Sources and pathways of the upscale effects on the Southern Hemisphere jet in MPAS‐CAM4 variable‐resolution simulations
Abstract Impacts of regional grid refinement on large‐scale circulations (“upscale effects”) were detected in a previous study that used the Model for Prediction Across Scales‐Atmosphere coupled to the physics parameterizations of the Community Atmosphere Model version 4. The strongest upscale effec...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
American Geophysical Union (AGU)
2016-12-01
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| Series: | Journal of Advances in Modeling Earth Systems |
| Subjects: | |
| Online Access: | https://doi.org/10.1002/2016MS000743 |
| _version_ | 1819113776615522304 |
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| author | Koichi Sakaguchi Jian Lu L. Ruby Leung Chun Zhao Yanjie Li Samson Hagos |
| author_facet | Koichi Sakaguchi Jian Lu L. Ruby Leung Chun Zhao Yanjie Li Samson Hagos |
| author_sort | Koichi Sakaguchi |
| collection | DOAJ |
| description | Abstract Impacts of regional grid refinement on large‐scale circulations (“upscale effects”) were detected in a previous study that used the Model for Prediction Across Scales‐Atmosphere coupled to the physics parameterizations of the Community Atmosphere Model version 4. The strongest upscale effect was identified in the Southern Hemisphere jet during austral winter. This study examines the detailed underlying processes by comparing two simulations at quasi‐uniform resolutions of 30 and 120 km to three variable‐resolution simulations in which the horizontal grids are regionally refined to 30 km in North America, South America, or Asia from 120 km elsewhere. In all the variable‐resolution simulations, precipitation increases in convective areas inside the high‐resolution domains, as in the reference quasi‐uniform high‐resolution simulation. With grid refinement encompassing the tropical Americas, the increased condensational heating expands the local divergent circulations (Hadley cell) meridionally such that their descending branch is shifted poleward, which also pushes the baroclinically unstable regions, momentum flux convergence, and the eddy‐driven jet poleward. This teleconnection pathway is not found in the reference high‐resolution simulation due to a strong resolution sensitivity of cloud radiative forcing that dominates the aforementioned teleconnection signals. The regional refinement over Asia enhances Rossby wave sources and strengthens the upper level southerly flow, both facilitating the cross‐equatorial propagation of stationary waves. Evidence indicates that this teleconnection pathway is also found in the reference high‐resolution simulation. The result underlines the intricate diagnoses needed to understand the upscale effects in global variable‐resolution simulations, with implications for science investigations using the computationally efficient modeling framework. |
| first_indexed | 2024-12-22T04:34:47Z |
| format | Article |
| id | doaj.art-6506fc227c944051a3ffe42d0c687336 |
| institution | Directory Open Access Journal |
| issn | 1942-2466 |
| language | English |
| last_indexed | 2024-12-22T04:34:47Z |
| publishDate | 2016-12-01 |
| publisher | American Geophysical Union (AGU) |
| record_format | Article |
| series | Journal of Advances in Modeling Earth Systems |
| spelling | doaj.art-6506fc227c944051a3ffe42d0c6873362022-12-21T18:38:55ZengAmerican Geophysical Union (AGU)Journal of Advances in Modeling Earth Systems1942-24662016-12-01841786180510.1002/2016MS000743Sources and pathways of the upscale effects on the Southern Hemisphere jet in MPAS‐CAM4 variable‐resolution simulationsKoichi Sakaguchi0Jian Lu1L. Ruby Leung2Chun Zhao3Yanjie Li4Samson Hagos5Atmospheric Sciences and Global Change DivisionPacific Northwest National LaboratoryRichland Washington USAAtmospheric Sciences and Global Change DivisionPacific Northwest National LaboratoryRichland Washington USAAtmospheric Sciences and Global Change DivisionPacific Northwest National LaboratoryRichland Washington USAAtmospheric Sciences and Global Change DivisionPacific Northwest National LaboratoryRichland Washington USAState Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid DynamicsInstitute of Atmospheric PhysicsBeijing ChinaAtmospheric Sciences and Global Change DivisionPacific Northwest National LaboratoryRichland Washington USAAbstract Impacts of regional grid refinement on large‐scale circulations (“upscale effects”) were detected in a previous study that used the Model for Prediction Across Scales‐Atmosphere coupled to the physics parameterizations of the Community Atmosphere Model version 4. The strongest upscale effect was identified in the Southern Hemisphere jet during austral winter. This study examines the detailed underlying processes by comparing two simulations at quasi‐uniform resolutions of 30 and 120 km to three variable‐resolution simulations in which the horizontal grids are regionally refined to 30 km in North America, South America, or Asia from 120 km elsewhere. In all the variable‐resolution simulations, precipitation increases in convective areas inside the high‐resolution domains, as in the reference quasi‐uniform high‐resolution simulation. With grid refinement encompassing the tropical Americas, the increased condensational heating expands the local divergent circulations (Hadley cell) meridionally such that their descending branch is shifted poleward, which also pushes the baroclinically unstable regions, momentum flux convergence, and the eddy‐driven jet poleward. This teleconnection pathway is not found in the reference high‐resolution simulation due to a strong resolution sensitivity of cloud radiative forcing that dominates the aforementioned teleconnection signals. The regional refinement over Asia enhances Rossby wave sources and strengthens the upper level southerly flow, both facilitating the cross‐equatorial propagation of stationary waves. Evidence indicates that this teleconnection pathway is also found in the reference high‐resolution simulation. The result underlines the intricate diagnoses needed to understand the upscale effects in global variable‐resolution simulations, with implications for science investigations using the computationally efficient modeling framework.https://doi.org/10.1002/2016MS000743upscale effectsvariable‐resolution simulationsSouthern Hemisphere jet |
| spellingShingle | Koichi Sakaguchi Jian Lu L. Ruby Leung Chun Zhao Yanjie Li Samson Hagos Sources and pathways of the upscale effects on the Southern Hemisphere jet in MPAS‐CAM4 variable‐resolution simulations Journal of Advances in Modeling Earth Systems upscale effects variable‐resolution simulations Southern Hemisphere jet |
| title | Sources and pathways of the upscale effects on the Southern Hemisphere jet in MPAS‐CAM4 variable‐resolution simulations |
| title_full | Sources and pathways of the upscale effects on the Southern Hemisphere jet in MPAS‐CAM4 variable‐resolution simulations |
| title_fullStr | Sources and pathways of the upscale effects on the Southern Hemisphere jet in MPAS‐CAM4 variable‐resolution simulations |
| title_full_unstemmed | Sources and pathways of the upscale effects on the Southern Hemisphere jet in MPAS‐CAM4 variable‐resolution simulations |
| title_short | Sources and pathways of the upscale effects on the Southern Hemisphere jet in MPAS‐CAM4 variable‐resolution simulations |
| title_sort | sources and pathways of the upscale effects on the southern hemisphere jet in mpas cam4 variable resolution simulations |
| topic | upscale effects variable‐resolution simulations Southern Hemisphere jet |
| url | https://doi.org/10.1002/2016MS000743 |
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