Geophysica, 35(1-2), 71-85, 1999.

Atmospheric Trends Above Finland:
II. Troposphere and Stratosphere

R. Kivi1, E. Kyrö1, T. Turunen1, Th.Ulich2 and E. Turunen2

1Finnish Meteorological Institute, Sodankylä Observatory, Sodankylä, Finland
2Sodankylä Geophysical Observatory, Sodankylä, Finland


Long-term meteorological monitoring activities at Sodankylä (67°N, 26°E) in Northern Finland are discussed. Observed time series of surface temperature, radio soundings, solar radiation, and ozone, are described in more detail and availability of short-term or campaign-based records of other data are summarized. The trends found in the data are discussed and references to earlier analyses on the data sets are given. Data from Jyväskylä and Jokioinen (Finland) are found to agree well with the observed trends in long-term radiosonde data of Sodankylä. The long-term measurements suggest that changes in the atmosphere may occur in a stepwise manner. Here we report enhanced cooling of the lower stratosphere as observed above Finland during the recent decade. For the time period January 1991 until December 1997 the observed cooling according to Sodankylä radiosondes has reached (-0.58 ± 0.11) K/year at 50 hPa, (-0.52 ± 0.14) K/year at 70 hPa, and (-0.45 ± 0.15) K/year at 100 hPa air pressure level. Recent stratospheric cooling has been accompanied by decrease in ozone partial pressure which has reached (-2.2 ± 1.4) %/year at the level of 50 hPa for spring season according to the ozone sonde data of 1988-1997. The annual decrease of ozone in the lower stratosphere layer of 150 hPa to 50 hPa has been (-1.3 ± 0.8) %/year according to the balloonborne ECC sonde data, while the measurements bt Brewer spectrophotometer suggest that total column ozone for the same period has decreased by (-1 ± 0.1) %/year.