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BIOTIC REGULATION OF THE ENVIRONMENT
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Presentations at European Geosciences Union 2007 Assembly
(15-20 April, Vienna, Austria)
Biotic pump of atmospheric moisture
as driver of the hydrological cycle on land
A.M. Makarieva, V.G. Gorshkov
Oral presentation in Session CL22 Climate: Past, Present and Future: Land-atmosphere coupling in past, present and future climate (solicited)
Key publication: Makarieva A.M., Gorshkov V.G. (2007) Hydrology and Earth System Sciences, 11: 1013-1033.
Under gravity land inevitably loses water to the ocean. To keep land moistened,
the gravitational water runoff must be continuously compensated by the atmospheric
ocean-to-land moisture transport. We show that the dependence of annual precipitation
on distance from the ocean differs markedly between the worldôs forested and non-forested
continent-scale regions. In the non-forested regions precipitation declines exponentially
with distance from the ocean with an established global mean e-folding
length of several hundred kilometers. In contrast, in forest-covered regions (Amazonia,
Equatorial Africa, Siberia) precipitation does not decrease or even grow along
several thousand kilometers inland despite significant runoff. This points to the existence
of an active biotic pump transporting atmospheric moisture inland from the
ocean. Physical principles of the biotic moisture pump are investigated based on the
previously unstudied properties of atmospheric water vapor, which can be either in or
out of hydrostatic equilibrium depending on the vertical lapse rate of air temperature.
A novel physical principle is formulated according to which the low-level air moves
from areas with weak evaporation to areas with more intensive evaporation. Thanks
to their high leaf area index, natural forests maintain high transpiration fluxes, which
support the ascending air motion over the forest and "suck in" moist air from the ocean,
which is the essence of the biotic pump of atmospheric moisture. Replacement of the
natural forest cover by a low leaf area index vegetation radically changes regional atmospheric
circulation and can lead to an up to tenfold reduction in mean continental
precipitation and runoff, in contrast to the previously available estimates made without
accounting for the biotic moisture pump. The analyzed body of evidence testifies
that the long-term stability of a human-friendly terrestrial water cycle is unachievable
without the recovery of natural, self-sustaining forests on continent-wide areas.
Interactive flash animations of intriguing atmospheric physical effects.
Click here and move the carriage on the right axis of the graph
up and down to see how the moist atmosphere comes out and returns back to static
equilibrium depending on vertical temperature gradient
- Click here and appreciate the difference between
the diffusional and dynamic fluxes of atmospheric air; see
what happens to a mixture of water vapor and dry air in a temperature gradient
- Click here to see the stationary dynamic motion
of moist air under the action of the evaporative force
A new scheme of accounting for the non-radiative heat fluxes
in the atmospheric transfer of thermal photons
A.M. Makarieva, V.G. Gorshkov
Poster presentation in Session PS 3.2 Planetary and Solar System Sciences:
Atmospheres of terrestrial planets
See Abstract PDF here.
See Poster (PDF, 25 x 50 cm) see
Full poster text see here.
Full RUSSIAN text see here.
Updated 14 April 2007.