An Exploration of Multi Decadal, Continental-Scale Evapotranspiration Inferred from Weather Data

GSTDTAP

项目编号	1446798
	An Exploration of Multi Decadal, Continental-Scale Evapotranspiration Inferred from Weather Data
	Guido Salvucci
主持机构	Trustees of Boston University
项目开始年	2015
	2015-03-01
项目结束日期	2018-02-28
资助机构	US-NSF
项目类别	Standard Grant
项目经费	333635(USD)
国家	美国
语种	英语
英文摘要	An Exploration of Multi Decadal, Continental-Scale Evapotranspiration Inferred from Weather Data Land surface evapotranspiration (ET) is the transformation of water in soils, plants and lakes into atmospheric water vapor. It is a significant part of the regional water balance with direct influence on streamflow and groundwater recharge. ET is also a significant part of the atmospheric water balance with direct influence on humidity and rainfall. Because of the energy required to vaporize water, the ET process also influences land and air temperature. Despite its relevance to water resources and climate, ET is notoriously difficult to measure, especially at regional scales. This proposal develops and applies a newly discovered method for estimating ET from readily available weather data, based on daily patterns of relative humidity. With this method, the proposal addresses these questions: * What is the seasonal and geographic variability of ET over the U.S? * What are the seasonal and geographic roles of forcing (temperature, humidity, wind and precipitation) and surface properties (soil, vegetation, topography) in these space-time patterns? * What trends have occurred in ET over the last 50 years, and what is responsible for those trends (for instance, wind, moisture availability, radiation, temperature)? * How do these seasonal, geographical, and decadal variabilities (including trends) compare with state-of-the art climate models; and * How do the interactions between the land surface, the lower atmosphere, and cloud formation influence relative humidity? Broader impacts of this work include development and demonstration of a practical means for water resource managers to estimate ET, better understanding of geographic water resource availability and new observational constraints on climate models. In addition, the work will involve a graduate and undergraduate student, as well as a high school senior. Progress in understanding surface and atmospheric controls on ET, feedbacks between the surface and atmosphere, and decadal time scale variations in ET, require reliable estimates of ET. Direct, continuous measurements, however, are recent (approximately one decade old), and spatially limited (a few hundreds of flux stations, each measuring approximately one square kilometer of land area). Because of this, hydroclimatological research on ET has been either limited in space and time or has relied on model output. The proposed work overcomes these limitations and addresses critical questions related to the space-time variations of ET over decadal time scales (including trends), the drivers of these variations, and the ability of current climate models to capture these variations. Typically estimating ET requires either measurement of soil water status and surface temperature, or temporally integrated modeling of the water and energy balance. For broad use, the former requires remotely sensed observations, and the latter requires calibration of numerous soil hydraulic and vegetation parameters, leading to highly model-formulation dependent results. The method developed here provides ET estimation without site-specific calibration. The parsimony of required forcing and surface data allows for broad geographic and temporal (e.g., prior to the satellite era) application, and yields results that are significantly less model dependent. The intellectual merit of the proposed research is in addressing a vital questions of hydrologic sciences - determination of the terrestrial evaporation component of the water balance at hourly to decadal time scales over continental scales.
来源学科分类	Geosciences - Earth Sciences
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/67649
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Guido Salvucci.An Exploration of Multi Decadal, Continental-Scale Evapotranspiration Inferred from Weather Data.2015.