Remote Sensing of Thermal Radiation from an Aircraft—An Analysis and Evaluation of Crop-Freeze Protection Methods

R. A. Sutherland Fruit Crops Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville 32611

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H. E. Hannah Fruit Crops Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville 32611

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A. F. Cook Fruit Crops Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville 32611

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J. D. Martsolf Fruit Crops Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville 32611

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Abstract

Thermal images from an aircraft-mounted scanner are used to evaluate the effectiveness of crop-freeze protection devices. Data from flights made while using fuel oil heaters, a wind machine and an undercanopy irrigation system are compared. Results show that the overall protection provided by irrigation (∼2°C) is comparable to the less energy-efficient heater-wind machine combination. Protection provided by the wind machine alone (∼1°C) was found to decrease linearly with distance from the machine by ∼1°C (100 m)−1. The flights were made over a 1.5 hectare citrus grove at an altitude of 450 m with an 8–14 μm detector. General meteorological conditions during the experiments, conducted during the nighttime, were cold (∼ −6°C) and calm with clear skies.

Abstract

Thermal images from an aircraft-mounted scanner are used to evaluate the effectiveness of crop-freeze protection devices. Data from flights made while using fuel oil heaters, a wind machine and an undercanopy irrigation system are compared. Results show that the overall protection provided by irrigation (∼2°C) is comparable to the less energy-efficient heater-wind machine combination. Protection provided by the wind machine alone (∼1°C) was found to decrease linearly with distance from the machine by ∼1°C (100 m)−1. The flights were made over a 1.5 hectare citrus grove at an altitude of 450 m with an 8–14 μm detector. General meteorological conditions during the experiments, conducted during the nighttime, were cold (∼ −6°C) and calm with clear skies.

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