The Miami2001 Infrared Radiometer Calibration and Intercomparison. Part I: Laboratory Characterization of Blackbody Targets

Abstract

The second calibration and intercomparison of infrared radiometers (Miami2001) was held at the University of Miami's Rosenstiel School of Marine and Atmospheric Science (RSMAS) during May?June 2001. The participants were from several groups involved with the validation of skin sea surface temperatures and land surface temperatures derived from the measurements of imaging radiometers on earth observation satellites. These satellite instruments include those currently on operational satellites and others that will be launched within two years following the workshop. There were two experimental campaigns carried out during the 1-week workshop: a set of measurements made by a variety of ship-based radiometers on board the Research Vessel F. G. Walton Smith in Gulf Stream waters off the eastern coast of Florida, and a set of laboratory measurements of typical external blackbodies used to calibrate these ship-based radiometers. This paper reports on the results obtained from the laboratory characterization on blackbody sources. A companion paper reports on the at-sea measurements. Five blackbody sources were intercompared by measurements of their brightness temperature using the National Institute of Standards and Technology (NIST) Thermal-infrared Transfer Radiometer (TXR). Four of these sources are used for calibration of sea surface temperature radiometers. The fifth was a NIST water bath blackbody used for calibration of the TXR. All blackbodies agreed to better than ±0.1°C at blackbody temperatures near the ambient room temperature. Some of the blackbodies had reduced effective emissivity relative to the NIST water bath blackbody, and hence they began to disagree at blackbody temperatures far enough away (>15°C) from the ambient room temperature. For these, relative effective emissivity values were determined so that corrections can be applied if they are used in conditions of nonlaboratory ambient temperatures.