Past missions CalVal orbit ("fast sampling" at 1 day)
Orbit requirements
The initial CalVal phase had a 1 day repeat period orbit, up to July 11th, 2023, for fast sampling to achieve the calibration objectives and study rapidly changing phenomena.
Orbit Characteristics
| Fast-sampling orbit | |
| Repeat orbit parameters (N+P/Q) | 14+0/1 |
| Mean semi-major axis (m) | 7235379.8 |
| Altitude (km)(mean sma minus equ. radius) | 857.244 |
| Inclination (deg) | 77.6 |
| Mean Eccentricity | 0.00105 |
| Number of orbits per cycle | 14 |
| Nodal period (sec) | 6131.25 |
| Exact repeat cycle duration (days) | 0.99349 |
| Longitude gap between 2 consecutive ground tracks (deg) | 25.714 |
| Longitude gap between 2 adjacent ground tracks (deg) | 25.714 |
| Drift of Right Ascension of Ascending Node local time(minutes/day) | -9.44 |
| Duration for 24h Right Ascension of Ascending Node local time change (days) | 152.6 |
*RAAN = Right Ascension of Ascending Node
Reference orbit files
Please find below the reference orbit files for the fast-sampling orbit.
The longitude offset has been chosen so that at 42.5°N, longitude is between 78.2°E and 78.3°E (recommendation of the Swot CalVal group after New York meeting in April 2015)
Ephemeris files (.txt)
Ephemeris in terrestrial frame.
Ephemeris length = one day (86400 seconds), time-step = 30 seconds
- ephem_calval_june2015_pv-v2.txt : position and velocity
=> time (s), x (m), y (m), z (m), vx (m/s), vy (m/s), vz (m/s)
- ephem_calval_june2015_ell-v2.txt : geodetic coordinates (/ WGS84)
=> time (s), longitude (deg), latitude (deg), altitude / ellipsoid (m)
- ephem_calval_june2015_sph-v2.txt : spherical coordinates
=> time (s), longitude (deg), latitude (deg), radius (m)
Ground track and Swath files (kml & shapefile)
Open Ocean (lower resolution "LR") Swot data coverage
- swot_calval_orbit_june2015-v2.kml
- shp_calval_nadir.zip & sph_calval_swath.zip including the shapefiles
Land waters and coastal (higher resolution "HR") Swot data theoretical coverage, 10 s time step
- swot_calval_hr_Dec2022-v07_perPass.kml
- swot_calval_hr_Dec2022-v07_nadir.zip & swot_calval_hr_Dec2022-v07_swath.zip including the shapefiles
Cross-overs times & passes
For each latitude (North as well as South), the number of passes and the time difference between the ascending and the descending passes at the crossovers are computed.
See the kml file for an overview of those crossovers. See also the 'adopt a crossover' initiative website, to participate to calibration campaigns, or see the calval phase ones.
| Latitude (degrees N or S) | minimum Difference in passes | minimum time (s) | minimum time | supplement in passes to the cycle | supplement in time (s) to the cycle | supplement in time to the cycle |
|---|---|---|---|---|---|---|
35.7 | 13 | 38606 | 10h43min26s | 15 | 47231 | 17h07min11s |
61.6 | 11 | 31537 | 08h45min37s | 17 | 54300 | 15h05min00s |
70.2 | 9 | 25058 | 06h57min38s | 19 | 60779 | 16h52min59s |
74.2 | 7 | 18733 | 05h12min13s | 21 | 67104 | 18h38min24s |
76.3 | 5 | 12467 | 03h27min47s | 23 | 73370 | 20h22min50s |
77.3 | 3 | 6229 | 01h43min49s | 25 | 79608 | 22h06min48s |
