1. On the relationship between total ozone and atmospheric dynamics and chemistry at mid-latitudes: Part 2 — The effects of the El Nino/Southern Oscillation, volcanic eruptions and contributions of atmo
- Author
-
Rieder H. E., Frossard L., Ribatet M., Staehelin J., Maeder J. A., Rocco S. D., Davison A. C., and Peter T.
- Abstract
We present the first spatial analysis of "fingerprints" of the El Niño/Southern Oscillation (ENSO) and atmospheric aerosol load after major volcanic eruptions (El Chichón and Mt. Pinatubo) in extreme low and high (termed ELOs and EHOs respectively) and mean values of total ozone for the northern and southern mid latitudes (defined as the region between 30° and 60° north and south respectively). Significant influence on ozone extremes was found for the warm ENSO phase in both hemispheres during spring especially towards low latitudes indicating the enhanced ozone transport from the tropics to the extra tropics. Further the results confirm findings of recent work on the connection between the ENSO phase and the strength and extent of the southern ozone "collar". For the volcanic eruptions the analysis confirms findings of earlier studies for the northern mid latitudes and gives new insights for the Southern Hemisphere. The results provide evidence that the negative effect of the eruption of El Chichón might be partly compensated by a strong warm ENSO phase in 1982–1983 at southern mid latitudes. The strong west east gradient in the coefficient estimates for the Mt. Pinatubo eruption and the analysis of the relationship between the AAO and ENSO phase the extent and the position of the southern ozone "collar" and the polar vortex structure provide clear evidence for a dynamical "masking" of the volcanic signal at southern mid latitudes. The paper also analyses the contribution of atmospheric dynamics and chemistry to long term total ozone changes. Here quite heterogeneous results have been found on spatial scales. In general the results show that EESC and the 11 yr solar cycle can be identified as major contributors to long term ozone changes. However a strong contribution of dynamical features (El Niño/Southern Oscillation (ENSO) North Atlantic Oscillation (NAO) Antarctic Oscillation (AAO) Quasi Biennial Oscillation (QBO)) to ozone variability and trends is found at a regional level. For the QBO (at 30 and 50 hPa) strong influence on total ozone variability and trends is found over large parts of the northern and southern mid latitudes especially towards equatorial latitudes. Strong influence of ENSO is found over the Northern and Southern Pacific Central Europe and central southern mid latitudes. For the NAO strong influence on column ozone is found over Labrador/Greenland the Eastern United States the Euro Atlantic Sector and Central Europe. For the NAO's southern counterpart the AAO strong influence on ozone variability and long term changes is found at lower southern mid latitudes including the southern parts of South America and the Antarctic Peninsula and central southern mid latitudes.
- Published
- 2013
- Full Text
- View/download PDF