 |
| Titel |
HONO/NOx ratio as a tool for the estimation of HONO levels in global models: Field Measurements Comparison and Global Impact |
| VerfasserIn |
Y. F. Elshorbany, B. Steil, J. Lelieveld  |
| Konferenz |
EGU General Assembly 2012
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250068957
|
|
|
|
|
|
| Zusammenfassung |
| The contribution of HONO photolysis to the radical budgets and ozone photochemical
formation has been under increasing scrutiny in the last decades. However, owing to the
so fare incomplete knowledge of HONO daytime sources, models significantly
underestimate HONO levels. Previous studies showed that HONO/NOx ratio is a
reasonable measure of HONO levels and that a strong unknown HONO daytime source
can be revealed from the high HONO/NOx ratios obtained in these studies during
afternoon. In this study, several data sets of different filed measurement campaigns
distributed all over the globe which encountered a wide variety of atmospheric
conditions within the last decade were investigated. From these studies, a median global
HONO/NOx ratio were calculated, which were found to reasonably simulate the measured
HONO levels based on the measured NOx levels, both on the ground and in gradient
measurements studies. Using a 3D chemistry-climate global model and applying an
iterative correction of the simulated HONO/NOx to reach the derived global value of
HONO/NOx ratio, much reasonable HONO levels were also obtained, in comparison to the
default case, which considers only the reaction of OH+NO=HONO as the sole
source of HONO, which significantly underestimate HONO levels. The increase of
HONO levels as a result of employing this global HONO/NOx ratio was found to
have a significant impact on HOx (OH+HO2) and also on the secondary oxidation
products (e.g, O3, PAN) only in high NOx polluted regions. The impact of using these
realistic HONO levels on aerosol formation in global models will be also discussed. |
|
|
|
|
|
|