Thermodynamics, irreversibility, and optimality in land surface hydrology

Authors:

Axel Kleidon, Stan Schymanski, and Marc Stieglitz

Abstract:

The water exchange at the land surface is driven by the input of water by precipitation and the loss by runoff generation and evapotranspiration into the atmosphere. It is strongly linked to the surface energy balance by the flux of latent heat associated with evapotranspiration, but also to the dynamics of the atmosphere and teh terrestrial biosphere. From a more general perspective, the exchange fluxes of water at the land surface are embedded in the global hydrologic cycle, which is driven by thermodynamic processes to a state far from thermodynamic equilibrium. This state far from thermodynamic equilibrium is maintained by a range of processes that continuously perform work, dissipate energy, and thereby produce entropy. Quantifying rates of entropy production allows us to measure the dissipative nature of the hydrologic cycle, its irreversibility, and can provide a basis to identify some general functional characteristics. This thermodynamic perspective then allows us to investigate the applicability of the principle of maximum entropy production (MEP, e.g., Ozawa et al. 2003; Kleidon and Lorenz 2005; Martyushev and Seleznev 2006) to surface and soil hydrology, and to test any general direction in fundamental, thermodynamic terms by which the biota alters these thermodynamic processes, such as increasing the rates of entropy production (e.g., Ulanowicz and Hannon 1987; Schneider and Kay 1994; Kleidon 2004; Tesar et al. 2007).

Reference:

• Bioclimatology and Natural Hazards, ed. by K. Strelcová et al., Springer Verlag, 2009.
• Weblink to publisher's web page.