Variations in the albedo of wheat and barley crops

Piggin, I. G.; Schwerdtfeger, Peter

doi:10.1007/bf02253314

Cited by 16 publications

(9 citation statements)

References 14 publications

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“…For the largest perturbation (+0.10), this leads to albedo values of 0.3. These values are within ranges of observed albedo of wheat and barley in Australia, with past field observations reporting values of daily albedo ranging from 0.13 to 0.25 for wheat and from 0.14 to 0.36 for barley in southeast Australia (Piggin and Schwerdtfeger, 1973). In summary, a total of 108 simulations were Table 1 WRF physics ensemble used in this study for the Planetary Boundary Layer (PBL), Surface Layer (SL), and Cumulus schemes.…”

Section: Model Description and Experimentssupporting

confidence: 68%

Could crop albedo modification reduce regional warming over Australia?

Kala¹,

Hirsch²

2020

Preprint

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Climate observations and projections for Australia show an increase in warm temperature extremes, including the frequency, duration and intensity of heatwaves. Recent global scale studies have suggested that agricultural land-use management options, such as increasing crop albedo, could reducing local warming. Australia has approximately 3,727,210 km2 of cropland agricultural land-use, the majority of which is in southwest Western Australia and southeast Australia. This presents a potential opportunity to reduce regional warming via crop albedo enhancement. We use a regional climate model at 10 km resolution, to show that crop albedo enhancement of up to 0.1 could reduce monthly mean daily maximum temperatures by -1.0&#176;C to -1.2&#176;C, and monthly highest maximum temperatures by up to -1.4&#176;C to -1.6&#176;C during the cropping season. This cooling is approximately 3 times higher over Australia than global climate models predict. We highlight stronger cooling over southwest Western Australia as compared to southeast Australia, the opposite to global model studies which poorly resolve southwestern agricultural regions. The regional cooling was driven by a reduction in surface net shortwave radiation leading to a decrease in both sensible and latent heat flux of up to 50 W m-2 and 20 W m-2 respectively, when albedo is increased by up to 0.1. There were no cloud feedbacks or effects on precipitation. Our results highlight the importance of using regional climate models at a sufficiently high spatial resolution when investigating agricultural land-use management to reduce regional warming.

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Section: Model Description and Experimentssupporting

confidence: 68%

Could crop albedo modification reduce regional warming over Australia?

Kala¹,

Hirsch²

2020

Preprint

View full text Add to dashboard Cite

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“…1 is around 0.2, which is a relatively high albedo for an agricultural soil (due to the relatively high loam/low organic matter content in this soil). Previously reported in situ (11)(12)(13) and satellite (14,15) measurements suggest that the albedo of brown agricultural soils can be lower than 0.1, whereas soils covered with stubble can have albedos largely above 0.3, implying albedo differences…”

Section: Resultsmentioning

confidence: 98%

Preferential cooling of hot extremes from cropland albedo management

Davin

Seneviratne

Ciais

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

175

162

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Changes in agricultural practices are considered a possible option to mitigate climate change. In particular, reducing or suppressing tillage (no-till) may have the potential to sequester carbon in soils, which could help slow global warming. On the other hand, such practices also have a direct effect on regional climate by altering the physical properties of the land surface. These biogeophysical effects, however, are still poorly known. Here we show that no-till management increases the surface albedo of croplands in summer and that the resulting cooling effect is amplified during hot extremes, thus attenuating peak temperatures reached during heat waves. Using a regional climate model accounting for the observed effects of no-till farming on surface albedo, as well as possible reductions in soil evaporation, we investigate the potential consequences of a full conversion to no-till agriculture in Europe. We find that the summer cooling from cropland albedo increase is strongly amplified during hot summer days, when surface albedo has more impact on the Earth's radiative balance due to clear-sky conditions. The reduced evaporation associated with the crop residue cover tends to counteract the albedo-induced cooling, but during hot days the albedo effect is the dominating factor. For heatwave summer days the local cooling effect gained from no-till practice is of the order of 2°C. The identified asymmetric impact of surface albedo change on summer temperature opens new avenues for climateengineering measures targeting high-impact events rather than mean climate properties.

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“…Uddin and Marshall [] measure albedo variations across 28 wheat cultivars and report a range of 0.06 to 0.10 associated with changes in wax content. Piggin and Schwerdtfeger [] report seasonal changes in albedo of 0.12 for a single wheat cultivar and 0.22 for a single barley cultivar that were attributed to changes in leaf area index and soil moisture. These higher estimates in albedo variation are likely to include the effects of changes in background soil reflectance.…”

Section: Methodsmentioning

confidence: 99%

Can climate‐effective land management reduce regional warming?

et al. 2017

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Limiting global warming to well below 2°C is an imminent challenge for humanity. However, even if this global target can be met, some regions are still likely to experience substantial warming relative to others. Using idealized global climate simulations, we examine the potential of land management options in affecting regional climate, with a focus on crop albedo enhancement and irrigation (climate‐effective land management). The implementation is performed over all crop regions globally to provide an upper bound. We find that the implementation of both crop albedo enhancement and irrigation can reduce hot temperature extremes by more than 2°C in North America, Eurasia, and India over the 21st century relative to a scenario without management application. The efficacy of crop albedo enhancement scales with the magnitude, where a cooling response exceeding 0.5°C for hot temperature extremes was achieved with a large (i.e., ≥0.08) change in crop albedo. Regional differences were attributed to the surface energy balance response with temperature changes mostly explained by latent heat flux changes for irrigation and net shortwave radiation changes for crop albedo enhancement. However, limitations do exist, where we identify warming over the winter months when climate‐effective land management is temporarily suspended. This was associated with persistent cloud cover that enhances longwave warming. It cannot be confirmed if the magnitude of this feedback is reproducible in other climate models. Our results overall demonstrate that regional warming of hot extremes in our climate model can be partially mitigated when using an idealized treatment of climate‐effective land management.

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Variations in the albedo of wheat and barley crops

Cited by 16 publications

References 14 publications

Could crop albedo modification reduce regional warming over Australia?

Could crop albedo modification reduce regional warming over Australia?

Preferential cooling of hot extremes from cropland albedo management

Can climate‐effective land management reduce regional warming?

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