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Lake-size dependency of wind shear and convection as controls on gas exchange

TitleLake-size dependency of wind shear and convection as controls on gas exchange
Publication TypeJournal Article
Year of Publication2012
AuthorsRead JS, Hamilton DP, Desai AR, Rose KC, MacIntyre S, Lenters JD, Smyth RL, Hanson PC, Cole JJ, Staehr PA, Rusak JA, Pierson DC, Brookes JD, Laas A, Wu CH
JournalGeophysical Research Letters
Date Published05/2012
Keywordsgas exchange, turbulence, wind shear

High-frequency physical observations from 40 temperate lakes were used to examine the relative contributions of wind shear (u*) and convection (w*) to turbulence in the surface mixed layer. Seasonal patterns of u* and w* were dissimilar; u* was often highest in the spring, while w* increased throughout the summer to a maximum in early fall. Convection was a larger mixed-layer turbulence source than wind shear (u*/w* < 0.75) for 18 of the 40 lakes, including all 11 lakes <10 ha. As a consequence, the relative contribution of convection to the gas transfer velocity (k, estimated by the surface renewal model) was greater for small lakes. The average k was 0.54 m day1 for lakes <10 ha. Because u* and w* differ in temporal pattern and magnitude across lakes, both convection and wind shear should be considered in future formulations of lake-air gas exchange, especially for small lakes.


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