Radiometer for remote sounding of the upper atmosphere.

Area of Science:

• Atmospheric science
• Remote sensing
• Radiometry

Background:

• The 40-80 km region of Earth's atmosphere is poorly understood.
• Rocket soundings indicate significant atmospheric phenomena in this region.
• Global coverage of the upper atmosphere is needed for comprehensive study.

Purpose of the Study:

• To introduce a novel instrument for atmospheric temperature sounding.
• To enable global monitoring of the upper atmosphere from a polar-orbiting satellite.
• To investigate phenomena in the 40-80 km atmospheric region.

Main Methods:

• Development of a pressure-modulated carbon dioxide (CO2) radiometer.
• Utilizing a CO2 cell as a filter with modulated pressure.
• Selecting thermal radiation from strong spectral lines of atmospheric CO2.
• Employing a high-sensitivity device with a large energy grasp.

Main Results:

• The instrument is capable of temperature soundings in the 40-80 km altitude range.
• Tests with prototype and balloon-borne instruments demonstrate feasibility.
• The radiometer can detect temperature changes of approximately 1 K at 65 km altitude.
• The technique effectively selects thermal radiation from low-pressure atmospheric levels.

Conclusions:

• The pressure-modulated CO2 radiometer offers a new method for upper atmospheric temperature measurement.
• The instrument provides global coverage for studying the under-sampled 40-80 km atmospheric region.
• This technology has the potential to significantly advance our understanding of upper atmospheric dynamics.