THE NEAR-SURFACE LAYER OF THE OCEAN
scale cool skin near the interface and the diurnal warm layer in the upper few
meters of the ocean, which estimate T 0 from T w .
The bulk coefficients C D , C T , C E , and, especially K P , are poorly known for
very high wind speeds. The COARE bulk flux algorithm has been validated
for wind speed ranging from 0 to 20 m s
-1 . There are some indications that
under very high wind speed conditions, starting from 35 or 40 m s
-1 , the bulk
coefficients may no longer be increasing with wind speed (Section 6.4.3).
The effects of sea spray, which are important under high wind speed
conditions, have yet to be satisfactorily quantified. Sea spray enhances
evaporation, influences atmospheric stratification and also transports
momentum. Sea spray effects have been included in a heuristic bulk flux
algorithm (Andreas, 2004) which, however, is not based on any data.
Since many trace gases of practical importance (CO 2 , O 2 , etc.) are almost
infinitely soluble in air, the main difference in gas concentration is on the
waterside of the air-sea interface (Bolin, 1960). The bulk-flux formulation
for air-sea gas exchange is therefore somewhat different from (1.31):
0
0
z
G G
K C
P
o
' ,
(1.44)
18
Figure 1-3. Covariance measurements of the streamwise momentum flux (W x) as a function of
10 m neutral wind speed. The individual points are nominal 1-hour averages. The solid curve
is the COARE 3.0 bulk flux algorithm. Reproduced from Fairall et al. (2003) by permission
of American Meteorological Society.