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Quantifying the thermodynamic entropy budget of the land surface: is this useful?
Brunsell, Nathaniel A. Schymanski, S. J. Kleidon, Axel
Brunsell, Nathaniel A.
Schymanski, S. J.
Kleidon, Axel
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Abstract
As a system is moved away from a state of thermodynamic
equilibrium, spatial and temporal heterogeneity
is induced. A possible methodology to assess these impacts
is to examine the thermodynamic entropy budget and assess
the role of entropy production and transfer between the surface
and the atmosphere. Here, we adopted this thermodynamic
framework to examine the implications of changing
vegetation fractional cover on land surface energy exchange
processes using the NOAH land surface model and eddy covariance
observations. Simulations that varied the relative
fraction of vegetation were used to calculate the resultant entropy
budget as a function of fraction of vegetation. Results
showed that increasing vegetation fraction increases entropy
production by the land surface while decreasing the overall
entropy budget (the rate of change in entropy at the surface).
This is accomplished largely via simultaneous increase in the
entropy production associated with the absorption of solar radiation
and a decline in the Bowen ratio (ratio of sensible to
latent heat flux), which leads to increasing the entropy export
associated with the latent heat flux during the daylight hours
and dominated by entropy transfer associated with sensible
heat and soil heat fluxes during the nighttime hours. Eddy
covariance observations also show that the entropy production
has a consistent sensitivity to land cover, while the overall
entropy budget appears most related to the net radiation
at the surface, however with a large variance. This implies
that quantifying the thermodynamic entropy budget and entropy
production is a useful metric for assessing biosphereatmosphere-
hydrosphere system interactions.
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Date
2011-06-20
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European Geosciences Union
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Brunsell, N. A., S. Schymanski and A. Kleidon: 2011, Quantifying the thermodynamic entropy budget of the land surface: is this useful? Earth System Dynamics, 2, 87-103. http://dx.doi.org/10.5194/esd-2-87-2011