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*-1 for lakes* 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. © 2012 by the American Geophysical Union.Jordan S. Read, David P. Hamilton, Ankur R. Desai, Kevin C. Rose, Sally MacIntyre, John D. Lenters, Robyn L. Smyth, Paul C. Hanson, Jonathan J. Cole, Peter A. Staehr, James A. Rusak, Donald C. Pierson, Justin D. Brookes, Alo Laas, and Chin H. W

Alo Laas

Amorocho

Ankur R. Desai

Bastviken

Chin H. Wu

Cole

David P. Hamilton

Donald C. Pierson

Downing

Eugster

Huotari

Imberger

James A. Rusak

Jeffery

John D. Lenters

Jonas

Jonathan J. Cole

Jordan S. Read

Justin D. Brookes

Kevin C. Rose

Lamont

MacIntyre

Markfort

McGillis

Paul C. Hanson

Persson

Peter A. Staehr

Read

Robyn L. Smyth

Rutgersson

Sally MacIntyre

Soloviev

Staehr

Tanentzap

Vachon

Verburg

Wanninkhof

Zappa

Geophysical Research Letters

English

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

Read, Jordan S.

Hamilton, David P.

Desai, Ankur R.

Rose, Kevin

MacIntyre, Sally

Lenters, John D.

Smyth, Robyn L.

Hanson, Paul C.

Cole, Jonathan J.

Staehr, Peter A.

Rusak, James A.

Pierson, Donald C.

Brookes, Justin D.

Laas, Alo

Wu, Chin H.

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Crossref

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* &lt; 0.75) for 18 of the 40 lakes, including all 11 lakes &lt;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 &lt;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.Jordan S. Read, David P. Hamilton, Ankur R. Desai, Kevin C. Rose, Sally MacIntyre, John D. Lenters, Robyn L. Smyth, Paul C. Hanson, Jonathan J. Cole, Peter A. Staehr, James A. Rusak, Donald C. Pierson, Justin D. Brookes, Alo Laas, and Chin H. W

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

Abstract

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