Impact of Pacific blocking on the intraseasonal winter sea ice seesaw between the Bering and Okhotsk Seas
Impact of Pacific blocking on the intraseasonal winter sea ice seesaw between the Bering and Okhotsk Seas
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DOI：
10.1016/j.atmosres.2024.107227
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发表时间：
2024-01
影响因子：
5.5
通讯作者：
Yao Yao-Yao;Wenqin Zhuo;Dehai Luo;Ian Simmonds;B. Luo;Linhao Zhong;Fei Huang
中科院分区：
文献类型：
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作者：
Yao Yao-Yao;Wenqin Zhuo;Dehai Luo;Ian Simmonds;B. Luo;Linhao Zhong;Fei Huang
白令海(BS)和鄂霍次克海(OS)冬季海冰覆盖(SIC)具有显著的协变性。特别是，可以在两个海洋之间的季节内尺度上观察到明显的拉锯式变化。然而，大气环流影响它们的机制尚不清楚，还需要进一步的了解。本文基于1979-2019年再分析资料，利用合成分析方法研究了大气阻塞的物理过程对季节内OS和BS之间的翘翘板变化的影响。研究表明，太平洋阻塞(PB)事件可以增强冬季OS和BS SIC的季节内翘板变化。根据反气旋中心的最大核心位置，将PB事件分为两个亚群：西部PB和东部PB。此外，考虑到平均纬向移动速度，我们进一步将它们划分为三个亚类：西移PB、准稳定PB和东移PB。合成结果表明，对于不同的PB亚基，碳化硅和表面温度的变化表现出不同的不对称特征。在五个PB区中，准稳定的PB与BS在其生命周期中的SIC的最大减少有关，无论是在大小上还是在持续时间上。此外，我们还发现，无论是在准静止PB爆发期间还是爆发之前，准静止PB上游的局地海面温度(SST)异常都表现出显著的偶极子模，并伴随着300hPa纬向风的正异常。SST偶极子可以作为前兆气候背景条件，可能触发准静止PB的发生，进而导致强烈的SIC变化。
The winter sea ice cover (SIC) over the Bering Sea (BS) and Okhotsk Sea (OS) shows significant co-variability. In particular, a clear seesaw-like variability can be observed on an intraseasonal scale between the two seas. However, the mechanism by which the atmospheric circulation affects them is unclear and further insight is needed. In this study, based on reanalysis data from 1979 to 2019, we use composite analyses to examine the physical processes of atmospheric blocking that affect the intraseasonal seesaw SIC changes between OS and BS. The investigation reveals that Pacific blocking (PB) events can enhance the existing intraseasonal seesaw variation of the OS and BS SIC in winter. Based on the maximum core position of the anticyclonic center, we divide PB events into two subgroups: western PB and eastern PB. In addition, considering average zonal shifting speed, we further classify them into three subgroups: westward shifting PB, quasi-stationary PB and eastward shifting PB. Composite results show that the changes of SIC and surface air temperature (SAT) show different asymmetric characteristics for the different PB subgroups. Of the five PB regimes, the quasi-stationary PB is associated with the greatest reduction in SIC in the BS over its lifetime, both in magnitude and duration. Furthermore, we find that the local sea surface temperature (SST) anomaly upstream of the quasi-stationary PB, both during and prior to its onset, exhibits a significant dipole mode, along with a positive anomaly in the 300-hPa zonal wind. The SST dipole could serve as a precursor climatic background condition, likely triggering the occurrence of quasi-stationary PB and subsequently leading to intense SIC changes.