ABOUT THIS DATA SET

This is a collection of Saturn ionospheric profiles obtained by radio
occultations of the Cassini spacecraft.  They cover a range of dates
from the first occultation on orbit 7 on May 5, 2005 until the
occultation occuring on the 191st orbit on May 31, 2013.  These have
been previously published in the references given below.  All
occultations after orbit 151 were done in two-way mode, while the
orbits 7 - 151 occultations were done in one-way mode.  All of these
profiles were taken directly from Arv Kliore's original files found
after his death and are unchanged except for the following.

In reproducing some of these results while developing and resurrecting
our own software to continue producing ionospheric profiles from more
recent radio occultation data we discovered that we didn't know what
altitude scale was used.  The publications vaguely mention "altitude
above 1-bar", but when we computed the electron density profiles the
profiles were approximately the same but the peaks were frequently
shifted in altitude from Kliore's results, often by a significant
amount.  Eventually we reproduced every Saturn ionospheric profile
using 2 different methods for the 1-way occultations, and both
techniques (ray tracing using an oblate atmosphere and the
differential frequency techinique using an Abel transform) agreed with
each other in so far as the altitude of the peaks and the electron
density structure.  So in converting Kliore's original files to the
.TAB files archived here, we have introduced an altitude shift.  The
shifted altitudes are now above the NAIF 1 bar reference ellipsoid
with polar radius 54364 km and equatorial radius 60268 km.  The NAIF
1 bar reference ellipsoid can differ by up to 200 km at mid latitudes from the
actual 1 bar surface we find doing inversions of occultation data for
the neutral atmosphere, but we use the NAIF ellipsoid here as a simple
easily reproduced reference altitude.  The shift can be undone to get
back to the original altitude scale by subtracting the ALTITUDE SHIFT
found in the NOTE in the .LBL file associated with the .TAB file.

--
Paul Schinder
Cornell University
February 2018

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References
Moore, L., Galand, M., Kliore, A. J., Nagy, A. F., & O'Donoghue, J., 2017, 
arXiv:1701.05178
Kliore, A. J., Nagy, A., Asmar, S., et al., 2014, GeoRL, 41, 5778
Nagy, A. F., Kliore, A. J., Marouf, E., et al., 2006, Journal of Geophysical 
Research (Space Physics), 111, A06310

