Cl. Mcneil et L. Merlivat, THE WARM OCEANIC SURFACE-LAYER - IMPLICATIONS FOR CO2 FLUXES AND SURFACE GAS MEASUREMENTS, Geophysical research letters, 23(24), 1996, pp. 3575-3578
The ocean and air-sea interface are important for the exchange of heat
, momentum, water vapour and carbon-dioxide. The details of the exchan
ge mechanisms, which are often coupled and complex, have to be underst
ood in order to assess the future role of the global oceans in climate
change. Recently; much attention has focused on the 'thermal skin eff
ect', cooling or warming of the uppermost millimeters of the sea Surfa
ce, and its global implications for enhancing CO2 uptake [Robertson an
d Watson, 1992; Van Scoy et al., 1995]. Routinely, air-sea flux estima
tes derived from oceanic pCO(2) measurements are corrected for the usu
ally cooler thermal Skin by applying a correction factor [Sarmiento an
d Sundquist, 1992; Wong et al,, 1995]. Here we describe how near surfa
ce warming of the upper few meters of the ocean by solar radiation, ro
utinely observed but not fully appreciated in this context, can signif
icantly affect the net daily exchange of CO2 over and above the skin e
ffect, and can even lead to a reversal of the direction of the air-sea
flux calculated from pCO(2) measurements and wind speed alone. The wa
rming and cooling cycle produces a net asymmetry between CO2 invasion
and evasion, having the effect of decreasing CO2 invasion:and increasi
ng CO2 evasion.