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Submitted to: Agricultural and Forest Meteorology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 9/25/2008 Publication Date: 2/1/2009 Citation: Kimball, B.A., Conley, M.M. 2009. Infrared heater arrays for warming field plots scaled up to 5-m diameter. Agricultural and Forest Meteorology (149), pp. 721-724. Interpretive Summary: In order to study the likely effects of global warming on future ecosystems, including agricultural fields, a method for applying a heating treatment to open-field plant canopies [i.e., a temperature free-air controlled enhancement (T-FACE) system] is needed which will warm vegetation as expected by the future climate. One approach which shows promise is infrared heating, which we have previously shown to work well on 3-m-diameter plots (7.1 m2). However, the small size limits the stature of vegetation to shorter than about 1 m and also limits the amount of plant material that can destructively harvested. Therefore, we tested a larger hexagonal 5-m-diameter array of infrared heaters, which was a near tripling of useable area (19.6 m2). The number of heaters was tripled from 6 to 18, and their height above the vegetation (wheat) canopy was scaled with the diameter (0.4 times diameter = 2.0m). The distribution of the resultant warming of the vegetation was quite uniform across the plot, and the efficiency was the same as that of the 3-m-diameter plots. Thus, no problems were encountered in tripling the area of the infrared-heater-warmed plots. This research will benefit all consumers of food and fiber. Technical Abstract: As Earth continues to warm globally, there is a need to conduct ecosystem plot warming experiments under conditions as representative of open fields in the future as possible. One promising approach is to use hexagonal arrays of infrared heaters such as described by Kimball et al. (2008). However, their plots were only 3 m in diameter (7.1 m2), which limits the stature of vegetation to shorter than about 1 m and also limits the amount of plant material that can destructively harvested. Therefore, we tested a larger hexagonal 5-m-diameter array of infrared heaters, which provided a near tripling of useable area (19.6 m2). The number of heaters was tripled from 6 to 18, and their height above the vegetative (wheat) canopy was scaled with the diameter (0.4 times diameter = 2.0m). Distributions of down-going thermal radiation and of the resultant warming of the vegetation were quite uniform across the plot. Moreover, the same equation previously determined from 3-m-diameter plots to describe the thermal radiation efficiency as a function of wind speed was still applicable. Thus, no problems were encountered in tripling the area of the infrared-heater-warmed plots. |
