Oltmans, Samuel

Tropospheric Ozone Changes Deduced from Surface and Ozonesonde Observations

Oltmans, S.

NOAA Earth System Research Laboratory, Boulder, Colorado, USA

Lefohn, A.

A.S.L. & Associates, Helena, Montana, USA

Scheel, H.-E.

Forschungzentrum Karlsruhe, IMK-IFU Garmisch-Partenkirchen, Germany

Brunke, E.-G.

South African Weather Service, Stellenbosch, South Africa

Claude, H.

Deutscher Wetterdienst, Observatorium Hohenpeissenberg, Germany

Tarasick, D. and Davies, J.

Environment Canada, Toronto, Canada

Galbally, I. and Meyer, C.

CSIRO, CMAR, Aspendale, Australia

Bodeker, G.

NIWA, Lauder Observatory, Lauder, New Zealand

Cuevas, E. and Redondas, A.

AEMET, Izaña Atmospheric Research Center, Santa Cruz de Tenerife, Spain

Simmonds, P.

School of Chemistry, University of Bristol, Bristol, United Kingdom

Koide, T.

Japan Meteorological Agency, Tokyo, Japan

Schmidlin, F.

NASA, Goddard Space Flight Center, Wallops Island Flight Facility, Virginia, USA

Johnson, B. and Harris, J.

NOAA Earth System Research Laboratory, Boulder, Colorado, USA

Shadwick, D.

320 Eastwood Road, Chapel Hill, North Carolina, USA

Growing recognition of the role of “background” tropospheric ozone on climate forcing and as a boundary condition for air quality changes highlights the importance of obtaining a broad picture of tropospheric ozone changes. Key surface and ozonesonde observing sites with tropospheric ozone measurement records longer than ~15 years have been selected to characterize longer term tropospheric ozone changes over broad geographic regions. The sites chosen vary from those with minimal impact by local ozone pollution sources to those that are in relatively close proximity to ozone precursor emissions and are thus affected in part by these sources. Consideration is given to the extent to which various time series represent broad geographic scales. Some series with more limited geographic representativeness can provide valuable information because of the length of the record, particularly in an underrepresented region. The vertical profile information from the ozonesonde stations, which have some of the longest tropospheric ozone records, provides a unique perspective on ozone in the free troposphere that is much less influenced by more local conditions. Although some overall patterns on changes emerge on regional scales and in some cases on continental scales, more general conclusions on hemispheric and global scales do not emerge. This is likely consistent with the varied pattern of ozone lifetimes, precursor emission changes, and transport regimes that influence tropospheric ozone trends.