Abstract
Abstract. The Balloon Lidar Experiment (BOLIDE) was the first high-power lidar flown and operated successfully on board a balloon platform. As part of the PMC Turbo payload, the instrument acquired high-resolution backscatter profiles of polar mesospheric clouds (PMCs) from an altitude of ∼ 38 km during its maiden ∼ 6 d flight from Esrange, Sweden, to northern Canada in July 2018. We describe the BOLIDE instrument and its development and report on the predicted and actual in-flight performance. Although the instrument suffered from excessively high background noise, we were able to detect PMCs with a volume backscatter coefficient as low as 0.6×10-10 m−1 sr−1 at a vertical resolution of 100 m and a time resolution of 30 s.
Highlights
For several decades light detection and ranging has been the only technology which allows for profiling of the neutral atmosphere from the troposphere to the upper mesosphere and lower thermosphere
We used the profile of βPMC scaled to a peak value of 2 × 10−10 m−1 sr−1 as a reference profile for the following simulations shown in Fig. 7b: the red profile represents the configuration as flown with a telescope field of view (FOV) of 165 μrad and a background which is 2.8 times the Rayleigh background
Two obvious solutions for this problem are the addition of a baffle to prevent stray light from entering the telescope and the use of an off-axis telescope
Summary
For several decades light detection and ranging (lidar) has been the only technology which allows for profiling of the neutral atmosphere from the troposphere to the upper mesosphere and lower thermosphere. In the picture of geometric optics the scattered light forms spherical waves, resulting in the lidar return signal decreasing with the range squared (or altitude squared in the case of a vertically looking lidar). The sodium density within the metal layer (approximately 80– 100 km altitude) is only on the order of a few thousand atoms per cubic centimeters and much smaller than the air density at these altitudes, the sodium fluorescence signal is much stronger than Rayleigh scattering due to the ∼ 16-orders-of-magnitude difference in the scattering cross sections The downside of these so-called metal fluorescence (or resonance) lidars was the technical complexity of the lasers. Omitting the filters considerably simplifies the optical design of the lidar but at the same time increases the overall transmission of the instrument The latter facilitates the use of even smaller lasers and/or telescopes while still achieving the same signal level as large ground-based instruments. The Balloon Winds payload, a technology demonstrator for a future satellite mission, was, lost during a launch mishap, and no inflight data were collected (Dehring et al, 2006)
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