MODIS Airborne Simulator (MAS)

Objective and Summary:

• Overfly several flight legs over the ARM site where relatively uniform stratus clouds are expected. Data will be used for cloud remote sensing and cloud masking validation, cloud bidirectional reflectance measurements, and sea ice retrievals.

NOTE: The Cloud Lidar System (CLS) was down for the remainder of the deployment making flights over multilevel clouds and cirrus more difficult for other ER-2 instruments to analyze. Therefore, this mission was planned for areas with well defined cloud layers or clear sky.

Coordinations:

• University of Washington CV-580 aircraft
• F-14 satellite (2112 UTC)

Key Flight Legs:

• The ER-2 flew a NW flight line toward the ARM site to begin a cross pattern with legs of about 280km in length. One-and-a-half flight legs were flown in a NW-SE orientation such that the imaging instruments scanned perpendicular to the solar azimuth, followed by a total of two flight legs in a direction chosen such that imaging instruments scanned into the solar plane.
• The CV-580 flew above the ARM site in coordination with the ER-2, making above and below-cloud bidirectional reflectance measurements and in situ profiles through the cloud. The CV-580 reported a stratocumulus deck with a top at about 2500ft. and about 1000ft. thick, with a little stratus below. They reported clear skies above the stratocumulus deck during ER-2 overpasses.
• The AirMISR was turned on for 5 acquisitions: twice over the Brooks range enroute to and from Barrow, and three times over the ARM site. The AirMISR operated at the following times with notes of observed clouds as seen by the instrument:
  • 1921-1933 UTC (outgoing leg over Brooks Range - gathered 8 of 9 angles; broken clouds)
  • 1957-2009 UTC (ARM - complete run; stratocumulus)
  • 2056-2108 UTC (ARM - complete run; stratocumulus)
  • 2127-2139 UTC (ARM - complete run; stratocumulus)
  • 2141-2154 UTC (return leg to Ft. Wainwright - complete run; broken clouds over land)

Pilot Report:

• The ER-2 pilot reported solid low-level stratus deck over the entire flight operations area.

Meteorology:

• At 1500 UTC, the ice station reported stratus overcast clouds with surface winds at 4kts, 310° and a ceilometer cloud base of about 0.5km. Radar showing two cloud layers: lower one at 0.2-0.8km and a higher layer at 3.9-4.5km. The 1113 UTC sounding showed moisture increasing in a broad layer centered about 9km. Satellite imagery showed broken high-to-midlevel clouds moving in from the Northwest. Cloud cover at all levels expected to be over the ship by the time of an ER-2 flight.
• The Barrow sounding showed two cloud layers, the upper one with cloud tops at about 3-3.5km. Imagery was showing a rather uniform stratus deck across the Barrow region with a possible breaking up of the upper level cloud layer.
• Due to lack of a working lidar on the ER-2, it was decided to focus a mission on Barrow where cloud layers were likely to be the most spatially uniform.

Instrument Status:

• AirMISR (Airborne Multi-angle Imaging Spectroradiometer): Worked well
• AMPR (Advanced Microwave Precipitation Radiometer): Worked well
• CLS (Cloud Lidar System): Failed
• HIS (High-resolution Interferometer Sounder): Worked well
• MAS (MODIS Airborne Simulator): Worked well
• MIR (Millimeter-wave Imaging Radiometer): Worked well
• SSFR (Solar Spectral Flux Radiometer): Worked well