Diurnal ocean surface warming drives convective turbulence and clouds in
Sunlight warms sea surface temperature (SST) under calm winds,
increasing atmospheric surface buoyancy flux, turbulence, and mixed
layer depth in the afternoon. The diurnal range of SST exceeded 1 °C for
24% of days in the central tropical Indian Ocean during the Dynamics of
the Madden Julian Oscillation experiment in October-December 2011.
Doppler lidar shows enhancement of the strength and height of convective
turbulence in the atmospheric mixed layer over warm SST in the
afternoon. The turbulent kinetic energy dissipation of the marine
atmospheric mixed layer scales with surface buoyancy flux like previous
measurements of convective mixed layers. The time of enhanced mixed
layer dissipation is out of phase with the buoyancy flux generated by
nocturnal net radiative cooling of the atmosphere. Diurnal atmospheric
convective turbulence over the ocean mixes moisture from the ocean to
the lifting condensation level and forms afternoon clouds.