Characterization of shortwave and longwave properties of several plastic film mulches and their impact on the surface energy balance and soil temperature
| Autor: | Rachhpal S. Jassal, Hughie Jones, Zoran Nesic, Sean Smukler, Mark Stephen Johnson, T. A. Black |
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| Rok vydání: | 2021 |
| Předmět: |
Materials science
Renewable Energy Sustainability and the Environment 020209 energy Analytical chemistry Longwave Plastic film 02 engineering and technology Sensible heat Molar absorptivity 021001 nanoscience & nanotechnology 0202 electrical engineering electronic engineering information engineering Radiative transfer General Materials Science Shortwave radiation 0210 nano-technology Shortwave Mulch |
| Zdroj: | Solar Energy. 214:457-470 |
| ISSN: | 0038-092X |
| DOI: | 10.1016/j.solener.2020.11.058 |
| Popis: | We used, and present, robust methodologies to measure the shortwave (S) and longwave (L) spectral radiative properties (reflectivity (ρ), transmissivity (τ) and absorptivity (α)) of nine plastic films and quantified their effect, when used as mulches, on soil heat flux density (G), net radiation (Rn, above the films) and soil temperature (Ts2cm, 2-cm depth; Ts10cm, 10-cm depth) in comparison to a control (bare soil). During the daytime, all treatments increased G when compared to the control to a maximum of ~45%, except for a plastic film that had a high shortwave ρ (ρs) value (0.45). The films with the highest αs and ρs values had the highest and lowest daytime Rn, respectively. As a general rule, films with high τs and αL values caused the greatest increases in G, Ts2cm and Ts10cm. In contrast, a comparison of three black plastic films with similarly high αs and different longwave properties showed that the film with the highest αL value achieved the lowest G and Ts2cm, which was unexpected. The daytime heat-sharing ratio (G/H, where H is sensible heat flux on the upward-facing side of the mulch) ranged in value from 0.80 ± 0.47 (mulch with τs = 0.79 αL = 0.39) to 0.26 ± 0.13 (mulch with αs = 0.96 αL = 0.94). The lowest total daily downwelling shortwave radiation (Sd) required for total daily G to become positive was 9.4 MJ m−2 compared to 17.6 MJ m−2 for the control, which shows the potential of plastic films for growing-season extension. |
| Databáze: | OpenAIRE |
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