The first field project for the University of Washington's (UW) Convair-580 research aircraft was in the Arctic. The aircraft was based at Barrow, Alaska, in support of the FIRE Arctic Cloud Experiment (FIRE-ACE) and SHEBA (Surface HEat Budget of the Arctic Ocean). Twenty-three research flights were carried out between 15 May through 26 June 1998.

The main research goals and tasks of the UW Cloud and Aerosol Research Group (CARG) in FIRE-ACE/SHEBA were:

• To carry out coordinated flights beneath the NASA ER-2 aircraft for the purpose of providing in situ measurements of cloud microphysical structures and thicknesses simultaneously with remote sensing measurements from the ER-2. Of particular interest were multi-cloud layer situations over highly reflecting ice surfaces (a scenario that provides a severe test for remote sensing of clouds).
  

• To obtain measurements of the absorption of solar radiation by layer clouds, using the NASA-Ames SSFR radiometers and the NASA-Goddard CAR (for clouds thick enough to be in the "diffusion domain").
  

• To obtain measurements of surface spectral albedo and the bidirectional reflectance distribution function (BRDF) using the SSFR radiometers and the CAR.
  

• To explore radiative interactions between layer clouds (or highly reflecting surfaces) and overlying absorbing aerosol layers.
  

• To obtain statistical measurements of the microstructures of arctic stratus clouds over long path lengths (to test a number of hypotheses based on previous measurements in the Arctic by the CARG).
  

• To see whether anthropogenic pollutants (from Barrow or from long-range transport) affect the microstructures and radiative properties of arctic clouds.
  

• To obtain in situ measurements (particularly of cloud heights and cloud structural and radiative properties) over the SHEBA research ship (frozen into the Arctic Ocean), and the ARM site at Barrow, for comparisons with surface-based remote sensing measurements at those two sites. Also, surface albedo and BRDF measurements around the SHEBA ship and ARM site.
  

• To evaluate the utility of the new Gerber Scientific Inc.'s g-meter (for measuring optical scattering and extinction, the asymmetry parameter, and the back-to-forward scattering ratio for cloud and precipitation particles in clouds--including mixed phase clouds).
  

• To obtain measurements of aerosols in non-cloudy and cloudy conditions, including vertical profiles over the ARM site at Barrow for "closure" studies with a ground-based sunphotometer at that site.
  

• To exploit the several new scanning modes of the CAR on the Convair-580.
  

A number of idealized flight scenarios to achieve the objectives outlined above were devised prior to the field project. These flight scenarios are described in the CAR report entitled "University of Washington Flight Scenarios for the Convair-580 in the Arctic (15 May-26 June 1998)" by Peter V. Hobbs, which is available on the CARG Homepage (http://cargsun2.atmos.washington.edu/sys/research/fire-ace/) or on request to the CARG.

Most of the data collected aboard the UW Convair-580 has been formally archived in the NASA Langley DAAC.

This was the first field deployment of the UW Convair-580 research aircraft. The aircraft performed very well, exceeding expectations in several respects. For example, the aircraft reached an altitude of 31,000 ft, and was able to fly from Barrow to the SHEBA ship, with adequate time on station to obtain important measurements, even when the ship was well over 400 nm from Barrow.

The instrumentation that was aboard the Convair-580 for these studies is listed in Table 1.

Twenty-three research flights, totaling over 97 research hours, were flown by the UW Convair-580 for FIRE-ACE/SHEBA during the period May 19 through June 24, 1998.

Table 2 gives an overview of the main accomplishments of these flights. Table 3 contains a complete listing of the flights. Tables 4 and 5 provide information on the Convair-580 flights over the SHEBA ship and the ARM site at Barrow, respectively. Table 6 lists the photographs that were taken aboard the Convair-580 during the FIRE-ACE/SHEBA flights.

(Text continued on Section 4.)

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