Albedos

 

As part of the ice-albedo feedback studies during SHEBA, we measured spectral and wavelength-integrated albedos. Measurements were made at least weekly every 2.5 m along a 200-m survey line from April through October. From June through August, albedo measurements were made every other day. Albedos integrated from 300 to 3000 nm were measured using a Kipp & Zonen albedometer. Spectral albedos from 300 to 2000 nm were measured using a Spectron Engineering SE-590 spectroradiometer. Albedos were accurate to within +/- 0.01.

 

The Kipp & Zonen albedometer and the SE-590 spectroradiometer are pictured on the right.
The black line denotes the albedo line. The photograph was taken on 20 July 1998 from an altitude of a few hundred meters. The line started in an interesting melt pond that was part light and part dark. It continued, crossing areas of bare ice and several other melt ponds.

 
 

Initially, this line was completely snow-covered, but as the melt season progressed it became a mixture of bare ice and melt ponds. Observed changes in albedo were a combination of a gradual evolution due to seasonal transitions and abrupt shifts resulting from synoptic weather events. The sequence of four photographs below shows the evolution of surface conditions from dry snow (April 17) to melting snow (June 3) to early melt ponds (June 25) to fully developed melt ponds (July 21).

 

 

Wavelength-integrated albedos    Spectral albedos   Transmittance    UV Incident

 
 
                                          

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