Monday, 10 February 2003: 4:00 PM
Bulk Parameterization of Air-Sea Fluxes: Updates and Verification for the COARE Algorithm
Direct measurement of air-sea fluxes remains a technological challenge that is practiced
by only a few research groups around the globe. Accurate measurements of fluxes from ships
and buoys in a routine, unattended mode are still not practical. Thus, virtually all estimates of
global or regional fluxes are obtained from bulk flux models, which use more easily obtained
near surface meteorological data. Ultimately, bulk model coefficients must be traced to direct
measurements obtained in very demanding intensive field programs. In the last decade great
progress has been made on several technological fronts to improve the quality of the direct flux
data. Similarly, several theoretical advances in representations of interfacial and boundary-layer
processes has removed earlier pathological problems and linked the parameterizations more
closely to the underlying physics.
In 1996 version 2.5 of the COARE bulk algorithm was published and has become one of
the most frequently used in the air-sea interaction community. In this paper we describe steps
taken to improve the algorithm and a comparison with new data. This new version of the
algorithm (COARE 3.0) was based on published results and 2777 one-hour covariance flux
measurements in the ETL inventory. To test it, we added 4439 new values from field
experiments between 1997 and 1999, which now dominate the database, especially in the wind
speed regime beyond 10 ms-1 where the number of observations increased from 67 to about 800.
After applying various quality controls, the database was used to evaluate the algorithm in
several ways. The average (mean and median) model results agreed with the measurements to
within about 5% for moisture from 0 to 20 ms-1. For stress, the covariance measurements were
about 10% higher than the model at wind speeds over 15 ms-1 while inertial-dissipation
measurements agreed closely at all wind speeds. In the paper we will discuss measurement
issues, how these results compare with classic results from other field programs and models, and
prospects for extending beyond 20 ms-1.
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