Midlatitude Synoptic Systems
Midlatitude synoptic systems produce most of the precipitation in
midlatitudes through forced ascent. The cloud structures associated
with these systems are extensive and comprise a rich mixture of
convective, layered, and stratiform types, which have important
effects on the energy and water balances in midlatitudes. Synoptic
systems in midlatitudes are responsible for extreme modifications of
the planetary boundary layer and intense interactions with the
ocean. The combination of EOS instruments with assimilated data
products, models, and in situ data will provide a unique opportunity
to better understand these important weather systems and their role in
climate.
Currently we are working with ERS-1 data to investigate the
usefulness of these data in better defining the surface wind field
variations associated with midlatitude synoptic systems, how these
wind variations affect heat fluxes, and how these surface winds and
fluxes compare with those produced by the current generation of
weather prediction and climate models. We show below the surface
pressure, SSM/I wind speed, and ERS-1 wind vectors associated with a
midlatitude system 
. Next we show the surface winds from the ECMWF
analysis and the surface wind analysis obtained by an
optimal combination of our planetary boundary-layer model winds and
the wind data from ERS-1 . The model and ERS-1 data produce a
much better definition of the shear and convergence near the cold
front and near the low pressure center. These wind differences have a
significant influence on the surface fluxes and on the convection that
is associated with the surface wind convergence along the front and in
the center of the low
and the surface wind analysis obtained by an
optimal combination of our planetary boundary-layer model winds and
the wind data from ERS-1 
. The model and ERS-1 data produce a
much better definition of the shear and convergence near the cold
front and near the low pressure center. These wind differences have a
significant influence on the surface fluxes and on the convection that
is associated with the surface wind convergence along the front and in
the center of the low