TY - JOUR
T1 - Evaporation from three water bodies of different sizes and climates
T2 - Measurements and scaling analysis
AU - Assouline, S.
AU - Tyler, S. W.
AU - Tanny, J.
AU - Cohen, S.
AU - Bou-Zeid, E.
AU - Parlange, M. B.
AU - Katul, G. G.
N1 - Funding Information:
This research was supported by Mekorot, Ltd. (The Israel National Water Company), the Swiss National Science Foundation, Research Grant No. IS3861-06 from BARD, the United States-Israel Binational Agricultural Research and Development Fund, and the U.S. National Science Foundation Grant (NSF EEC01-39659, NSF-EAR-06-28432, NSF-EAR-06-35787). This support is gratefully acknowledged.
PY - 2008/1
Y1 - 2008/1
N2 - Evaporation from small reservoirs, wetlands, and lakes continues to be a theoretical and practical problem in surface hydrology and micrometeorology because atmospheric flows above such systems can rarely be approximated as stationary and planar-homogeneous with no mean subsidence (hereafter referred to as idealized flow state). Here, the turbulence statistics of temperature (T) and water vapor (q) most pertinent to lake evaporation measurements over three water bodies differing in climate, thermal inertia and degree of advective conditions are explored. The three systems included Lac Léman in Switzerland (high thermal inertia, near homogeneous conditions with no appreciable advection due to long upwind fetch), Eshkol reservoir in Israel (intermediate thermal inertia, frequent strong advective conditions) and Tilopozo wetland in Chile (low thermal inertia, frequent but moderate advection). The data analysis focused on how similarity constants for the flux-variance approach, CT/Cq, and relative transport efficiencies RwT/Rwq, are perturbed from unity with increased advection or the active role of temperature. When advection is small and thermal inertia is large, CT/Cq < 1 (or RwT/Rwq > 1) primarily due to the active role of temperature, which is consistent with a large number of studies conducted over bare soil and vegetated surfaces. However, when advection is significantly large, then CT/Cq > 1 (orRwT/Rwq < 1). When advection is moderate and thermal inertia is low, then CT/Cq ∼ 1. This latter equality, while consistent with Monin-Obukhov similarity theory (MOST), is due to the fact that advection tends to increase CT/Cq above unity while the active role of temperature tends to decrease CT/Cq below unity. A simplified scaling analysis derived from the scalar variance budget equation, explained qualitatively how advection could perturb MOST scaling (assumed to represent the idealized flow state).
AB - Evaporation from small reservoirs, wetlands, and lakes continues to be a theoretical and practical problem in surface hydrology and micrometeorology because atmospheric flows above such systems can rarely be approximated as stationary and planar-homogeneous with no mean subsidence (hereafter referred to as idealized flow state). Here, the turbulence statistics of temperature (T) and water vapor (q) most pertinent to lake evaporation measurements over three water bodies differing in climate, thermal inertia and degree of advective conditions are explored. The three systems included Lac Léman in Switzerland (high thermal inertia, near homogeneous conditions with no appreciable advection due to long upwind fetch), Eshkol reservoir in Israel (intermediate thermal inertia, frequent strong advective conditions) and Tilopozo wetland in Chile (low thermal inertia, frequent but moderate advection). The data analysis focused on how similarity constants for the flux-variance approach, CT/Cq, and relative transport efficiencies RwT/Rwq, are perturbed from unity with increased advection or the active role of temperature. When advection is small and thermal inertia is large, CT/Cq < 1 (or RwT/Rwq > 1) primarily due to the active role of temperature, which is consistent with a large number of studies conducted over bare soil and vegetated surfaces. However, when advection is significantly large, then CT/Cq > 1 (orRwT/Rwq < 1). When advection is moderate and thermal inertia is low, then CT/Cq ∼ 1. This latter equality, while consistent with Monin-Obukhov similarity theory (MOST), is due to the fact that advection tends to increase CT/Cq above unity while the active role of temperature tends to decrease CT/Cq below unity. A simplified scaling analysis derived from the scalar variance budget equation, explained qualitatively how advection could perturb MOST scaling (assumed to represent the idealized flow state).
KW - Advection
KW - Flux-variance method
KW - Lake evaporation
KW - Monin-Obukhov similarity theory
KW - Scalar similarity
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U2 - 10.1016/j.advwatres.2007.07.003
DO - 10.1016/j.advwatres.2007.07.003
M3 - Article
AN - SCOPUS:36048981191
SN - 0309-1708
VL - 31
SP - 160
EP - 172
JO - Advances in Water Resources
JF - Advances in Water Resources
IS - 1
ER -