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  • Author or Editor: Joseph G. Alfieri x
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Margaret A. LeMone
,
Fei Chen
,
Joseph G. Alfieri
,
Richard H. Cuenca
,
Yutaka Hagimoto
,
Peter Blanken
,
Dev Niyogi
,
Songlak Kang
,
Kenneth Davis
, and
Robert L. Grossman

The May–June 2002 International H2O Project was held in the U.S. Southern Great Plains to determine ways that moisture data could be collected and utilized in numerical forecast models most effectively. We describe the surface and boundary layer components, and indicate how the data can be acquired. These data document the eddy transport of heat and water vapor from the surface to the atmosphere (in terms of sensible heat flux H and latent heat flux LE), as well as radiative, atmospheric, soil, and vegetative factors that affect it, so that the moisture and heat supply to the atmosphere can be related to surface properties both for observational studies and tests of land surface models. The surface dataset was collected at 10 surface flux towers at locations representing the major types of land cover and extending from southeast Kansas to the Oklahoma Panhandle. At each location, the components of the surface energy budget (H, LE, net radiation, and soil heat flux) are documented each half-hour, along with the weather (wind, temperature, mixing ratio, air pressure, and precipitation), soil temperature, moisture, and matric potential down to 70–90 cm beneath the surface at 9 of the 10 sites. Observations of soil and vegetation properties and their horizontal changes were taken near all 10 towers during periodic visits. Aircraft measurements of H and LE from repeated low-level flight tracks along three tracks collocated with the surface sites extend the flux tower measurements horizontally. We illustrate the effects of vegetation and soil moisture on the H and LE and their horizontal variability.

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William P. Kustas
,
Martha C. Anderson
,
Joseph G. Alfieri
,
Kyle Knipper
,
Alfonso Torres-Rua
,
Christopher K. Parry
,
Hector Nieto
,
Nurit Agam
,
William A. White
,
Feng Gao
,
Lynn McKee
,
John H. Prueger
,
Lawrence E. Hipps
,
Sebastian Los
,
Maria Mar Alsina
,
Luis Sanchez
,
Brent Sams
,
Nick Dokoozlian
,
Mac McKee
,
Scott Jones
,
Yun Yang
,
Tiffany G. Wilson
,
Fangni Lei
,
Andrew McElrone
,
Josh L. Heitman
,
Adam M. Howard
,
Kirk Post
,
Forrest Melton
, and
Christopher Hain

Abstract

Particularly in light of California’s recent multiyear drought, there is a critical need for accurate and timely evapotranspiration (ET) and crop stress information to ensure long-term sustainability of high-value crops. Providing this information requires the development of tools applicable across the continuum from subfield scales to improve water management within individual fields up to watershed and regional scales to assess water resources at county and state levels. High-value perennial crops (vineyards and orchards) are major water users, and growers will need better tools to improve water-use efficiency to remain economically viable and sustainable during periods of prolonged drought. To develop these tools, government, university, and industry partners are evaluating a multiscale remote sensing–based modeling system for application over vineyards. During the 2013–17 growing seasons, the Grape Remote Sensing Atmospheric Profile and Evapotranspiration eXperiment (GRAPEX) project has collected micrometeorological and biophysical data within adjacent pinot noir vineyards in the Central Valley of California. Additionally, each year ground, airborne, and satellite remote sensing data were collected during intensive observation periods (IOPs) representing different vine phenological stages. An overview of the measurements and some initial results regarding the impact of vine canopy architecture on modeling ET and plant stress are presented here. Refinements to the ET modeling system based on GRAPEX are being implemented initially at the field scale for validation and then will be integrated into the regional modeling toolkit for large area assessment.

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