STUDY OF A CONTINENTAL SURFACE ALBEDO ON THE BASIS OF FLIGHT MEASUREMENTS AND STRUCTURE OF THE EARTH'S SURFACE COVER OVER NORTH AMERICA*

Abstract

A series of 12 monthly flights along a fixed path inWisconsin and a series of 4 long-range flights overextensive areas of the United States and Canada wereperformed during 1963 to measure systematically thesurface albedo over various types of the earth'ssurface, using an instrumented light airplane operatingat a low level. An approximate total of 24,000 mi. wasflown and roughly 210,000 sets of the measurements wereprocessed for this study. Techniques of measurement anddata treatment are discussed.It is shown, and discussedin detail, that the regional differences and seasonalvariations of the surface albedo due to thc structureand state of the earth's surface cover aresignificant. The snow cover is the most importantmodification of the earth's surface, giving asignificantly higher albedo. A quantitativerelationship between the increase of surface albedo andsnow cover is examined. The surface albedo measuredduring the flights over typical surface covers overNorth America, including cities, is presented. Thesurface covers and their textures over the NorthAmerican Continent were studied mainly in terms of landuse, vegetation type and phenology, soil type, andground snow cover. The surface albedo values wereestimated for various regions of the continent from theflight measurement data, considering the similarity anddifferences in surface structure among the regions. Theresulting seasonal albedo maps of North America arepresented and discussed, along with the seasonalvariation of the meridional profile of thc continentalsurface albedo.*This research was supported byAtmospheric Science Division, National ScienceFoundation, Grant GP-444, and by the Geophysical FluidDynamics Laboratory, U.S. Weather Bureau.