A Lagrangian analysis of stratospheric ozone variability and long‐term trends above Payerne (Switzerland) during 1970–2001

[1] A systematic Lagrangian investigation is performed of wintertime high-resolution stratospheric ozone soundings at Payerne, Switzerland, from January 1970 to March 2001. During the winter season, ozone variability is largest in the lower stratosphere (p > 120 hPa) where the trend is not statistically significant (on the 95%-level) considering the whole time period. A significant negative trend (−5% per decade) exists only above this level. For every ozone sounding, 10-day backward trajectories have been calculated on 16 isentropic levels using NCEP reanalysis data. Both the minimum/maximum latitude and potential vorticity (PV) averaged along the trajectories are used as indicators of the air parcels' “origin.” A detailed case study of an ozone minihole (198 Dobson units; 1 DU = 0.001 atm cm) in November 2000 reveals that this extreme event was due to the concurrent transport to central Europe of subtropical air in the lowermost stratosphere (where the climatological ozone gradient points to the north) and of polar air in the lower to middle stratosphere (where the ozone gradient is reversed). The importance of transport for the understanding of single ozone profiles is confirmed by the statistical analysis which shows that negative/positive ozone deviations generally coincide with transport from regions with climatologically low/high ozone values. Some important differences arise when considering the layers from 340–440 K and 460–700 K separately. In the lower layer the frequency of transport from the subtropics has increased since 1970 which leads to a (statistically not significant) ozone decrease. The stable relationship between PV and ozone for the 32-year period indicates either no direct chemical impact or no temporal change of this impact. In the upper layer the PV-ozone relationship changes significantly after 1987, and a separate trend analysis for air masses transported from the polar, midlatitude and subtropical regions shows negative ozone trends in all three categories (with a maximum for the polar region). This is not direct evidence for, but would be in agreement with, an increased chemical ozone depletion in the Arctic since the late 1980s. The reasons for the negative trend in the midstratospheric air masses with subtropical origin that are in qualitative agreement with recent satellite observations are presently unknown.

[1]  G. Kiladis,et al.  Erratum: ``On the changing abundance of ozone minima at northern midlatitudes'' , 2000 .

[2]  A. J. Miller,et al.  Upper‐stratospheric ozone trends 1979–1998 , 2000 .

[3]  E. Reimer,et al.  A Study of Ozone Laminae Using Diabatic Trajectories, Contour Advection and Photochemical Trajectory Model Simulations. , 1998 .

[4]  J. McCormack,et al.  An investigation of dynamical contributions to midlatitude ozone trends in winter , 1997 .

[5]  H. Dütsch,et al.  Vertical ozone distribution on a global scale , 1978 .

[6]  Wolfgang Steinbrecht,et al.  Correlations between tropopause height and total ozone: Implications for long‐term changes , 1998 .

[7]  Johannes Staehelin,et al.  North Atlantic Oscillation modulates total ozone winter trends , 2000 .

[8]  M. Fromm,et al.  Origin of extreme ozone minima at middle to high , 2001 .

[9]  W. Lahoz,et al.  Evidence for a substantial role for dilution in northern mid‐latitude ozone depletion , 1998 .

[10]  J. Staehelin,et al.  Chemical and dynamical contributions to ozone profile trends of the Payerne (Switzerland) balloon soundings , 2001 .

[11]  Johannes Staehelin,et al.  Trend analysis of the homogenized total ozone series of Arosa (Switzerland), 1926–1996 , 1998 .

[12]  R. Barry,et al.  Intraseasonal variation in the thermoinsulation effect of snow cover on soil temperatures and energy balance , 2002 .

[13]  Dimitris Balis,et al.  Characteristics of episodes with extremely low ozone values in the northern middle latitudes 1957?2000 , 2001 .

[14]  G. Vaughan,et al.  Transport of near‐tropopause air into the lower midlatitude stratosphere , 1998 .

[15]  R. Garcia,et al.  The role of aerosol variations in anthropogenic ozone depletion at northern midlatitudes , 1996 .

[16]  B. Connor,et al.  The global mass of ozone: 1978–1998 , 2001 .

[17]  Heini Wernli,et al.  Midstratospheric ozone variability over Bern related to planetary wave activity during the winters 1994–1995 to 1998–1999 , 2001 .

[18]  J. Staehelin,et al.  Ozone trends: A review , 2001 .

[19]  S. Solomon,et al.  Rethinking reactive halogen budgets in the midlatitude lower stratosphere , 1999 .

[20]  Interannual changes of total ozone and northern hemisphere circulation patterns , 2001 .

[21]  Heini Wernli,et al.  A Lagrangian‐based analysis of extratropical cyclones. I: The method and some applications , 1997 .

[22]  J. Grooß,et al.  Northern midlatitude stratospheric ozone dilution in spring modeled with simulated mixing , 2000 .

[23]  Measurements of the Amount of Ozone in the Earth's Atmosphere and Its Relation to Other Geophysical Conditions. Part II , 1926 .

[24]  Seasonal acceleration of the rate of total ozone decreases over Central Europe: impact of tropopause height changes , 1998 .

[25]  H. Kelder,et al.  An ozone climatology based on ozonesonde and satellite measurements , 1998 .

[26]  Randel,et al.  Trends in the vertical distribution of ozone , 1999, Science.

[27]  E. Remsberg,et al.  Ozone changes in the lower stratosphere from the Halogen Occultation Experiment for 1991 through 1999 , 2001 .

[28]  H. Claude,et al.  On the correlation between tropopause pressure and ozone above central Europe , 1996 .

[29]  P. James,et al.  The Lagrangian structure of ozone mini-holes and potential vorticity anomalies in the Northern Hemisphere , 2002 .