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Quantifying energy and mass transfer in crop canopies: sensors for measurement of temperature and air velocityHere we report on the in situ performance of inexpensive, miniature sensors that have increased our ability to measure mass and energy fluxes from plant canopies in controlled environments: 1. Surface temperature. Canopy temperature measurements indicate changes in stomatal aperture and thus latent and sensible heat fluxes. Infrared transducers from two manufacturers (Exergen Corporation, Newton, MA; and Everest Interscience, Tucson, AZ, USA) have recently become available. Transducer accuracy matched that of a more expensive hand-held infrared thermometer. 2. Air velocity varies above and within plant canopies and is an important component in mass and energy transfer models. We tested commercially-available needle, heat-transfer anemometers (1 x 50 mm cylinder) that consist of a fine-wire thermocouple and a heater inside a hypodermic needle. The needle is heated and wind speed determined from the temperature rise above ambient. These sensors are particularly useful in measuring the low wind speeds found within plant canopies. 3. Accurate measurements of air temperature adjacent to plant leaves facilitates transport phenomena modeling. We quantified the effect of radiation and air velocity on temperature rise in thermocouples from 10 to 500 micrometers. At high radiation loads and low wind speeds, temperature errors were as large as 7 degrees C above air temperature.
Document ID
20040089954
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Bugbee, B.
(Utah State University Logan, United States)
Monje, O.
Tanner, B.
Date Acquired
August 21, 2013
Publication Date
January 1, 1996
Publication Information
Publication: Advances in space research : the official journal of the Committee on Space Research (COSPAR)
Volume: 18
Issue: 4-5
Subject Category
Man/System Technology And Life Support
Distribution Limits
Public
Copyright
Other
Keywords
NASA Program CELSS
NASA Discipline Number 61-10
NASA Discipline Life Support Systems
Non-NASA Center

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