Intercomparing results of ice nuclei concentration measurements carried out simultaneously using cloud chamber and filter method

Abstract

The application of data on ice nuclei to cloud and climatic models is complicated by the discrepancy between results obtained by different methods used to measure ice nuclei concentration. For field measurements, a filter technique is the most suitable and widely used. However, its peculiarity consisting in activation of ice nuclei on a substrate instead of a cloud makes the results less reliable. A more realistic modeling of cloud conditions is accomplished in cloud chambers. This chapter analyzes the results of simultaneous measurements of ice nuclei (IN) concentration using a cloud chamber and a filter technique. The measurements were conducted in separate series at two measuring sites on the territory of the former USSR during a five-year period. It was found that the agreement between the results obtained by the two techniques depends on the overall pollution of the region and is higher at a site with lower Aitken nuclei concentrations. The results of the two techniques become closer when the atmospheric concentration of more active ice nuclei detected at temperatures of -10° C to -15° C increases. An effort is made to account for the data, proceeding from the peculiarities of IN detection by filter technique.