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Simulating sunflower canopy temperatures to infer root-zone soil water potentialA soil-plant-atmosphere model for sunflower (Helianthus annuus L.), together with clear sky weather data for several days, is used to study the relationship between canopy temperature and root-zone soil water potential. Considering the empirical dependence of stomatal resistance on insolation, air temperature and leaf water potential, a continuity equation for water flux in the soil-plant-atmosphere system is solved for the leaf water potential. The transpirational flux is calculated using Monteith's combination equation, while the canopy temperature is calculated from the energy balance equation. The simulation shows that, at high soil water potentials, canopy temperature is determined primarily by air and dew point temperatures. These results agree with an empirically derived linear regression equation relating canopy-air temperature differential to air vapor pressure deficit. The model predictions of leaf water potential are also in agreement with observations, indicating that measurements of canopy temperature together with a knowledge of air and dew point temperatures can provide a reliable estimate of the root-zone soil water potential.
Document ID
19830015398
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Choudhury, B. J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Idso, S. B. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
September 4, 2013
Publication Date
February 1, 1983
Subject Category
Earth Resources And Remote Sensing
Report/Patent Number
NAS 1.15:84990
NASA-TM-84990
Accession Number
83N23669
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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