PSC volume data overview
Here you will find monthly averages of potential PSC volume and a proxy for ozone column based on PSC volume. Temperatures are based on reanalysis data from ECMWF ERA-40 (Uppala et al., 2005) and NCEP (Kistler et al., 2001). If these data are used in scientific publications, please let us know and acknowledge properly. If you have further questions, mail us.
Cautionary note: Use the data at your own risk. There are several issues in the used data sets and the methods used to calculate the PSC volume (for the method, see last paragraph). Some known problems are: Data in high southern latitudes is very unreliable before the introduction of satellite data into the analyses in 1979, notably there is a severe cold bias. There are some temperature issues in ERA-40 data in the 1975/76 and unrealistic temperature oscillations for some of the later ERA-40 years (see Uppala et al., 2005 for both). The trend in water vapor is poorly known (SPARC).
VPSC time series
PSC volume for every time step of the ERA-40 or NCEP reanalysis (every 6 h) and for the northern and southern hemisphere. The file contains the columns "Year", "Month", "Day", "Hour", "PSC I (NAT) volume north", "PSC II (Ice) volume north", "PSC I (NAT) volume south", "PSC II (Ice) volume south". Volume is in 1015 m3.
VPSC ERA-40 with trend in water vapor and nitric acid
VPSC NCEP with trend in water vapor and nitric acid
VPSC proxy
Proxy for use in models of northern hemispheric ozone column. Please use only for monthly or seasonal data (e.g. a time series containing measurements from January 1970, January 1971 and so on). The proxy will not work for data sets that contain all months of the year. The files contain the columns "Year", "Month", "PSC I (NAT) volume". Volume is in 1015 m3. Volumes are integrated in time from the last October preceding the "Month" to the "Month" itself. The proxy is set to zero for October and November, since PSC volumes are very small in this period. Only use for the northern hemisphere.
VPSC proxy ERA-40 north with trend in water vapor and nitric acid
VPSC proxy NCEP north with trend in water vapor and nitric acid
VPSC proxy ERA-40 north without trend in water vapor and nitric acid
VPSC proxy NCEP north without trend in water vapor and nitric acid
The proxy for the southern hemisphere is only available from 1979 on. Volumes are integrated from the last May preceding the "Month" to the month itself. April is set to zero.
VPSC proxy ERA-40 south with trend in water vapor and nitric acid
VPSC proxy NCEP south with trend in water vapor and nitric acid
VPSC proxy ERA-40 south without trend in water vapor and nitric acid
VPSC proxy NCEP south without trend in water vapor and nitric acid
Calculation of PSC volume
PSC volume is calculated by counting all grid points below the formation temperature of NAT or ice north of 60 degrees and weighting them with their volume. In the vertical, the integral is approximated by the trapezoid formula. NAT formation temperatures are calculated according to Hanson and Mauersberger (1988) as a function of nitric acid mixing ratio, water vapor mixing ratio and pressure. Ice formation temperatures (with water vapor saturation pressure over ice) are calculated according to Marti and Mauersberger (1993). A constant water vapor profile of 5 ppm and a nitric acid profile of [5 6 7 8 10 10 7 5] ppb for pressures of [200 150 100 70 50 30 20 10] hPa is assumed. A trend of 10% per decade in water vapor (SPARC) and of 3% decade in nitric acid (IPCC) is assumed for the data sets where it is marked (from 01/2002 backwards from the initial profiles).
References
S. M. Uppala et al. (2005), The ERA-40 reanalysis, Q. J. R. Meteorol. Soc., 131, 2961-3012.
R. E. Kistler et al. (2001), The NCEP-NCAR 50-year reanalysis: Monthly means CD-ROM and documentation, Bull. Amer. Meteorol. Soc., 82, 247-268.
J. T. Houghton et al. (2001), Climate change 2001: The scientific basis. Contribution of working group I to the third assessment report of the Intergovernmental Panel on Climate Change (IPCC), Cambridge University Press.
SPARC assessment of upper tropospheric and stratospheric water vapour, SPARC report no. 2, 2000
J. Marti and K. Mauersberger (1993), A survey and new measurementsof ice vapor pressure at temperatures between 170 K and 250 K, Geophys. Res. Lett., 20, 363-366.
D. Hanson and K. Mauersberger (1988), Laboratory studies of the nitric acid trihydrate: Implications for the south polar stratosphere, Geophys. Res. Lett., 15, 853-858.