The analytical solution for the heat flux from an anisothermal canopy
developed from K theory by Brutsaert and Sugita [1996] (hereinafter re
ferred to as B&S) has been extended to provide a parameterization of t
he difference between the radiometric and the equivalent isothermal su
rface temperature. The latter is the isothermal temperature at which a
canopy would give the correct sensible heat flux if the sensible heat
roughness length z(0h) was given its theoretical, isothermal value de
rived by B&S. A parameterization of the canopy temperature seen by a r
adiometer is developed which incorporates the same foliage temperature
profile as that used by B&S. From this the weighting fraction (i.e.,
the fraction of canopy top versus canopy bottom temperature ''seen'' b
y the radiometer) can be derived, as can an equation for the view zeni
th angle at which the radiometric and equivalent isothermal surface te
mperatures are the same. Field data indicate that multiangle radiometr
ic surface temperatures alone cannot determine the three unknowns desc
ribing the foliage temperature profile. Several strategies to overcome
this problem are outlined. The parameterization may eventually help t
o interpret remotely sensed infrared surface temperatures and to impro
ve estimates of sensible heat flux and evapotranspiration, but compreh
ensive field testing is still needed.