Turbulent Transport Mechanism in the Surface Layer over the Tropical Ocean

[摘要] Turbulent flux measurements by the eddy correlation method were performed on board a ship in the tropical western Pacific during the summer MONEX field phase.The turbulent fluxes of momentum, sensible heat, and latent heat were estimated for three different stages, -the disturbed period influenced by the ITCZ, the equatorial doldrums, and the undisturbed period. The average Bowen ratio was 0.068 for the undisturbed period and 0.136 for the disturbed period. The Bowen ratio also varied significantly during the passage of a local convective disturbance.The reduced bulk transfer coefficients were 1.04×10-3 for momentum, 1.50×10-3 for sensible heat, and 0.91×10-3 for latent heat. These bulk transfer coefficients were mostly consistent with other results obtained over the tropical oceans. The drag coefficient was almost constant in the moderate wind speed range (1.50.2, and agreed well with Kaimal's unstable limit for f<0.2. The w spectrum had the expected -2/3 fall-off, and also showed a marked bimodal shape. However, the whole shape agreed approximately with Kaimal's unstable limit. The temperature spectrum had a plateau between 0.2<ƒ<2.0, and agreed well with Kaimal's unstable limit for ƒ<0.2. The humidity spectrum agrees approximately with Kaimal's temperature spectrum, and was similar to the horizontal velocity spectrum.A flatter shape was apparent in the uw cospectrum, and the wT cospectrum exhibited a plateau for 0.2<ƒ<1. The wq cospectrum approximately followed Kaimal's generalized form of the wT cospectrum for f<2.

[学科分类] 大气科学