Introduction

The ETHmeg database is specifically designed to support CTM and Chemistry-GCM modelling groups in evaluating their (global) models by comparing simulated with observed distributions of the most relevant tracers related to ozone photochemistry.

The database is based on the former "TRADEOFF database", which supported global model evaluation in the European Fifth Framework Program TRADEOFF.

The ETHmeg database contains data from numerous measurement campaigns making use of both scientific and commercial aircraft as observation platforms, ozone soundings, and surface data. These data have been processed in a way that supports an easy and direct comparison with output from a model. During TRADEOFF, the measurements spanned the period 1995 to 1998. The database has now been extended to contain measurements for the period 1966 until 2005.

References:

An evaluation of the performance of chemistry transport models - Part 2: Detailed comparison with two selected campaigns, D. Brunner, J. Staehelin, H. L. Rogers, M. O. Köhler, J. A. Pyle, D. A. Hauglustaine, L. Jourdain, T. K. Berntsen, M. Gauss, I. S. A. Isaksen, E. Meijer, P. van Velthoven, G. Pitari, E. Manzini, V. Grewe, R. Sausen, Atmos. Chem. Phys.,5, 107-129, 2005
Online accessible from Atmospheric Chemistry and Physics

An evaluation of the performance of chemistry transport models by comparison with research aircraft observations. Part 1: Concepts and overall model performance, D. Brunner, J. Staehelin, H. L. Rogers, M. O. Köhler, J. A. Pyle, D. Hauglustaine, L., Jourdain, T. K. Berntsen, M. Gauss, I. S. A. Isaksen. E. Meijer, P. van Velthoven, G. Pitari, E. Mancini, V. Grewe, and R. Sausen, Atmos. Chem. Phys., 3, 1609-1631, 2003
Online accessible from Atmospheric Chemistry and Physics

Why the ETHmeg database?

An excellent collection of aircraft measurements, the GCTM archive, has previously been established by Louisa Emmons, Guy Brasseur and Mary Anne Carroll at NCAR. The data are now available for registered users at the NCAR Community Data Portal. Their database is a "climatology" of tracer data consisting of gridded composites at 5x5 degree horizontal and 1 km vertical resolution, and of vertical profiles. It is most suitable for the comparison with monthly or seasonally averaged model data.

In contrast to this, the ETHmeg database is built upon the "raw" along-flight-path data, averaged over typically 1-min time intervals and merged to a single table per campaign and month. To allow for an easy and direct comparison with observations additional "time and position tables" were created by combining the times and locations of all observations of all campaigns available for a specific month. As demonstrated for instance in the TRADEOFF project, these tables can be used to interpolate at each model time step the simulated tracer concentrations to all observation points available during that time step (e.g., Brunner et al., 2003). In this way model runs can be directly compared to observations taking into account the specific meteorological conditions during each individual measurement campaign. Since for many tracers the overall coverage of measurements in time and space is still poor and data representativity correspondingly low, such a direct comparison offers many advantages over a more climatological approach.

Data sets included

The ETHmeg database contains additional data not (or only partially) included in the GCTM archive including the following:

• Complete set of MOZAIC O3 and H2O data for the period 1995-2003
• CO, CH4 and CO2 measurements from the Japanes JAL project
• CARIBIC CO and ozone measurements up to April 2002
• Stratospheric measurements from ER-2 missions STRAT and POLARIS
• Complete data sets from five STREAM campaigns
• Measurements from several ACSOE campaigns
• Long-term ozone sonde measurements from 1966 to 2005
• Surface measurements from the WDCGG archive
• Complete set of GASP ozone data 1975-79