SA036-0006
Comparison of ICON O+ density profiles with electron density profiles provided by COSMIC-2 and ground-based ionosondes

Wednesday, 16 December 2020
Poster
Gilles Wautelet, Université de Liège, Liege, Belgium, Benoit A Hubert, University of Liège, Liège, Belgium, Jean-Claude M. C. Gerard, Université de Liège, LPAP - STAR Institute, Liege, Belgium, Thomas J Immel, Univ of California, Berkeley, CA, United States, Harald U Frey, University of California, Berkeley, Space Sciences Laboratory, Berkeley, CA, United States, Stephen B Mende, Univ California, Berkeley, CA, United States, Farzad Kamalabadi, University of Illinois, Department of Electrical and Computer Engineering, Urbana, IL, United States, Ulas Kamaci, University of Illinois, Urbana, IL, United States and Andrew W Stephan, U.S. Naval Research Laboratory, Washington, DC, United States
Abstract:
In October 2019, NASA-ICON was launched to observe the low-latitude ionosphere using in-situ and remote sensing instruments, from a LEO circular orbit at about 595 km altitude. The six satellites of the radio-occultation program COSMIC-2 were also successfully launched and currently provide up to 3000 electron density profiles on a daily basis since October 1, 2019. Besides, the network of ground-based ionosondes is constantly growing and allows retrieving very accurate measurements of the electron density profile up to the peak altitude. These three sources of scientific observation of the Earth ionosphere therefore provide a very complementary set of data.

We compare O+ density profiles provided during nighttime by the ICON-FUV instrument and during daytime by the ICON-EUV instrument against electron density profiles measured by COSMIC-2 and ionosondes. Co-located and simultaneous observations are compared on statistical grounds, and the differences between the several methods are investigated. Particular attention is given to the most important variables, such as the altitude and the density of the F-peak, hmF2 and NmF2. The time interval considered in this study covers the whole ICON data availability period, which started on November 16, 2019. Manual screening and scaling of ionograms is performed to ensure reliable ionosonde data, while COSMIC-2 data are carefully selected using an automatic quality control algorithm.

A particular attention has been brought to the geometry of the observation, because the line-of-sight integration of both airglow and radio-occultation measurements assimilates horizontal and vertical gradients. As a consequence, the local density profiles obtained by inversion of the ICON and COSMIC-2 observation cannot be exactly assimilated to vertical measurements, such as vertical incidence soundings from ionosondes. This slightly limits the reach of the interpretation of the comparison between data of different origin. However, using similar observing geometries, the comparison of ICON and COSMIC-2 data does nevertheless provide very reliable and valuable comparisons.

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