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Influence of submeso motions on scalar oscillations and surface energy balance
Author(s) -
Stefanello Michel,
Cava Daniela,
Giostra Umberto,
Acevedo Otávio,
Degrazia Gervasio,
Anfossi Domenico,
Mortarini Luca
Publication year - 2020
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.3714
Subject(s) - daytime , stratification (seeds) , planetary boundary layer , turbulence , energy balance , atmospheric sciences , wind speed , boundary layer , advection , scalar (mathematics) , internal wave , environmental science , mechanics , meteorology , mixed layer , surface layer , physics , geometry , materials science , mathematics , thermodynamics , seed dormancy , germination , botany , layer (electronics) , dormancy , composite material , biology
The presence of wave‐like structures in the planetary boundary layer and their influence on the scalar fluxes and on the surface energy balance were investigated analyzing one year of continuous measurements collected in southern Brazil. Submeso oscillating patterns in the wind velocity components, temperature and scalar (CO2, H2O) concentrations were isolated using their auto‐correlation functions. The analysis showed that low wind speeds are necessary to trigger wavy motions. During night‐time, in the presence of large vertical temperature gradients, horizontal meandering and internal gravity waves are dominant features of the stable boundary layer. Furthermore, a significant number of meandering cases were identified also during daytime in neutral conditions associated with low values of net radiation. One case‐study showed how, during daytime, the wave‐like patterns may be triggered by variations in the net radiation. Spectral analysis on the whole dataset showed that oscillations in the wind velocity and temperature field are frequently associated with CO2and H2O wavy patterns with similar time‐scales. These non‐turbulent oscillations produce unpredictable large‐scale contributions to vertical fluxes of temperature and scalar concentrations. The energy budget analysis showed how the choice of a proper averaging time filters out these contributions and improves the energy budget closure, as well as the estimation of the net ecosystem exchange. The results confirm the influence of submeso motions in scalar dispersion, flux patterns and surface energy balance during low wind speed conditions and stable stratification.