Airborne Compact Atmospheric Mapper (ACAM)

Drs. Scott J. Janz (PI) and Paul A. Newman (Co-I)
Code 613.3 - Atmospheric Chemistry and Dynamics Branch
Laboratory for Atmospheres
NASA's Goddard Space Flight Center
Greenbelt, MD 20771

Janz phone: 301-614-5987
Newman phone: 301-614-5985
fax: 301-614-5903

• Provide cloud and surface information for AURA satellite instruments and instruments on the NASA WB-57F.
• Determine whether these miniature spectrograph systems are stable enough and have sufficient S/N to perform trace gas retrievals of NO2 for validation, and if so determine the minimum measurable slant-column concentration for a given spatial resolution element.
• Determine whether we can calibrate the spectrographs and maintain the calibration sufficiently to enable absolute radiance transfers with satellite instruments (e.g., OMI) at the sub-5% accuracy level.
• Make remote sensing observations of tropospheric pollutants: O3, NO2, SO2, BrO, CHCO and aerosols

Cockpit: Forward viewing

• Camera: Nikon 8700
  • Digital camera (3,264 x 2,448 pixels) preprogrammed to shoot 1 frame every minute. Has 10X optical zoom.
  • The camera's purpose is to give a forward view of vertical and lateral cloud structure

Wing Hatch: Nadir viewing

• Camera: Nikon 8800
  • Digital camera (3,264 x 2,448 pixels)preprogrammed to shoot 1 frame every 35 seconds. Has 10X optical zoom and vibration reduction.
  • The camera's purpose is to give a nadir view of horizontal cloud structure and to aid in surface type identification.
• Ocean optics spectrograph 1: 290-370 nm coverage, 1 nm spectral resolution
• Ocean optics spectrograph 2: 350-556 nm coverage, 1 nm spectral resolution
  • The spectrographs share a common fiber optic feed to a collimator which will image a circular FOV of ~1.5 km diameter from an altitude of 18 km. This FOV can be scanned via a small mirror mounted on a galvanometer up to angles of ±40 degrees. The Nikon will be synchronized with the scanner such that a pre-programmed number of cross-track scans can be performed in between every Nikon image.
  • The spectrographs cover wavelengths of interest for trace gas retrievals of O3, NO2, SO2, BrO, CHCO and aerosols

ACAM has been designed for mounting on the NASA JSC WB-57F aircraft. The forward viewing Nikon camera is mounted on a bracket on the cockpit's dashboard looking directly forward. The nadir viewing camera and spectrometers are mounted in an enclosure that sits on a hatch up inside the wing (a wing hatch).

ACAM nadir measures the UV/Vis spectra in a "scan pattern" that is timed with the photographs from the Nikon camera. As the plane flies along, a small mirror rotates around giving views of various points from the left-to-right along the aircraft's flight direction.

The dotted line shows the edges of camera's image, while the circles show the areas of the UV/Vis spectra. As the mirror steps from point-to-point, a single left-to-right scan takes 7.5 seconds, and the plane moves 1500 meters. The tilt of the scans occurs because of the plane's movement.

• Aura Validation Experiment (June 2005), Houston, TX.

  Raw and reduced resolution ACAM images can be found at the Aura Validation Data Center (AVDC). A log-in account is required to access the images.

  ACAM imagery has been formulated into H.264 quicktime movies for rapid scanning of imagery from this flight series.

  If you have problems viewing the movies, download the new version of QuickTime: QuickTime 7 for Mac download or QuickTime 7 for Windows download

  • 2005-06-09: a few images, Nadir view fogging, Forward view failed
  • 2005-06-11: Tropical cyclone Arlene, Nadir view fogging, Forward View (1.2M)
  • 2005-06-13: Nadir View (1.7M), Forward View (1.0M),
  • 2005-06-15: Nadir View (4.6M), Forward View failed.
  • 2005-06-17: Nadir View (5.6M), Forward View failed.
  • 2005-06-19: Nadir View (2.9M), Forward View (1.1M)
  • 2005-06-21: Nadir View (1.8M), Forward View (0.9M),
  • 2005-06-22: Nadir View (3.2M), Forward View (0.9M),
  • 2005-06-24: Nadir View (2.7M), Forward View failed.

The building of ACAM resulted from a need by the AURA satellite instruments for cloud imagery during the AVE campaign. The solution was to mount a simple digital camera in a wing hatch, but this gave us the opportunity to add the spectrometers with the camera. ACAM has been inexpensively constructed with the assistance of P. K. Bhartia and the OMI group, Scott Janz, and Paul Newman. Bob Frederickson of SWALES did the mechanical design, Tom Riley of NASA did the electrical design, and Kent McCullough of SSAI has built the instrument in the lab. Paul Newman is not allowed to touch anything.

View of the ACAM mounting plate with Kent McCullough of GSFC installing the electronics (May 17, 2005).

Top view of the ACAM nadir-view instrument without wing hatch or enclosure. Nikon 8800 camera is not installed (May 17, 2005).

Bottom view of ACAM nadir-view instrument without wing hatch or enclosure. Nikon 8800 camera lens is in the left middle, spectrometers are the silver squares in the bottom right middle. The two spectrometers are stacked atop one another (May 24, 2005).

Scott Janz (ACAM PI) tests ACAM in the lab (May 24, 2005).

Kent McCullough displays the kevlar blanket enclosure that will cover ACAM. ACAM is on the bench to Kent's right. The enclosure has velcro tabs that allow for easy removal. The enclosure was sewn together by Reed McCullough of Reed McCullough Reupolstery (Rockville, MD) (May 31, 2005).

Bob Frederickson inspects ACAM and the top of its enclosure (the aluminum box)(May 31, 2005).

Scott Janz does a pressure check of the ACAM enclosure (June 2, 2005).

• Scott Janz (PI)
  GSFC
  Ph: 301-614-5987
  Fx: 301-614-5903
  scott.janz@nasa.gov
  
• Paul Newman (CO-I)
  GSFC
  Ph: 301-614-5985
  Fx: 301-614-5903
  paul.a.newman@nasa.gov
  
• John T. Riley (Systems Eng.)
  GSFC
  Ph: 301-286-0712
  Fx: 301-286-1763
  tom.riley@nasa.gov
  
• Robert Frederickson (Mechanical design)
  Swales
  Ph: 301-286-2382
  Fx: 301-286-1613
  rfrederickson@swales.com
  
• Kent McCullough (Technician)
  SSAI
  Ph: 301-614-5975
  Fx: 301-614-5903
  kentmcc@ventus.gsfc.nasa.gov
  
• Matt Kowalewski (Calibration Engineer)
  SSAI
  Ph: 301 867-2168
  Fx: 301-614-5903
  mattk@ventus.gsfc.nasa.gov