50 



downstream trade, wind regipn by^mean? of an^airbprne radiometer as 

 to RasoolTs (1964) evaluation of radxation data taken by tne TIROt 



well as 



satellites. 



SENSIBLE AND LATENT HEAT EXCHANGE 



Considering the exchange of sensible and latent heat at the sea surface 

 I think the present situation here is somewhat better than it is in the field 

 of radiation, although it is not entirely satisfactory. The chief aim being 

 to furnish reliable values of the turbulent fluxes of sensible and latent heat 

 between ocean and atmosphere, we must try to derive formulae by means of which 

 these transfer quantities can be calculated with sufficient reliability. It 

 would be particularly welcome if such computations could be done by only using 

 the meteorological elements which are usually n^asured on a routine basis at 

 sea. 



Remarkable success has already been achieved with relatively simple 

 procedures. I am thinking of the so-called "bulk aerodynamice formulae" for 

 the vertical fluxes of sensible and latent heat through the marine boundary 

 layer which have been widely used, among others by Jacobs (1951) for his 

 road-showing study on the climatology of air-sea interaction. However, 

 these formulae are not without any problems . In addition, there are fxmda- 

 mental questions as e.g. the role of the molecular transport at the sea 

 surface, the effect of sea spray, the influence of surface films, which 

 require detailed consideration. 



Let me first give a discussion of the bulk aerodynamic formulae . They 

 are mostly derived in such a way that the ratios of the fluxes H (heat), 

 E( evaporation), and t (momentum) are formed 



H/T = -c (3e'/3z)/Ou/3z) and E/t = -Oq/3z) • (3u/3z) 



P (t) 



(c = spec, heat at constant pressure) which can be obtained by dividing 

 the equations of definition of these fluxes and assuming that the turbulent 

 exchange coefficients for momentum, heat, and moisture are equal. This is 

 already a questionable assumption. Immediately at the sea surface, where 

 molecular transfer comes into play, these exchange coefficients are certainly 

 not equal. Further, the vertical gradients of mean wind speed u, mean 

 potential temperature F and mean _specif ic humidity q are approximated by 

 the vertical differences u, AQ , Aq between these meteorological quantities 

 at a certain height and their values at the sea surface. When doing so we 

 assume that at the sea surface the wind speed is equal to zero and the 

 temperature and moisture of the air are detennined by the temperature of 

 the sea surface (saturation assumed). If finally the wind stress t is 

 replaced by the expression t = pC u ^ we arrive at the bulk 

 aerodynamic formulae ^ ^ 



H = c dC^CF - e" )u and E = pC (q - q )u ^^^ 



pao aa aoaa 



