Surface downwelling solar radiation measurements at the four original GML baseline observatories began when each of the observatories was founded. Subsequently, additional measurement of thermal longwave, upwelling irradiances, and aerosol optical depth were added at these sites. The Trinidad Head site was established later. The intent of these measurements was to maintain long-term records of surface radiation budget components at globally remote sites and to support the other GML research programs being conducted at these sites. Two of these sites (Barrow and South Pole) also contribute to the BSRN program as described below.
In 1988, the World Climate Research Program (WCRP) promoted the implementation of the Baseline Surface Radiation Network (BSRN), which is designed to provide frequent, state-of-the-art measurements of surface radiation fluxes according to internationally agreed standard operational and instrument calibration procedures. These measurements are needed to assess theoretical treatments of radiative transfer in the atmosphere, to verify climate model computations, and for monitoring regional trends in surface radiation. These activities are important in assessing potential modification of the Earth's radiation budget as the atmospheric concentration of greenhouse gases and aerosol loadings changes. The BSRN stations are currently organized to fulfill the goals of the WCRP, which are to
The BSRN now consists of numerous sites throughout the world, representing a diverse geographical coverage with many different climatic zones. The GRAD group maintains sites that are contributers to the BSRN, located at
and the sites of the SURFRAD network.
The locations were selected for the site's spatial representativeness and suitability for the applications in climate research involving global climate models and/or satellite-derived related data sets. Bermuda and Kwajalein are funded by NASA HQ Radiation Sciences.
Further information about the BSRN program, including meetings, publications, members and contact information, how to obtain the data from the archive in Switzerland, etc., can be found at http://www.bsrn.awi.de/.