The Fast and Slow Response of the Hydrological Cycle

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项目编号	1753656
	The Fast and Slow Response of the Hydrological Cycle
	Brian Soden
主持机构	University of Miami Rosenstiel School of Marine&Atmospheric Sci
项目开始年	2018
	2018-04-01
项目结束日期	2021-03-31
资助机构	US-NSF
项目类别	Standard Grant
项目经费	539210(USD)
国家	美国
语种	英语
英文摘要	The hydrological cycle, besides being responsible for the formation of clouds and producing rainfall, is a key component of the atmospheric energy cycle that links surface cooling via evaporation to atmospheric heating via latent heating release in the atmosphere. Changes in atmospheric water vapor and clouds due to changes in the hydrological cycle also alter the surface-atmosphere exchanges via changes in absorption and reflection of the incoming solar energy and in emission of infrared radiation. Changes in the amount of rainfall and the frequency of heavy rain events have been observed over the last century. These changes are, in part, a result of human emission of greenhouse gases. Increasing levels of carbon dioxide, aerosols, and other greenhouse gases causes warming of the surface and atmosphere, which in turns leads to more evaporation from (ocean) surfaces and increases of the amount of moisture and clouds in the atmosphere, as well as more rainfall. The extra heat transferred away from the surface associated with the strengthening of hydrological cycle warms the atmosphere further. This together with the stronger greenhouse effect due to more moisture in the atmosphere leads to a stronger emission of infrared radiation to the surface, which compensates the surface warming reduction due to stronger evaporation. These changes can occur on both slow (years to decades) and fast (days to months) timescales. It is these changes in the flow of energy, not the increase in moisture, that causes rainfall to increase globally in response to increasing greenhouse gases. Thus, in order to fully understand and predict future changes in rainfall requires a better understanding how the transfer of energy between the surface and atmosphere will change in a warmer climate. This research uses an innovative method of computing the effects of an increase in greenhouse gases and aerosols, and a warmer and more humid climate, on the flow of energy between the surface and atmosphere. Through this new method, termed radiative kernels, the individual contributions of different processes can be isolated and their contributions to the changes in precipitation quantified. In doing so, this research will provide a better understanding of the physical mechanisms that underlie model projections of future precipitation change. In particular, this research strives to better understand the cause of disparities between different model projections of rainfall change and use this information to improve models and ultimately provide more reliable projections of future changes. Because of the role of rainfall in determining the availability of fresh water and agricultural food production, changes in its amount, distribution or intensity have significant impacts on people and the environment. In addition, changes in the occurrence of heavy rainfall events alters the frequency of floods, which cause damage to infrastructure, loss of property, and loss of life. Predicting future changes in rainfall that stem from changes in climate therefore represents a key scientific challenge with important societal benefits. The knowledge gained from this research will ultimately lead to both a better understanding of the underlying physical processes that govern rainfall change and improved predictions of future rainfall change. By increasing the reliability of long term projections of changes in rainfall, this project will help decision makers plan for adequate adaptation and mitigation strategies that, in turn, lessen the cost and consequences of future changes in climate. 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.
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/72481
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Brian Soden.The Fast and Slow Response of the Hydrological Cycle.2018.