Total ozone observations prior to the IGY. II: Data and quality

This paper is the second part of a systematic compilation of total ozone observations prior to the International Geophysical Year (IGY), July 1957 to June 1958. The first part provides an overview of the locations, instruments, observers and type of observations. For this second part, 17 data series were selected for further evaluation and quality assessment. We present daily observations from 13 Dobson‐stations in Europe (1952–57), from College, Alaska (1952–54, 1957), New York (1941–44) and Zi‐Ka‐Wei in China (1932–36) as well as monthly mean values for Århus, Denmark (1940–44) and Zi‐Ka‐Wei (1937–42). The data were mostly re‐evaluated using statistical techniques because original instrument readings and calibration information were not available in most cases. The quality was assessed by comparisons with meteorological variables (local 100 hPa temperature and 300 hPa geopotential height) and neighbouring total ozone series. Unreliable values were flagged, and corrections are proposed in some cases. The quality assessment shows that about half of the series can be used for scientific applications. They cannot be used, however, for trend analysis.