Accurate lidar temperatures with narrowband filters

Area of Science:

• Atmospheric physics and remote sensing
• Laser spectroscopy and lidar technology

Background:

• Daytime mesopause temperature measurements using metal resonance lidars require narrowband spectral filtering.
• Faraday anomalous dispersion optical filters are used in lidar receivers for Doppler temperature measurements.

Purpose of the Study:

• To investigate the impact of wavelength-dependent filter transmission on daytime lidar temperature measurements.
• To demonstrate accurate daytime temperature measurements by correctly accounting for filter effects.

Main Methods:

• Utilized a potassium (K) lidar system equipped with a Faraday anomalous dispersion optical filter.
• Analyzed the wavelength dependence of filter transmission on Rayleigh scattered light for normalization.
• Modeled and corrected for all filter-induced effects on temperature derivations.

Main Results:

• Identified a potential 10 K temperature shift in derived resonance temperatures due to filter transmission normalization.
• Showed that this shift is caused by the wavelength dependence of the filter for Rayleigh scattered light.
• Demonstrated that accurate daytime temperature measurements are achievable by correcting for these filter effects.

Conclusions:

• Daytime mesopause temperature measurements with K lidar can achieve accuracy comparable to nighttime measurements.
• Proper consideration and correction of Faraday filter effects are crucial for precise daytime lidar thermometry.
• Accurate temperature data from the upper atmosphere can be obtained during daytime using corrected lidar techniques.