On the scaling up leaf stomatal resistance to canopy resistance using photosynthetic photon flux density

A dynamic surface conductance to predict crop water use from partial to full canopy cover

“…Moreover, crop ET is synthetically determined by a number of interacting environmental and biological processes (Allen et al, 1998;Ortega-Farias et al, 2006). Nowadays, one key scientific challenge in the determination of ET is to develop mathematical Due to the lack of independent estimates of G s , many researchers have assumed that G s was equivalent to the integrated leaf stomatal conductance, g s , weighted by leaf area and adjusted by the environmental variables (Campbell and Norman, 1998;Irmak et al, 2008). The g s at the single leaf-level is determined through the Jarvis or Ball-Berry type model, and then scaled-up to G s at the canopy level (Irmak et al, 2008;Zhang et al, 2011b).…”

“…Nowadays, one key scientific challenge in the determination of ET is to develop mathematical Due to the lack of independent estimates of G s , many researchers have assumed that G s was equivalent to the integrated leaf stomatal conductance, g s , weighted by leaf area and adjusted by the environmental variables (Campbell and Norman, 1998;Irmak et al, 2008). The g s at the single leaf-level is determined through the Jarvis or Ball-Berry type model, and then scaled-up to G s at the canopy level (Irmak et al, 2008;Zhang et al, 2011b). Generally, the scaled-up G s is compared to G s derived by inverting the P-M equation when ET and the meteorological variables measured over the crop canopy were known inputs (Ortega-Farias et al, 2006;Rana et al, 2012).…”

Actual and Reference Evaporative Losses and Surface Coefficients of a Maize Field during Nongrowing (Dormant) Periods

“…[40°34°N, 98°W, 552 m mean sea level (MSL)]. Detailed descriptions of field experimental procedures, data collection, and Bowen ratio energy balance measurements have been outlined in detail by , Irmak and Mutiibwa (2008), and Irmak et al (2008b). Some of the basic experimental practices will be described here.…”

Evapotranspiration of Partially Vegetated Surfaces

“…A second method is to make a one-step estimate of ET based on the Penman-Monteith (P-M) equation (Monteith, 1965), with crop-to-crop differences represented by the use of cropspecific values of surface and aerodynamic resistances (Shuttleworth, 2006). ET estimations using the one-step approach with the P-M model have been studied by several authors (Stannard, 1993;Farahani & Bausch, 1995;Rana et al, 1997;Alves & Pereira, 2000;Kjelgaard & Stockle, 2001;Ortega-Farias et al, 2004;Shuttleworth, 2006;Katerji & Rana, 2006;Flores, 2007;Irmak et al, 2008). Although different degrees of success have been achieved, the model has generally performed more satisfactorily when the leaf area index (LAI) is large (LAI>2).…”