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3. Thin ice growth in the area of Szczecin Lagoon 
Knowledge of the ice development and expected ice thickness in a particular water area is of 
high practical value to shipping and offshore engineering. In general, the thickness of the ice 
(h) is a function of a whole series of factors: 
h = f (tp, X, S%o, T, t w , 
v, H’, H s , L, Q, Q’, Q m , Q l , p, x), 
where 
cp and X 
S%c, t w , v 
H’ 
H s 
L 
Q 
Q' 
Qm 
p 
X 
T 
- latitude and longitude of the water area, 
- water salinity, water temperature and flow velocity, 
- depth of water, 
- snow depth, 
- distance from the shore, 
- sun radiation, 
- heat storage of the water, 
- heat flux to atmosphere, 
- density of ice and snow, 
- thermal conductivity of ice and snow, 
- air temperature. 
Theoretically, ice thickness can be derived from an equation describing the heat flux through 
the ice. With respect to the thickness of sea ice, the first equation of this type was set up by 
Stefan in 1891 
h 2 = 2% / Ql p * E ( , E t = J 6dt, where 
/0 
0 is the temperature difference between the top surface of an ice cover and the water below 
the ice cover, Q L is the latent heat released by freezing an additional ice layer, and the integral 
E, is called the freezing exposure and usually quoted in degree-days [Pounder, 1965]. The 
solution was later completed and developed by Subow [1945], Doronin [1963, 1975], Hibler 
[1974] and others. 
To calculate the ice thickness for a particular water area under specific conditions, numerous 
physical characteristics must be known which are practically not available. By simplification 
and use of mean values for relevant characteristics, the theoretical equations attain the form of 
empirical deduced formulas for the description of ice growth, for example: 
h 2 + 50 *h = 8 *Ks [Subow, 1945], 
h = -25 ± ((25 + h 0 ) 2 + 8*K s ) m [Subow, 1945], 
h = -7.7*H S + ((7.7*H S + h 0 ) 2 + 12 *K s ) m [Doronin, 1969,1975]. 
Systematic observations of ice growth have made it possible to establish a relationship 
between ice thickness (h) and the sum of coldness (Ks). This dependence is well described by 
the curve which is most often given by a parabola: 
h = a*(Ks)”, 
where a and n are the characteristic coefficients of the special water area.