GMD-Radiation group (G-Rad)

Radiation sensors

G-Rad is involved in observational and theoretical research of the Earth's surface and atmospheric radiation budgets. The group specializes in the investigation of climatically significant variations in long-term radiation and meteorological measurements made at diverse globally-remote sites and continental US sites (SURFRAD). In addition, we make observations of spectral solar radiation for the purpose of remote sensing of certain atmospheric constituents and determination of variations in the UV irradiance.   Our research interests include the extent and cause of observed radiation and climate variations, and in collaborating with other research groups making satellite observations and climate model calculations. A relatively new program in the group is the absolute measurement of spectral solar UV for the investigation of the interaction of ozone and solar radiation.

Grad Network

Observing Networks

The G-Rad group makes continuous measurements of surface radiation quantities at field sites around the world and across the continental US. The individual sites have varying characteristics and attributes and, therefore, are involved in different projects and applications.

Grad Solar Calculators

Solar Calculator

The NOAA Solar calculator allows users to pinpoint their desired location on a map. Accurate latitude and longitude coordinates are then combined with the user’s desired date and time values to generate estimates for sunrise, sunset, solar noon and the position of the sun in the sky.

Grad Research


The data collected from the observing network are used by the G-Rad group and its collaborators in a wide variety of research projects. Many of those projects are primarily related to the role of radiation and aerosols in climate variability and forcing.

Grad Instruments


Broadband solar and thermal irradiances are measured as well as relative spectral direct solar measurements for purposes of determining aerosol optical depth and precipitable water.

Grad Data


Raw data from the observing networks are centrally collected and processed in our Boulder office, where the data have preliminary calibrations applied and initial data editing is performed.

Grad Calibration Facilities

Calibration Facilities

G-Rad maintains basic independent but traceable calibration facilities for broadband solar, broadband IR, and spectral solar primarily in the UV spectrum.