TY - JOUR
T1 - Relaxed Eddy Accumulation Outperforms Monin-Obukhov Flux Models Under Non-Ideal Conditions
AU - Zahn, Einara
AU - Bou-Zeid, Elie
AU - Dias, Nelson Luís
N1 - Funding Information:
EZ and EBZ are supported by the US National Science Foundation under award number AGS 2128345 and EAR 2126206 and by the Cooperative Institute for Modeling the Earth System at Princeton University under Award NA18OAR4320123 from the National Oceanic and Atmospheric Administration. This material is based upon work supported by the High Meadows Environmental Institute at Princeton University through the Walbridge Fund Graduate Award for Environmental Research. The authors would also like to thank Gabriel G. Katul for his insight on the derivations in Section S1 in Supporting Information S1 .
Publisher Copyright:
© 2023. The Authors.
PY - 2023/4/16
Y1 - 2023/4/16
N2 - The Monin-Obukhov Similarity Theory (MOST) links turbulent statistics to surface fluxes through universal functions. Here, we investigate its performance over a large lake, where none of its assumptions (flat homogeneous surface) are obviously violated. We probe the connection between the variance budget terms and departure from the nondimensional flux-variance function for CO2, water vapor, and temperature. Our results indicate that both the variance storage and its vertical transport affect MOST, and these terms are most significant when small fluxes and near neutral conditions were prevalent. Such conditions are common over lakes and oceans, especially for CO2, underlining the limitation of using any MOST-based methods to compute small fluxes. We further show that the relaxed eddy accumulation (REA) method is more robust and less sensitive to storage and transport, adequately reproducing the eddy-covariance fluxes even for the smallest flux magnitudes. Therefore, we recommend REA over MOST methods for trace-gas flux estimation.
AB - The Monin-Obukhov Similarity Theory (MOST) links turbulent statistics to surface fluxes through universal functions. Here, we investigate its performance over a large lake, where none of its assumptions (flat homogeneous surface) are obviously violated. We probe the connection between the variance budget terms and departure from the nondimensional flux-variance function for CO2, water vapor, and temperature. Our results indicate that both the variance storage and its vertical transport affect MOST, and these terms are most significant when small fluxes and near neutral conditions were prevalent. Such conditions are common over lakes and oceans, especially for CO2, underlining the limitation of using any MOST-based methods to compute small fluxes. We further show that the relaxed eddy accumulation (REA) method is more robust and less sensitive to storage and transport, adequately reproducing the eddy-covariance fluxes even for the smallest flux magnitudes. Therefore, we recommend REA over MOST methods for trace-gas flux estimation.
KW - Monin-Obukhov Similarity Theory
KW - carbon dioxide fluxes
KW - eddy covariance
KW - lake evaporation
KW - relaxed eddy accumulation
KW - variance budget
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U2 - 10.1029/2023GL103099
DO - 10.1029/2023GL103099
M3 - Article
AN - SCOPUS:85153403007
SN - 0094-8276
VL - 50
JO - Geophysical Research Letters
JF - Geophysical Research Letters
IS - 7
M1 - e2023GL103099
ER -