NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Due to the lapse in federal government funding, NASA is not updating this website. We sincerely regret this inconvenience.

Back to Results
GCM Studies on the Interactions Between Photosynthesis and Climate at Diurnal to Decadal Time ScalesTranspiration, a major component of total evaporation from vegetated surfaces, is an unavoidable consequence of photosynthetic carbon fixation. Because of limiting soil moisture and competition for solar radiation plants invest most of their fixed carbon into structural and hydraulic functions (roots and stems) and solar radiation absorption (leaves). These investments permit individuals to overshadow competitors and provide for transport of water from the soil to the leaves where photosynthesis and transpiration occur. Often low soil moisture or high evaporative demand limit the supply of water to leaves reducing photosynthesis and thus transpiration. The absorption of solar radiation for photosynthesis and dissipation of this energy via radiation, heat, mass and momentum fluxes represents the link between photosynthesis and climate. Recognition of these relationships has led to the development of hydro/energy balance models that are based on the physiological ecology of photosynthesis. We discuss an approach to study vegetation-climate interactions using photosynthesis-centric models embedded in a GCM. The rate at which a vegetated area transpires and photosynthesizes is determined by the physiological state of the vegetation, its amount and its type. The latter two are specified from global satellite data collected since 1982. Climate simulations have been carried out to study how this simulated climate system responds to changes in radiative forcing, physiological capacity, atmospheric CO2, vegetation type and variable vegetation cover observed from satellites during the 1980's. Results from these studies reveal significant feedbacks between the vegetation activity and climate. For example, vegetation cover and physiological activity increases cause the total latent heat flux and precipitation to increase while mean and maximum air temperatures decrease. The reverse occurs if cover or activity'decreases. In general climate response of a particular region was dominated by local processes but we also find evidence that plausible climate-vegetation scenarios lead to changes in global atmospheric circulation and strong non-local influences in some cases.
Document ID
19990021533
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Collatz, G. James
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Bounoua, Lahouari
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Sellers, Piers
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Los, Sietse
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Randall, David
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Berry, Joseph
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Tucker, Compton J.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1998
Subject Category
Life Sciences (General)
Meeting Information
Meeting: AGU Fall Meeting
Location: San Francisco, CA
Country: United States
Start Date: December 6, 1998
End Date: December 10, 1998
Sponsors: American Geophysical Union
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
No Preview Available