Initialization and Ensemble Generation for Decadal Climate Predictions: A Comparison of Different Methods
Five initialization and ensemble generation methods are investigated with respect to their impact on the prediction skill of the German decadal prediction system “Mittelfristige Klimaprognose” (MiKlip). Among the tested methods, three tackle aspects of model‐consistent initialization using the ensem...
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ftfuberlin:oai:refubium.fu-berlin.de:fub188/25128 2023-05-15T17:35:28+02:00 Initialization and Ensemble Generation for Decadal Climate Predictions: A Comparison of Different Methods Polkova, Iuliia Brune, Sebastian Kadow, Christopher Illing, Sebastian Romanova, Vanya Gollan, Gereon Baehr, Johanna Glowienka-Hense, Rita Greatbatch, Richard J. Hense, Andreas u.v.m. 2019 24 Seiten application/pdf https://refubium.fu-berlin.de/handle/fub188/25128 https://doi.org/10.17169/refubium-2883 https://doi.org/10.1029/2018MS001439 eng eng https://refubium.fu-berlin.de/handle/fub188/25128 http://dx.doi.org/10.17169/refubium-2883 doi:10.1029/2018MS001439 https://creativecommons.org/licenses/by-nc-nd/4.0/ CC-BY-NC-ND decadal prediction system initialization methods ensemble generation methods ddc:551 doc-type:article 2019 ftfuberlin https://doi.org/10.17169/refubium-2883 https://doi.org/10.1029/2018MS001439 2022-05-15T20:45:58Z Five initialization and ensemble generation methods are investigated with respect to their impact on the prediction skill of the German decadal prediction system “Mittelfristige Klimaprognose” (MiKlip). Among the tested methods, three tackle aspects of model‐consistent initialization using the ensemble Kalman filter, the filtered anomaly initialization, and the initialization method by partially coupled spin‐up (MODINI). The remaining two methods alter the ensemble generation: the ensemble dispersion filter corrects each ensemble member with the ensemble mean during model integration. And the bred vectors perturb the climate state using the fastest growing modes. The new methods are compared against the latest MiKlip system in the low‐resolution configuration (Preop‐LR), which uses lagging the climate state by a few days for ensemble generation and nudging toward ocean and atmosphere reanalyses for initialization. Results show that the tested methods provide an added value for the prediction skill as compared to Preop‐LR in that they improve prediction skill over the eastern and central Pacific and different regions in the North Atlantic Ocean. In this respect, the ensemble Kalman filter and filtered anomaly initialization show the most distinct improvements over Preop‐LR for surface temperatures and upper ocean heat content, followed by the bred vectors, the ensemble dispersion filter, and MODINI. However, no single method exists that is superior to the others with respect to all metrics considered. In particular, all methods affect the Atlantic Meridional Overturning Circulation in different ways, both with respect to the basin‐wide long‐term mean and variability and with respect to the temporal evolution at the 26° N latitude. Article in Journal/Newspaper North Atlantic Freie Universität Berlin: Refubium (FU Berlin) Pacific |
institution |
Open Polar |
collection |
Freie Universität Berlin: Refubium (FU Berlin) |
op_collection_id |
ftfuberlin |
language |
English |
topic |
decadal prediction system initialization methods ensemble generation methods ddc:551 |
spellingShingle |
decadal prediction system initialization methods ensemble generation methods ddc:551 Polkova, Iuliia Brune, Sebastian Kadow, Christopher Illing, Sebastian Romanova, Vanya Gollan, Gereon Baehr, Johanna Glowienka-Hense, Rita Greatbatch, Richard J. Hense, Andreas u.v.m. Initialization and Ensemble Generation for Decadal Climate Predictions: A Comparison of Different Methods |
topic_facet |
decadal prediction system initialization methods ensemble generation methods ddc:551 |
description |
Five initialization and ensemble generation methods are investigated with respect to their impact on the prediction skill of the German decadal prediction system “Mittelfristige Klimaprognose” (MiKlip). Among the tested methods, three tackle aspects of model‐consistent initialization using the ensemble Kalman filter, the filtered anomaly initialization, and the initialization method by partially coupled spin‐up (MODINI). The remaining two methods alter the ensemble generation: the ensemble dispersion filter corrects each ensemble member with the ensemble mean during model integration. And the bred vectors perturb the climate state using the fastest growing modes. The new methods are compared against the latest MiKlip system in the low‐resolution configuration (Preop‐LR), which uses lagging the climate state by a few days for ensemble generation and nudging toward ocean and atmosphere reanalyses for initialization. Results show that the tested methods provide an added value for the prediction skill as compared to Preop‐LR in that they improve prediction skill over the eastern and central Pacific and different regions in the North Atlantic Ocean. In this respect, the ensemble Kalman filter and filtered anomaly initialization show the most distinct improvements over Preop‐LR for surface temperatures and upper ocean heat content, followed by the bred vectors, the ensemble dispersion filter, and MODINI. However, no single method exists that is superior to the others with respect to all metrics considered. In particular, all methods affect the Atlantic Meridional Overturning Circulation in different ways, both with respect to the basin‐wide long‐term mean and variability and with respect to the temporal evolution at the 26° N latitude. |
format |
Article in Journal/Newspaper |
author |
Polkova, Iuliia Brune, Sebastian Kadow, Christopher Illing, Sebastian Romanova, Vanya Gollan, Gereon Baehr, Johanna Glowienka-Hense, Rita Greatbatch, Richard J. Hense, Andreas u.v.m. |
author_facet |
Polkova, Iuliia Brune, Sebastian Kadow, Christopher Illing, Sebastian Romanova, Vanya Gollan, Gereon Baehr, Johanna Glowienka-Hense, Rita Greatbatch, Richard J. Hense, Andreas u.v.m. |
author_sort |
Polkova, Iuliia |
title |
Initialization and Ensemble Generation for Decadal Climate Predictions: A Comparison of Different Methods |
title_short |
Initialization and Ensemble Generation for Decadal Climate Predictions: A Comparison of Different Methods |
title_full |
Initialization and Ensemble Generation for Decadal Climate Predictions: A Comparison of Different Methods |
title_fullStr |
Initialization and Ensemble Generation for Decadal Climate Predictions: A Comparison of Different Methods |
title_full_unstemmed |
Initialization and Ensemble Generation for Decadal Climate Predictions: A Comparison of Different Methods |
title_sort |
initialization and ensemble generation for decadal climate predictions: a comparison of different methods |
publishDate |
2019 |
url |
https://refubium.fu-berlin.de/handle/fub188/25128 https://doi.org/10.17169/refubium-2883 https://doi.org/10.1029/2018MS001439 |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
https://refubium.fu-berlin.de/handle/fub188/25128 http://dx.doi.org/10.17169/refubium-2883 doi:10.1029/2018MS001439 |
op_rights |
https://creativecommons.org/licenses/by-nc-nd/4.0/ |
op_rightsnorm |
CC-BY-NC-ND |
op_doi |
https://doi.org/10.17169/refubium-2883 https://doi.org/10.1029/2018MS001439 |
_version_ |
1766134643438911488 |