A mechanistic analysis of tropical Pacific dynamic sea level in GFDL-OM4 under OMIP-I and OMIP-II forcings
<p>The sea level over the tropical Pacific is a key indicator reflecting vertically integrated heat distribution over the ocean. Here, we use the Geophysical Fluid Dynamics Laboratory global ocean–sea ice model (GFDL-OM4) forced by both the Coordinated Ocean-Ice Reference Experiment (CORE) an...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-05-01
|
| Series: | Geoscientific Model Development |
| Online Access: | https://gmd.copernicus.org/articles/14/2471/2021/gmd-14-2471-2021.pdf |
| _version_ | 1818599301982453760 |
|---|---|
| author | C.-W. Hsu J. Yin S. M. Griffies S. M. Griffies R. Dussin |
| author_facet | C.-W. Hsu J. Yin S. M. Griffies S. M. Griffies R. Dussin |
| author_sort | C.-W. Hsu |
| collection | DOAJ |
| description | <p>The sea level over the tropical Pacific is a key indicator reflecting vertically integrated heat distribution over the ocean.
Here, we use the Geophysical Fluid Dynamics Laboratory global ocean–sea ice model (GFDL-OM4) forced by both the Coordinated Ocean-Ice Reference Experiment (CORE) and Japanese 55-year Reanalysis (JRA-55)-based surface dataset for driving ocean–sea ice models (JRA55-do) atmospheric states (Ocean Model Intercomparison Project (OMIP) versions I and II) to evaluate the model performance and biases compared against available observations.
We find persisting mean state dynamic sea level (DSL) bias along 9<span class="inline-formula"><sup>∘</sup></span> N even with updated wind forcing in JRA55-do relative to CORE.
The mean state bias is related to biases in wind stress forcing and geostrophic currents in the 4 to 9<span class="inline-formula"><sup>∘</sup></span> N latitudinal band.
The simulation forced by JRA55-do significantly reduces the bias in DSL trend over the northern tropical Pacific relative to CORE.
In the CORE forcing, the anomalous westerly wind trend in the eastern tropical Pacific causes an underestimated DSL trend across the entire Pacific basin along 10<span class="inline-formula"><sup>∘</sup></span> N.
The simulation forced by JRA55-do significantly reduces the bias in DSL trend over the northern tropical Pacific relative to CORE.
We also identify a bias in the easterly wind trend along 20<span class="inline-formula"><sup>∘</sup></span> N in both JRA55-do and CORE, thus motivating future improvement.
In JRA55-do, an accurate Rossby wave initiated in the eastern tropical Pacific at seasonal timescale corrects a biased seasonal variability of the northern equatorial countercurrent in the CORE simulation.
Both CORE and JRA55-do generate realistic DSL variation during El Niño.
We find an asymmetry in the DSL pattern on two sides of the Equator is strongly related to wind stress curl that follows the sea level pressure evolution during El Niño.</p> |
| first_indexed | 2024-12-16T12:17:26Z |
| format | Article |
| id | doaj.art-77c8ad6a79eb437a84816d65a14a7850 |
| institution | Directory Open Access Journal |
| issn | 1991-959X 1991-9603 |
| language | English |
| last_indexed | 2024-12-16T12:17:26Z |
| publishDate | 2021-05-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Geoscientific Model Development |
| spelling | doaj.art-77c8ad6a79eb437a84816d65a14a78502022-12-21T22:32:04ZengCopernicus PublicationsGeoscientific Model Development1991-959X1991-96032021-05-01142471250210.5194/gmd-14-2471-2021A mechanistic analysis of tropical Pacific dynamic sea level in GFDL-OM4 under OMIP-I and OMIP-II forcingsC.-W. Hsu0J. Yin1S. M. Griffies2S. M. Griffies3R. Dussin4University of Arizona, Department of Geoscience, 1040 E 4th St, Tucson, AZ, USAUniversity of Arizona, Department of Geoscience, 1040 E 4th St, Tucson, AZ, USANOAA Geophysical Fluid Dynamics Laboratory, Princeton, NJ, USAPrinceton University Atmospheric and Oceanic Sciences Program, Princeton, NJ, USANOAA Geophysical Fluid Dynamics Laboratory, Princeton, NJ, USA<p>The sea level over the tropical Pacific is a key indicator reflecting vertically integrated heat distribution over the ocean. Here, we use the Geophysical Fluid Dynamics Laboratory global ocean–sea ice model (GFDL-OM4) forced by both the Coordinated Ocean-Ice Reference Experiment (CORE) and Japanese 55-year Reanalysis (JRA-55)-based surface dataset for driving ocean–sea ice models (JRA55-do) atmospheric states (Ocean Model Intercomparison Project (OMIP) versions I and II) to evaluate the model performance and biases compared against available observations. We find persisting mean state dynamic sea level (DSL) bias along 9<span class="inline-formula"><sup>∘</sup></span> N even with updated wind forcing in JRA55-do relative to CORE. The mean state bias is related to biases in wind stress forcing and geostrophic currents in the 4 to 9<span class="inline-formula"><sup>∘</sup></span> N latitudinal band. The simulation forced by JRA55-do significantly reduces the bias in DSL trend over the northern tropical Pacific relative to CORE. In the CORE forcing, the anomalous westerly wind trend in the eastern tropical Pacific causes an underestimated DSL trend across the entire Pacific basin along 10<span class="inline-formula"><sup>∘</sup></span> N. The simulation forced by JRA55-do significantly reduces the bias in DSL trend over the northern tropical Pacific relative to CORE. We also identify a bias in the easterly wind trend along 20<span class="inline-formula"><sup>∘</sup></span> N in both JRA55-do and CORE, thus motivating future improvement. In JRA55-do, an accurate Rossby wave initiated in the eastern tropical Pacific at seasonal timescale corrects a biased seasonal variability of the northern equatorial countercurrent in the CORE simulation. Both CORE and JRA55-do generate realistic DSL variation during El Niño. We find an asymmetry in the DSL pattern on two sides of the Equator is strongly related to wind stress curl that follows the sea level pressure evolution during El Niño.</p>https://gmd.copernicus.org/articles/14/2471/2021/gmd-14-2471-2021.pdf |
| spellingShingle | C.-W. Hsu J. Yin S. M. Griffies S. M. Griffies R. Dussin A mechanistic analysis of tropical Pacific dynamic sea level in GFDL-OM4 under OMIP-I and OMIP-II forcings Geoscientific Model Development |
| title | A mechanistic analysis of tropical Pacific dynamic sea level in GFDL-OM4 under OMIP-I and OMIP-II forcings |
| title_full | A mechanistic analysis of tropical Pacific dynamic sea level in GFDL-OM4 under OMIP-I and OMIP-II forcings |
| title_fullStr | A mechanistic analysis of tropical Pacific dynamic sea level in GFDL-OM4 under OMIP-I and OMIP-II forcings |
| title_full_unstemmed | A mechanistic analysis of tropical Pacific dynamic sea level in GFDL-OM4 under OMIP-I and OMIP-II forcings |
| title_short | A mechanistic analysis of tropical Pacific dynamic sea level in GFDL-OM4 under OMIP-I and OMIP-II forcings |
| title_sort | mechanistic analysis of tropical pacific dynamic sea level in gfdl om4 under omip i and omip ii forcings |
| url | https://gmd.copernicus.org/articles/14/2471/2021/gmd-14-2471-2021.pdf |
| work_keys_str_mv | AT cwhsu amechanisticanalysisoftropicalpacificdynamicsealevelingfdlom4underomipiandomipiiforcings AT jyin amechanisticanalysisoftropicalpacificdynamicsealevelingfdlom4underomipiandomipiiforcings AT smgriffies amechanisticanalysisoftropicalpacificdynamicsealevelingfdlom4underomipiandomipiiforcings AT smgriffies amechanisticanalysisoftropicalpacificdynamicsealevelingfdlom4underomipiandomipiiforcings AT rdussin amechanisticanalysisoftropicalpacificdynamicsealevelingfdlom4underomipiandomipiiforcings AT cwhsu mechanisticanalysisoftropicalpacificdynamicsealevelingfdlom4underomipiandomipiiforcings AT jyin mechanisticanalysisoftropicalpacificdynamicsealevelingfdlom4underomipiandomipiiforcings AT smgriffies mechanisticanalysisoftropicalpacificdynamicsealevelingfdlom4underomipiandomipiiforcings AT smgriffies mechanisticanalysisoftropicalpacificdynamicsealevelingfdlom4underomipiandomipiiforcings AT rdussin mechanisticanalysisoftropicalpacificdynamicsealevelingfdlom4underomipiandomipiiforcings |