Jupiter horizontal wind velocities at cloud level from Cassini

This dataset contains horizontal wind velocity vectors at the top of Jupiter’s main cloud deck, covering four rotation periods during December 2000.

Click $\rightarrow$ here $\leftarrow$ to access the dataset via ORA-Data.

These wind measurements are based on a series of visible camera images taken by NASA’s Cassini spacecraft. They were analysed using a cloud tracking procedure based on a Correlation Imaging Velocimetry (CIV) method developed to analyse fluid dynamics experiments. The dataset contains 1 123 505 horizontal wind velocity vectors covering 360 degrees in longitude and +/-50 degrees in planetocentric latitude.

During late 2000 NASA’s Cassini spacecraft flew past the planet Jupiter, taking images and other scientific measurements over a several month period up to and after closest approach in early December 2000. The Imaging Science Subsystem (ISS) narrow angle camera (Porco et al., 2004) took data in several filters during this time, covering the whole planet in longitude and latitude. A small subset of these images near closest approach (around 140 Jupiter radii) have been projected onto a System III west longitude / planetocentric latitude grid and been made available to the public via the NASA Planetary Data System.

The procedure used to calculate the wind vectors was fully described by Galperin et al. (2014), and the user is referred to that paper for full details. That paper included, as Supplementary Material, gridded velocity fields in plaintext format, as a function of planetocentric latitude and east longitude, assuming a spherical planet with Jupiter’s mean radius of 69 911 km.

Instead of gridded data, this dataset contains the raw, irregularly spaced, velocity vectors computed by the CIV procedure. This avoids errors introduced by the mosaicing procedure, and hence is a more accurate dataset. It is also more versatile as each velocity vector has its own time associated with it, and users may also wish to combine the vectors in their own way.

Example data from a single image pair. This example shows pair 41, one of the image pairs mainly covering the southern hemisphere, and this one contains the Great Red Spot. White is eastward and northward, and black is westward and southward.

example_pair.2.pngexample_pair.3.png

The dataset also includes a Python script to convert the velocity vectors from spherical geometry to oblate spheroidal geometry, and to estimate observational uncertainties.

The dataset is held by ORA-Data and is licensed under ODC-By v1.0.

Citation

Please cite the dataset as

Young, R.M.B., Read, P.L., Armstrong, D. & Lancaster, A.J. (2017) Jupiter horizontal wind velocities at cloud level from Cassini [data-set]. Oxford: Oxford University Research Archive [distributor] $<$DOI 10.5287/bodleian:D5oVPJVRv$>$.

Contacts

Roland M. B. Young roland.young [at] physics.ox.ac.uk University of Oxford (UK)
Peter L. Read peter.read [at] physics.ox.ac.uk University of Oxford (UK)