Turbulent Transport and Energy Balance as Affected by a Windbreak in an Irrigated Sugar Beet (Beta vulgaris) Field1

Abstract

AbstractTurbulent exchange coefficients for sugar beets sheltered by corn windbreaks and unsheltered were calculated by means of an energy balance. Occasionally measurements were made within the boundary layer characteristic of the underlying surfaces at four locations in shelter and in the open field. At such times the coefficients were 25% lower on the average in the sheltered area. These results agree with the few available reports on this subject.Decreased exchange coefficient in the sheltered area acts to suppress the transport of sensible heat. The suppression of upward sensible heat transport in a Great Plains irrigated valley during the morning results in an increase in energy available for consumption as latent heat. During the afternoon, however, when sensible heat is advected to the crop, latent heat flux is lower in the sheltered crop than in the open field. Thus the total daily latent heat flux may be the same in both plots. The sheltered crop is subjected to a reduced evaporative demand, however, during periods when water stress is most likely.