Reduction of Pacific Double‐ITCZ Bias by Convection Parameterization in NCAR CESM2.2
Abstract The impact of convective closure on the double‐ITCZ bias in the NCAR CESM2.2 is investigated in this study. The standard CESM2.2 simulates a remarkable double‐ITCZ bias in the central and eastern Pacific, especially in boreal winter and spring. Modifications to the closure in convection par...
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| Language: | English |
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American Geophysical Union (AGU)
2025-01-01
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| Series: | Journal of Advances in Modeling Earth Systems |
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| Online Access: | https://doi.org/10.1029/2024MS004309 |
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| author | Xiaoliang Song Guang J. Zhang |
| author_facet | Xiaoliang Song Guang J. Zhang |
| author_sort | Xiaoliang Song |
| collection | DOAJ |
| description | Abstract The impact of convective closure on the double‐ITCZ bias in the NCAR CESM2.2 is investigated in this study. The standard CESM2.2 simulates a remarkable double‐ITCZ bias in the central and eastern Pacific, especially in boreal winter and spring. Modifications to the closure in convection parameterization scheme greatly reduce the double‐ITCZ bias in all seasons, demonstrating that convection parameterization can substantially influence the double‐ITCZ bias in CESM2.2. Further analyses suggest that convection parameterization can modulate the tropical atmosphere‐ocean feedback processes, through which it influences the SST in the southern ITCZ region and hence the double‐ITCZ bias. The changes in the upper ocean temperature advection induced by modified convective closure plays important roles in reducing the warm SST bias and double‐ITCZ precipitation bias in the southern ITCZ region. The modified convective closure improves the low‐level cloud and shortwave cloud radiative forcing in the southeastern Pacific. However, surface heat flux plays only a limited role in reducing warm SST bias and double ITCZ bias because the impacts of shortwave radiation changes are largely canceled by changes in longwave radiation and latent heat flux. |
| format | Article |
| id | doaj-art-a8a34a4139c44ee6966cda650fc6d4af |
| institution | Kabale University |
| issn | 1942-2466 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | American Geophysical Union (AGU) |
| record_format | Article |
| series | Journal of Advances in Modeling Earth Systems |
| spelling | doaj-art-a8a34a4139c44ee6966cda650fc6d4af2025-01-28T13:21:09ZengAmerican Geophysical Union (AGU)Journal of Advances in Modeling Earth Systems1942-24662025-01-01171n/an/a10.1029/2024MS004309Reduction of Pacific Double‐ITCZ Bias by Convection Parameterization in NCAR CESM2.2Xiaoliang Song0Guang J. Zhang1Scripps Institution of Oceanography La Jolla CA USAScripps Institution of Oceanography La Jolla CA USAAbstract The impact of convective closure on the double‐ITCZ bias in the NCAR CESM2.2 is investigated in this study. The standard CESM2.2 simulates a remarkable double‐ITCZ bias in the central and eastern Pacific, especially in boreal winter and spring. Modifications to the closure in convection parameterization scheme greatly reduce the double‐ITCZ bias in all seasons, demonstrating that convection parameterization can substantially influence the double‐ITCZ bias in CESM2.2. Further analyses suggest that convection parameterization can modulate the tropical atmosphere‐ocean feedback processes, through which it influences the SST in the southern ITCZ region and hence the double‐ITCZ bias. The changes in the upper ocean temperature advection induced by modified convective closure plays important roles in reducing the warm SST bias and double‐ITCZ precipitation bias in the southern ITCZ region. The modified convective closure improves the low‐level cloud and shortwave cloud radiative forcing in the southeastern Pacific. However, surface heat flux plays only a limited role in reducing warm SST bias and double ITCZ bias because the impacts of shortwave radiation changes are largely canceled by changes in longwave radiation and latent heat flux.https://doi.org/10.1029/2024MS004309double‐ITCZ biasconvection parameterizationatmosphere‐ocean feedback |
| spellingShingle | Xiaoliang Song Guang J. Zhang Reduction of Pacific Double‐ITCZ Bias by Convection Parameterization in NCAR CESM2.2 Journal of Advances in Modeling Earth Systems double‐ITCZ bias convection parameterization atmosphere‐ocean feedback |
| title | Reduction of Pacific Double‐ITCZ Bias by Convection Parameterization in NCAR CESM2.2 |
| title_full | Reduction of Pacific Double‐ITCZ Bias by Convection Parameterization in NCAR CESM2.2 |
| title_fullStr | Reduction of Pacific Double‐ITCZ Bias by Convection Parameterization in NCAR CESM2.2 |
| title_full_unstemmed | Reduction of Pacific Double‐ITCZ Bias by Convection Parameterization in NCAR CESM2.2 |
| title_short | Reduction of Pacific Double‐ITCZ Bias by Convection Parameterization in NCAR CESM2.2 |
| title_sort | reduction of pacific double itcz bias by convection parameterization in ncar cesm2 2 |
| topic | double‐ITCZ bias convection parameterization atmosphere‐ocean feedback |
| url | https://doi.org/10.1029/2024MS004309 |
| work_keys_str_mv | AT xiaoliangsong reductionofpacificdoubleitczbiasbyconvectionparameterizationinncarcesm22 AT guangjzhang reductionofpacificdoubleitczbiasbyconvectionparameterizationinncarcesm22 |