Degree Type

Dissertation

Date of Award

1999

Degree Name

Doctor of Philosophy

Department

Theses & dissertations (Interdisciplinary)

Major

Water Resources

First Advisor

Eugene S. Takle

Abstract

Two micrometeorological studies into surface energy fluxes are presented in this dissertation. In the first investigation, fluxes at the atmosphere-water interface were estimated by examining the heat accumulation into an advected two-dimensional volume of air. Meteorological conditions were selected based on measurable horizontal differences in temperature. Under the condition of warm air advected over cold water layer, the net loss of heat from the advected air was approximately --45 ill m--2. Latent fluxes could not be determined due to negligible differences in upwind and downwind water vapor profiles. The combined radiative loss and soil/detritus and sensible heat fluxes predicted a nighttime gain in heat storage ranging from 36 to 41 W m--2. The independently estimated heating rate for the water layer showed reasonable agreement, with estimates ranging from 28 to 45 W m--2. Under the condition of cold air advected over warm water layer, the sensible heat input ranged from 13 to 34 W m --2, and the latent heat loss due to evaporation ranged from --2 to --6 W M--2. Combined fluxes predicted a loss of heat from storage ranging from --20 to --45 W m --2. Independent estimates ranged from --20 to --25 W m--2;The second investigation is a re-analysis of the heat exchange of a volume of warm, dry air as it advected across an irrigated alfalfa field in Arizona. Net heat input of heat from horizontal advection, vertical advection, and horizontal diffusion are compared. Integrated profiles of wind speed, temperature, and water vapor were calculated base on velocity and temperature scales. Horizontal advection is a major contributor to the net heat accumulation, with vertical advection contributing as much as 25%. Horizontal diffusion was found to be negligible. Negative short-term heat fluxes of sensible and latent heat indicated a flux of heat toward the evaporating surface. Results showed reasonable agreement (less than 13% relative error between estimated fluxes of sensible and latent heat and estimated fluxes from five eddy-correlation stations.

DOI

https://doi.org/10.31274/rtd-180813-13756

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Michael Ralph Taber

Language

en

Proquest ID

AAI9950124

File Format

application/pdf

File Size

111 pages

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