On the Chemical Climate and its Variation with the Atmospheric Circulation Pattern

Abstract

A study of the chemical composition of monthly precipitation samples from a number of stations in Sweden brings out the existence of significant variations in the relative proportions of chlorides and sodium depending upon the general character of the prevailing circulation. In maritime westerly flows the weight ratio of chloride to sodium decreases eastward to values which lie far below the value characteristic of sea water. In precipitation falling from arctic or polar continental air masses the chloride component is almost completely absent. The highest amounts of chlorides relative to sodium are observed in precipitation from warm and most air masses reaching Sweden from the south or southeast. Significant variations are observed also in the yearly means of the sodium and sulphur deposits depending upon the dominance of maritime or continental air currents. A sketch map of the “average” chloride concentration in European precipitation prepared from miscellaneous older data lends support to the results of the analysis of the monthly data. The separation of the chemical components indicated by this study would seem to be of considerable geochemical interest since it would permit different maritime salts to be deposited in widely separated parts of the continents. It is not inconceivable that a detailed study of the association between different circulation patterns and the corresponding chemical climates might permit us to draw inferences concerning variations in the atmospheric circulation during post-glacial times, e.g. from the data on the chemical stratification in raised bogs now becoming available through the investigations by Mattson and Koutler-Andersson. DOI: 10.1111/j.2153-3490.1955.tb01145.x