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

作者：Read Jordan S^*; Hamilton David P; Desai Ankur R; Rose Kevin C; 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

来源：Geophysical Research Letters, 2012, 39(9): L09405.

DOI：10.1029/2012GL051886

• Gas exchange
• Gas transfer
• High frequency HF
• Relative contribution
• Renewal model
• Seasonal patterns
• Surface mixed layers
• Temporal pattern
• Wind shears

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(*) %26lt; 0.75) for 18 of the 40 lakes, including all 11 lakes %26lt; 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 %26lt; 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. Citation: Read, J. S., et al. (2012), Lake-size dependency of wind shear and convection as controls on gas exchange, Geophys. Res. Lett., 39, L09405, doi:10.1029/2012GL051886.

• 出版日期2012-5-10