The Dynamics of the Hadley Circulation and its Response to a Wide Range of Climate Changes: From a Hierarchy of Models to New Theories

这笔拨款将资助对哈德利环流的研究。哈德利环流是一种翻转的大气环流，在赤道附近的多雨地区有上升运动，在赤道两侧的亚热带地区有下沉运动。哈德利环流对热带和亚热带的气候非常重要，因为环流下沉分支下的地区以干旱或半干旱气候为特征。该研究解决了哈德利单元的行为，包括它的宽度、强度和上升运动的中心纬度，在各种模拟的行星气候状态下。该项目有三个主要目标：1)确定哈德利环流如何在广泛的气候范围内变化，以便在更大的背景下放置过去、现在和未来可能发生的变化。例如，这项研究将确定哈德利环流是否随着气候变暖而普遍变宽，即使在与现在非常不同的气候下也是如此。2)在日益复杂的气候模拟中，确定哈德利环流如何响应气候变化，包括世界表面完全是海洋而没有陆地的模拟，包括海冰的海洋模拟，以及理想大陆的配置。这些模拟旨在确定哈德利单元受外部因素影响的机制，如与冰期周期相关的日照变化。3)发展解释观测和模拟哈德利环流变化的科学理论。气候变暖中的哈德利细胞变化问题具有社会影响，因为观测和模拟表明，由于全球变暖，北半球和南半球的哈德利细胞可能正在扩大，这可能导致某些地区的干旱化。此外，这项工作将通过资助一名博士后学者、两名研究生和两名夏季本科生研究人员来促进下一代科学家的教育和培训。

This grant will fund research on the Hadley cell, an overturning atmospheric circulation with rising motion in the rainy regions near the equator and subsiding motions over the subtropics on either side of the equator. The Hadley cell is quite important for the climate of the tropics and subtropics, as regions under the subsiding branches of the circulation are characterized by arid or semi-arid climates. The research addresses the behavior of the Hadley cell, including its width, strength, and the central latitude of the rising motions, under a variety of simulated planetary climate states. The project has three main objectives: 1) To determine how the Hadley circulation changes over a wide range of climates, in order to place possible past, present, and future changes in a larger context. The research will determine, for example, whether the Hadley circulation generally widens as the climate warms, even in climates very different from the present. 2) To determine how the Hadley circulation responds to climate changes in climate simulations of increasing complexity, including simulations in which the world's surface is entirely ocean with no landmasses, ocean-only simulations including sea ice, and configurations with idealized continents. These simulations are intended to identify mechanisms through which the Hadley cell is influenced by external factors such the insolation changes associated with the ice age cycles. 3) To develop scientific theories that account for observed and simulated changes of the Hadley circulation.The issue of Hadley cell change in a warming climate has societal impacts, as observations and simulations suggest that the Northern and Southern Hemisphere Hadley cells may be widening due to global warming, which could result in aridification in some regions. In addition, the work will promote the education and training of the next generation of scientists by funding a postdoctoral scholar, two graduate students, and two summer undergraduate research fellows.