Мақола

Evaluating multi-year, multi-site data on the energy balance closure of eddy-covariance flux measurements at cropland sites in southwestern Germany

Ravshan EshonkulovEnvironmental Protection and Ecology, Karshi Engineering Economic Institute, Mustakillik Avenue 225, 180100 Karshi, UzbekistanArne PoydaInstitute of Soil Science and Land Evaluation, Biogeophysics, University of Hohenheim, Emil-Wolff Str. 27, 70593 Stuttgart, GermanyJoachim IngwersenInstitute of Soil Science and Land Evaluation, Biogeophysics, University of Hohenheim, Emil-Wolff Str. 27, 70593 Stuttgart, GermanyHans‐Dieter WizemannInstitute of Physics and Meteorology, Physics and Meteorology, University of Hohenheim, Garben Str. 30, 70593 Stuttgart, GermanyTobias K. D. WeberInstitute of Soil Science and Land Evaluation, Biogeophysics, University of Hohenheim, Emil-Wolff Str. 27, 70593 Stuttgart, GermanyPascal KremerInstitute of Soil Science and Land Evaluation, Biogeophysics, University of Hohenheim, Emil-Wolff Str. 27, 70593 Stuttgart, GermanyPetra HögyInstitute of Landscape and Plant Ecology, Plant Ecology and Ecotoxicology, University of Hohenheim, August-von-Hartmann-Str. 3, 70593 Stuttgart, GermanyAlim PulatovEcoGIS center, Tashkent Institute of Irrigation and Agricultural Mechanization Engineers, Kary Niyoziy Str.39, 100000 Tashkent, UzbekistanThilo StreckInstitute of Soil Science and Land Evaluation, Biogeophysics, University of Hohenheim, Emil-Wolff Str. 27, 70593 Stuttgart, Germany

Biogeosciencesjournal2019en

ABI

Аннотация

Abstract. The energy balance of eddy-covariance (EC) measurements is typically not closed, resulting in one of the main challenges in evaluating and interpreting EC flux data. Energy balance closure (EBC) is crucial for validating and improving regional and global climate models. To investigate the nature of the gap in EBC for agroecosystems, we analyzed EC measurements from two climatically contrasting regions (Kraichgau – KR – and Swabian Jura – SJ) in southwestern Germany. Data were taken at six fully equipped EC sites from 2010 to 2017. The gap in EBC was quantified by ordinary linear regression, relating the energy balance ratio (EBR), calculated as the quotient of turbulent fluxes and available energy, to the residual energy term. In order to examine potential reasons for differences in EBC, we compared the EBC under varying environmental conditions and investigated a wide range of possible controls. Overall, the variation in EBC was found to be higher during winter than summer. Moreover, we determined that the site had a statistically significant effect on EBC but no significant effect on either crop or region (KR vs SJ). The time-variable footprints of all EC stations were estimated based on data measured in 2015, complimented by micro-topographic analyses along the prevailing wind direction. The smallest mean annual energy balance gap was 17 % in KR and 13 % in SJ. Highest EBRs were mostly found for winds from the prevailing wind direction. The spread of EBRs distinctly narrowed under unstable atmospheric conditions, strong buoyancy, and high friction velocities. Smaller footprint areas led to better EBC due to increasing homogeneity. Flow distortions caused by the back head of the anemometer negatively affected EBC during corresponding wind conditions.

Ҳали таржима қилинмаган

Мавзулар

Plant Water Relations and Carbon Dynamics Plant responses to elevated CO2 Horticultural and Viticultural Research

Идентификаторлар

DOI: 10.5194/bg-16-521-2019

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2 та иқтибос 77 та фойдаланилган манба

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