Saturn's north polar vortex structure extracted from cloud images by the optical flow method
The paper presents velocity fields with ~3‐km spatial resolution of Saturn's north polar vortex (NPV) retrieved using the optical flow method from a sequence of polar‐projected cloud images captured by the Imaging Science Subsystem camera on board NASA's Cassini spacecraft. The fields of t...
Published in: | Journal of Geophysical Research: Planets |
---|---|
Main Authors: | , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
American Geophysical Union
2019
|
Subjects: | |
Online Access: | https://authors.library.caltech.edu/99276/ https://authors.library.caltech.edu/99276/2/Liu_et_al-2019-Journal_of_Geophysical_Research__Planets.pdf https://resolver.caltech.edu/CaltechAUTHORS:20191015-133656221 |
id |
ftcaltechauth:oai:authors.library.caltech.edu:99276 |
---|---|
record_format |
openpolar |
spelling |
ftcaltechauth:oai:authors.library.caltech.edu:99276 2023-05-15T17:39:52+02:00 Saturn's north polar vortex structure extracted from cloud images by the optical flow method Tianshu, Liu Sayanagi, Kunio M. Brueshaber, Shawn R. Blalock, John J. Ingersoll, Andrew P. Dyudina, Ulyana A. Ewald, Shawn P. 2019-11 application/pdf https://authors.library.caltech.edu/99276/ https://authors.library.caltech.edu/99276/2/Liu_et_al-2019-Journal_of_Geophysical_Research__Planets.pdf https://resolver.caltech.edu/CaltechAUTHORS:20191015-133656221 en eng American Geophysical Union https://authors.library.caltech.edu/99276/2/Liu_et_al-2019-Journal_of_Geophysical_Research__Planets.pdf Tianshu, Liu and Sayanagi, Kunio M. and Brueshaber, Shawn R. and Blalock, John J. and Ingersoll, Andrew P. and Dyudina, Ulyana A. and Ewald, Shawn P. (2019) Saturn's north polar vortex structure extracted from cloud images by the optical flow method. Journal of Geophysical Research. Planets, 124 (11). pp. 3041-3062. ISSN 2169-9097. doi:10.1029/2019JE005974. https://resolver.caltech.edu/CaltechAUTHORS:20191015-133656221 <https://resolver.caltech.edu/CaltechAUTHORS:20191015-133656221> other Article PeerReviewed 2019 ftcaltechauth https://doi.org/10.1029/2019JE005974 2021-11-18T18:52:42Z The paper presents velocity fields with ~3‐km spatial resolution of Saturn's north polar vortex (NPV) retrieved using the optical flow method from a sequence of polar‐projected cloud images captured by the Imaging Science Subsystem camera on board NASA's Cassini spacecraft. The fields of the velocity magnitude, velocity variation, relative vorticity, divergence, and second invariant are determined to characterize the flow structures of the inner core of the NPV. The mean zonal and mean meridional velocity profiles of the NPV are compared with previous measurements. We also describe the relevant details of application of the optical flow method to planetary cloud‐tracking wind measurements. The mean zonal velocity profile is consistent with the previous measurements using correlation image velocimetry methods. The small but significant meridional velocity corresponds to outwardly spiraling streams observed in the region near the north pole (NP). The concentrated vorticity and second invariant within 1° planetographic latitude of the NP indicate strong rotational motion of the fluid. An analysis is presented to explore a possible physical origin of the observed spiraling node at the NP. Article in Journal/Newspaper North Pole Caltech Authors (California Institute of Technology) North Pole Journal of Geophysical Research: Planets 124 11 3041 3062 |
institution |
Open Polar |
collection |
Caltech Authors (California Institute of Technology) |
op_collection_id |
ftcaltechauth |
language |
English |
description |
The paper presents velocity fields with ~3‐km spatial resolution of Saturn's north polar vortex (NPV) retrieved using the optical flow method from a sequence of polar‐projected cloud images captured by the Imaging Science Subsystem camera on board NASA's Cassini spacecraft. The fields of the velocity magnitude, velocity variation, relative vorticity, divergence, and second invariant are determined to characterize the flow structures of the inner core of the NPV. The mean zonal and mean meridional velocity profiles of the NPV are compared with previous measurements. We also describe the relevant details of application of the optical flow method to planetary cloud‐tracking wind measurements. The mean zonal velocity profile is consistent with the previous measurements using correlation image velocimetry methods. The small but significant meridional velocity corresponds to outwardly spiraling streams observed in the region near the north pole (NP). The concentrated vorticity and second invariant within 1° planetographic latitude of the NP indicate strong rotational motion of the fluid. An analysis is presented to explore a possible physical origin of the observed spiraling node at the NP. |
format |
Article in Journal/Newspaper |
author |
Tianshu, Liu Sayanagi, Kunio M. Brueshaber, Shawn R. Blalock, John J. Ingersoll, Andrew P. Dyudina, Ulyana A. Ewald, Shawn P. |
spellingShingle |
Tianshu, Liu Sayanagi, Kunio M. Brueshaber, Shawn R. Blalock, John J. Ingersoll, Andrew P. Dyudina, Ulyana A. Ewald, Shawn P. Saturn's north polar vortex structure extracted from cloud images by the optical flow method |
author_facet |
Tianshu, Liu Sayanagi, Kunio M. Brueshaber, Shawn R. Blalock, John J. Ingersoll, Andrew P. Dyudina, Ulyana A. Ewald, Shawn P. |
author_sort |
Tianshu, Liu |
title |
Saturn's north polar vortex structure extracted from cloud images by the optical flow method |
title_short |
Saturn's north polar vortex structure extracted from cloud images by the optical flow method |
title_full |
Saturn's north polar vortex structure extracted from cloud images by the optical flow method |
title_fullStr |
Saturn's north polar vortex structure extracted from cloud images by the optical flow method |
title_full_unstemmed |
Saturn's north polar vortex structure extracted from cloud images by the optical flow method |
title_sort |
saturn's north polar vortex structure extracted from cloud images by the optical flow method |
publisher |
American Geophysical Union |
publishDate |
2019 |
url |
https://authors.library.caltech.edu/99276/ https://authors.library.caltech.edu/99276/2/Liu_et_al-2019-Journal_of_Geophysical_Research__Planets.pdf https://resolver.caltech.edu/CaltechAUTHORS:20191015-133656221 |
geographic |
North Pole |
geographic_facet |
North Pole |
genre |
North Pole |
genre_facet |
North Pole |
op_relation |
https://authors.library.caltech.edu/99276/2/Liu_et_al-2019-Journal_of_Geophysical_Research__Planets.pdf Tianshu, Liu and Sayanagi, Kunio M. and Brueshaber, Shawn R. and Blalock, John J. and Ingersoll, Andrew P. and Dyudina, Ulyana A. and Ewald, Shawn P. (2019) Saturn's north polar vortex structure extracted from cloud images by the optical flow method. Journal of Geophysical Research. Planets, 124 (11). pp. 3041-3062. ISSN 2169-9097. doi:10.1029/2019JE005974. https://resolver.caltech.edu/CaltechAUTHORS:20191015-133656221 <https://resolver.caltech.edu/CaltechAUTHORS:20191015-133656221> |
op_rights |
other |
op_doi |
https://doi.org/10.1029/2019JE005974 |
container_title |
Journal of Geophysical Research: Planets |
container_volume |
124 |
container_issue |
11 |
container_start_page |
3041 |
op_container_end_page |
3062 |
_version_ |
1766140638366007296 |