under a Creative Commons License. Atmospheric Chemistry and Physics Volcanic effects on climate: revisiting the mechanisms
Abstract. The characteristics of planetary wave energy prop-agation are being compared based on NCEP reanalysis data from 1958 to 2002 between boreal winters after strong vol-canic eruptions, non-volcanic winters and episodes of strong polar vortex lasting at least 30 days. It shows that in the vol-...
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| Format: | Text |
| Language: | English |
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2007
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.631.2432 http://www.atmos-chem-phys.org/7/4503/2007/acp-7-4503-2007.pdf |
| Summary: | Abstract. The characteristics of planetary wave energy prop-agation are being compared based on NCEP reanalysis data from 1958 to 2002 between boreal winters after strong vol-canic eruptions, non-volcanic winters and episodes of strong polar vortex lasting at least 30 days. It shows that in the vol-canically disturbed winters much more planetary wave en-ergy is produced in the troposphere, passes through the low-ermost stratosphere and enters the upper stratosphere than in any other times. This is contradicting earlier interpretations and model simulations. Possibly the observed El Ninos coin-ciding with the three significant eruptions in the second half of the 20th century contributed to the planetary wave energy. In order to produce the observed robust climate anomaly pat-terns in the lower troposphere, these planetary waves are sug-gested to be reflected near the stratopause instead of break-ing. While a strong polar vortex is observed after volcanic eruptions in the stratosphere and in the troposphere, specific episodes of strong polar vortex regime exhibit much stronger anomalies and different dynamics. Hence it is suggested that the climate effects of volcanic eruptions are not being ex-plained by the excitation of inherent zonal mean variabil-ity modes such as Strong Polar Vortex or Northern Annular Mode, but rather is another mode that possibly reflects upon the North Atlantic Oscillation. 1 |
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