[SPARC_list] Spring AGU Special Session on Water Vapor A02

[Natalia Andronova]

Dear Colleagues:

	We invite you to  submit an abstract to a 
Special Session A02 at the Spring AGU/Joint 
Assembly Meeting in Baltimore, Maryland, USA, 
23-26 May, 2006  entitled  “Role of Atmospheric 
Water Vapor for Climate and Atmospheric 
Composition"  (A02).

The deadline for the  abstract submission  is 01 March 2006, at 2359UT.

Please visit 
http://aoss.engin.umich.edu/events/05-06_events/06-JA_NA-JP/ 
to learn more about the session, invited speakers 
of the session and make an on-line  submission.

Also, you can submit an abstract directly at 
http://www.agu.org/meetings/ja06/?content=program.

Please feel free to advertise the session among 
your colleagues to make it more valuable.

A general description of the 2006 Joint Assembly 
is available at 
http://www.agu.org/meetings/ja06/>http://www.agu.org/meetings/ja06/  .


With the best wishes,

Dr. Natalia Andronova
Department of Atmospheric, Oceanic and Space Sciences
University of Michigan
1541D Space Research Building.
2455 Hayward Street
Ann Arbor, MI 48109-2143
Phone: 734-763-5833
Fax: 734-936-0503
Email: natand at umich.edu

Dr. Joyce Penner
Department of Atmospheric, Oceanic and Space Sciences
University of Michigan
1538 Space Research Building
2455 Hayward
Ann Arbor, MI
Phone: 734-936-0519
Fax: 734-936-0503
Email: penner at umich.edu

Dr. Ben Santer
Program for Climate Model Diagnosis and Intercomparison
Lawrence Livermore National Laboratory
P.O. Box 808, Mail Stop L-103
Livermore, CA 94550, U.S.A.
Phone: 925-422-2486
Fax: 925-422-7675
Email: santer1 at llnl.gov


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Since the early 1970's the study of the middle 
atmosphere has focused on understanding the 
variability of its chemical and dynamical states 
as driven by both natural and anthropogenic 
processes. Concurrent with these efforts, studies 
have been carried out to understand both 
short-term and long-term climatic variations that 
occur both naturally and due to the emissions 
and/or alterations of optically active gases by 
humanity. In these areas of study, stratospheric 
and tropospheric ozone (O3) and water vapor (H2O) 
have been of particular interest, as have the 
upward trending halocarbons (HC's), nitrous oxide 
(N2O), methane (CH4), carbon dioxide (CO2), and 
tropospheric and stratospheric aerosols, both of 
natural and anthropogenic origin. While some 
progress has been made in simulating the changing 
atmosphere, a number of observed phenomena remain 
unexplained, among them the reasons for the 
recently observed trends in upper 
tropospheric/lower stratospheric (UT/LS) water 
vapor and temperature.
The distribution, variability, and trends of 
water vapor in the upper troposphere and lower 
stratosphere are important for understanding the 
Earth's climate. Trends in stratospheric water 
vapor may cause a change in the radiative forcing 
of climate. Water vapor is the dominant 
greenhouse gas in the atmosphere, and can also be 
a cooling agent in the middle and upper 
troposphere. Despite the stratosphere's being 
relatively dry, small changes in the 
stratospheric water content can substantially 
alter the stratospheric chemical composition and 
surface climate.
Water vapor is also important for atmospheric 
chemistry. It is the source of the hydroxyl 
radical, OH, which is extremely important for 
many chemical cycles. Reactive hydrogen oxides 
(HOX = OH + HO2), together with reactive odd 
nitrogen (NOX = ON + NO2) take part in regulating 
the production and destruction of ozone. The 
hydroxyl radical is important in many aspects of 
atmospheric chemistry and regulates the lifetimes 
of the longer-lived species such as CH4 in the 
troposphere. Also, water vapor plays an important 
role in atmospheric heterogeneous chemistry, 
defining aerosol effect on climate via formation 
of the stratospheric clouds.
There are three major questions to be addressed in this session:
	1.	What are the influences of the 
atmospheric methane trends, solar variability, 
volcanic eruptions and energetic electron 
precipitation (EEP) on the stratospheric water 
vapor, ozone and surface climate?
	2.	Can these factors be responsible 
for dehydration of the equatorial tropopause 
region and the observed temperature trend in the 
upper troposphere/lower stratosphere?
	3.	Is the stratospheric water budget 
influenced by the observed trends in upper 
tropospheric water vapor?
This session is expected to scope further 
understanding the long-term changes in climate, 
and therefore has important practical benefits to 
society.








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