Advanced Prototypes of the Aerosol Limb Imager
Date
2022-04-19
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0000-0002-3713-6927
Type
Thesis
Degree Level
Doctoral
Abstract
Over the past decades, the call for global monitoring of aerosol has amplified to better understand its role in climate change. The Canadian Space Agency has identified targeted program funding for mission development to address this call. The Aerosol Limb Imager, or ALI, is a candidate remote sensing instrument that will provide this monitoring.
ALI is a Canadian developed atmospheric remote sensing instrument specifically designed to be sensitive to aerosol and clouds from the mid-troposphere through the stratosphere. An orbital-based viewing platform is necessary to realize global coverage. This work presents the development of two sub-orbital prototype instruments that inform the design of a satellite instrument.
The first ALI prototype presented is a technology demonstration aimed at validating the performance of state-of-the-art optical technologies on a high-altitude balloon observatory. The instrument pairs an extended range acousto-optic tunable filter with a liquid crystal polarization rotator to capture spectrally resolved polarimetric imagery of the atmospheric limb. These technologies provide the capability to extract particle size information from the sampled radiance and to identify cloud structures. The instrument met performance expectations from a balloon platform in 2018.
The ALI elegant breadboard is the latest hardware development and is designed to measure scattered sunlight from a high-altitude aircraft. An aircraft platform offers a varying spatial scene, which is analogous to the variation observed from orbit. Along-track sampling and signal-to-noise requirements are met with a state-of-the-art large-aperture acousto-optic tunable filter. The optical design surrounding the filter is equally advanced, incorporating diamond-turned mirrors and precision optical alignment. The ALI elegant breadboard is being assembled to meet a flight opportunity on the NASA ER-2 observatory in late 2022.
The insight and experience gained through the development of these two prototypes are paramount to the design of a future satellite-based sensor. Teams from the Canadian Space Agency, a Canadian University consortium and industry partners have assembled to ensure that ALI is the right instrument to address a global need. If selected for a satellite mission, ALI will fuel new research into how aerosol shapes climate and the health of the planet.
Description
Keywords
Stratospheric Aerosol, Remote Sensing, Acousto-Optics, Multi-Spectral Polarimetry
Citation
Degree
Doctor of Philosophy (Ph.D.)
Department
Physics and Engineering Physics
Program
Physics