Characterization of springtime leads in the Beaufort/Chukchi seas from airborne and satellite observations during FIRE/SHEBA

Abstract

Airborne remote sensing observations in the vicinity of the Surface Heat Budget of the Arctic Ocean (SHEBA) camp in the Beaufort and Chukchi Seas during May 1998 are used to characterize leads. This characterization was accomplished using observations from a passive microwave radiometer, video camera, and infrared pyrometer. An automated methodology is presented to determine lead fraction, width, and orientation. Refrozen lead fraction decreased in the latter half of May, due in part to local convergence in the ice pack. Airborne passive microwave and video observations are combined to produce a lead width distribution for the SHEBA region. Narrow leads are most prevalent, with lead fraction decreasing exponentially with increasing lead width. Lead orientation showed a preference in a northwesterly direction, which is consistent with prevailing wind patterns and ocean circulation. The lead width distribution and lead orientation observed by the airborne sensors are similar to the characteristics derived from an advanced very high resolution radiometer (AVHRR) albedo image encompassing the Beaufort/Chukchi Seas during the same time period. The AVHRR albedos in the SHEBA vicinity are also comparable to the larger region. These similarities suggest that the area of study used by SHEBA investigators was representative of the Western Arctic during this time period for these surface characteristics.