The Infrared Interferometer Experiment on Nimbus 3
Abstract
The Michelson interferometer experiment carried on the Nimbus 3 satellite has successfully obtained thermal emission spectra of the earth and atmosphere between 400 and 2000 cm-1 with a resolution equivalent to 5 cm-1. Comparison of a measured spectrum with a spectrum calculated theoretically from near-simultaneous radiosonde measurements indicates generally good agreement over most of the spectral range covered. A preliminary search for spectral features attributable to minor atmospheric constituents other than CO2 H2O, and O3 has resulted in a positive identification of only CH4 thus far. Comparisons of temperature profiles estimated from selected spectra with those obtained from radiosonde measurements on an individual basis and in the form of maps for selected locations and times indicate that meaningful atmospheric temperatures can be obtained, even in the presence of clouds. Similar comparisons of water vapor estimates with radiosonde measurements demonstrate that good humidity profiles can be obtained under almost clear sky conditions, but, when clouds are present within the field of view, the estimates become unreliable. Total ozone amounts in an atmospheric column obtained from the spectra are in generally good agreement with Dobson spectrometer measurements, and the estimates are found to be insensitive to clouds within the field of view under most circumstances. A global map of ozone, constructed from data taken over a 24-hour period, shows anticipated correlations with a conventional 300-mb pressure height map in the northern hemisphere. The possibility of obtaining information on surface composition is investigated by using a spectrum obtained over Egypt that shows a depression of as much as 10°K in brightness temperature in parts of the atmospheric window. This effect can be attributed to reststrahlen due to the presence of SiO2 in the desert soil.
- Publication:
-
Journal of Geophysical Research
- Pub Date:
- 1970
- DOI:
- 10.1029/JC075i030p05831
- Bibcode:
- 1970JGR....75.5831C
- Keywords:
-
- Aeronomy: Atmospheric composition (atomic or molecular);
- Aeronomy: Atmospheric pressure;
- density;
- and temperature;
- Aeronomy: Instruments and techniques;
- Meteorology: Chemical composition and chemical interactions