Nimbus Satellite Infrared Spectrometer Experiment

Two infrared grating spectrometers have been developed for the Nimbus meteorological satellite program to determine the feasibility of indirectly sensing vertical atmospheric temperature and humidity profiles from space. Each instrument senses radiation in the 15 m carbon dioxide band. The second instrument flown on Nimbus IV, has the added capability of a sensing-beam scan for better geographic-data sampling, and it also measures in six additional spectral intervals in the water-vapor rotation band. From inflight calibrations the digitized voltage outputs are transformed into spectral radiances which are in turn transformed into vertical profiles of temperature and humidity. Examples of temperature profiles near the Philippine Islands are shown. These indicate time and location differences in the temperatures of the upper troposphere and the stratosphere obtained from the two independent satellite measurements.