Sensitivity of the Freie Universität Berlin Climate Middle Atmosphere Model (FUB-CMAM) to different gravity-wave drag parameterisations
We report the sensitivity of the Berlin Climate Middle Atmosphere Model (CMAM) to different gravity-wave (GW) parameterisations. We perform five perpetual January experiments: 1) Rayleigh friction (RF) (control), 2) non-orographic GWs, 3) orographic GWs, 4) orographic and non-orographic GWs with no...
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ftcopernicus:oai:publications.copernicus.org:angeo35363 2023-05-15T18:02:19+02:00 Sensitivity of the Freie Universität Berlin Climate Middle Atmosphere Model (FUB-CMAM) to different gravity-wave drag parameterisations Mieth, P. Grenfell, J. L. Langematz, U. Kunze, M. 2018-09-27 application/pdf https://doi.org/10.5194/angeo-22-2693-2004 https://angeo.copernicus.org/articles/22/2693/2004/ eng eng doi:10.5194/angeo-22-2693-2004 https://angeo.copernicus.org/articles/22/2693/2004/ eISSN: 1432-0576 Text 2018 ftcopernicus https://doi.org/10.5194/angeo-22-2693-2004 2020-07-20T16:27:34Z We report the sensitivity of the Berlin Climate Middle Atmosphere Model (CMAM) to different gravity-wave (GW) parameterisations. We perform five perpetual January experiments: 1) Rayleigh friction (RF) (control), 2) non-orographic GWs, 3) orographic GWs, 4) orographic and non-orographic GWs with no background stress, and 5) as for 4) but with background stress. We also repeat experiment 4) but for July conditions. Our main aim is to improve the model climatology by introducing orographic and non-orographic parameterisations and to investigate the individual effect of these schemes in the Berlin CMAM. We compare with an RF control to determine the improvement upon a previously-published model version employing RF. Results are broadly similar to previously-published works. The runs having both orographic and non-orographic GWs produce a statistically-significant warming of 4-8K in the wintertime polar lower stratosphere. These runs also feature a cooling of the warm summer pole in the mesosphere by 10-15K, more in line with observations. This is associated with the non-orographic GW scheme. This scheme is also associated with a heating feature in the winter polar upper stratosphere directly below the peak GW-breaking region. The runs with both orographic and non-orographic GWs feature a statistically-significant deceleration in the polar night jet (PNJ) of 10-20ms -1 in the lower stratosphere. Both orographic and non-orographic GWs individually produce some latitudinal tilting of the polar jet with height, although the main effect comes from the non-orographic waves. The resulting degree of tilt, although improved, is nevertheless still weaker than that observed. Accordingly, wintertime variability in the zonal mean wind, which peaks at the edge of the vortex, tends to maximise too far polewards in the model compared with observations. Gravity-planetary wave interaction leads to a decrease in the amplitudes of stationary planetary waves 1 and 2 by up to 50% in the upper stratosphere and mesosphere, more in line with observations. Comparing modelled and observed Eliassen-Palm fluxes suggests that planetary wave (PW) breaking occurs too far polewards in the model. The wind and temperature changes are consistent with changes in the Brewer-Dobson (BD) circulation. Results suggest that the effect of enforcing a minimum background wave stress in the McFarlane scheme could be potentially important. In the Southern Hemisphere (SH) in July, the GW schemes had only a small impact on the high-latitude lower stratosphere but there featured strong warming near 0.1hPa. Text polar night Copernicus Publications: E-Journals Tilting ENVELOPE(-54.065,-54.065,49.700,49.700) Annales Geophysicae 22 8 2693 2713 |
institution |
Open Polar |
collection |
Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
We report the sensitivity of the Berlin Climate Middle Atmosphere Model (CMAM) to different gravity-wave (GW) parameterisations. We perform five perpetual January experiments: 1) Rayleigh friction (RF) (control), 2) non-orographic GWs, 3) orographic GWs, 4) orographic and non-orographic GWs with no background stress, and 5) as for 4) but with background stress. We also repeat experiment 4) but for July conditions. Our main aim is to improve the model climatology by introducing orographic and non-orographic parameterisations and to investigate the individual effect of these schemes in the Berlin CMAM. We compare with an RF control to determine the improvement upon a previously-published model version employing RF. Results are broadly similar to previously-published works. The runs having both orographic and non-orographic GWs produce a statistically-significant warming of 4-8K in the wintertime polar lower stratosphere. These runs also feature a cooling of the warm summer pole in the mesosphere by 10-15K, more in line with observations. This is associated with the non-orographic GW scheme. This scheme is also associated with a heating feature in the winter polar upper stratosphere directly below the peak GW-breaking region. The runs with both orographic and non-orographic GWs feature a statistically-significant deceleration in the polar night jet (PNJ) of 10-20ms -1 in the lower stratosphere. Both orographic and non-orographic GWs individually produce some latitudinal tilting of the polar jet with height, although the main effect comes from the non-orographic waves. The resulting degree of tilt, although improved, is nevertheless still weaker than that observed. Accordingly, wintertime variability in the zonal mean wind, which peaks at the edge of the vortex, tends to maximise too far polewards in the model compared with observations. Gravity-planetary wave interaction leads to a decrease in the amplitudes of stationary planetary waves 1 and 2 by up to 50% in the upper stratosphere and mesosphere, more in line with observations. Comparing modelled and observed Eliassen-Palm fluxes suggests that planetary wave (PW) breaking occurs too far polewards in the model. The wind and temperature changes are consistent with changes in the Brewer-Dobson (BD) circulation. Results suggest that the effect of enforcing a minimum background wave stress in the McFarlane scheme could be potentially important. In the Southern Hemisphere (SH) in July, the GW schemes had only a small impact on the high-latitude lower stratosphere but there featured strong warming near 0.1hPa. |
format |
Text |
author |
Mieth, P. Grenfell, J. L. Langematz, U. Kunze, M. |
spellingShingle |
Mieth, P. Grenfell, J. L. Langematz, U. Kunze, M. Sensitivity of the Freie Universität Berlin Climate Middle Atmosphere Model (FUB-CMAM) to different gravity-wave drag parameterisations |
author_facet |
Mieth, P. Grenfell, J. L. Langematz, U. Kunze, M. |
author_sort |
Mieth, P. |
title |
Sensitivity of the Freie Universität Berlin Climate Middle Atmosphere Model (FUB-CMAM) to different gravity-wave drag parameterisations |
title_short |
Sensitivity of the Freie Universität Berlin Climate Middle Atmosphere Model (FUB-CMAM) to different gravity-wave drag parameterisations |
title_full |
Sensitivity of the Freie Universität Berlin Climate Middle Atmosphere Model (FUB-CMAM) to different gravity-wave drag parameterisations |
title_fullStr |
Sensitivity of the Freie Universität Berlin Climate Middle Atmosphere Model (FUB-CMAM) to different gravity-wave drag parameterisations |
title_full_unstemmed |
Sensitivity of the Freie Universität Berlin Climate Middle Atmosphere Model (FUB-CMAM) to different gravity-wave drag parameterisations |
title_sort |
sensitivity of the freie universität berlin climate middle atmosphere model (fub-cmam) to different gravity-wave drag parameterisations |
publishDate |
2018 |
url |
https://doi.org/10.5194/angeo-22-2693-2004 https://angeo.copernicus.org/articles/22/2693/2004/ |
long_lat |
ENVELOPE(-54.065,-54.065,49.700,49.700) |
geographic |
Tilting |
geographic_facet |
Tilting |
genre |
polar night |
genre_facet |
polar night |
op_source |
eISSN: 1432-0576 |
op_relation |
doi:10.5194/angeo-22-2693-2004 https://angeo.copernicus.org/articles/22/2693/2004/ |
op_doi |
https://doi.org/10.5194/angeo-22-2693-2004 |
container_title |
Annales Geophysicae |
container_volume |
22 |
container_issue |
8 |
container_start_page |
2693 |
op_container_end_page |
2713 |
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1766172132643962880 |