Escherichia coli are rodent bacteria that are usually found in the gastrointestinal tract of warmblooded
organisms. Because of its recognizability, it is used as one of the potential indicators
of contaminated water. We modeled the coefficient K by non-stationary solar radiation over
a period of one day for three different types of weather using a summer and a winter sunny day
and a summer cloudy day. The modeling was performed in Matlab environment, where we considered
data on salinity, temperature, solar radiation, depth and the coefficient of water turbidity.
As a result, we created a four-dimensional matrix containing coefficient K, which depends
on the time, mixed layer depth and location of the bacteria in the horizontal plane.
Furthermore, we compared the obtained results with the results of another master’s thesis
(Lešek, 2018). The difference between the coefficient K within individual layers increases
with depth reaching the discrepancies between 3 and 20 %. Therefore, applying daily averaged
solar radiation gives a too optimistic prediction of the E. coli decay rate.