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Lake-size dependency of wind shear and convection as controls on gas exchange
Abstract
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 day⁻¹ 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.
Type
Journal Article
Type of thesis
Series
Citation
Read, J. S., Hamilton, D. P., Desai, A. R., Rose, K. C., MacIntyre, S., Lenters, J. D., & Wu, C. H. (2012). Lake-size dependency of wind shear and convection as controls on gas exchange. Geophysical Research Letters, 39(9), L09405.
Date
2012
Publisher
American Geophysical Union (AGU)
Degree
Supervisors
Rights
This article is published in the Geophysical Research Letters. © 2012 American Geophysical Union (AGU).