ntration 
is nearly 
nonoto- 
nedium con- 
ion - cha- 
(according 
absorption 
nm (curve 
10 nm are 
Jer 
ncentration 
E yellow 
ons of 
ad patterns 
surface 
(Clarke 
Ferme and 
sk (1980)), 
ophyll and 
we have 
| following 
nns corres- 
1 depths, 
n Plg.l. 
is to answer 
^ Sea sur- 
concen- 
ow much 
ubstances?" 
le 1. 
le 1 
ance of 
HF Es Cy 
c(z = 0) 
1-6 c=i.0 
.55 0.63 
,48 || 0.58 
„421 0.51 
„541 0.65 
2563-1 n0. 76 
9104 0.99 
00 1.00 
94 20,88 
79 © 0471 
.58 0.50 
.35 p.29 
27, 0.32 
239% 09109 
19 0.16 
235 0.12 
‚14 0.12 
    
a0 0.0 
Obviously, there exists a very weak dependence of the DR 
values near the water surface on the intensity and location of 
Cmax ; especially in cases of this maximum located in greater 
depths. The DR(z = 0) spectra give us information mainly about the 
subsurface values of the concentration of optically active matters 
in the water. The values of the total amount of these matters for 
sea layers with different thicknesses are shown in Table 2 (com- 
puted by the formula (3)). As a result of comparing the data of 
Table 1 to those of Table 2, we may see that for the cases under 
consideration there exists a good correlation between the DR(z -0) 
and the values of the total amount of admixtures in the layer with 
a thickness about 4-6 m. We may presume that for some other cases 
such a "correlating" subsurface layer may differ in thickness 
depending on. the degree of water purity. However, our main 
conclusion is that for contaminated water bodies (as, e.g., the 
Baltic) on the bases of the DR spectra determined at the sea sur- 
face or by remote measurements the concentration of optically ac- 
tive matters only in the subsurface layer can be estimated. As a 
particular case such estimations are possible for the entire 
euphotic layer if there exists a good correlation between the sur- 
face concentration c(z = 0) and the averaged in the euphotic zone 
concentration. 
Table 2 
The total amount of optically active substances in the 
layers 0-5, 0-10, 0-20 and 0-30 m for the profiles I-IV and for 
the cases c = c(z = 0) 
  
  
  
Thickness of : 
the layer (m) 0-5 0 - 10 P 0 - 20 0 - 30 
Profile I 15.8 20.9 30.8 10.8 
Profile II 13.6 27.3 37.3 47.3 
Profile III 5.0 20.4 40.9 50.9 
Profile IV 5.0 10.0 51.9 61.9 
= 3.25 16.2 32.5 64.9 97.4 
z00.63 8.1 16.3 32.6 48.9 
= 1.03 55.1 10.3 20.6 30.9 
=i] 500 5.0 10.1 20.2 30,3 
  
  
The conclusion that the quantity of backscattered from water 
radiation is mainly influenced by the subsurface layer and the 
contribution of each layer diminishes with the increase of depth, 
has been made previously by Gordon et al. (1975, 1980) and Smith, 
Baker (1978, 1981). In the investigation of Smith (1981) the 
averaged chlorophyll concentration in the euphotic zone is esti- 
mated on the basis of special formula for remote optical measure- 
ments proposed by Gordon. Three cases of typical chlorophyll 
profiles in the ocean are considered. A good correlation is found 
between the values of cc , obtained by the remote measurements 
formula for the euphotic zone and the actually existing averaged 
values. However, there is a remarkably better correlation between 
the "remote" cc and the actual cc(z = 0). and a good correlation 
between the total amount of chlorophyll in the euphotic layer and 
the cc(z 2» 0) too. Thus, the results of the investigation by Smith