1. The University of Toronto’s Balloon-Borne Fourier Transform Spectrometer
Debra Wunch, James R. Drummond, Clive Midwinter, Kimberly Strong
University of Toronto
Hans Fast
Meteorological Service of Canada
Atmospheric Science from Space using Fourier Transform Spectrometry
12th Workshop
Quebec City, May 18-20, 2005

2. Outline Motivation Instrument: The University of Toronto’s FTS Results
MANTRA high-altitude balloon campaign
FTS instruments on MANTRA
Instrument: The University of Toronto’s FTS
History
Preparation for MANTRA
Results
Ground-based
Balloon-based
Conclusions and Future Work
Atmospheric Science from Space using FTS; 12th Workshop, Quebec City, May 18-20, 2005

3. Motivation: MANTRA Middle Atmosphere Nitrogen TRend Assessment
Investigates the changing chemical balance of the mid-latitude stratosphere, with a focus on the role of nitrogen chemistry on the depletion of ozone.
Scientific Objectives
Measurement of profiles of relevant chemical species
O3, NO, NO2, HNO3, HCl, ClONO2, N2O5, CFC-11, CFC-12, OH, H2O, N2O, CH4, J-values for O(1D) and NO2, aerosol, wind, pressure, temperature and humidity
Intercomparison between instruments using different measurement techniques
FTS, grating spectrometers, radiometers and sondes
Solar occultation, emission, in situ
Validation of satellite data
SCISAT: ACE-FTS, MAESTRO
Odin: OSIRIS, SMR
ENVISAT: SCIAMACHY, MIPAS, GOMOS
Atmospheric Science from Space using FTS; 12th Workshop, Quebec City, May 18-20, 2005

4. Motivation: MANTRA High-altitude balloon platform
Float height around 40 km
He-filled balloon
Payload size around 2 m by 2 m by 2 m
Main gondola pointing system
Four campaigns: 1998, 2000, 2002, 2004 in Vanscoy, Saskatchewan (52°N, 107°W)
Launch balloons during late summer stratospheric zonal wind turnaround
photochemical control regime
low winds allow for longer float times
launch window is August 26 – September 5 at 52°N
Atmospheric Science from Space using FTS; 12th Workshop, Quebec City, May 18-20, 2005

5. FTS Instruments on MANTRA
Measure most atmospheric trace gas species simultaneously
DU FTS on 1998, 2002, 2004
University of Denver
30 years of flight heritage
0.02 cm-1 resolution; cm-1 spectral range
PARIS FTS on 2004
Portable Atmospheric Research Interferometric Spectrometer, U. of Waterloo
0.02 cm-1 resolution; cm-1 spectral range
An ACE FTS clone built in 2003/4 as a balloon-borne validation instrument
MSC FTS on 2002, 2004
Occultation mode instruments (solar absorption through sunrise/sunset)
Atmospheric Science from Space using FTS; 12th Workshop, Quebec City, May 18-20, 2005

6. The Role of the MSC FTS on MANTRA
Develop a Canadian capacity for balloon-borne FTS measurements
Compare a well-understood instrument (DU) with new Canadian instruments (MSC, PARIS)
Compare linear Michelson-type FTS with a pendulum-style FTS (PARIS)
Measure HCl, O3, N2O, CO2, CO, etc.
Complement MANTRA’s science goals of measuring ozone depletion and the molecules that contribute to the ozone budget
Ground-based and balloon-based intercomparisons
Compare with ground-based instruments on-site and other balloon-borne instruments
Satellite validation
Atmospheric Science from Space using FTS; 12th Workshop, Quebec City, May 18-20, 2005

7. The MSC FTS: History Bomem DA2 instrument built in the 1980s
Purchased by the Meteorological Service of Canada (MSC)
Built as a ground-based instrument
Upgraded to a DA5 instrument with DA8 electronics (including the dynamic alignment) in the mid-1990s
Obtained by the University of Toronto from the MSC in 2001
0.02 cm-1 resolution; cm-1 spectral range
InSb and MCT detectors that measure simultaneously, CaF2 beamsplitter
Flown on MANTRA 2002 and 2004
MANTRA 2002 flight was an engineering flight
Test of temperatures and voltages
Atmospheric Science from Space using FTS; 12th Workshop, Quebec City, May 18-20, 2005

8. The MSC FTS: History Original Software
Software contained user prompts in the form of “pop-up” boxes
Inaccessible housekeeping information
Control software embedded in hardware (bios)
Original Hardware and Electronics
Dependable dynamic alignment (compensation for motion in moving mirror)
Large electronics box with circa 1990’s electronics boards and power supplies
Power consumption: 140 W
Mass: 90 kg
Atmospheric Science from Space using FTS; 12th Workshop, Quebec City, May 18-20, 2005

9. Tasks in Preparation for MANTRA 2004
Convert the MSC FTS from a ground-based FTS into an instrument that can take ground-based and balloon-based data
Update the software and electronics
Remove pop-up boxes
Use modern technology without compromising performance
Address issue of accurate pointing for solar occultation measurements
Atmospheric Science from Space using FTS; 12th Workshop, Quebec City, May 18-20, 2005

10. Preparation for MANTRA 2004
Re-engineered control of the dynamic alignment system
Almost entirely new electronics
3 boards kept (DA), 7 discarded
Replaced two control computers with one low-power motherboard
Wrote control software in LabVIEW
Controls DA
Includes automated scheduler
No human intervention required
Full uplink and downlink capabilities
Housekeeping
Temperatures, voltages, interferograms
New power supply system
Vicor power supplies
New data acquisition system
USB 16-bit ADC for interferograms
USB 12-bit ADC for housekeeping
Atmospheric Science from Space using FTS; 12th Workshop, Quebec City, May 18-20, 2005

11. Preparation for MANTRA 2004: Results
Mass reduction
Electronics box no longer necessary
All necessary electronics fit into spectrometer box
Mass reduced from ~90kg to ~55kg
Power reduction
Power reduced from ~140W to ~65W due to new electronic components
Improves temperature performance – less power means less heat
Now about half the mass/power of the other two FTS instruments
Atmospheric Science from Space using FTS; 12th Workshop, Quebec City, May 18-20, 2005

12. Preparation for MANTRA 2004: Pointing
Obtained a dedicated sunseeker that tracks the sun within ±10 degrees in zenith and azimuth
Had flown before on other balloon campaigns
No longer dependent on main gondola pointing system
Only dependent on being pointed in general direction of sun
Would still get no data if payload rotated uncontrollably
True for any solar-mode instrument on payload
Atmospheric Science from Space using FTS; 12th Workshop, Quebec City, May 18-20, 2005

13. MANTRA 2004 Ground-based campaign Flight on September 1st at 8:34 am
5 dedicated ground-based instruments
Brewer, grating spectrometers
~43 days of measurements
Flight on September 1st at 8:34 am
Successful launch, followed by loss of commanding to the payload
Pointing system overheated before sunset
Payload began rotating
Two spectra recorded on each detector
Atmospheric Science from Space using FTS; 12th Workshop, Quebec City, May 18-20, 2005

14. MSC FTS Ground-Based Data
Good quality ground-based data
Can resolve CO, CO2, O3, CH4, N2O, HCl, H2O and other molecules
Data acquired during almost every clear-sky opportunity (~10 days)
Can participate in the ground-based campaign
Can compute column amounts of O3, which every other ground-based instrument measures
Atmospheric Science from Space using FTS; 12th Workshop, Quebec City, May 18-20, 2005

15. MSC FTS Ground-Based Data
Atmospheric Science from Space using FTS; 12th Workshop, Quebec City, May 18-20, 2005

16. MSC FTS Flight Data
Two spectra (on each detector) during sunset on the first MANTRA 2004 flight at ~91°
acquired during rotation of payload at sunset
Signal-to-noise ratio reduced
lower SNR attributed to rotation of payload – tracker at ends of its field of view
Resolution reduced
reduced resolution attributed to rotation of payload, temperature, poor alignment before flight?
Can resolve CO, CO2, O3, CH4, N2O, HCl, H2O
should be able to retrieve slant columns
No vertical profile retrievals possible
Atmospheric Science from Space using FTS; 12th Workshop, Quebec City, May 18-20, 2005

17. MSC FTS Flight Data
Atmospheric Science from Space using FTS; 12th Workshop, Quebec City, May 18-20, 2005

18. Conclusions and Future Work
New instrument is improvement over old
Lower power consumption
Lower mass
Robust software
Continued work
Build “delta”-tracker with larger field of view
Improve detector alignment system
Slant column amounts from balloon data
Intercomparisons of ground-based data
Future work
Fly FTS on MANTRA 2006 payload and get data from a full occultation
Atmospheric Science from Space using FTS; 12th Workshop, Quebec City, May 18-20, 2005

19. Acknowledgements
The authors wish to thank Pierre Fogal, John Olson, Tom McElroy, Kaley Walker and the MANTRA 2002 and 2004 science teams.
Funding is provided by the Canadian Space Agency, the Meteorological Service of Canada and NSERC.
Atmospheric Science from Space using FTS; 12th Workshop, Quebec City, May 18-20, 2005