HR: 1340h
AN: H13C-0451    [Abstracts]
TI: An evaluation of complementary relationship assumptions
AU: * Pettijohn, J C
EM: geocory@bu.edu
AF: Department of Earth Sciences, Boston University, 685 Commonwealth Ave., Boston, MA 02215 United States
AU: Salvucci, G D
EM: gdsalvuc@bu.edu
AF: Department of Earth Sciences, Boston University, 685 Commonwealth Ave., Boston, MA 02215 United States
AB: Complementary relationship (CR) models, based on Bouchet's (1963) somewhat heuristic CR hypothesis, are advantageous in their sole reliance on readily available climatological data. While Bouchet's CR hypothesis requires a number of questionable assumptions, CR models have been evaluated on variable time and length scales with relative success. Bouchet's hypothesis is grounded on the assumption that a change in potential evapotranspiration (E$_p}$) is equal and opposite in sign to a change in actual evapotranspiration (E$_{a}$), i.e., $-$dE$_{p}$ $/$ dE$_{a}$ $=$ 1. In his mathematical rationalization of the CR, Morton (1965) similarly assumes that a change in potential sensible heat flux (H$_{p}$) is equal and opposite in sign to a change in actual sensible heat flux (H$_{a}$), i.e., $-$dH$_{p}$ $/$ dH$_{a}$ $=$ 1. CR models have maintained these assumptions while focusing on defining E$_{p}$ and equilibrium evapotranspiration (E$_{po}$). We question Bouchet and Morton's aforementioned assumptions by revisiting CR derivation in light of a proposed variable, $\phi$ $=$ $-$dE$_{p}$$/$dE$_{a}$. We evaluate $\phi$ in a simplified Monin Obukhov surface similarity framework and demonstrate how previous error in the application of CR models may be explained in part by previous assumptions that $\phi$=1. Finally, we discuss the various time and length scales to which $\phi$ may be evaluated.
DE: 3322 Land/atmosphere interactions
DE: 3307 Boundary layer processes
DE: 1818 Evapotranspiration
DE: 1833 Hydroclimatology
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting