 |
| Titel |
Improved SAGE II cloud/aerosol categorization and observations of the Asian tropopause aerosol layer: 1989-2005 |
| VerfasserIn |
L. W. Thomason, J.-P. Vernier |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 13, no. 9 ; Nr. 13, no. 9 (2013-05-03), S.4605-4616 |
| Datensatznummer |
250018629
|
| Publikation (Nr.) |
 copernicus.org/acp-13-4605-2013.pdf |
|
|
|
|
|
| Zusammenfassung |
| We describe the challenges associated with the interpretation of extinction
coefficient measurements by the Stratospheric Aerosol and Gas Experiment
(SAGE II) in the presence of clouds. In particular, we have found that
tropospheric aerosol analyses are highly dependent on a robust method for
identifying when clouds affect the measured extinction coefficient. Herein,
we describe an improved cloud identification method that appears to capture
cloud/aerosol events more effectively than early methods. In addition, we
summarize additional challenges to observing the Asian Tropopause Aerosol
Layer (ATAL) using SAGE II
observations. Using this new approach, we perform analyses of the upper
troposphere, focusing on periods in which the UTLS (upper troposphere/lower
stratosphere) is relatively free of
volcanic material (1989–1990 and after 1996). Of particular interest is the
Asian monsoon anticyclone where CALIPSO (Cloud-Aerosol Lidar Pathfinder Satellite Observations) has observed an
aerosol enhancement. This enhancement, called the ATAL, has a similar morphology to observed enhancements in
long-lived trace gas species like CO. Since the CALIPSO record begins in
2006, the question of how long this aerosol feature has been present
requires a new look at the long-lived SAGE II data sets despite significant
hurdles to its use in the subtropical upper troposphere. We find that there
is no evidence of ATAL in the SAGE II data prior to 1998. After 1998, it is
clear that aerosol in the upper troposphere in the ATAL region is
substantially enhanced relative to the period before that time. In addition,
the data generally supports the presence of the ATAL beginning in 1999
and continuing through the end of the mission, though some years (e.g., 2003)
are complicated by the presence of episodic enhancements most likely of
volcanic origin. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|