows in November and December 2016 against remote and in situ observations. We study the 18 km grid spacing, used in the ensemble, 9 km for the current operational deterministic model runs, and 5 km for the planned future deterministic runs. The 9 and 5 km versions fall within the range of grid spacings that resolve convection partly but not fully. Therefore, we also do sensitivity tests with and without deep convection parametrization. Finally, we examine the added value from the operational limited‐area model AROME‐Arctic with 2.5 km grid spacing. The 18 km version performed worst in magnitude of wind speed, but it did forecast the locations of the polar lows as well as the other models. Thus, the ensemble can be used for polar low probability products. The 5 and 9 km versions with parametrized convection were the best‐performing models over the ocean, while AROME‐Arctic was the best model along the coast and over land. The 5 and 9 km versions with resolved deep convection produced fewer but larger convective cells with patches of both under‐ and overestimation of wind speed. The fact that there was almost no difference between the 9 and 5 km grid spacing, but a clear impact from the handling of convection, suggests that, to improve polar low forecasts in the ECMWF deterministic runs, special attention to convection is needed. Article in Journal/Newspaper Arctic Wiley Online Library Arctic Quarterly Journal of the Royal Meteorological Society 147 734 150 165 |
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Open Polar |
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Wiley Online Library |
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crwiley |
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English |
description |
Abstract The horizontal resolution in numerical weather prediction models can have a large impact on the quality of polar low forecasts. However, there are few studies on the effect of the horizontal grid spacings which are currently in operational use at the European Centre for Medium‐Range Weather Forecasts (ECMWF). Here, we evaluate the 10 m wind speed forecasts for four polar lows in November and December 2016 against remote and in situ observations. We study the 18 km grid spacing, used in the ensemble, 9 km for the current operational deterministic model runs, and 5 km for the planned future deterministic runs. The 9 and 5 km versions fall within the range of grid spacings that resolve convection partly but not fully. Therefore, we also do sensitivity tests with and without deep convection parametrization. Finally, we examine the added value from the operational limited‐area model AROME‐Arctic with 2.5 km grid spacing. The 18 km version performed worst in magnitude of wind speed, but it did forecast the locations of the polar lows as well as the other models. Thus, the ensemble can be used for polar low probability products. The 5 and 9 km versions with parametrized convection were the best‐performing models over the ocean, while AROME‐Arctic was the best model along the coast and over land. The 5 and 9 km versions with resolved deep convection produced fewer but larger convective cells with patches of both under‐ and overestimation of wind speed. The fact that there was almost no difference between the 9 and 5 km grid spacing, but a clear impact from the handling of convection, suggests that, to improve polar low forecasts in the ECMWF deterministic runs, special attention to convection is needed. |
author2 |
Research Council of Norway |
format |
Article in Journal/Newspaper |
author |
Hallerstig, Matilda Magnusson, Linus Kolstad, Erik W. Mayer, Stephanie |
spellingShingle |
Hallerstig, Matilda Magnusson, Linus Kolstad, Erik W. Mayer, Stephanie How grid‐spacing and convection representation affected the wind speed forecasts of four polar lows |
author_facet |
Hallerstig, Matilda Magnusson, Linus Kolstad, Erik W. Mayer, Stephanie |
author_sort |
Hallerstig, Matilda |
title |
How grid‐spacing and convection representation affected the wind speed forecasts of four polar lows |
title_short |
How grid‐spacing and convection representation affected the wind speed forecasts of four polar lows |
title_full |
How grid‐spacing and convection representation affected the wind speed forecasts of four polar lows |
title_fullStr |
How grid‐spacing and convection representation affected the wind speed forecasts of four polar lows |
title_full_unstemmed |
How grid‐spacing and convection representation affected the wind speed forecasts of four polar lows |
title_sort |
how grid‐spacing and convection representation affected the wind speed forecasts of four polar lows |
publisher |
Wiley |
publishDate |
2020 |
url |
http://dx.doi.org/10.1002/qj.3911 https://onlinelibrary.wiley.com/doi/pdf/10.1002/qj.3911 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/qj.3911 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.3911 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic |
genre_facet |
Arctic |
op_source |
Quarterly Journal of the Royal Meteorological Society volume 147, issue 734, page 150-165 ISSN 0035-9009 1477-870X |
op_rights |
http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.1002/qj.3911 |
container_title |
Quarterly Journal of the Royal Meteorological Society |
container_volume |
147 |
container_issue |
734 |
container_start_page |
150 |
op_container_end_page |
165 |
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1800746481189126144 |