Harmonic propagation of variability in surface energy balance within a coupled soil-vegetation-atmosphere system
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Entekhabi_Harmonic propagation.pdf
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Author(s)
Gentine, Pierre
Polcher, J.
Entekhabi, Dara
Date Issued
May 2011
Journal
Water Resources Research
Publisher
American Geophysical Union
Citation
Gentine, P., J. Polcher, and D. Entekhabi. “Harmonic Propagation of Variability in Surface Energy Balance Within a Coupled Soil-vegetation-atmosphere System.” Water Resources Research 47.5 (2011): 1-21. CrossRef. Web. Copyright 2011 by the American Geophysical Union.
Version
Final published version
Abstract
[1] The response of a soil-vegetation-atmosphere continuum model to incoming radiation forcing is investigated in order to gain insights into the coupling of soil and atmospheric boundary layer (ABL) states and fluxes. The response is characterized through amplitude and phase propagation of the harmonics in order to differentiate between the response of the system to forcing at different frequencies (daily to hourly to near instantaneous). Stochastic noise is added to the surface energy balance. The amplitude of the noise is maximum at midday when the incoming radiative forcing is also at its peak. The temperatures and turbulent heat fluxes are shown to act as low-pass filters of the incoming radiation or energy budget noise variability at the surface. Conversely, soil heat flux is shown to act as a high-pass filter because of the strong contrast in the soil and air heat capacities and thermal conductivities. As a consequence, heat diffusion formulations that numerically dampen such forcing are potentially incapable of representing rapid fluctuations in soil heat flux (≤30 min) and therefore introduce errors in the land-surface energy partitioning. The soil-vegetation-ABL continuum model and an electrical analogy for it are used to explain the frequency-dependent differences in the relative effectiveness of turbulent heat fluxes versus ground heat flux in dissipating noise in radiative forcing.
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
Parsons Laboratory for Environmental Science and Engineering (Massachusetts Institute of Technology)
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1029/2010wr009268
