<p>The eddy-driven jet streams, which are regions of strong westerly wind in the mid-latitudes of both hemispheres, exert a leading influence on regional climate. In this Review, we outline the seasonally and regionally varying drivers, characteristics and changes in the jet streams. State-of-the-art models commonly predict a future polewards shift of the zonal-mean and annual-mean jet streams, typically ranging between 0° and 2° latitude by the end of the century under a high-emissions scenario, but with large model-to-model uncertainty. Furthermore, regional and seasonal projections can deviate substantially from the annual-mean and zonal-mean picture, and the drivers of these projected changes are not fully understood. Jet trends have emerged in the reanalysis record since 1979, of which a polewards shift of the summertime austral jet of ~0.3° per decade is the trend most clearly attributable to anthropogenic forcing. Although other trends have been observed, potentially large internal variability and incomplete understanding of the drivers of these trends precludes clear anthropogenic attribution at this point. Research is unevenly distributed across regions and seasons, with winter receiving the most attention, particularly in the North Atlantic. To support physical understanding and impact assessments, future research should provide a more complete picture of the seasonally and regionally varying jet stream drivers, and their changes, especially in spring and autumn.</p>

错误:搜索内容不能为空,请输入英文关键词
错误:关键词超出字数限制,请精简
高级检索

Seasonal and regional jet stream changes and drivers

  • Philipp Breul,
  • Paulo Ceppi,
  • Isla R. Simpson,
  • Tim Woollings

摘要

The eddy-driven jet streams, which are regions of strong westerly wind in the mid-latitudes of both hemispheres, exert a leading influence on regional climate. In this Review, we outline the seasonally and regionally varying drivers, characteristics and changes in the jet streams. State-of-the-art models commonly predict a future polewards shift of the zonal-mean and annual-mean jet streams, typically ranging between 0° and 2° latitude by the end of the century under a high-emissions scenario, but with large model-to-model uncertainty. Furthermore, regional and seasonal projections can deviate substantially from the annual-mean and zonal-mean picture, and the drivers of these projected changes are not fully understood. Jet trends have emerged in the reanalysis record since 1979, of which a polewards shift of the summertime austral jet of ~0.3° per decade is the trend most clearly attributable to anthropogenic forcing. Although other trends have been observed, potentially large internal variability and incomplete understanding of the drivers of these trends precludes clear anthropogenic attribution at this point. Research is unevenly distributed across regions and seasons, with winter receiving the most attention, particularly in the North Atlantic. To support physical understanding and impact assessments, future research should provide a more complete picture of the seasonally and regionally varying jet stream drivers, and their changes, especially in spring and autumn.