Publication Date:
2017-04-03
Description:
The long-term evolution of upper stratospheric ozone has been recorded by lidars and
microwave radiometers within the ground-based Network for the Detection of
Stratospheric Change (NDSC), and by the space-borne Solar Backscatter Ultra-Violet
instruments (SBUV), Stratospheric Aerosol and Gas Experiment (SAGE), and Halogen
Occultation Experiment (HALOE). Climatological mean differences between these
instruments are typically smaller than 5% between 25 and 50 km. Ozone anomaly time
series from all instruments, averaged from 35 to 45 km altitude, track each other very
well and typically agree within 3 to 5%. SBUV seems to have a slight positive drift against
the other instruments. The corresponding 1979 to 1999 period from a transient simulation
by the fully coupled MAECHAM4-CHEM chemistry climate model reproduces many
features of the observed anomalies. However, in the upper stratosphere the model shows
too low ozone values and too negative ozone trends, probably due to an underestimation of
methane and a consequent overestimation of ClO. The combination of all observational
data sets provides a very consistent picture, with a long-term stability of 2% or better.
Upper stratospheric ozone shows three main features: (1) a decline by 10 to 15% since
1980, due to chemical destruction by chlorine; (2) two to three year fluctuations by 5 to
10%, due to the Quasi-Biennial Oscillation (QBO); (3) an 11-year oscillation by about
5%, due to the 11-year solar cycle. The 1979 to 1997 ozone trends are larger at the southern
mid-latitude station Lauder (45 S), reaching 8%/decade, compared to only about
6%/decade at Table Mountain (35 N), Haute Provence/Bordeaux ( 45 N), and
Hohenpeissenberg/Bern( 47 N). At Lauder, Hawaii (20 N), Table Mountain, and Haute
Provence, ozone residuals after subtraction of QBO- and solar cycle effects have levelled
off in recent years, or are even increasing. Assuming a turning point in January 1997,
the change of trend is largest at southern mid-latitude Lauder, +11%/decade, compared to
+7%/decade at northern mid-latitudes. This points to a beginning recovery of upper
stratospheric ozone. However, chlorine levels are still very high and ozone will remain
vulnerable. At this point the most northerly mid-latitude station, Hohenpeissenberg/Bern
differs from the other stations, and shows much less clear evidence for a beginning
recovery, with a change of trend in 1997 by only +3%/decade. In fact, record low upper
stratospheric ozone values were observed at Hohenpeissenberg/Bern, and to a lesser degree
at Table Mountain and Haute Provence, in the winters 2003/2004 and 2004/2005.
Description:
Published
Description:
D10308
Description:
open
Keywords:
stratospheric
;
Network
;
01. Atmosphere::01.01. Atmosphere::01.01.02. Climate
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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