Open AccessEvolution of Turbulence in the Diurnal Warm Layer
Author(s) -
Aurélie J. Moulin,
James N. Moum,
Emily L. Shroyer
Publication year - 2018
Publication title -
journal of physical oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.706
H-Index - 143
eISSN - 1520-0485
pISSN - 0022-3670
DOI - 10.1175/jpo-d-17-0170.1
Subject(s) - daytime , turbulence , atmospheric sciences , stratification (seeds) , buoyancy , environmental science , magnitude (astronomy) , climatology , mechanics , physics , geology , astrophysics , germination , botany , dormancy , biology , seed dormancy
The daily evolution of temperature, stratification, and turbulence in the diurnal warm layer is described from time series measurements at low to moderate winds and strong insolation in the equatorial Indian Ocean. At 2.0-m depth, turbulence dissipation rates ( ε ) decreased by two orders of magnitude over 1–2 h immediately after sunrise, initiated by stratification caused by penetrating solar radiation prior to the change in sign of net surface heat flux from cooling to warming. Decaying turbulence preceded a period of rapid growth, in which ε increased by two orders of magnitude over a few hours, and following which ε approached a daytime period of near-steady state. Decay and growth rates predicted by a simplified turbulence model are consistent with those observed. During the daytime period of near-steady state, asymmetric temperature ramps were associated with enhanced ε , supporting the interpretation that this period represents a balance between buoyancy and shear production associated with a shear-driven response to trapping of momentum within the diurnal warm layer.