Surface turbulent fluxes over pack ice inferred from TOVS observations

A one-dimensional, atmospheric boundary-layer model is coupled to a thermodynamic ice model to estimate the surface turbulent fluxes over thick sea ice. The principal forcing parameters in this time-dependent model are the air temperature, humidity, and wind speed at a specified level (either at 2 m or at 850 mb) and the down-welling surface radiative fluxes, The free parameters are the air temperature, humidity, and wind-speed profiles below the specified level, the surface skin temperature and ice-temperature profile, and the surface turbulent fluxes. The goal is to determine how well we can estimate the turbulent surface heat and momentum fluxes using forcing parameters from atmospheric temperatures and radiative fluxes retrieved Irom the TlROS-N Operational Vertical Sounder TOVS) data. Meteorological observations from the Lead Experiment (LeadEx, April 1992) ice camp are used to validate turbulent fluxes computed with the surface observations, and the results are used to compare with estimates based on radiosonde observations or with estimates based on TOVS data. We and that the TOVS-based estimates of the stress are significantly more accurate than those found with a constant geostrophic drag coefficient, with a rool mean square error about half as large. This improvement is due to stratification effects included in the boundary-layer model. The errors in the sensible heat flux estimates, however, are large compared Io the small mean values observed during the field experiment.