9:15 AM - 9:30 AM
[PEM12-20] Resonance-scattering Ca/Ca+ lidar: simultaneous observation of Ca and Ca+ layers and preliminary measurements of temperature and wind velocity
Keywords:Resonance Scattering Lidar, Ca, Ca+, Ti:sapphire laser
We have developed a resonance-scattering Ca/Ca+ lidar that can simultaneously observe both meteoric Ca and Ca+ in the MLT region. The lidar is configured of a dual-wavelength injection-locked nanosecond pulsed Ti:sapphire laser as a core of the system, having a remarkable feature to simultaneously emit a variety of two wavelengths from a single laser resonator. Here, we tuned the two wavelengths to the resonant transitions of Ca (845.5836 nm) and Ca+ (786.9540 nm), respectively. The laser performance: the simultaneous oscillation of the above two wavelengths, which are separated by more than 50 nm, was realized by designing the precise wavelength-dependent reflectivity at the output coupler of the laser resonator, in addition to the standard configuration.
Since the development of this lidar has reached a practically applicable stage, we have attempted the simultaneous observation of Ca and Ca+ over a long time for the first time. We could successfully conduct the simultaneous observation of Ca and Ca+ for an entire night (24, Dec., 2024). We found that the spatial-temporal evolutions of Ca and Ca+, distributed at the same altitude range of 80 – 105 km, were similar. However, closer comparison would lead to differences in complex detailed structures, which should be studied in future.
The developed resonance-scattering Ca/Ca+ lidar has a high frequency-purity of 30 MHz and a high frequency-accuracy of several MHz. Namely, the lidar system has the ability to also estimate temperatures and velocities of the target atoms/ions in the observed altitude region by measuring the Doppler broadened resonance profiles. In fact, we conducted a preliminary test of continuous observation of Ca+ temperature for one hour, in which the frequency scanning was set to a cycle of 3 minutes. We were able to confirm that the temperature in the upper atmosphere (ion temperature) could be estimated by measuring Doppler broadened resonance profiles of Ca+. Here, the ion temperature was estimated to be 168 ± 6 K at an altitude of 95 km (UT 11 – 12, 15, Jan. 2025), where the NRLMSIS predicted the atmospheric temperature to be 183 K.
In the presentation, we will report the above-mentioned results by focusing on the capability of the developed lidar system, including some prospects on what we can do with this resonance-scattering Ca/Ca+ lidar system and what we can expect in the future.
Since the development of this lidar has reached a practically applicable stage, we have attempted the simultaneous observation of Ca and Ca+ over a long time for the first time. We could successfully conduct the simultaneous observation of Ca and Ca+ for an entire night (24, Dec., 2024). We found that the spatial-temporal evolutions of Ca and Ca+, distributed at the same altitude range of 80 – 105 km, were similar. However, closer comparison would lead to differences in complex detailed structures, which should be studied in future.
The developed resonance-scattering Ca/Ca+ lidar has a high frequency-purity of 30 MHz and a high frequency-accuracy of several MHz. Namely, the lidar system has the ability to also estimate temperatures and velocities of the target atoms/ions in the observed altitude region by measuring the Doppler broadened resonance profiles. In fact, we conducted a preliminary test of continuous observation of Ca+ temperature for one hour, in which the frequency scanning was set to a cycle of 3 minutes. We were able to confirm that the temperature in the upper atmosphere (ion temperature) could be estimated by measuring Doppler broadened resonance profiles of Ca+. Here, the ion temperature was estimated to be 168 ± 6 K at an altitude of 95 km (UT 11 – 12, 15, Jan. 2025), where the NRLMSIS predicted the atmospheric temperature to be 183 K.
In the presentation, we will report the above-mentioned results by focusing on the capability of the developed lidar system, including some prospects on what we can do with this resonance-scattering Ca/Ca+ lidar system and what we can expect in the future.