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Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 2/15/2015 Publication Date: 5/5/2015 Citation: Kimball, B.A. 2015. Using canopy resistance for infrared heater control when warming open-field plots. Agronomy Journal. 107:1105-1112. Interpretive Summary: Several research groups are using or planning to use arrays of infrared heaters to simulate global warming in open-field plots with a control strategy that involves maintaining a constant rise in canopy temperatures of the heated plots above those of un-heated reference plots. . However, if the warming treatment itself alters canopy architecture, plant physiology, albedo, etc. in ways that affect the energy balances of the heated plots so as to make them materially different from those of the reference plots, then the reference plots no longer are proper references against which to determine the desired temperature rise. Therefore, a new alternative control strategy is proposed whereby energy balance measurements are used to determine the canopy resistances of the heated plots, which in turn are used to calculate how much infrared radiation is needed to achieve the desired degrees of warming. Then the voltages supplied to the heaters can be modulated accordingly. This accomplishment should improve the reliability of such research to determine the likely effects of global warming, with will benefit all consumers of agricultural products, i.e., everyone, as well as improving our understanding of likely effects on natural ecosystems. Technical Abstract: Several research groups are using or planning to use arrays of infrared heaters to simulate global warming in open-field plots with a control strategy that involves maintaining a constant rise in canopy temperatures of the heated plots above those of un-heated Reference plots. . However, if the warming treatment itself alters canopy architecture, plant physiology, albedo, etc. in ways that affect the energy balances of the heated plots so as to make them materially different from those of the Reference plots, then the Reference plots no longer are proper references against which to determine the desired temperature rise. Herein, an alternative control strategy is proposed whereby energy balance measurements are used to determine the canopy resistances of the heated plots, which in turn are used to calculate how much infrared radiation is needed to achieve the desired degrees of warming. Then the voltages supplied to the heaters can be modulated accordingly. |
