The Process‐Oriented Understanding on the Reduced Double‐ITCZ Bias in the High‐Resolution CESM1
Abstract The double‐Intertropical Convergence Zone (ITCZ) bias is a common model bias, which has puzzled the climate model community for several decades. Here, by comparing a high‐ and low‐resolution state‐of‐the‐art model CESM1, it is found that the double‐ITCZ bias is largely reduced in the high‐r...
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Wiley
2025-01-01
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| Series: | Geophysical Research Letters |
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| Online Access: | https://doi.org/10.1029/2024GL112087 |
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| _version_ | 1832593451770707968 |
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| author | Enze Dong Fengfei Song Lixin Wu Lu Dong Shengpeng Wang Fukai Liu Hong Wang |
| author_facet | Enze Dong Fengfei Song Lixin Wu Lu Dong Shengpeng Wang Fukai Liu Hong Wang |
| author_sort | Enze Dong |
| collection | DOAJ |
| description | Abstract The double‐Intertropical Convergence Zone (ITCZ) bias is a common model bias, which has puzzled the climate model community for several decades. Here, by comparing a high‐ and low‐resolution state‐of‐the‐art model CESM1, it is found that the double‐ITCZ bias is largely reduced in the high‐resolution CESM1. The key reason is the realistic colder sea surface temperature (SST) over the southeast Pacific (SEP) in the high‐resolution model. This realistic SEP SST is mainly due to a spuriously deeper mixed layer with a more realistic wind, as the sensitivity of mixed layer depth to wind is overestimated in both versions of CESM1. The better representation of terrain, such as Andes Mountains, elevates warm advection from inland to the coastal region, which maintains the inversion structure favorable for low cloud. The resultant increased coastal cloud in the high‐resolution CESM1 causes the colder coastal SST, thus improving the wind and deepening the mixed layer. |
| format | Article |
| id | doaj-art-16379dadf41446e6ae42fc77fd712bc3 |
| institution | Kabale University |
| issn | 0094-8276 1944-8007 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geophysical Research Letters |
| spelling | doaj-art-16379dadf41446e6ae42fc77fd712bc32025-01-20T13:05:57ZengWileyGeophysical Research Letters0094-82761944-80072025-01-01521n/an/a10.1029/2024GL112087The Process‐Oriented Understanding on the Reduced Double‐ITCZ Bias in the High‐Resolution CESM1Enze Dong0Fengfei Song1Lixin Wu2Lu Dong3Shengpeng Wang4Fukai Liu5Hong Wang6Physical Oceanography Laboratory Frontier Science Center for Deep Ocean Multispheres and Earth System Ocean University of China Qingdao ChinaPhysical Oceanography Laboratory Frontier Science Center for Deep Ocean Multispheres and Earth System Ocean University of China Qingdao ChinaPhysical Oceanography Laboratory Frontier Science Center for Deep Ocean Multispheres and Earth System Ocean University of China Qingdao ChinaPhysical Oceanography Laboratory Frontier Science Center for Deep Ocean Multispheres and Earth System Ocean University of China Qingdao ChinaLaoshan Laboratory Qingdao ChinaPhysical Oceanography Laboratory Frontier Science Center for Deep Ocean Multispheres and Earth System Ocean University of China Qingdao ChinaPhysical Oceanography Laboratory Frontier Science Center for Deep Ocean Multispheres and Earth System Ocean University of China Qingdao ChinaAbstract The double‐Intertropical Convergence Zone (ITCZ) bias is a common model bias, which has puzzled the climate model community for several decades. Here, by comparing a high‐ and low‐resolution state‐of‐the‐art model CESM1, it is found that the double‐ITCZ bias is largely reduced in the high‐resolution CESM1. The key reason is the realistic colder sea surface temperature (SST) over the southeast Pacific (SEP) in the high‐resolution model. This realistic SEP SST is mainly due to a spuriously deeper mixed layer with a more realistic wind, as the sensitivity of mixed layer depth to wind is overestimated in both versions of CESM1. The better representation of terrain, such as Andes Mountains, elevates warm advection from inland to the coastal region, which maintains the inversion structure favorable for low cloud. The resultant increased coastal cloud in the high‐resolution CESM1 causes the colder coastal SST, thus improving the wind and deepening the mixed layer.https://doi.org/10.1029/2024GL112087double‐ITCZhigh‐resolutionsoutheastern Pacificsea surface temperaturemixed layer depthlow cloud |
| spellingShingle | Enze Dong Fengfei Song Lixin Wu Lu Dong Shengpeng Wang Fukai Liu Hong Wang The Process‐Oriented Understanding on the Reduced Double‐ITCZ Bias in the High‐Resolution CESM1 Geophysical Research Letters double‐ITCZ high‐resolution southeastern Pacific sea surface temperature mixed layer depth low cloud |
| title | The Process‐Oriented Understanding on the Reduced Double‐ITCZ Bias in the High‐Resolution CESM1 |
| title_full | The Process‐Oriented Understanding on the Reduced Double‐ITCZ Bias in the High‐Resolution CESM1 |
| title_fullStr | The Process‐Oriented Understanding on the Reduced Double‐ITCZ Bias in the High‐Resolution CESM1 |
| title_full_unstemmed | The Process‐Oriented Understanding on the Reduced Double‐ITCZ Bias in the High‐Resolution CESM1 |
| title_short | The Process‐Oriented Understanding on the Reduced Double‐ITCZ Bias in the High‐Resolution CESM1 |
| title_sort | process oriented understanding on the reduced double itcz bias in the high resolution cesm1 |
| topic | double‐ITCZ high‐resolution southeastern Pacific sea surface temperature mixed layer depth low cloud |
| url | https://doi.org/10.1029/2024GL112087 |
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