Intercomparison of four algorithms for detecting tropical cyclones using ERA5
<p>The assessment of tropical cyclone (TC) statistics requires the direct, objective, and automatic detection and tracking of TCs in reanalyses and model simulations. Research groups have independently developed numerous algorithms during recent decades in order to answer that need. Today, the...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2022-09-01
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| Series: | Geoscientific Model Development |
| Online Access: | https://gmd.copernicus.org/articles/15/6759/2022/gmd-15-6759-2022.pdf |
| _version_ | 1811259543044227072 |
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| author | S. Bourdin S. Fromang W. Dulac J. Cattiaux F. Chauvin |
| author_facet | S. Bourdin S. Fromang W. Dulac J. Cattiaux F. Chauvin |
| author_sort | S. Bourdin |
| collection | DOAJ |
| description | <p>The assessment of tropical cyclone (TC) statistics requires the direct, objective, and automatic detection and tracking of TCs in reanalyses and model simulations. Research groups have independently developed numerous algorithms during recent decades in order to answer that need. Today, there is a large number of trackers that aim to detect the positions of TCs in gridded datasets.
The questions we ask here are the following: does the choice of tracker impact the climatology obtained? And, if it does, how should we deal with this issue?</p>
<p>This paper compares four trackers with very different formulations in detail. We assess their performances by tracking TCs in the ERA5 reanalysis and by comparing the outcome to the IBTrACS observations database.</p>
<p>We find typical detection rates of the trackers around 80 %. At the same time, false alarm rates (FARs) greatly vary across the four trackers and can sometimes exceed the number of genuine cyclones detected. Based on the finding that many of these false alarms (FAs) are extra-tropical cyclones (ETCs), we adapt two existing filtering methods common to all trackers. Both post-treatments dramatically impact FARs, which range from 9 % to 36 % in our final catalogs of TC tracks.
We then show that different traditional metrics can be very sensitive to the particular choice of tracker, which is particularly true for the TC frequencies and their durations. By contrast, all trackers identify a robust negative bias in ERA5 TC intensities, a result already noted in previous studies.</p>
<p>We conclude by advising against using as many trackers as possible and averaging the results. A more efficient approach would involve selecting one or a few trackers with well-known and complementary properties.</p> |
| first_indexed | 2024-04-12T18:33:12Z |
| format | Article |
| id | doaj.art-a1d9d69841264cc3b18e653a01f3fcad |
| institution | Directory Open Access Journal |
| issn | 1991-959X 1991-9603 |
| language | English |
| last_indexed | 2024-04-12T18:33:12Z |
| publishDate | 2022-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Geoscientific Model Development |
| spelling | doaj.art-a1d9d69841264cc3b18e653a01f3fcad2022-12-22T03:21:01ZengCopernicus PublicationsGeoscientific Model Development1991-959X1991-96032022-09-01156759678610.5194/gmd-15-6759-2022Intercomparison of four algorithms for detecting tropical cyclones using ERA5S. Bourdin0S. Fromang1W. Dulac2J. Cattiaux3F. Chauvin4Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ-Université Paris-Saclay, Gif-sur-Yvette, FranceLaboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ-Université Paris-Saclay, Gif-sur-Yvette, FranceCentre National de Recherches Météorologiques, Université de Toulouse, Météo France, CNRS, Toulouse, FranceCentre National de Recherches Météorologiques, Université de Toulouse, Météo France, CNRS, Toulouse, FranceCentre National de Recherches Météorologiques, Université de Toulouse, Météo France, CNRS, Toulouse, France<p>The assessment of tropical cyclone (TC) statistics requires the direct, objective, and automatic detection and tracking of TCs in reanalyses and model simulations. Research groups have independently developed numerous algorithms during recent decades in order to answer that need. Today, there is a large number of trackers that aim to detect the positions of TCs in gridded datasets. The questions we ask here are the following: does the choice of tracker impact the climatology obtained? And, if it does, how should we deal with this issue?</p> <p>This paper compares four trackers with very different formulations in detail. We assess their performances by tracking TCs in the ERA5 reanalysis and by comparing the outcome to the IBTrACS observations database.</p> <p>We find typical detection rates of the trackers around 80 %. At the same time, false alarm rates (FARs) greatly vary across the four trackers and can sometimes exceed the number of genuine cyclones detected. Based on the finding that many of these false alarms (FAs) are extra-tropical cyclones (ETCs), we adapt two existing filtering methods common to all trackers. Both post-treatments dramatically impact FARs, which range from 9 % to 36 % in our final catalogs of TC tracks. We then show that different traditional metrics can be very sensitive to the particular choice of tracker, which is particularly true for the TC frequencies and their durations. By contrast, all trackers identify a robust negative bias in ERA5 TC intensities, a result already noted in previous studies.</p> <p>We conclude by advising against using as many trackers as possible and averaging the results. A more efficient approach would involve selecting one or a few trackers with well-known and complementary properties.</p>https://gmd.copernicus.org/articles/15/6759/2022/gmd-15-6759-2022.pdf |
| spellingShingle | S. Bourdin S. Fromang W. Dulac J. Cattiaux F. Chauvin Intercomparison of four algorithms for detecting tropical cyclones using ERA5 Geoscientific Model Development |
| title | Intercomparison of four algorithms for detecting tropical cyclones using ERA5 |
| title_full | Intercomparison of four algorithms for detecting tropical cyclones using ERA5 |
| title_fullStr | Intercomparison of four algorithms for detecting tropical cyclones using ERA5 |
| title_full_unstemmed | Intercomparison of four algorithms for detecting tropical cyclones using ERA5 |
| title_short | Intercomparison of four algorithms for detecting tropical cyclones using ERA5 |
| title_sort | intercomparison of four algorithms for detecting tropical cyclones using era5 |
| url | https://gmd.copernicus.org/articles/15/6759/2022/gmd-15-6759-2022.pdf |
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