Air-sea exchanges of heat and freshwater plays an important role
in driving the circulations of both the atmosphere and ocean. These
fluxes are parameterised to force numerical models of the ocean and
atmosphere and measurements are essential for validation of coupled
ocean-atmosphere models. Despite their importance these
fluxes are poorly known and the quality of their representation in
models not well quantified. The turbulent fluxes of sensible and
latent (evaporative) heat are difficult to measure directly and
quantitative measurements of precipitation over the ocean from both
rain gauges and remote sensing are notoriously unreliable.
From the limited information available there is little evidence
for major changes in air-sea fluxes of heat and water in regions
around the UK, despite important changes in variables such as sea
temperature on which the fluxes depend. Natural variability is
high, and the confidence in the measurements low, making the signal
to noise ratio unfavourable. The global water cycle is likely to
intensify but the effect of this change within the UK is
uncertain.
Current research which may in time improve our knowledge of the
air-sea fluxes of heat and water includes: planned long time series
of direct flux measurements; improved parameterisations of the
fluxes; bias adjustments of marine meteorological observations used
as input to the parameterisations; and crucially improved
representation of the fluxes in numerical weather prediction and
climate models.
