Collaborative Research: Physical Drivers of Equivalent Temperature Variability

这项研究项目将量化美国东部等值温度的历史变化和预测的未来变化。当量温度是一种通过同时考虑干(显热)和湿(潜热)成分来考虑近地表空气总能量含量的指标。因此，它与人类的热应激很好地吻合，当温度和湿度同时升高时，热应激会增加。由于当量温度对温度和湿度的变化都很敏感，因此当量温度的变化可以反映从全球到区域的各种尺度上发生的过程。该项目的目的是诊断等值温度的历史变化，并将其归因于区域尺度(例如土壤湿度异常引起的湿度变化)、天气尺度(例如与大气环流变化有关的温度和湿度变化)和全球尺度(例如与温室气体辐射强迫变化有关的温度和湿度变化)的过程。该项目将在开发21世纪当量温度项目的背景下，在耦合的大气海洋环流模式和区域气候模式中调查这些过程。该项目将满足国家气候评估进程中确定的研究需要：更好地了解大气对大气成分变化的反应，并提高对可能威胁人类健康和福祉的大气变化的了解。以前还没有从影响的多个尺度来考虑等效温度变率。将等值温度的变化归因于它们作用的空间尺度上的基本过程，将使我们能够探索对历史记录中等值温度趋势的机械性理解。使用统计和动力学方法并了解驱动过程的缩小尺度大气-海洋环流模型，将使研究人员能够对未来的等值温度输出作出最佳的现有预测，并在严格理解历史变化的驱动因素的情况下将这些预测联系起来。该项目的结果将对气候变化的适应和规划产生广泛的影响，因为当量温度及其组成部分的变化可能对本世纪的人类健康和农业都至关重要。项目成果将被系统地存档，并提供给研究界。该项目为每个机构的多名研究生提供支持，从而有助于培养下一代地理学家和大气科学家。

This research project will quantify historical and projected future variability in equivalent temperature in the eastern United States. Equivalent temperature is a metric that considers the total energy content of near-surface air by accounting for both the dry (sensible heat) and moist (latent heat) components. It therefore aligns well with human heat stress, which increases when temperature and humidity are simultaneously elevated. Because equivalent temperature is sensitive to changes in both temperature and humidity, variations in equivalent temperature can reflect processing occurring across a range of scales from global to regional. The objective of this project is to diagnose and attribute historical changes in equivalent temperature to processes occurring at the regional scale (e.g. changes in humidity resulting from soil moisture anomalies), the synoptic scale (e.g. changes in temperature and humidity associated with changes in the atmospheric circulation), and the global scale (e.g. changes in temperature and humidity associated with changes in radiative forcing from greenhouse gases). The project will investigate these processes within coupled atmosphere ocean general circulation models and regional climate models in the context of developing 21st-century equivalent temperature projections.This project will address research needs identified in the National Climate Assessment process: to better understand atmospheric responses to atmospheric composition change and to improve understanding of atmospheric changes that may threaten human health and well-being. Equivalent temperature variability has not been previously considered in terms of multiple scales of influence. Attributing variations in equivalent temperature to the underlying processes across the spatial scales at which they act will allow exploration of mechanistic understanding of equivalent temperature tendencies in the historical record. Downscaling atmosphere ocean general circulation models using statistical and dynamical approaches with knowledge of the driving processes will allow the researchers to develop the best available projections of future equivalent temperature output and to contextualize those projections within a rigorous understanding of drivers of historical change. The results of the project will have broad implications for climate change adaptation and planning, because changes in equivalent temperature and its components may be critical for both human health and agriculture this century. Project results will be institutionally archived and made available to the research community. The project provides support for multiple graduate students at each institution, and thus contributes to development of the next generation of geographers and atmospheric scientists.