Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys
A Research Project Sponsored by NASA
SEAC4RS was an airborne research project based out of Ellington Field near Houston. The study
period consisted of August and September, 2013. Two aircraft were utilized. The NASA DC-8 provided
observations from near the surface to 12 km, and the NASA ER-2 provides high altitude observations
reaching into the lower stratosphere as well as important remote sensing observations connecting
satellites with observations from lower flying aircraft and surface sites. The flight tracks are shown below,
with blue denoting ER-2 flights, and red denoted DC-8 Flights.
The goals of SEAC4RS were:
To determine how pollutant emissions are redistributed via deep convection throughout the troposphere.
To determine the evolution of gases and aerosols in deep convective outflow and the implications for UT/LS chemistry.
To identify the influences and feedbacks of aerosol particles from anthropogenic pollution and biomass burning on
meteorology and climate through changes in the atmospheric heat budget (i.e., semi-direct effect) or through microphysical changes in clouds (i.e., indirect effects).
To serve as a calibration/validation test bed for future satellite instruments and missions.
Attention also was given to the influence of biomass burning and pollution, their temporal evolution,
and ultimately impacts on meteorological processes which in turn feed back into regional air quality. With
respect to meteorological feedbacks, the opportunity to examine the impact of polluting aerosols on cloud
properties and ultimately dynamics will be of particular interest.
The FSU research during SEAC4RS is to perform high resolution simulations of the period using the
Weather Research and Forecast-Chemistry model (WRF-Chem). Our finest resolution grid nest will
explicitly resolve deep convection and will be embedded within two larger scale domains that surround
the convective area. Such detailed simulations have not been reported previously in the literature.
Final model output will be used to help answer the following outstanding research questions about the
upper troposphere/lower stratosphere (UTLS):
Does WRF-Chem adequately reproduce the locations of convection, its areal coverage, and the range of cloud tops that are observed?
Are chemical data acquired by the SEAC4RS aircraft consistent with those simulated by WRF-Chem?
What are the horizontal and vertical paths by which air parcels reach the UTLS? What proportion is due
to convection, and how much is due to other, perhaps slower processes?
How is pollution transported from the main convective outflow layer of ~ 12 km to higher altitudes,
including the lower stratosphere? Does some stratospheric pollution bypass the tropical tropopause entirely?
What are the relative contributions of CO emissions from industrial and transportation sources as well as natural,
agricultural, and household biomass burning to concentrations in the UTLS during SEAC4RS?
What is the role of lightning in creating NOx and ultimately ozone?
What is the role of convective injection in increasing global water vapor content at the cold point tropopause level?
Where are the simulated locations of likely convective injection in the SEAC4RS domain?
How do the simulated locations compare with broad-based MLS observations of CO?