Background

Radiative fluxes at the top of the atmosphere are now well observed from satellites. In contrast, fluxes at the surface are less well observed, due to the variable quality and sparse distribution of measurements. As a result, estimates of the radiation balance of the atmosphere are not well constrained. For example, estimates of the absorption of solar radiation vary from 67 to 93 Wm^-2, with similar disagreements for thermal fluxes.

Attempts to resolve these uncertainties have been beset by sampling problems:

• Limited global distribution of surface sites and limited instrumentation
• Limited spatial and temporal sampling by in situ experiments using aircraft
• Limited spatial, temporal and/or spectral sampling by satellites above the few well-instrumented surface sites

In order to minimise these, we need long-term, broad-band observations from both space and the surface, with high temporal resolution. This in effect means a combination of a geostationary satellite and a well-instrumented surface site. RADAGAST achieves this for the first time, by bringing together the new ARM Mobile Facility and the GERB radiation budget instrument, both operating during AMMA.

Documents

• The original RADAGAST proposal (pdf format)
• Presentation at the ARM Science Team meeting at Daytona Beach in March 2005 (PowerPoint format, 24.2 Mb)
• A poster about the project (pdf format)
• ARM Deployment at Niamey (pdf format, 2Mb)