Tuesday, 4 June 2002
The Earth Radiation Budget 15-year Data Set
The Earth Radiation Budget Satellite carries a package of non-scanning radiometers which began operation in November 1984 and operated well until October 1999, providing a data set for outgoing longwave radiation and solar radiation reflected from the Earth. The spacecraft is in an orbit with an inclination of 57 degrees and an altitude of 620 km, so that it precesses around the Earth every 72 days, providing measurements at all local times so as to sample the full diurnal cycle over that period. The non-scanner package contained 2 wide field-of-view radiometers (WFOV), which view the Earth from limb to limb, and 2 medium field-of-view radiometers, which view a circle of 10 degree diameter of the Earth. Also, there is an active cavity radiometer for measuring the solar output.
The Earth-viewing data set has recently been reprocessed to improve its usefulness for research applications, e.g. in climate studies. The calibrations of both the total and the shortwave radiometers were revised slightly. The retrieval of top-of-atmosphere fluxes from the measurements had been improved in an earlier revision. Minor details of the assignment of discrete time values to regional means were made. The major difference between the reprocessed data set and the previous data set is in a quality-assurance algorithm which computes the temporal sampling error in the computed monthly mean top-of-atmosphere fluxes. Monthly mean values are not reported for regions for which the computed temporal sampling error exceeds 12 W/m**2.