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DOI	10.5194/hess-24-4923-2020
	Imprints of evaporative conditions and vegetation type in diurnal temperature variations
	Panwar A.; Renner M.; Kleidon A.
发表日期	2020
ISSN	1027-5606
起始页码	4923
结束页码	4942
卷号	24 期号:10
英文摘要	Diurnal temperature variations are strongly shaped by the absorption of solar radiation, but evaporation, or the latent heat flux, also plays an important role. Generally, evaporation cools. Its relation to diurnal temperature variations, however, is unclear. This study investigates the diurnal response of surface and air temperatures to evaporative conditions for different vegetation types. We use the warming rate, defined as the increase in temperature in response to absorbed solar radiation in the morning, and evaluate how it changes with evaporative fraction, which is an indicator of the evaporative conditions. Results for 51 FLUXNET sites show that the warming rate of air temperature carries very weak imprints of evaporative fraction across all vegetation types. However, the warming rate of surface temperature is highly sensitive to evaporative fraction with a value of ∼ 23×10-3 K(Wm-2/-1, indicating stronger evaporative cooling for moister conditions. Contrarily, the warming rates of surface and air temperatures are similar at forest sites and carry literally no imprints of evaporative fraction.We explain these contrasting patterns with an analytical surface energy balance model. The derived expressions reproduce the observed warming rates and their sensitivity to evaporative fraction in all vegetation types. Multiplying the warming rate with daily maximum solar radiation gives an approximation for the diurnal surface temperature range (DTsR).We use our model to compare the individual contributions of solar radiation, evaporative conditions, and vegetation (by its aerodynamic conductance) in shaping DTsR and show that the high aerodynamic conductance of forests reduces DTsR substantially more (-56 %) than evaporative cooling (-22 %). We further show that the strong diurnal variation in aerodynamic conductance (∼ 2:5 times of the mean across vegetation types) reduces DTsR by ∼ 35% in short vegetation and savanna but only by∼ 22%in forests.We conclude that diurnal temperature variations may be useful for predicting evaporation for short vegetation. In forests, however, the diurnal variations in temperatures are mainly governed by their high aerodynamic conductance, resulting in negligible imprints of evaporative conditions. © Author(s) 2020.
语种	英语
scopus关键词	Aerodynamics; Atmospheric temperature; Cooling; Evaporation; Evaporative cooling systems; Forestry; Heat flux; Solar radiation; Surface properties; Temperature distribution; Absorbed solar radiations; Absorption of solar radiation; Aerodynamic conductances; Diurnal temperatures; Evaporative cooling; Evaporative fraction; Surface energy balance modeling; Surface temperatures; Vegetation; aerodynamics; air temperature; cooling; diurnal variation; energy balance; evaporation; latent heat flux; savanna; solar radiation; surface energy; surface temperature
来源期刊	Hydrology and Earth System Sciences
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/159282
作者单位	Panwar, A., Biospheric Theory and Modeling Group, Max Planck Institute for Biogeochemistry, Jena, 07745, Germany; Renner, M., Biospheric Theory and Modeling Group, Max Planck Institute for Biogeochemistry, Jena, 07745, Germany; Kleidon, A., Biospheric Theory and Modeling Group, Max Planck Institute for Biogeochemistry, Jena, 07745, Germany
推荐引用方式 GB/T 7714	Panwar A.,Renner M.,Kleidon A.. Imprints of evaporative conditions and vegetation type in diurnal temperature variations[J],2020,24(10).
APA	Panwar A.,Renner M.,&Kleidon A..(2020).Imprints of evaporative conditions and vegetation type in diurnal temperature variations.Hydrology and Earth System Sciences,24(10).
MLA	Panwar A.,et al."Imprints of evaporative conditions and vegetation type in diurnal temperature variations".Hydrology and Earth System Sciences 24.10(2020).