Results from Tests of Direct Wave Mixing in the Ocean's Surface Mixed Layer

The parameterization of direct wave mixing proposed by Qiao et al. (2004) was tested with data from the Ocean Weathership Station (OWS) Papa in the northeast Pacific and with data from three NOAA buoys, two in the northeast Pacific and one in the northwest Atlantic. Previous testing has indicated that the commonly used Mellor-Yamada-type mixed-layer models tend to underpredict the mixed-layer depth (MLD) in the open ocean. Adding the vertical mixing proposed by Qiao et al. (2004) to the vertical mixing predicted by the Mellor-Yamada Level 2 turbulence model increased the predicted MLD and improved the agreement between the predicted and observed sea-surface temperature (SST) at Papa. However, the results of the tests showed two significant problems with the parameterization of the wave mixing. At OWS Papa, the wave mixing caused too much diffusion of heat through the seasonal thermocline below the mixed layer, and too much diffusion of the thermocline itself. At the NOAA buoys and, less conclusively, at OWS Papa, the wave mixing inhibited the formation of shallow mixed layers and their associated SST spikes during periods of light winds due to the presence of swell. The original document contains color images.