SciSat-1, otherwise known as the Atmospheric Chemistry Experiment (ACE), is a Canadian satellite mission for remote sensing of the Earth's atmosphere. It was launched into low Earth orbit (altitude 650 km, inclination 74 degrees) in August 2003. The primary instrument onboard ACE is a high resolution (maximum path difference ± 25 cm) Fourier Transform Spectrometer (FTS) operating from 2.4 to 13.3 microns (750-4100 cm-1). The satellite also features a dual spectrograph known as MAESTRO with wavelength coverage 280-1000 nm and resolution 1-2 nm. A pair of filtered CMOS detector arrays takes images of the sun at 0.525 and 1.02 nm. Working primarily in solar occultation, the satellite provides altitude profile information for temperature, pressure, and the volume mixing ratios for several dozen molecules of atmospheric interest. Scientific goals for ACE include: (1) understanding the chemical and dynamical processes that control the distribution of ozone in the stratosphere and upper troposphere; (2) exploring the relationship between atmospheric chemistry and climate change; (3) studying the effects of biomass burning in the free troposphere; and (4) measuring aerosols to reduce the uncertainties in their effects on the global energy balance.
The Atmospheric Chemistry Experiment (ACE) was launched in August 2003 on board the Canadian scientific satellite SciSat-1. The ACE payload consists of two instruments: ACE-FTS, a high resolution (0.02 cm-1) Fourier transform infrared spectrometer and MAESTRO (Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation), a dual UV-visible-NIR spectrograph. Primarily, the two instruments use a solar occultation technique to make measurements of trace gases, temperature, pressure and atmospheric extinction. It will also be possible to make near-nadir observations with the ACE instruments.
The on-orbit commissioning of the instruments and spacecraft were undertaken in the months following launch. At the end of this period, a series of science-oriented commissioning activities were undertaken. These activities had two aims: the first was to verify and extend the measurement results obtained during the pre-launch Science Calibration Test campaign and the second was to confirm appropriate parameters and establish procedures for operational measurements (occultation and near-nadir observations and exo-atmospheric calibration measurements). One of the most important activities was to determine the relative location of each instrument field of view and optimize the pointing of the sun-tracker to provide the best viewing for both instruments.
SciSat-1, otherwise known as the Atmospheric Chemistry Experiment (ACE), is a Canadian satellite mission for remote sensing of the Earth's atmosphere. It was launched into low Earth orbit (altitude 650 km, inclination 74 degrees) in August 2003. The primary instrument onboard ACE is a high resolution (maximum path difference ± 25 cm) Fourier Transform Spectrometer (FTS) operating from 2.4 to 13.3 microns (750-4100 cm-1). The satellite also features a dual spectrograph known as MAESTRO with wavelength coverage 280-1000 nm and resolution 1-2 nm. A pair of filtered CMOS detector arrays takes images of the sun at 0.525 and 1.02 nm. Working primarily in solar occultation, the satellite provides altitude profile information for temperature, pressure, and the volume mixing ratios for several dozen molecules of atmospheric interest. Scientific goals for ACE include: (1) understanding the chemical and dynamical processes that control the distribution of ozone in the stratosphere and upper troposphere; (2) exploring the relationship between atmospheric chemistry and climate change; (3) studying the effects of biomass burning in the free troposphere; and (4) measuring aerosols to reduce the uncertainties in their effects on the global energy balance.
A novel and simple technique is described for the calibration of satellite instruments for the measurement of atmospheric ozone. Ozone is generated in a gas cell and spectral measurements of the ozone absorption are measured with a standard Fourier-transform spectrometer (FTS) in order to determine the amount of ozone in the cell. The satellite instrument then views the cell using an appropriate illumination source. In this presentation the preliminary results from the ozone calibration procedure are presented for the ACE FTS and MAESTRO instruments to show how consistently both instruments measure ozone. The thermal infrared band of ozone at 4.7 microns was used to provide the calibration of the ACE interferometer, whereas the Chappuis band at 600 nm was used to characterize the response of the MAESTRO instrument. The ozone transmission spectra that were derived from the ACE FTS and MAESTRO spectrograph measurements were found to be in good agreement with the simulated spectra of known amounts of ozone from a radiative transfer model. All of the results yielded column ozone amounts that were within 10% of each other. These calibration measurements were taken at the University of Toronto in March 2003, before the expected launch date of the SciSat-1 satellite in August 2003.
KEYWORDS: Fourier transforms, Sensors, Databases, Signal to noise ratio, Atmospheric modeling, Data modeling, Imaging systems, Molecules, Satellites, Temperature metrology
The SCISAT-1 mission, also known as the Atmospheric Chemistry Experiment (ACE), is a Canadian satellite mission to investigate the chemical and dynamical processes that control the distribution of ozone in the stratosphere and upper troposphere. The satellite is scheduled to launch in August 2003, carrying two main instruments: a high-resolution infrared Fourier transform spectrometer (ACE-FTS) and a dual grating UV-Vis-NIR spectrometer known as MAESTRO (Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation) both operating primarily in solar occultation mode. Aspects of the mission pertaining to work done by ACE science team members from the University of Waterloo will be described, such as: the ACE-FTS forward model for retrieval of temperature, pressure and VMR profiles; ACE-FTS instrument testing and results; and the ACE Database along with data storage and processing hardware.
SciSat-1, otherwise known as the Atmospheric Chemistry Experiment (ACE), is a satellite mission designed for remote sensing of the Earth’s atmosphere using occultation spectroscopy. It has been developed under the auspices of the Canadian Space Agency and is scheduled for launch in August 2003. The suite of instruments on the satellite consists of a high-resolution (25 cm maximum path difference) Fourier Transform Spectrometer (FTS) operating in the infrared (2.4 to 13.3 microns), a UV/Visible Spectrometer operating between 0.285 and 1.03 microns with a resolution of 1 to 2 nm, and a pair of filtered imagers operating at 1.02 and 0.525 microns. The primary science goal of the ACE mission is to investigate the chemical and dynamical processes that govern ozone distribution in the stratosphere and upper troposphere. To this end, vertical profiles for trace gases, aerosols, temperature and pressure will be deduced from analysis of the solar occultation spectra. In particular, the role of heterogeneous reactions on ozone loss will be investigated, with a focus on the Arctic winter stratosphere.
Scisat-1, otherwise known as the Atmospheric Chemistry Experiment, is a satellite mission designed for remote sensing of the Earth's atmosphere using occultation spectroscopy. The primary goal of the mission is to investigate the chemical and dynamical processes that govern ozone distribution in the stratosphere and upper troposphere. It has been developed under the auspices of the Canadian Space Agency and is scheduled for launch in December of 2002. The primary instrument on board Scisat-1 is a high resolution Fourier transform spectrometer (FTS) operating in the infrared. Pressure and temperature as a function of altitude will be determined from the FTS measurements through analysis of carbon dioxide absorption. Volume mixing ratio (vmr) profiles will be retrieved for more than thirty molecules of atmospheric interest. Both the pressure/temperature and vmr retrievals use non-linear least squares Global Fit type approaches. For the pressure/temperature analysis, several variations are being developed; the choice of which version to implement depends on the quality of the pointing information obtained from the satellite. In the case of poor pointing knowledge, tangent height separations between measurements will be determined directly from the FTS data (simultaneously with the pressure and temperature determination) through the imposition of hydrostatic equilibrium.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.