Ecoinformatics Problems of the World Ocean - New Ecoinformatics Tools in Environmental Science: Applications and Decision-making - page 268

where the index refers to the pre-industrial period. However, numerous

observations show that the use of only this coef

“ o ”

uxes
H 2 and H 3 (Fig. 1.30 and Table 1.10 ) gives rough estimates, without taking into
account the effect of many factors.
One of the

cient when calculating the fl

first attempts to consider the spatial heterogeneity of the World Ocean
and to simulate the impact of temperature gradients on the CO 2 exchange between
the upper layer of the ocean and the atmosphere has been made by Bjorkstrom
(1979). An idea to divide the World Ocean basins into two parts corresponding to
warm and cold waters has been later developed by numerous authors (Nefedova
and Tarko 1993). Pervaniuk (2001) developed this scheme dividing the World
Ocean surface into 211 homogeneous basins. This discretization was based on
combining the basins 4 o 5 o in size. The adjacent cells of this grid with similar

directions of the vertical components of the water

×

fl flow velocities are combined into

one water basin. The average annual flow velocities was con-

sidered at a depth of 75 m. The size of water basins was determined taking into
account the dependence of CO 2 fl

field of the water fl

fluxes on the climatic factors. A maximum of the
latitudinal size of the basin was assumed to be 8 o . Above 80 o N the World Ocean is
presented as one site.
A most complete study of the physical mechanisms of the CO 2 transport under
different conditions of the water-air interface has been carried out in Alexeev et al.
(1992). Here for the uxes have been

made, and their dependence on the parameters of the state of the atmosphere-ocean
interface has been analyzed, taking into account the wind-driven mixing, the
appearance of foam on the water surface, waves breaking, and pollution. Parametric
descriptions of the process of the ocean-atmosphere gas exchange have been pro-
posed for each type of the water-air interface conditions (McGillis et al. 2001). For
instance, it was shown that the intensity of gas exchange grows substantially as the
sea roughness and foam layer increase. For a foam layer 5 cm thick, the rate of gas
exchange exceeds the gas exchange across a free surface by a factor of 2.4. This fact
is important for the evaluation of the gas exchange in the tidal zones and strong-
storm regions, where the foam stretches may be several cm thick. The result con-
nected with the availability of the surface active substances (SASs) in the upper
layer of the ocean is also very interesting. When SASs reach about 7.8

first time, detailed measurements of CO 2 fl

10 − 4 %
(volume), other conditions being equal, the rate of gas exchange reduces to 60 %.
However, where there is foam formation this effect decreases substantially.
On the whole, over the World Ocean basins the estimates of the CO 2 fl

×

ux
between the atmosphere and the upper layer of the ocean vary between 16 and
1,250 mol/m 2 /year). This variability means that the global model of the CO 2 bio-
geochemical cycle should accurately consider every feature mentioned.
In a stationary state the hydrosphere and atmosphere are in a certain equilibrium
with respect to CO 2 exchange, being broken with fluctuations of temperature, ocean

surface level, vertical circulation regime, etc. An amount of CO 2 assimilated and
emitted in the process of exchange between the ocean and the atmosphere consti-
tutes 55.6

fl

10 9 10 9 × tC/year. The algae assimilate 16.7 × tC/year from the