CASSIOPE SPACECRAFT (Swarm-E)
PROCESSED DATA HANDBOOK
e-POP Data Change Log
This table details a summary of the latest changes made to e-POP data files.
| Instrument | Product | Version | Date | Changes |
| Spacecraft | CAS Ephemeris txt | 1.2 | 2022-06-10 | Minor bug fix in calculation of geodetic latitude and altitude. Fixes errors on the order of 0.001 degrees latitude and 0.01 km altitude. |
| Spacecraft | Attitude Quaternions | 2.0 | 2024-01-24 | – Introduced the ‘Sun Vector Spin’ (SVS) frame to smooth out attitude interpolation for times when the spacecraft is spin stabilized (after December 2021) – Updated the star sensor camera mounting quaternion information for improved attitude accuracy. The two camera sensors now agree to within 0.0281 degrees. – Attitudes are now discarded if there are no data points within 3 minutes (down from 10 minutes), fixing issues with bad interpolation during spin stabilized attitudes – Minor adjustments to discard less raw attitude data during processing |
| CER | TEC zip | n/a | 2013-09-13 | Initial version |
| FAI | lv1 h5 | v5.0 | 2021-10-08 | – New format (hdf5) – Image data is now in units of Rayleighs – Files now include latitude and longitude of projection of image onto the Earth at 110 km (NIR) or 220 km (VIS) altitude – Updated ephemeris and attitude data – Now one file per pass rather than one file per image |
| FAI | lv1 h5 | v6.0 | 2023-03-08 | – Change camera source message in attributes from ‘Visible(630 nm)’ to ‘Visible (630 nm)’ – Fixed bug that allowed the projection of FAI image to clip through the earth – Fixed bug that caused double ‘.preliminary’ file names – Updated ephemeris library use to v1.2 – .png files now stored in an unzipped folder |
| GAP | lv1 binary | v2.0 | 2018-06-22 | – Filenames now have a major and minor version number – Data files are now split after two minutes of break rather than twenty – Fixed bug that caused minor loss of data at the end of some files |
| GAP | lv1 binary | v3.1 | 2020-08-25 | Filename now supports the major.minor.reprocessCount versioning standard |
| GAP | LOS_TEC netCDF | v2.1 | 2021-10-26 | Initial version of Line-of-sight TEC |
| GAP | LOS_TEC netCDF | v2.2 | 2023-08-31 | – Replaced cycle slip detection and correction algorithm based on Wide-Lane combination (Blewitt, 1990) with cycle slip detection and correction algorithm based on Melbourne-Wübbena and geometry-free combinations (Sanchez, 2016), which better distinguishes between cycle slips and outliers, and improves cycle slip detection in intervals of high noise and multipath. – Increased threshold of multipath/noise combination (MP1/MP2; Stephens et al. 2011) from 1.5cm to 2.0cm. Data intervals exceeding this threshold are discarded. – Implemented an algorithm to detect and eliminate outliers based on the interquartile rule (https://www.thoughtco.com/what-is-the-interquartile-range-rule-3126244) – Cumulatively, these modifications to the GPS LOSTEC data processing reduce the presence of noise, multipath, and outliers, and reduce the incidence rate of discarding useful data through an improved cycle slip detection algorithm. These changes also provide more accurate phase leveling and receiver differential code bias (DCB) estimation, resulting in more accurate TEC calibration. Blewitt, 1990. An automated editing algorithm for GPS data. Geophysical Research Letters, 17(3), https://doi.org/10.1029/GL017i003p00199. Sanchez, 2016. Design and implementation of cycle-slip detectors for dual-frequency GNSS signals. Master’s Thesis, Universitat Politècnica de Catalunya Barcelonatech, https://upcommons.upc.edu/handle/2117/85776. Stephens, P., Komjathy, A., Wilson, B., & Mannucci, A. (2011). New leveling and bias estimation algorithms for processing COSMIC/FORMOSAT-3 data for slant total electron content. Radio Science, 46, RS0D10. https://doi.org/10.1029/2010RS004588. |
| IRM | SSC h5 | v1.0 | 2021-10-08 | – Initial version of Sensor Skin Current (SSC) h5 product. – Note that this version supercedes the IRM_skin_current lv1 data product which has now been retired. |
| IRM | SSC h5 | v1.1 | 2022-04-20 | eclipse_status and attitude_quality attributes are now returned as lower case strings. |
| MGF | lv1b CDF | v0202 | 2022-05-25 | – New format (Swarm-like CDF) – Complete overhaul of calibration – Now includes flags and quality indicators – Now includes attitude and ephemeris data – Now includes CHAOS model magnetic field values |
| RRI | lv1 h5 | v11.0 | 2021-09-27 | Updated ephemeris and attitude data to match the CAS_Orbit sp3 ephemeris files and CAS_attQuat attitude data. ** THIS VERSION CONTAINS A TIMING BUG IN THE RADIO DATA (times are off by up to one second) ** |
| RRI | lv1 h5 | v12.0 | 2021-10-29 | – Fixed incorrect radio data times – GSM position values are now reported in km |
| RRI | lv1 h5 | v13.0 | 2021-11-17 | Fixed creation of preliminary files for times when the orbit data is not available. |
| RRI | lv1 h5 | v13.1 | 2023-22-02 | Implemented a fix for times when the RRI packet counter reports incorrectly for four packets, causing a timing error of 1.856 milliseconds in subsequent packets. |
| RRI | lv1 h5 | v13.2 | 2024-10-04 | – Added Digital Down Converter Sampling Rate, UTC Time and Ephemeris UTC datasets into the hdf5 files. – Added dataset information as attributes for all hdf5 data. – Fixed an error in the reported Channel A Frequency values (errors on the order of a fraction of a Hz up to 2 Hz). – Updated calibration of the 40 MHz driving clock frequency in RRI resulted in an adjustment to the radio data values by a factor of 1.000005429. |
Data Processing Status
| Changes | Status | Date | Description |
| Full Mission Reprocessing | Completed | 2022-04-06 | Application of the new AttQuat v2.0 attitude solution to the entire mission of all instruments, excluding MGF. Correction of clock drift from 2023-06-22 to 2023-06-29. |
| Ephemeris Reprocessing for June 2024 – March 2025 | Completed | 2025-03-18 | Errors from a data dropout in June 2024 propagated in the ephemeris data products to March 2025. These errors could be quite large (up to thousands of km in some cases) so it is advised to re-download any data retrieved between June 2024 and March 2025. |