ISSN:
1365-2486
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
,
Energy, Environment Protection, Nuclear Power Engineering
,
Geography
Notes:
Land–air exchanges of energy and matter are modulated by several feedback processes at both small and large space and time scales, with implications for the linked carbon, water and energy cycles. This paper studies the influences of four local feedbacks, occurring at single-patch spatial scales and subdiurnal temporal scales, on the surface energy balance (SEB) and land–air carbon fluxes. The feedbacks are: (i) radiative feedback, the modulation of available energy through the effect of surface temperature, Ts, on outgoing longwave radiation; (ii) physiological feedback, the interaction between vegetation physiology and the SEB through Ts; (iii) aerodynamic feedback, the modulation of turbulent heat and moisture transfer by atmospheric stability; and (iv) Convective Boundary Layer (CBL) feedback, the coupling between the daytime evolution of the SEB and CBL through saturation deficit.It is found that radiative feedback is significant only over very smooth surfaces. Physiological feedback is positive with respect to Ts at moderate to high temperatures, pushing stomata towards complete closure and the SEB towards very low evaporation rates. The SEB is quite sensitive to whether or not such closure occurs. Aerodynamic feedback, on the other hand, is negative with respect to Ts at these temperatures, reducing Ts and attenuating the tendency for heat-induced stomatal closure. CBL feedback alone does not dampen the sensitivity of the SEB to physiological feedback and stomatal closure. However, when aerodynamic feedback is included, this sensitivity is greatly reduced.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1046/j.1365-2486.1998.t01-1-00155.x
