Retrieval of aerosol backscatter, extinction, and lidar ratio from Raman lidar with optimal estimation
Optimal estimation retrieval is a form of nonlinear regression which determines the most probable circumstances that produced a given observation, weighted against any prior knowledge of the system. This paper applies the technique to the estimation of aerosol backscatter and extinction (or lidar ra...
Published in: | Atmospheric Measurement Techniques |
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European Geosciences Union
2016
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Online Access: | https://doi.org/10.5194/amt-7-757-2014 https://ora.ox.ac.uk/objects/uuid:929a3bdf-07a6-4fdd-82a3-75562bfb8c45 |
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ftuloxford:oai:ora.ox.ac.uk:uuid:929a3bdf-07a6-4fdd-82a3-75562bfb8c45 2023-05-15T16:09:37+02:00 Retrieval of aerosol backscatter, extinction, and lidar ratio from Raman lidar with optimal estimation Povey, A Grainger, R Peters, D Agnew, J 2016-07-28 https://doi.org/10.5194/amt-7-757-2014 https://ora.ox.ac.uk/objects/uuid:929a3bdf-07a6-4fdd-82a3-75562bfb8c45 unknown European Geosciences Union doi:10.5194/amt-7-757-2014 https://ora.ox.ac.uk/objects/uuid:929a3bdf-07a6-4fdd-82a3-75562bfb8c45 https://doi.org/10.5194/amt-7-757-2014 info:eu-repo/semantics/openAccess CC Attribution (CC BY) CC-BY Journal article 2016 ftuloxford https://doi.org/10.5194/amt-7-757-2014 2022-06-28T20:18:27Z Optimal estimation retrieval is a form of nonlinear regression which determines the most probable circumstances that produced a given observation, weighted against any prior knowledge of the system. This paper applies the technique to the estimation of aerosol backscatter and extinction (or lidar ratio) from two-channel Raman lidar observations. It produces results from simulated and real data consistent with existing Raman lidar analyses and additionally returns a more rigorous estimate of its uncertainties while automatically selecting an appropriate resolution without the imposition of artificial constraints. Backscatter is retrieved at the instrument’s native resolution with an uncertainty between 2 and 20 %. Extinction is less well constrained, retrieved at a resolution of 0.1–1km depending on the quality of the data. The uncertainty in extinction is >15 %, in part due to the consideration of short 1 min integrations, but is comparable to fair estimates of the error when using the standard Raman lidar technique. The retrieval is then applied to several hours of observation on 19 April 2010 of ash from the Eyjafjallajökull eruption. A depolarising ash layer is found with a lidar ratio of 20– 30 sr, much lower values than observed by previous studies. This potentially indicates a growth of the particles after 12– 24 h within the planetary boundary layer. A lower concentration of ash within a residual layer exhibited a backscatter of 10Mm−1 sr−1 and lidar ratio of 40 sr. Article in Journal/Newspaper Eyjafjallajökull ORA - Oxford University Research Archive Atmospheric Measurement Techniques 7 3 757 776 |
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ORA - Oxford University Research Archive |
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ftuloxford |
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description |
Optimal estimation retrieval is a form of nonlinear regression which determines the most probable circumstances that produced a given observation, weighted against any prior knowledge of the system. This paper applies the technique to the estimation of aerosol backscatter and extinction (or lidar ratio) from two-channel Raman lidar observations. It produces results from simulated and real data consistent with existing Raman lidar analyses and additionally returns a more rigorous estimate of its uncertainties while automatically selecting an appropriate resolution without the imposition of artificial constraints. Backscatter is retrieved at the instrument’s native resolution with an uncertainty between 2 and 20 %. Extinction is less well constrained, retrieved at a resolution of 0.1–1km depending on the quality of the data. The uncertainty in extinction is >15 %, in part due to the consideration of short 1 min integrations, but is comparable to fair estimates of the error when using the standard Raman lidar technique. The retrieval is then applied to several hours of observation on 19 April 2010 of ash from the Eyjafjallajökull eruption. A depolarising ash layer is found with a lidar ratio of 20– 30 sr, much lower values than observed by previous studies. This potentially indicates a growth of the particles after 12– 24 h within the planetary boundary layer. A lower concentration of ash within a residual layer exhibited a backscatter of 10Mm−1 sr−1 and lidar ratio of 40 sr. |
format |
Article in Journal/Newspaper |
author |
Povey, A Grainger, R Peters, D Agnew, J |
spellingShingle |
Povey, A Grainger, R Peters, D Agnew, J Retrieval of aerosol backscatter, extinction, and lidar ratio from Raman lidar with optimal estimation |
author_facet |
Povey, A Grainger, R Peters, D Agnew, J |
author_sort |
Povey, A |
title |
Retrieval of aerosol backscatter, extinction, and lidar ratio from Raman lidar with optimal estimation |
title_short |
Retrieval of aerosol backscatter, extinction, and lidar ratio from Raman lidar with optimal estimation |
title_full |
Retrieval of aerosol backscatter, extinction, and lidar ratio from Raman lidar with optimal estimation |
title_fullStr |
Retrieval of aerosol backscatter, extinction, and lidar ratio from Raman lidar with optimal estimation |
title_full_unstemmed |
Retrieval of aerosol backscatter, extinction, and lidar ratio from Raman lidar with optimal estimation |
title_sort |
retrieval of aerosol backscatter, extinction, and lidar ratio from raman lidar with optimal estimation |
publisher |
European Geosciences Union |
publishDate |
2016 |
url |
https://doi.org/10.5194/amt-7-757-2014 https://ora.ox.ac.uk/objects/uuid:929a3bdf-07a6-4fdd-82a3-75562bfb8c45 |
genre |
Eyjafjallajökull |
genre_facet |
Eyjafjallajökull |
op_relation |
doi:10.5194/amt-7-757-2014 https://ora.ox.ac.uk/objects/uuid:929a3bdf-07a6-4fdd-82a3-75562bfb8c45 https://doi.org/10.5194/amt-7-757-2014 |
op_rights |
info:eu-repo/semantics/openAccess CC Attribution (CC BY) |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5194/amt-7-757-2014 |
container_title |
Atmospheric Measurement Techniques |
container_volume |
7 |
container_issue |
3 |
container_start_page |
757 |
op_container_end_page |
776 |
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1766405474287091712 |