Global Assessment Data

An international team of 21 scientists from 14 countries, working under the auspices of the WMO Global Atmosphere Watch Scientific Advisory Group for Precipitation Chemistry, has produced a global assessment of precipitation chemistry and deposition. This assessment appears in a Special Issue of the journal, Atmospheric Environment, Volume 93 (2014), and includes three articles:

(1) Preface by Guest Editors, Robert Vet (Environment Canada), Richard Artz (National Oceanic and Atmospheric Administration), and Silvina Carou (Environment Canada).
(2) Robert Vet, Richard S. Artz, Silvina Carou, Mike Shaw, Chul-Un Ro, Wenche Aas, Alex Baker, Van C. Bowersox, Frank Dentener, Corinne Galy-Lacaux, Amy Hou, Jacobus J. Pienaar, Robert Gillett, M. Cristina Forti, Sergey Gromov, Hiroshi Hara, Tamara Khodzer, Natalie M. Mahowald, Slobodan Nickovic, P.S.P. Rao, and Neville W. Reid. A global assessment of precipitation chemistry and deposition of sulfur, nitrogen, sea salt, base cations, organic acids, acidity and pH, and phosphorus.
(3) Addendum by Vet, et al.

The goal of the assessment was to provide the international science and policy communities with the best available data and information on regionally-representative precipitation chemistry and atmospheric deposition. The information in this publication, together with the supporting data and maps, is an important contribution to the study of atmospheric deposition and to related scientific studies, such as the study of ecosystem impacts, human health effects, nutrient processing, climate change, global and hemispheric modeling, and biogeochemical cycling.

Data used in the assessment included best-available estimates of precipitation concentrations and wet, dry, and total deposition of major ions, sea salt, and phosphorus in North America, South America, Europe, Africa, Asia, Oceania, and the oceans for two periods, 2000-2002 and 2005-2007. Due to the limited contemporary data for phosphorus and organic acids, it was necessary to extend the study period back to the mid-1990s for these species.

In order to fill gaps in the geographic coverage of the measurements, 2000-2002 data were combined with 2001 ensemble-mean results from 21 global chemical transport models. The model results were produced during Phase I of the Coordinated Model Studies Activities of the Task Force on Hemispheric Transport of Air Pollution (Dentener, et al. 2006. Global Biogeochem. Cycles 20, 21. Maps of major ions in precipitation and deposition were generated from the combined measurement and model results.

A major product of the assessment was the preparation of data sets of quality-assured ion concentrations and wet deposition, dry deposition estimates, and model results.