Favre and Coantio 



radiative flux (see e.g. Munn [ 1967]). 



This problem has been approached theoretically, using seml- 

 emplrlcal expressions fitted to the emissivlty curves, and assuming 

 logarithmic temperature and humidity profiles. A first approxima- 

 tion of the radiative heat flux divergence is thus obtained analytically, 

 as a function of the surface layer parameters (Coantlc and Seguin 

 [1970]). Numerical values of the infrared flux gradient, dq./dz, 

 in the first ten meters of the marine atmosphere are shown in Fig. 2, 

 for two different wind velocities (A: U|o = 3 m/s; B: U|o = 9 m/s); 

 two sea surface temperatures (cases 1,2: 0q = + 5 C; cases 3,4: 

 9q = + 20 °C); and two temperature differences (cases 1,3: 9|o - 9o = 

 - 5 °C; cases 2,4: 9,0 - 9o = + 1 °C). The resulting vertical vari- 

 ations of the turbulent heat flux, shown by Fig. 3, are seen to attain 

 unexpectedly large values, of the order of 30 to 40%, when wind 

 velocity is low and humidity is high. 



These results are considered as preliminary. If confirmed, 

 they could lead to a relnterpretatlon of some experimented data, 

 and should appeal to an extension of turbulent transfer theories to 

 the case of a variable heat flux. 



Z m 



10 m 



10m 



10cm 



1cm 



+ 0A ^ mw/cm*/m 

 dZ 



Fig. 2. Computed vertical variations of radiative flux divergence 

 for various atmospheric situations 



42 



