Airalb

	Aerial albedo

On a few of the helo flights, the ASD Ice-1 spectroradiometer was used to measure incident and reflected irradiance. One detector was mounted on a metal plate with an unobstructed view looking downward. The other detector was mounted high on the fuselage looking upward. Unfortunately, the field of view of this detector was somewhat blocked by the cowling of the helicopter. To minimize the effects of this, we: 1) only measured on cloudy days with a dense uniform cloud cover and 2) tried to calibrate the two sensors in the working configuration by measuring a lead, where the surface was uniform and the albedo known. As the figure shows, our precautions were only partially successful. The discrete jumps occured when the helicopter turned to do a different leg of the flight pattern. These jumps are artifacts of sensor shadowing. Information can be obtained from the legs where the incident detector was not shadowed.


Full suite of helo albedo measurements from July 28, 1998.

Albedo above the albedo line as a function of altitude.	Albedo along a 16 km transect.