Profiling atmosphere temperature from space using lidar with a Mach-Zehnder interferometer: principle and assessment

Area of Science:

• Atmospheric Physics
• Optical Metrology

Background:

• The Mach Zehnder interferometer is crucial for characterizing light coherence.
• Rayleigh Brillouin (RB) backscattering provides information about atmospheric molecular motion.

Purpose of the Study:

• To determine atmospheric temperature profiles using a Mach Zehnder interferometer.
• To establish a relationship between interference contrast and atmospheric temperature.

Main Methods:

• Analyzing four-channel interference signals from the Mach Zehnder interferometer.
• Measuring interference contrast of RB backscattering from atmospheric molecules.
• Relating interference contrast to RB spectrum width and molecular thermal motion.

Main Results:

• Interference contrast is directly proportional to the average speed of molecular thermal motion.
• This average speed correlates with atmospheric temperature at the backscattering point.
• Vertical temperature profiling is achievable by measuring RB backscatter interference contrast at different altitudes.

Conclusions:

• A Mach Zehnder interferometer with a large optical path difference enables accurate temperature measurements in the troposphere.
• The ultraviolet spaceborne lidar system can achieve a random temperature accuracy of 1 K.
• The system offers a vertical resolution of 500 m and a horizontal resolution of 50 km for tropospheric temperature profiling.