| 项目编号: | 1545675
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| 项目名称: | Seasonal Sensitivity of the Midlatitude Circulation to Future Climate Warming |
| 作者: | Elizabeth Barnes
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| 承担单位: | Colorado State University
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| 批准年: | 2016
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| 开始日期: | 2016-05-01
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| 结束日期: | 2019-04-30
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| 资助金额: | 599693
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| 资助来源: | US-NSF
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| 项目类别: | Standard Grant
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| 国家: | US
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| 语种: | 英语
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| 特色学科分类: | Geosciences - Atmospheric and Geospace Sciences
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| 英文关键词: | jet stream
; shift
; greenhouse warming
; fall
; jet shift
; future climate
; winter
; deep tropospheric warming maximum
; summer
; spring
; future workforce
; global warming simulation
; global warming
; climate model simulation
; local climate
; atmospheric circulation
; climate change
; climate impact
|
| 英文摘要: | The climate change induced by increases in greenhouse gas concentrations is generally characterized as an increase in globally averaged temperature, but the climate impacts experienced locally will be determined in part by the changes in atmospheric circulation that are induced by global warming. In particular, climate model simulations suggest that the westerly jet streams found at upper levels in the middle latitudes will shift towards the poles, so that the mean Northern Hemisphere jet stream will migrate northward, with a corresponding southward shift for its the Southern Hemisphere counterpart. These shifts are small but consequential, as patterns of rainfall and storminess in the middle latitudes are determined in large part by the positions of the jet streams.
The poleward shift of jet streams as a consequence of greenhouse warming is a robust feature of global warming simulations and has been a research topic since at least 2005, but the seasonality and geography of the response has not yet been fully explored. Preliminary work for this project shows that in the Southern Hemisphere the largest shift is in the Fall (March to May), followed by Summer (December to February), Winter (June to August), and Spring (September to November). In the North Atlantic the order is, from largest to smallest, Fall (September to November), Summer (June to August), Spring (March to May), and Winter (December to February). The ordering is again different in the North Pacific, with Fall leading by a large margin followed by Winter, Spring, and Summer. By now several theories have been proposed to explain why the jets shift poleward in an year-round, longitudinally averaged sense, but none of these theories provides a clear intuition for the seasonality (i.e. why the shift is largest in Fall) or the regional variations.
Research under this award consists of analysis of observational data from reanalysis products and simulations of future climate from the Coupled Model Intercomparison Project and the Large Ensemble archive of simulations using the Community Earth System Model. This analysis is followed by numerical experiments using models of varying levels of complexity, intended to isolate and study possibly physical mechanisms leading seasonally and geographically varying jet shifts. One issue to be considered is that the pattern of greenhouse warming generally includes a deep tropospheric warming maximum in the tropics together with surface trapped warming near the poles (referred to as polar amplification). The jet shifts can be regarded as a combined response to the tropical and polar influences, which are likely to have opposing effects and very different seasonalities.
The work is of societal as well as scientific interest due to the strong impacts of jet shifts on local climate, for instance a northward shift of jet streams could cause drying in the region downwind of the present-day jet location accompanied by excessive rain and snow to the north. In addition, the project will support and train two students, thereby contributing to the future workforce in this research area. The PI and her students will also organize a special session at an annual geosciences meeting to publicize results of the study and encourage further investigation of the topic. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/92495
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| Appears in Collections: | 全球变化的国际研究计划
科学计划与规划
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| Recommended Citation: | |
Elizabeth Barnes. Seasonal Sensitivity of the Midlatitude Circulation to Future Climate Warming. 2016-01-01.
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