Upper Troposphere - Lower Stratosphere

Integrated Studies of Dynamics, Chemistry,
Clouds and Radiation of the
Upper Troposphere and
Lower Stratosphere

UTLS Science Mission Pages:

START-05: Stratosphere-Troposphere Analyses of Regional Transport 2005

START-08: Stratosphere-Troposphere Analyses of Regional Transport 2008

T-REX: Terrain-induced Rotor EXperiment

DC3: Deep Convective Clouds & Chemistry experiment - updated January 2009

Satellite Analysis

Modelling

The overarching goal of this Initiative is to investigate a set of coupled processes in the UTLS region, all of which are known or suspected to affect atmospheric composition and climate. The Initiative synthesizes multi-scale observations from aircraft and satellites and seeks to improve representations of these in regional and global models.

The UTLS is a highly coupled region: dynamics, chemistry, microphysics and radiation are fundamentally interconnected. Water vapor and ozone, perhaps the two most important greenhouse gases in the UTLS, are controlled by both transport processes, such as stratosphere-troposphere exchange, and chemical processes including multiphase chemistry, and cloud microphysics, which in turn are influenced by the temperature and aerosol distributions.

Goals

• To plan and to conduct integrated UTLS studies using the new HIAPER aircraft optimize integration with observations from the NASA A-train satellites and with NCAR multi-scale models.
• To facilitate crosscutting collaboration within NCAR and partnerships with the university community.
• To provide community service and help the build up of HIAPER capability (instrument development and campaign support).

This schematic figure (adapted from Stohl et al. 2003) highlights the important processes coupling dynamics, chemistry and cloud microphysics in the UTLS region. The green line denotes the time average tropopause. In the tropics, maximum outflow from deep convection occurs near ~12-14 km, while the cold point tropopause occurs near 17 km. The intervening region has characteristics intermediate between the troposphere and stratosphere, and is termed the tropical transition layer (TTL). Extratropical stratosphere-troposphere exchange occurs in tropopause folds and intrusions linked with synoptics weater systems; these events transport stratospheric ozone into the troposphere. In addition, convection brings near-surface pollutants (from boimass burning or anthropogenci emissions) into the upper troposphere, strongly influencing global-scale chemistry.