April 26, 2021 Owen R. Cooper Cooperative Institute for Research in Environmental Sciences (CIRES) University of Colorado Boulder/NOAA Chemical Sciences Laboratory Sam Oltmans NOAA/ESRL Global Monitoring Laboratory, Boulder This directory (ftp://aftp.cmdl.noaa.gov/data/ozwv/SurfaceOzone/Historical/) contains historical hourly ozone observations from Mauna Loa Observatory (MLO) and Antarctica, as measured by the United States Government. The data were originally recorded on paper chart recorders and were later digitized by Samuel J. Oltmans, NOAA GML (retired). These historical ozone observations were made with a variety of methods that pre-date the modern UV absorption method. A comprehensive overview of the early measurement techniques, and their biases compared to modern UV absorption methods is provided by TOAR-Observations [Tarasick and Galbally et al., 2019]. These data are archived according to the original reported values and the data have not been corrected for known biases. Before drawing any conclusions from these data the user should carefully consider the measurement method and its uncertainties and biases compared to the modern UV absorption method. As an example of the uncertainties associated with the historical data, a figure (SPO_O3_trend_1975_2017_plus_1960s.png) accompanying this README file compares the historical surface ozone observations at South Pole (1960s) to the continuous ozone record (modern UV absorption method), which began in 1975. MAUNA LOA OBSERVATORY: Ozone was measured at Mauna Loa Observatory over a 2-year period from August, 1957 to July, 1959 [Price and Pales, 1963] using the Regener Automatic instrument, based on the Ehmert technique [Bowen and Regener, 1951]. As discussed by TOAR [Tarasick and Galbally et al., 2019], the Ehmert technique is a wet chemical method that uses a neutral buffered sampling solution containing iodide and thiosulfate. The technique is reliable and compares very well to the UV-absorption method [Tarasick and Galbally et al., 2019]. A comparison of the 1950s observations to the continuous MLO ozone record (1973-2018) is provided by Cooper et al. [2020]. A Mast ozone meter was used to measure ozone at MLO from 1962 to 1966; further details of these measurements are unknown. ANTARCTICA: A Regener Automatic instrument measured ozone at South Pole Observatory (SPO) from February 1961 to July 1963, and these data are also included in this directory [Oltmans and Komhyr, 1976a,b]. Other historical ozone observations from South Pole include: - Regener chemiluminescent observations at South Pole, 1962-1966 [Oltmans and Komhyr, 1976b] - Regener automatic observations at South Pole, 1961-1963 [Oltmans and Komhyr, 1976b] - Mast ozone meter observations at South Pole, 1963-1966 [Oltmans and Komhyr, 1976b] - Carbon-iodine (CI) observations at South Pole, 1967-1969 [Oltmans and Komhyr, 1976b] - Electrochemical concentration cell (ECC) observations at South Pole, 1971-1973 [Oltmans and Komhyr, 1976b] Other historical ozone observations from Antarctica include: - Mast ozone meter observations at Byrd, 1963-1965 [Oltmans and Komhyr, 1976b] - Regener chemiluminescent observations at Byrd, 1963-1965 [Oltmans and Komhyr, 1976b] - Regener chemiluminescent observations at Eights, 1964-1965 [Oltmans and Komhyr, 1976b] - Mast ozone meter observations at Hallett, 1962-1963 [Oltmans and Komhyr, 1976b] - Regener chemiluminescent observations at Hallett, 1962-1963 [Oltmans and Komhyr, 1976b] - Dasibi UV absorption measurements from Palmer, 1982-1984 [Robinson et al., 1984; Howard et al., 1986] References: Cooper, OR, et al. 2020. Multi-decadal surface ozone trends at globally distributed remote locations. Elem Sci Anth, 8: 23. DOI: https://doi.org/10.1525/elementa.420 Bowen, IG and Regener, VH. 1951. On the automatic chemical determination of atmospheric ozone. Journal of Geophysical Research 56(3): 307–324. DOI: https://doi.org/10.1029/JZ056i003p00307 Howard, H.M.; Cronn, D.R.; Bamesberger, W.L.; Menzia, F.A. (1986), Air chemistry monitoring at Palmer Station, Antarctic Journal of the United States, 21, p. 250-251 https://www.coldregions.org/vufind/Content/ajus Oltmans, SJ and Komhyr, WD. 1976a. Air Resources Laboratories. Surface Ozone in Antarctica; NOAA Technical Memorandum, Erl Arl-56; Boulder, Colo: Air Resources Laboratory, Environmental Research Laboratories. Oltmans, SJ and Komhyr, WD. 1976b. Surface ozone in Antarctica. J. Geophys. Res., 81: 5359–5364. DOI: https://doi.org/10.1029/JC081i030p05359 Price, S and Pales, JC. 1963. Mauna Loa Observatory: The first five years. Monthly Weather Review, October–December, 1963. DOI: https://doi.org/10.1175/1520-0493(1963)091%3C0665:MLOTFF%3E2.3.CO;2 Robinson, E., W.L. Bamesberger, F.A. Menzia, A.S. Waylett, and S.F.Waylett. 1984. Atmospheric trace gas measurements at Palmer Station, Antarctica: 1982-1983. Journal of Atmospheric Chemistry, 2, 65-81. Tarasick, D.W., and I.E. Galbally et al. (2019), Tropospheric Ozone Assessment Report: Tropospheric ozone from 1877 to 2016, observed levels, trends and uncertainties. Elem Sci Anth., 7(1). DOI: https://doi.org/10.1525/elementa.376