Collaborative Research: Dynamic and Thermodynamic Mechanisms of Heat Extremes in the Northern Hemisphere

合作研究：北半球极端高温的动力和热力学机制

• 批准号: 1934383
• 负责人: Deepti Singh
• 金额: $ 27.84万
• 依托单位: Washington State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-04-01 至 2025-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1934383&HistoricalAwards=false
• 关键词: Collaborative; Research; Dynamic; Thermodynamic; Mechanisms

We commonly think of heat waves as merely unpleasant or inconvenient, but they can also be deadly. For instance a 1995 heat wave resulted in over 600 deaths in Chicago, and the European heat wave of 2003 claimed more than 50,000 lives. Heat waves also cause indirect harm by contributing to crop failures, wildfires, droughts, and poor air quality. Heat wave frequency has increased dramatically over the past decades, accompanying the rise of global mean temperature, and further increases are expected as temperature continues to rise. Warmer temperatures also lead to more "concurrent heat waves", meaning simultaneous heat waves that cover a substantial fraction of the summer hemisphere land surface.Weather patterns leading to heat waves are easy to identify, commonly involving stagnant high-pressure systems accompanied by clear skies and subsiding air. But more perceptive analysis is required to understand why those weather patterns form, how long they remain in place, and the extent to which maximum temperatures within them are affected by the dryness of the surface or other local effects. A further consideration is that heat waves are typically identified as prolonged periods of extremely hot weather, but high humidity can matter as much as high temperature for human health effects. Compared to traditional heat waves the meteorology of humid heat waves is relatively unexplored.Research conducted here considers the contributions of dynamic and thermodynamic processes to heat waves considering both dry and humid events. A key consideration is the extent to which heat waves are prolonged and intensified by dry soil, which prevents evaporative cooling of the land surface. Another is the extent to which distinct physical mechanisms lead to dry and humid events, where humid events are defined as extremes of the wet bulb temperature (WBT). WBT is the lowest temperature that can be achieved through evaporative cooling given ambient temperature and moisture. It is a good indicator of human heat stress as we rely on evaporation of perspiration to avoid heat stress at high temperatures.One analysis tool is causal effect networks (CENs), a graphical technique borrowed from information theory and machine learning in which causality is established through lagged regression. Preliminary work using CENs suggests that an early summer heat wave can lead to reduced precipitation, which dries the soil and promotes additional heat waves. The work is performed using a combination of observations and output from climate model simulations of present-day and projected future climate, and model simulations are devised to further test and examine physical mechanisms.The work is of practical as well as scientific interest given the severe consequences of heat waves as noted above. Outreach to stakeholders concerned with heat wave impacts is performed through the Consortium for Climate Risk in the Urban Northeast (CCRUN), where one of the researchers has a leadership role. Interactions with students interested in climate impacts is enabled through the lead researcher's role as Director of the Masters degree granting Climate and Society program at Columbia University. The project also involves a Primarily Undergraduate Institution (PUI), and results are incorporated into undergraduate classroom teaching. In addition, two graduate students are supported through this award.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

我们通常认为热浪只是令人不快或不方便，但它们也可能是致命的。例如，1995年的热浪导致芝加哥600多人死亡，2003年的欧洲热浪夺去了5万多人的生命。热浪还会造成间接危害，造成农作物歉收、野火、干旱和空气质量差。在过去的几十年里，热浪的频率随着全球平均温度的上升而急剧增加，并且随着温度的继续上升，预计会进一步增加。气温升高还会导致更多的“同步热浪”，这意味着同时出现的热浪覆盖了夏季半球陆地表面的很大一部分。导致热浪的天气模式很容易识别，通常涉及停滞的高压系统，伴随着晴朗的天空和下沉的空气。但是，要理解这些天气模式形成的原因，它们保持的时间，以及它们内部的最高温度在多大程度上受到地表干燥或其他局部影响，还需要更敏锐的分析。进一步的考虑是，热浪通常被认为是长时间的极端炎热天气，但高湿度对人体健康的影响与高温一样重要。与传统的热浪相比，潮湿热浪的气象学研究相对较少。这里进行的研究考虑了动力和热力学过程对考虑干燥和潮湿事件的热浪的贡献。一个关键的考虑因素是干燥的土壤在多大程度上延长和加剧了热浪，因为干燥的土壤阻止了陆地表面的蒸发冷却。另一个是不同的物理机制导致干燥和潮湿事件的程度，潮湿事件被定义为湿球温度（WBT）的极端。WBT是在给定环境温度和湿度的情况下，通过蒸发冷却所能达到的最低温度。这是人体热应激的一个很好的指标，因为我们依靠汗水的蒸发来避免高温下的热应激。一种分析工具是因果效应网络（cns），这是一种借鉴信息理论和机器学习的图形技术，通过滞后回归建立因果关系。利用cns进行的初步工作表明，夏季早期的热浪可能导致降水减少，从而使土壤干燥并促进额外的热浪。这项工作结合了观测和气候模式对当前和预估未来气候的模拟结果，模式模拟的设计是为了进一步检验和检查物理机制。鉴于如上所述的热浪的严重后果，这项工作既具有实际意义，又具有科学意义。与关注热浪影响的利益相关者的联系是通过东北城市气候风险联盟（CCRUN）进行的，其中一名研究人员在该联盟中担任领导角色。作为哥伦比亚大学气候与社会硕士项目主任，首席研究员与对气候影响感兴趣的学生进行互动。该项目还包括一个初级本科院校（PUI），其成果将纳入本科课堂教学。此外，还有两名研究生通过该奖项获得资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Regional and elevational patterns of extreme heat stress change in the US

美国极端热应激变化的区域和海拔模式

• DOI: 10.1088/1748-9326/ac7343
• 发表时间: 2022
• 期刊: Environmental Research Letters
• 影响因子: 6.7
• 作者: Raymond, Colin;Waliser, Duane;Guan, Bin;Lee, Huikyo;Loikith, Paul;Massoud, Elias;Sengupta, Agniv;Singh, Deepti;Wootten, Adrienne
• 通讯作者: Wootten, Adrienne

Increased extreme humid heat hazard faced by agricultural workers

农业工人面临的极端湿热危险增加

• DOI: 10.1088/2515-7620/ad028d
• 发表时间: 2023
• 期刊: Environmental Research Communications
• 影响因子: 2.9
• 作者: Diaz, Connor D.;Ting, Mingfang;Horton, Radley;Singh, Deepti;Rogers, Cassandra D. W.;Coffel, Ethan
• 通讯作者: Coffel, Ethan

Sixfold Increase in Historical Northern Hemisphere Concurrent Large Heatwaves Driven by Warming and Changing Atmospheric Circulations

• DOI: 10.1175/jcli-d-21-0200.1
• 发表时间: 2022-02-01
• 期刊: JOURNAL OF CLIMATE
• 影响因子: 4.9
• 作者: Rogers, Cassandra D. W.;Kornhuber, Kai;Singh, Deepti
• 通讯作者: Singh, Deepti

Subseasonal Variability of Humid Heat During the South Asian Summer Monsoon

南亚夏季风期间湿热的次季节变化

• DOI: 10.1029/2023gl107382
• 发表时间: 2024
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Ivanovich, C. C.;Horton, R. M.;Sobel, A. H.;Singh, D.
• 通讯作者: Singh, D.

Enhanced solar and wind potential during widespread temperature extremes across the U.S. interconnected energy grids

在美国互联能源网普遍出现极端温度的情况下，太阳能和风能潜力得到增强

• DOI: 10.1088/1748-9326/ad2e72
• 发表时间: 2024
• 期刊: Environmental Research Letters
• 影响因子: 6.7
• 作者: Singh, Deepti;Bekris, Yianna S;Rogers, Cassandra D;Doss-Gollin, James;Coffel, Ethan D;Kalashnikov, Dmitri A
• 通讯作者: Kalashnikov, Dmitri A