The Earth Radiation Budget Spacecraft (ERBS) was placed into orbit in October 1984, carrying a scanning radiometer and a nonscanning radiometer package as part of the Earth Radiation Budget Experiment (ERBE). The scanning radiometer provided measurements of outgoing longwave radiation (OLR) and reflected solar radiation or albedo for 5 years before ceasing operation. The nonscanning wide field of view radiometers continue to operate, so that they have provided a 13-year data record of OLR and albedo thus far. The ERBS is in a 57 degree inclination orbit, and data are processed onto a grid covering an area from 60 degrees north to 60 degrees south, which accounts for 86 percent of the Earth's surface. Moreover, the strongest interannual variations of radiation are within this portion of the Earth. This paper briefly discusses the algorithms which have evolved for computing the top-of-atmosphere TOA fluxes for instantaneous and monthly mean results and examines the interannual variability of the data set.
The TOA fluxes are computed using a shape factor method and also with a numerical filter technique which enhances the resolution alongtrack. These data are available on a pixel basis, and on a monthly mean basis. The ERBS orbit altitude is 620 km so that the resolution of the gridded monthly-mean data products are 10 degrees latitude-longitude for the shape-factor products and 5 degrees latitude-longitude for the numerical-filter products. A calculation of temporal sampling errors is now included in the quality control procedures for the numerical filter products in order to reject monthly mean gridded values of OLR and albedo which have unacceptable errors.
The mean OLR and albedo for each calendar month are computed for this 13-year period, and maps of the standard deviations of the monthly means about these climatological mean months are examined. The interannual variability of the OLR and albedo is expressed in terms of empirical orthogonal functions for this 13-year period.