From natand at umich.edu Tue Jan 31 06:25:11 2006 From: natand at umich.edu (Natalia Andronova) Date: Tue, 31 Jan 2006 09:25:11 -0500 Subject: [SPARC_list] Spring AGU Special Session on Water Vapor A02 Message-ID: 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 ------------------------------------ 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. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.nwra.com/pipermail/sparc_list/attachments/20060131/269d828c/attachment.html