Martin G' Mlynczak

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ASIC3 Workshop
Far-Infrared Spectroscopy of the Troposphere
FIRST
Martin G. Mlynczak Climate Science Branch NASA
Langley Research Center
16 May 2006
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FIRST Team and Sponsors

• Technology Development and Flight Demonstration
  Team
• Marty Mlynczak NASA Langley
• Dave Johnson NASA Langley
• Charlie Hyde NASA Langley
• Stan Wellard Utah State/SDL
• Gail Bingham Utah State/SDL
• Mike Watson Utah State/SDL
• Harri Latvakoski Utah State/SDL
• Ken Jucks Smithsonian Astrophysical Observatory
  
• Wes Traub Smithsonian Astrophysical Observatory
  
• Jess Landeros JPL
• Jim Margitan JPL
• Bill Stepp Team Columbia Scientific Balloon
  Facility
• Science Advisory Team
• Dave Kratz NASA Langley
• Ping Yang Texas A M University

Sponsors and Supporters NASA Earth Science
Technology Office Ken Anderson George
Komar Carl Wagenfuehrer Brian Killough
(LaRC) NASA Science Mission Directorate Hal
Maring Jack Kaye Mike Kurylo Don
Anderson Phil DeCola
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Far-Infrared Spectroscopy of the Troposphere
Outline

• Science Motivation and Justification for far-IR
• FIRST Sensor Overview
• FIRST Flight Summary and Performance Assessment
• Future plans and directions to spaceflight
• FORGE and RHUBC campaigns
• FIDTAP
• Summary

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Far-Infrared Spectroscopy of the Troposphere
A Brief History of Earth Radiation Budget
Measurements
ERB measurements from space first proposed by V.
Suomi in late 1950s First quantitative
measurement of Earth System from space was ERB in
late 1950s, early 1960s Measurement is of 2
classic energy flows 1. Total Radiation
Emitted Thermal Reflected Solar 2. Reflected
Solar Radiation Emitted thermal radiation
obtained by subtraction of classic energy
flows In the past 40 years these measurements
have been refined in terms of 1. Improved
spatial resolution 2. Improved calibration 3.
Improved angular sampling Two critical
dimensions remain temporal (GERB) and spectral
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Far-Infrared Spectroscopy of the Troposphere
Far-IR
Mid-IR
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Far-Infrared Spectroscopy of the Troposphere
Compelling Science and Applications of the
Far-Infrared

• Up to 50 of OLR (surface atmosphere) is
  beyond 15.4 mm
• Between 50 and 75 of the atmosphere OLR is
  beyond 15.4 mm
• Basic greenhouse effect (50) occurs in the
  far-IR
• Clear sky cooling of the free troposphere occurs
  in the far-IR
• - Potential to derive atmospheric cooling rates
  directly from the radiances
• Upper Tropospheric H2O radiative feedbacks occur
  in far-IR
• Cirrus radiative forcing has a major component
  in the far-IR
• Longwave cloud forcing in tropical deep
  convection occurs in the far-IR
• Improved water vapor sensing is possible by
  combining the far-IR and standard mid-IR
  emission measurements

Direct Observation of Key Atmospheric
Thermodynamics
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Far-Infrared Spectroscopy of the Troposphere
Annual mean TOA fluxes for all sky conditions
from the NCAR CAM
Reference Collins and Mlynczak, Fall AGU, 2001
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Far-Infrared Spectroscopy of the Troposphere
Annual mean TOA fluxes for clear-sky conditions
from the NCAR CAM.
Reference Collins and Mlynczak, Fall AGU, 2001
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Far-Infrared Spectroscopy of the Troposphere
Clear-Sky Spectral Cooling Rate
Far-IR
Mid-IR
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Far-Infrared Spectroscopy of the Troposphere
Unobserved
Observed
Spectrally Integrated Cooling Mid-IR vs. Far-IR
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FIRST Sensitivity to Cirrus Clouds
Brightness temperature difference between two
channels n1250.0 cm-1 and n2559.5 cm-1 as a
function of effective particle size for four
cirrus optical thicknesses
FIRST spectra can be used to derive optical
thickness of thin cirrus clouds (t lt 2).
Reference Yang et al., JGR, 2003
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Far-IR Measurements in our Solar System
Nimbus III/IV, 1969/70
Hanel et al., 2003
Far IR least measured from space on Earth!
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FIRST System Performance Requirements

• At present, no extant sensor in development for
  spaceflight with spectral sensing capability
  longer than 15 mm wavelength
• FIRST developed technology needed to attain daily
  global coverage, from low-earth orbit, of the
  far-infrared spectrum (10 km IFOV from 900 km)
• Spectral coverage 10 to 100 mm (1000 to 100
  cm-1)
• Requires bilayer beamsplitter with gt 92
  efficiency 10-100 mm
• Spectral Resolution 0.625 cm-1 (unapodized), 0.8
  cm OPD
• Scan time 1.4 s
• NEDT 0.2 K (10 to 60 mm) 0.5 K (60 to 100 mm)
• Optical throughput
• Sufficient to meet the NETD requirement for 100
  fields in 1.4 s (10 x 10 array)
• Technology to be demonstrated in space-like
  environment

FIRST Developed under NASAs Instrument Incubator
Program (IIP)
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FIRST Key Technology Requirements

• Instrument Type Fourier Transform Spectrometer
• Gives greatest possible span of wavelengths in a
  single instrument
• Beamsplitter Germanium on polypropylene
• Excellent response in far-IR, minimal absorption
  features
• Detectors with kilohertz sampling frequencies
• To record gt 1000 samples in 1 second from orbit
• Single focal plane
• To simplilfy the optical design and calibration
• Complete system to be deployed on a high altitude
  balloon
• To simulate the space environment

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FIRST Interferometer Block Diagram
Remote Alignment
Tach/Torque motor
Stationary mirror
Beamsplitter
Translating mirror
Carriage Section
Beam Splitter Section
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FIRST Interferometer Cube and Mirror Drive
Assembly
Scene Radiance
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FIRST Interferometer Cube
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FIRST Broad Bandpass Beamsplitter
4 x RT
Example FIRST beamsplitter performance curves
FIRST beamsplitter in mounting ring at USU/SDL
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Sample relative response curves (taken with SAO
FIRS-2)
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FIRST Focal Plane Layout
Performance of Center (1, 10) and corner (4, 5)
detectors will be used to demonstrate that FIRST
has sufficient throughput to meet the NETD
requirement for a 10 x 10 array
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FIRST Balloon Payload System
Interdewar Window
Scatter Filter
Polypropylene Vacuum Window
Aft Optics
Beamsplitter
Scene Select Motor
Interferometer Cube
Remote Alignment Assembly
Passive LN2 Heat Exchanger
Active LN2 Heat Exchanger
LN2 Volume
Scene Select Mirror
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FIRST Scene Select Assembly
Mechanical Limit Switch (3)
Scene Select Mirror Baffle
Optical Encoder
Scene Select Mirror
Bearings
Flex Coupling
Stepper Motor
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FIRST Balloon Payload System
Interferometer Laser Box
Sensor Dewar
In-Flight Blackbody
Dewar Interface Plate
Plumbing / Vacuum Port
Scene Select Assembly
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FIRST Calibration

• FIRST designed with absolute calibration in mind,
  from the start
• Instrument cooled to 180 K to simulate space
  environment and reduce instrument background
• Full field external calibration sources
• Multiple calibration sources (warm, cold) in
  laboratory
• Multiple calibration sources in flight (warm,
  space)
• Spectral range designed to cover 10 15 mm (
  far-IR)
• Allows verification against standard
  instruments, e.g, AIRS, AERI, in mid-IR

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FIRST Space View Simulator

• Provide a cold source for calibration (lt25K)
• Capable of operating while attached to any of the
  three scene select positions
• 2 hour hold time
• Silicon diode temperature detectors

LN2 Tank
LHe Tank
Specular Paint
Diffuse Paint
77-95K Surface
6-12K Surface
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FIRST 300K In-Flight Blackbody
Cone Temperature Sensor
Cylinder Heater
Cone Heater
G-10 Support / Thermal Leak
Baffle
Electrical Connectors
MLI Blanketing
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FIRST on the Flight Line June 7 2005
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FIRST Flight Specifics

• Launched on 11 M cu ft balloon June 7 2005
• Float altitude of 27 km
• Recorded 5.5 hours of data
• 1.2 km footprint of entire FPA 0.2 km footprint
  per detector
• 15,000 interferograms (total) recorded on 10
  detectors
• Overflight of AQUA at 225 pm local time AIRS,
  CERES, MODIS
• Essentially coincident footprints FIRST, AQUA
  instruments
• FIRST met or exceeded technology development
  goals
• FIRST, AIRS, CERES comparisons in window imply
  excellent calibration (better than 1 K agreement
  in skin temperature)

FIRST records complete thermal emission spectrum
of the Earth at high spatial and spectral
resolution
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FIRST First Light Spectrum
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FIRST Spectrum, Center Detector
Mlynczak et al., GRL, 2006
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FIRST Spectrum, Corner Detector
Mlynczak et al., GRL, 2006
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Comparison of AIRS, FIRST in Window Region
Mlynczak et al., GRL, 2006
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FIRST Spectra Compared with L-b-L
SimulationDemonstration of FIRST Recovery of
Spectral Structure
Note FIRST, LbL spectra offset by 0.05 radiance
units
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FIRST Measured, Calculated Radiance
Mlynczak et al., GRL, 2006
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FIRST Spectra Comparisons with L-B-L using AIRS
Retrievals
L-b-L does not yet include FIRST Instrument
Response Functions
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FIRST Performance Assessment

• Project finished on time and within budget
• Spectra on Corner, Center detectors verify
  optical throughput requirement met (0.47 cm2 sr)
• Spectral coverage (50 to 2000 cm-1) verify
  spectral response requirement exceeded
• Calibration appears to be within 1-2 K of 3 NASA
  spaceflight sensors (MODIS, AIRS, CERES)
  calibration met to first order
• In-depth analysis of accuracy, precision, and
  noise underway
• FIRST system now at TRL-6 and ready for science
  flights/campaigns

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FIRST Future Directions

• Confirmation of far-IR calibration
• RHUBC Radiative Heating in Underexplored Bands
  Campaign
• FORGE Far-IR Observations of the Radiative
  Greenhouse Effect
• Zenith view, ground based with multiple
  instruments
• AERI, FIRST, TAFTS (UK)
• Cold, dry conditions at altitude (few km)
• See spectral development in far-IR to 300 cm-1
• See blackbody spectrum at lower wavenumbers
• Derive radiative cooling of mid-troposphere
• Observe far-IR optical properties of cirrus in
  windows
• Validate far-IR water vapor spectroscopy
• Development of Far-IR Radiometric Standards
• FIRST low-temp blackbodies
• Detector development FIDTAP Achieve fast,
  broadband detectors capable of operation at temps
  gt 10 K

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FIRST Simulated Zenith Radiance
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FIRST Simulated Zenith Radiance
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FIRST Status and Summary

• FIRST successfully completed technology
  demonstration flight 6/2005
• Met or exceeded technology goals now at TRL/6
• Combined sounder and radiation budget
  capabilities
• Awaiting opportunity for spaceflight proposal
• Continue to improve calibration and related
  technologies
• Develop improved radiometric standards
• Compare extant far-IR spectral instruments
• Develop remaining technology (detectors)
• Validate cryo-cooler (gt 10 K) technology for
  flight

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FIRST Lands Safely after a Successful Flight
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FIRST Bibliography

• Formal Publications
• Mlynczak, M. G., D. G. Johnson, H. Latvakoski, K.
  Jucks, M. Watson, G. Bingham, D. P. Kratz, W. A.
  Traub, S. J. Wellard, and C. R. Hyde, First light
  from the Far-Infrared Spectroscopy of the
  Troposphere (FIRST) instrument, Geophys. Res.
  Lett., doi10.1029/2005GL025114.
• Conference Proceedings and Presentations through
  Calendar Year 2005
• Mlynczak, M. G., D. G. Johnson, H. Latvakoski, K.
  Jucks, M. Watson, G. Bingham, W. Traub, S.
  Wellard, and C. R. Hyde, FIRST Instrument
  description, performance, and results, Fall
  Meeting, American Geophysical Union, San
  Francisco, CA, paper IN13B-1084, 2005.
• Liu, X., M. G. Mlynczak, D. G. Johnson, D. Kratz,
  H. Latvakoski, and G. Bingham, Atmospheric Remote
  Sensing using FIRST, World Scientific and
  Engineering Academy and Society (WSEAS) Meeting,
  Venice, Italy, 2005.
• Bingham, G.E., H. Latvakoski, S. Wellard, D.
  Garlick, M. Mlynczak, D. Johnson, W. Traub, K.
  Jucks. 2005. Far-infrared spectroscopy of the
  troposphere (FIRST) sensor calibration
  performance. International Symposium on Remote
  Sensing of Environment. St. Petersburg, RU. June
  20 24, 2005.
• M. G. Mlynczak, D. G. Johnson, G. E. Bingham, K.
  W. Jucks, W. A. Traub, L. Gordley, P. Yang, The
  far-infrared spectroscopy of the troposphere
  project, SPIE Fourth International Asia-Pacific
  Environmental Remote Sensing Symposium, Honolulu,
  HI, 2004.
• Kratz, D. P., Mlynczak, M. G., Johnson, D. G.,
  Bingham, G. P., Traub, W. A., Jucks, K., Hyde, C.
  R., Wellard, S., FIRST, The Far-Infrared
  Spectroscopy of the Troposphere Project, Fall AGU
  Meeting, San Francisco, CA Paper SF43A-0782,
  2004.

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FIRST Bibliography

• G. E. Bingham, Harri M. Latvakoski, Stanley J.
  Wellard, MartinG. Mlynczak, David G. Johnson,
  Wesley A. Traub, and Kenneth W. Jucks,
  Far-infrared spectroscopy of the troposphere
  (FIRST) sensor calibration performance. SPIE
  Fourth International Asia-Pacific Environmental
  Remote Sensing Symposium. Multispectral and
  Hyperspectral Remote Sensing Instruments and
  Applications II. Paper 5655-25. Honolulu, HI,
  USA, 2004.
• Bingham, G.E.,, H.M. Latvakoski, S.J. Wellard,
  M.G. Mlynczak, D.G. Johnson, W.A. Traub, and
  K.W. Jucks, Far-infrared spectroscopy of the
  troposphere (FIRST) sensor development and
  performance drivers. Optical Spectroscopic
  Techniques and Instrumentation for Atmospheric
  and Space Research V. International Symposium on
  Optical Science and Technology, SPIE, v. 5157,
  San Diego, CA. August 7-8, 2003.
• Mlynczak, M., D. Johnson, G. Bingham, K. Jucks,
  W. Traub, L. Gordley, and J. Harries, The
  far-infrared spectroscopy of the troposphere
  (FIRST) project, IGARSS 2003, Toulouse, France.
  Invited, July 2003.
• Bingham, G.E., and H. M. Latvakoski, Far Infrared
  Technology Development for Space Surveillance,
  Space Based EO/IR Surveillance Technology
  Conference Kirtland Air Force Base, Albuquerque,
  NM. May 13-15, 2003.
• Bingham, G.E., S.J. Wellard, M.G. Mlynczak, D.G.
  Johnson, W.A. Traub, and K.W. Jucks, Far InfraRed
  Spectroscopy of the Troposphere (FIRST) Sensor
  Concept, Asia-Pacific SPIE 02, Hangzhou, China,
  Paper 4897-23, 2002.
• Mlynczak, M. G., D. Johnson, E. Kist, D. Kratz,
  C. Mertens, and W. Collins, Far-Infrared
  Spectroscopy of the Troposphere, Fall Meeting,
  American Geophysical Union, San Francisco,
  December 2001.
• Collins, W. D., and M. G. Mlynczak, Prospects for
  measurement of far-infrared tropospheric spectra
  Implications for climate modeling, Fall Meeting,
  American Geophysical Union, San Francisco,
  December, 2001.

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FIRST Bibliography

• Mlynczak, M. G., J.E. Harries, R. Rizzi, P. W.
  Stackhouse, D. P. Kratz, D. G. Johnson, C. J.
  Mertens, R. R. Garcia, and B. Soden, The
  far-infrared A frontier in remote sensing of
  Earths climate and energy balance, in Optical
  Spectroscopic Techniques, Remote Sensing, and
  Instrumentation for Atmospheric and Space
  Research IV, Allen M. Larar and Martin G.
  Mlynczak, Editors, Proceedings of SPIE, Vol 4485,
  150-158, 2001.
• Mertens, C. J., Feasibility of retrieving upper
  tropospheric water vapor from observations of
  far-infrared radiation, in Optical Spectroscopic
  Techniques, Remote Sensing, and Instrumentation
  for Atmospheric and Space Research IV, Allen M.
  Larar and Martin G. Mlynczak, Editors,
  Proceedings of SPIE, Vol 4485, 191-201, 2001.
• Kratz, D. P., High resolution modeling of the
  far-infrared, in Optical Spectroscopic
  Techniques, Remote Sensing, and Instrumentation
  for Atmospheric and Space Research IV, Allen M.
  Larar and Martin G. Mlynczak, Editors,
  Proceedings of SPIE, Vol 4485, 171-180, 2001.
• Johnson, D. G., Design of a far-infrared
  spectrometer for atmospheric thermal emission
  measurements, in Optical Spectroscopic
  Techniques, Remote Sensing, and Instrumentation
  for Atmospheric and Space Research IV, Allen M.
  Larar and Martin G. Mlynczak, Editors,
  Proceedings of SPIE, Vol 4485, 220-224, 2001.