HR: 1330h
AN: A42C-0778    [PDF]
TI: The Atmospheric Chemistry Experiment (ACE): Mission Overview
AU: * Bernath, P F
EM: bernath@uwaterloo.ca
AF: University of Waterloo, Dept. of Chemistry 200 University Ave. W, Waterloo, ON N2L 3G1 Canada
AU: Boone, C
EM: cboone@sciborg.uwaterloo.ca
AF: University of Waterloo, Dept. of Chemistry 200 University Ave. W, Waterloo, ON N2L 3G1 Canada
AU: Walker, K
EM: kwalker@uwaterloo.ca
AF: University of Waterloo, Dept. of Chemistry 200 University Ave. W, Waterloo, ON N2L 3G1 Canada
AU: McLeod, S
EM: sdmcleod@acebox.uwaterloo.ca
AF: University of Waterloo, Dept. of Chemistry 200 University Ave. W, Waterloo, ON N2L 3G1 Canada
AU: Nassar, R
EM: rnassar@acebox.uwaterloo.ca
AF: University of Waterloo, Dept. of Chemistry 200 University Ave. W, Waterloo, ON N2L 3G1 Canada
AB: The ACE mission goals are: (1) to measure and to understand the chemical and dynamical processes that control the distribution of ozone in the upper troposphere and stratosphere, with a particular emphasis on the Arctic region; (2) to explore the relationship between atmospheric chemistry and climate change; (3) to study the effects of biomass burning in the free troposphere; (4) to measure aerosol number density, size distribution and composition in order to reduce the uncertainties in their effects on the global energy balance. ACE will make a comprehensive set of simultaneous measurements of trace gases, thin clouds, aerosols, and temperature by solar occultation from a satellite in low earth orbit. A high inclination (74 degrees) low earth orbit (650 km) gives ACE coverage of tropical, mid-latitudes and polar regions. The solar occultation advantages are high sensitivity and self-calibration. A high-resolution (0.02 cm$^{-1}$) infrared Fourier Transform Spectrometer (FTS) operating from 2 to 13 microns (750-4100 cm$^{-1}$) will measure the vertical distribution of trace gases, and the meteorological variables of temperature and pressure. The ACE concept is derived from the now-retired ATMOS FTS instrument, which flew on the Space Shuttle in 1985, 1992, 1993, 1994. Climate-chemistry coupling may lead to the formation of an Arctic ozone hole. ACE will provide high quality data to confront these model predictions and will monitor polar chemistry as chlorine levels decline. The ACE-FTS can measure water vapor and HDO in the tropical tropopause region to study dehydration and strat-trop exchange. The molecular signatures of massive forest fires will evident in the ACE infrared spectra. The CO$_2$ in our spectra can be used to either retrieve atmospheric pressure or (if the instrument pointing knowledge proves to be satisfactory) for an independent retrieval of a CO$_2$ profile for carbon cycle science. Aerosols and clouds will be monitored using the extinction of solar radiation at 0.525 and 1.02 microns as measured by two filtered imagers as well as by their infrared spectra. A dual spectrograph called MAESTRO has been added to the mission to extend the wavelength coverage to the 280-1000 nm spectral region. The broad-band atmospheric extinction measured with high signal-to-noise ratio by MAESTRO is particularly useful for the derivation of aerosol and cloud physical properties. The PI for the MAESTRO instrument is T. McElroy from the Meteorological Service of Canada (MSC). ACE is unique in that MAESTRO, the ACE-FTS and the imagers all share the same suntracker and make simultaneous measurements of the same scene. The FTS and imagers have been built by ABB-Bomem in Quebec City, while the satellite bus has been made by Bristol Aerospace in Winnipeg. ACE was selected in the Canadian Space Agency's SCISAT-1 program, and was successfully launched by NASA on August 12, 2003 for a 2 year mission. The main international partners for ACE are NASA, for the launch and algorithm work at NASA-Langley, and Belgium/ESA, for the CMOS imaging arrays and scientific support.
DE: 0340 Middle atmosphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting