The Laboratory Studies and Modeling Group has two principal foci:
- Laboratory Studies:
This activity involves the use of state-of-the-art experimental techniques to measure kinetic, photochemical and spectroscopic parameters related to elementary atmospheric processes. Rate coefficients, cross sections and quantum yields are measured using methods such as laser photolysis, discharge-flow and steady-state photolysis combined with high-sensitivity detection methods such as molecular beam mass spectrometry, long-path UV-visible-NIR absorption, diode laser wavelength modulation spectroscopy and laser-induced fluorescence.
Particular importance is placed on processes which play important roles in polar ozone depletion, long-term trends in stratospheric ozone at mid-latitudes, the oxidizing potential of the troposphere, and the formation of oxidants in urban and regional environments.
Quantitative spectroscopy is another key focus of the laboratory studies program. Group members use a variety of high resolution spectrometers operating from the microwave through the ultraviolet spectral regions to measure spectroscopic parameters of atmospheric molecules with extremely high precision and accuracy. These parameters are required for the measurement of atmospheric composition and structure by NASA remote sensing instruments for studies in Earth and planetary sciences, astrobiology and astrophysics.
In this area, computer models of atmospheric processes are developed and used to interpret data from field measurements, as prognostic tools to understand long-term changes in climate and composition, and to diagnose elementary processes in atmospheric transport and chemistry.
For tropospheric studies, the group uses a three-dimensional chemical transport model that incorporates winds derived from a weather model. In combination with detailed emission inventories of trace gases, this model has been used to study long-range pollution transport, the effects of biomass burning on global air quality, and the relationships between large-scale weather features and patterns in trace-gas composition. Another important objective is to compare global measurements of trace gases from space with model calculations.
The group also has a strong emphasis on stratospheric modeling. This work focuses on the comparison of aircraft, satellite, balloon and ground-based measurements with model predictions to test the fundamental chemical processes that constrain the budgets of ozone and trace gases in the important lower stratosphere and upper troposphere regions.
People in this Group