Long-term trends in laminae in ozone profiles

A very strong negative trend (decrease typically by about 50% over 20-25 years for the period 1970-1995) of the overall ozone content in laminae in ozone profiles was confirmed for all examined stations between 36° and 74°N. Such a strong trend was found in no other parameter in the mid-latitudinal middle atmosphere. However, this negative trend changed to a positive one in the mid-1990s. Cooling of Arctic winters in 1970-1995 and unusually warm Arctic winters in 1997/98-2003/04, which cause lower and higher release of laminae near polar vortex edge, seems to be important (if not dominant) contributor to the change of lamina trend. The Southern Hemisphere displays much less laminae and no evident trend in laminae and its change as the Northern Hemisphere does, very probably due to much more regular high latitude stratospheric circulation with much more stable vortex.

Križan, P., Laštovička, J. (2005): Trends in positive and negative ozone laminae in the Northern Hemisphere. Journal of Geophysical Research, 110, D10107, doi: 10.1029/2004JD005477.
Križan, P., Laštovička, J. (2006): Ozone laminae: Comparison of the Southern and Northern Hemisphere, and tentative explanation of trends. Journal of Atmospheric and Solar-Terrestrial Physics, 68, 1962-1972.

Ozone – effects of geomagnetic storms on total ozone

Data over several solar cycles reveal the existence of geomagnetic storm effects in total ozone only for strong storms, in winter, under high solar activity and E-QBO phase conditions, at 50oN, as a re-distribution leading to large suppression of longitudinal variation of total ozone (neither production, nor loss of ozone). Forbush decreases appear to play an important, if not decisive role in effects of strong geomagnetic storms in total ozone. Such effects of strong storms in total ozone have not been observed in 40-60oS, probably due to different dynamics and resulting much less longitudinal variation of total ozone (not yet published).

Laštovička, J., Križan, P. (2005) Geomagnetic storms, Forbush decreases of cosmic rays and total ozone at northern higher middle latitudes. Journal of Atmospheric and Solar-Terrestrial Physics, 67, 119-124.

Middle atmosphere dynamics – long-term trends

This area of research was re-opened in late 2007 due to point Czech-German project on this topic. A student was hired in January 2008 and is preparing his diploma work on trend sin stratospheric circulation.

Institute of Atmospheric Physics, Department of Aeronomy, 2008