Early-winter North Atlantic low-level jet latitude biases in climate models: implications for simulated regional atmosphere-ocean linkages
Early-winter North Atlantic low-level jet latitude biases in climate models: implications for simulated regional atmosphere-ocean linkages
复制标题
气候模型中的初冬北大西洋低空急流纬度偏差：对模拟区域大气-海洋联系的影响
DOI：
10.1088/1748-9326/ac417f
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发表时间：
2021
影响因子：
6.7
通讯作者：
Bracegirdle T
中科院分区：
文献类型：
--
作者：
Bracegirdle T
北大西洋（NA）低层对流层西风急流的气候模式偏差是可靠地代表NA气候系统的变化及其更广泛的影响，特别是在西欧的一个主要障碍。的偏差的一个主要方面是一个突出的初冬赤道急流偏差耦合模型相互比较项目第5阶段（CMIP 5）模型，NA大气-海洋耦合的影响。在这里，我们评估这种偏见是否减少在新的CMIP 6模型和评估NA大气-海洋联系的模型表示的影响，特别是在副极地环流（SPG）区域。将CMIP 5和CMIP 6模型数据集的历史模拟与1861-2005年期间的再分析数据进行了比较。结果表明，初冬赤道偏差仍然存在于CMIP 6模式中，尽管与CMIP 5相比减少了大约五分之一。赤道偏置主要与弱于观测到的频率的极向游览的射流到其北方的位置。一个潜在的解释是通过确定NA喷纬偏差和系统太弱的模型模拟的低层斜压性在北美东部初冬之间的强联系。CMIP模型具有较大的向赤道射流偏差表现出较弱的相关性，在SPG的射流速度和海面条件（海面温度和湍流热通量）的时间变化。结果表明，在CMIP模式中，喷流纬度的初冬向赤道偏差可以部分解释其他已知的偏差，如弱于观测到的季节-年代际可预测性的NA气候系统。
Climate model biases in the North Atlantic (NA) low-level tropospheric westerly jet are a major impediment to reliably representing variability of the NA climate system and its wider influence, in particular over western Europe. A major aspect of the biases is the occurrence of a prominent early-winter equatorward jet bias in Coupled Model Inter-comparison Project Phase 5 (CMIP5) models that has implications for NA atmosphere-ocean coupling. Here we assess whether this bias is reduced in the new CMIP6 models and assess implications for model representation of NA atmosphere-ocean linkages, in particular over the sub-polar gyre (SPG) region. Historical simulations from the CMIP5 and CMIP6 model datasets were compared against reanalysis data over the period 1861–2005. The results show that the early-winter equatorward bias remains present in CMIP6 models, although with an approximately one-fifth reduction compared to CMIP5. The equatorward bias is mainly associated with a weaker-than-observed frequency of poleward excursions of the jet to its northern position. A potential explanation is provided through the identification of a strong link between NA jet latitude bias and systematically too-weak model-simulated low-level baroclinicity over eastern North America in early-winter. CMIP models with larger equatorward jet biases exhibit weaker correlations between temporal variability in speed of the jet and sea surface conditions (sea surface temperatures and turbulent heat fluxes) over the SPG. The results imply that the early-winter equatorward bias in jet latitude in CMIP models could partially explain other known biases, such as the weaker-than-observed seasonal-decadal predictability of the NA climate system.
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影响因子：
--
作者：
Liping Zhang;Chunzai Wang
通讯作者：
Liping Zhang;Chunzai Wang
北大西洋年代际可预测性的深渊起源
影响因子：
4.6
作者：
Yeager, Stephen
通讯作者：
Yeager, Stephen
影响因子：
5.2
作者：
Fiedler, S.;Putrasahan, D.
通讯作者：
Putrasahan, D.
影响因子：
5.1
作者：
Eyring, Veronika;Bony, Sandrine;Taylor, Karl E.
通讯作者：
Taylor, Karl E.
影响因子：
64.8
作者：
D. Smith;Adam A. Scaife;R. Eade;P. Athanasiadis;A. Bellucci;I. Bethke;R. Bilbao;L. Borchert;L. Caron;F. Counillon;G. Danabasoglu;T. Delworth;F. Doblas-Reyes;N. Dunstone;V. Estella-Perez;S. Flavoni;L. Hermanson;N. Keenlyside;V. Kharin;M. Kimoto;W. Merryfield;J. Mignot;T. Mochizuki;K. Modali;P. Monerie;W. Müller;D. Nicolì;P. Ortega;K. Pankatz;H. Pohlmann;J. Robson;P. Ruggieri;R. Sospedra‐Alfonso;D. Swingedouw;Y. Wang;S. Wild;S. Yeager;X. Yang;L. Zhang
通讯作者：
D. Smith;Adam A. Scaife;R. Eade;P. Athanasiadis;A. Bellucci;I. Bethke;R. Bilbao;L. Borchert;L. Caron;F. Counillon;G. Danabasoglu;T. Delworth;F. Doblas-Reyes;N. Dunstone;V. Estella-Perez;S. Flavoni;L. Hermanson;N. Keenlyside;V. Kharin;M. Kimoto;W. Merryfield;J. Mignot;T. Mochizuki;K. Modali;P. Monerie;W. Müller;D. Nicolì;P. Ortega;K. Pankatz;H. Pohlmann;J. Robson;P. Ruggieri;R. Sospedra‐Alfonso;D. Swingedouw;Y. Wang;S. Wild;S. Yeager;X. Yang;L. Zhang