The Bowen Ratio/Energy Balance method and detailed temperature profile measurements to improve data quality control

0456516 - ÚVGZ 2016 RIV CZ eng C - Konferenční příspěvek (zahraniční konf.)
Pozníková, Gabriela - Fischer, Milan - Orság, Matěj - Trnka, Miroslav - Žalud, Zdeněk
The Bowen Ratio/Energy Balance method and detailed temperature profile measurements to improve data quality control.
Global Change: A Complex Challenge : Conference Proceedings. Brno: Global Change Research Centre, The Czech Academy of Sciences, v. v. i., 2015 - (Urban, O.; Šprtová, M.; Klem, K.), s. 62-65. ISBN 978-80-87902-10-3.
[Global Change: A Complex Challenge /4th/. Brno (CZ), 23.03.2015-24.03.2015]
Grant CEP: GA MŠMT(CZ) EE2.3.20.0248; GA MŠMT LH12037; GA MŠMT(CZ) LD13030; GA MŠMT(CZ) LO1415
Institucionální podpora: RVO:67179843
Klíčová slova: temperature * Bowen ratio/energy balance method * data quality control
Kód oboru RIV: DG - Vědy o atmosféře, meteorologie

Water plays a key role in the functionality and sustainability of ecosystems. In light of predicted climate change, research should focus on the water cycle and its individual components. The main component of water balance driving water from ecosystems is evapotranspiration (ET). One standard method for measuring ET is the Bowen Ratio/Energy Balance (BREB) method. It is based on the assumption that water vapour and heat are transported by identical eddies with equal efficiency. When using the BREB method, we assume that the profiles of temperature and air humidity are ideally logarithmic or at least consistent. Since the BREB method is usually based on measurements of temperature and humidity at only two heights, it is difficult to verify whether this assumption has been fulfilled. Potential profile inconsistencies are more likely for temperature because the sensible heat flux changes its sign more often and negative latent heat flux is not physically possible during positive sensible heat flux. We therefore conducted a field experiment using a 4-mhigh measurement mast with 20 thermocouples for detailed measurement of air temperature profiles above different covers, e.g. grassland, spring barley, and poplar plantations. Our main objective was to investigate the basic assumptions of the BREB method, i.e. the temperature profile’s consistency under various weather conditions. To be more specific, we aimed to investigate whether inflexion points occurred within the temperature profile and if so when.
Trvalý link: http://hdl.handle.net/11104/0257042