title: The dependence of the beta coefficient of REA system with dynamic deadband on atmospheric conditions.
abstract: We simulated the REA system with dynamic deadband to study numerical value and the effect of atmospheric conditions on the empirical constant beta which relates vertical flux to concentration difference between updrafts and downdrafts. We found that the value of beta depends only weakly on the friction velocity and atmospheric stability. In agreement with previous studies, the median value obtained for a system with dynamic deadband proportional to 0.5 times the running mean of the standard deviation of vertical wind speed was beta=0.42+/-0.03. For a single half-hour measurement one has to consider the large uncertainty of +/-0.2. According to our study, the dynamic deadband enables the use of a constant value of beta in flux calculation.
authors.affiliation: Department of Physical Sciences, University of Helsinki, P.O. Box 64, FIN-00014, Finland. tiia.gronholm@helsinki.fi
authors.forename: Tiia
authors.initials: T
authors.lastname: Grönholm
authors.forename: Sami
authors.initials: S
authors.lastname: Haapanala
authors.forename: Samuli
authors.initials: S
authors.lastname: Launiainen
authors.forename: Janne
authors.initials: J
authors.lastname: Rinne
authors.forename: Timo
authors.initials: T
authors.lastname: Vesala
authors.forename: Ullar
authors.initials: U
authors.lastname: Rannik
mesh_terms: D000392:Air Movements; D000397:Air Pollution / Q000032:analysis*; D000465:Algorithms; D002245:Carbon Dioxide / Q000032:analysis*; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods; D008962:Models, Theoretical; D013696:Temperature