Intraseasonal to convective air-sea fluxes in DYNAMO

Surface meteorology and air-sea fluxes over the Indian Ocean were measured aboard the research vessel /Revelle/ over the course of 3 Madden-Julian Oscillation (MJO) convective events in DYNAMO. Sunny calm periods alternated with windy convective periods, the most intense of which coincided with passage of active phases of the MJO.

Gridded flux data sets provide seamless boundary conditions and verification for regional models of intraseasonal variability. Intraseasonal variability in daily gridded air-sea flux products from reanalysis and satellites are shown for 2011 and verified with ship observations during the DYNAMO intensive observation period.

Numerous ~400 m deep cold pools spreading from atmospheric convection are responsible for 1C temperature anomalies and gusts to 140% of the mean wind speed. These conditions temporarily increase the turbulent heat flux out of the ocean. Evaporation increases from 120 to 180 W/m^2, and sensible heat flux increases from 10 to 30 W/m^2. The structure of the cold pools is inferred from hydrostatic pressure and temperature anomalies measured at the surface. Images of their 3D structures are presented from the NOAA high-resolution Doppler lidar. Fine-scale vertical velocities are sampled by the NOAA motion-stabilized Doppler cloud radar in shelf clouds at the leading edge of cold pools passing over the ship.