The 2021 Pacific Northwest Heat Wave and Associated Blocking: Meteorology and the Role of an Upstream Cyclone as a Diabatic Source of Wave Activity
The 2021 Pacific Northwest Heat Wave and Associated Blocking: Meteorology and the Role of an Upstream Cyclone as a Diabatic Source of Wave Activity
复制标题
DOI：
10.1029/2021gl097699
复制
发表时间：
2022-04-28
影响因子：
5.2
通讯作者：
Nakamura, Noboru
中科院分区：
文献类型：
--
作者：
Neal, Emily;Huang, Clare S. Y.;Nakamura, Noboru
我们研究了导致2021年6月下旬至7月上旬太平洋西北地区极端高温的气象和动力条件。在极端高温之前，上层大气阻塞了低纬度地区的暖气团。在阻塞的反气旋内部发生了吸热稳定分层，显著提高了地表温度。在阿拉斯加海岸外，对流层上层的波浪破裂和伴随的地面气旋形成引发了地块的形成。区域局地波活动收支显示，与该风暴相关的局地非绝热源对下游纬向波活动通量的增强起了关键作用，其在加拿大上空的辐合推动了阻塞。基于观察到的波活动预算的简单重建预测，当上游非绝热源仅减少30%时，强度降低41%，块体向东位移10度。
We investigate the meteorological and dynamical conditions that led to the extreme heat in the Pacific Northwest from late June to early July 2021. The extreme heat was preceded by an upper-level atmospheric blocking that snatched a warm pool of air from lower latitudes. A heat-trapping stable stratification ensued within the blocking anticyclone, raising the surface temperatures significantly. An upper-tropospheric wave breaking and the concomitant surface cyclogenesis off the coast of Alaska initiated the block formation. The regional local wave activity budget reveals that a localized diabatic source associated with this storm critically contributed to an enhanced zonal wave activity flux downstream, whose convergence over Canada drove the blocking. A simple reconstruction based on the observed wave activity budget predicts a 41 percent reduction in strength and a 10-degree eastward displacement of the block when the upstream diabatic source is reduced by just 30 percent.