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

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

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

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

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; 700-1300 cm-1 spectral range PARIS FTS on 2004 Portable Atmospheric Research Interferometric Spectrometer, U. of Waterloo 0.02 cm-1 resolution; 750-4100 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

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

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; 1200-5000 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

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

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

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

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

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

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

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

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

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

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

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

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