 |
| Titel |
On the role of hydroxyl radicals in the self-cleansing capacity of the troposphere |
| VerfasserIn |
J. Lelieveld  , F. J. Dentener, W. Peters, M. C. Krol |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 4, no. 9/10 ; Nr. 4, no. 9/10 (2004-11-30), S.2337-2344 |
| Datensatznummer |
250001415
|
| Publikation (Nr.) |
 copernicus.org/acp-4-2337-2004.pdf |
|
|
|
|
|
| Zusammenfassung |
| Thousands of megatons natural and anthropogenic gases are released and
subsequently removed from the troposphere each year. Photochemical
reactions, initiated by hydroxyl (OH) radicals, oxidise most gases to
products which are more easily removed by precipitation and dry deposition
at the earth's surface. Since human-induced pollution emissions strongly
affect OH formation and loss, large global changes in OH concentrations are
possible. Global models and observations of trace gas distributions from
global networks have been used to study geographical and temporal changes in
tropospheric OH. Here we present a synopsis of recent studies, indicating
that global mean OH has changed remarkably little in the past century, even
though regional changes have probably been substantial. Globally, depletion
of OH by reactive carbon gases has been compensated by increased OH
formation by nitrogen oxides, an act of "inadvertent geo-engineering".
However, OH analyses for the past 1-2 decades, partly based on methyl
chloroform measurements, are inconclusive. Some work, assuming that methyl
chloroform emissions have largely ceased, suggests a very strong downward
global OH trend in the 1990s, inconsistent with modelling studies. The
discrepancy could be much reduced by assuming continued small emissions of
methyl chloroform. We recommend the continuation of high precision
monitoring of this compound and improved analyses based on detailed
meteorological-chemical models. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|