Contribution to the planning of the station network for measuring the chemical composition of precipitation

The data on the chemical composition of precipitation obtained during the period from 1958 through 1965 at 28 stations situated on the European Territory of the USSR (ETU) are used to calculate correlation functions of Ca··, Na·, SO₄ ion and ion sum concentrations in precipitation and deposition. Correlation distances for various ions are found to be in the range of 90 to 450 km. The mean square random errors in ion composition measurements (35–45%) are estimated using calculated correlation functions. It is shown that the mean station separation of about 100 km gives the error of optimum interpolation to the point for the total ion concentration in precipitation equal to the random error of observations. The optimum averaging of the deposition value over some area can give the same error, 2–3 stations being in the square of 300 times 300 km².