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README
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University of Bern
Astronomical Institute (AIUB)
Daniel Arnold
daniel.arnold@aiub.unibe.ch
+41 31 684 3802
or:
Adrian Jaeggi
adrian.jaeggi@aiub.unibe.ch
+41 31 684 8596
Address: Sidlerstrasse 5
3012 Bern, Switzerland
Short notice on AIUB GRACE kinematic orbits:
|------------------------------------------------------------------------------|
| Processing strategy |
|-------------------------------------|----------------------------------------|
| Software | Bernese GNSS Software v5.3 |
| GNSS system | GPS |
| Arc length | 1.0 days |
| Reference system | |
| Time | GPS time (GPST) |
| Position | Earth-centered Earth-fixed (see below) |
| Polar motion and UT1 | CODE final products |
| Pole model | IERS 2010 conventions |
| Precession/Nutation | IERS 2010 conventions |
| GPS orbits | CODE final products |
| GPS clocks | CODE final clocks |
| GPS measurements | |
| Observations | Ionosphere-free linear combination of |
| | phase measurements, pseudo-range used |
| | for clock synchronization and wide-lane|
| | ambiguity resolution |
| Sampling | 10s |
| Elevation angle cutoff | 0 deg |
| Antenna offset (w.r.t. CoM) | Time-dependent values |
| GPS antenna phase center var. | Determined for each antenna from |
| | stacking of carrier phase residuals of |
| | reduced-dynamic orbit determination |
| Observation weighting | Constant |
| Antenna phase-center wind-up | Correction applied |
| Relativistic corrections | Applied |
| Solution strategy | Daily least-squares solution based on |
| | data from 00:00:00 to 23:59:59 |
| Estimated parameters | |
| Receiver position | Every epoch |
| Receiver clock correction | Every epoch |
| Carrier phase ambiguities | Float |
|------------------------------------------------------------------------------|
General remarks
===============
This product contains kinematic orbit positions of the GRACE satellites given
in daily batches per single satellite.
File naming convention: GRC_RL_.KIN
: A or B (specifying the corresponding GRACE satellite)
: Release number (see below)
: year (last two digits)
: day of year
Format description
==================
File header:
Line 1: description of orbit including release number and orbit generation date
and time
Line 2: dummy line
Line 3: information about geodetic datum and date & time of first epoch
(GPS time)
Line 4: a posteriori standard deviation of L1 GPS carrier phase res. [m]
Line 5: description of columns
Line 6: dummy line
Data records:
After the header each line represents one epoch. The columns contain the
following quantities:
Column 1: LEO name (GRACE-A: GRCA, GRACE-B: GRCB)
Column 2: modified SVN number (GRACE-A: L09, GRACE-B: L10)
Column 3: GPS week
Column 4: GPS second within the given GPS week [s]
Column 5: position x-component (Earth-centered Earth-fixed) [m]
Column 6: position y-component (Earth-centered Earth-fixed) [m]
Column 7: position z-component (Earth-centered Earth-fixed) [m]
Column 8: quality flag (possible values are K, X, S and G, see below)
Column 9: xx-element of 3x3 epoch-wise cofactor matrix
Column 10: yy-element of 3x3 epoch-wise cofactor matrix
Column 11: zz-element of 3x3 epoch-wise cofactor matrix
Column 12: xy-element of 3x3 epoch-wise cofactor matrix
Column 13: xz-element of 3x3 epoch-wise cofactor matrix
Column 14: yz-element of 3x3 epoch-wise cofactor matrix
Meaning of quality flags:
K: kinematic orbit position could be properly determined
X: kinematic orbit position could not be determined (less than 4 satellites)
S: kinematic orbit position could be determined, but less than 5 satellites
were available
G: kinematic orbit position has been flagged during internal AIUB orbit
screening (if screening applied)
Please note:
- Users who would like to use all available epochs or do their own orbit
screening should use all epochs marked with the flags K or G.
- Users who would like to rely on the internal AIUB orbit screening should use
only epochs marked with flag K.
- It is recommended not to use epochs denoted with the flag S.
Note on cofactors:
Columns 9-14 contain the epoch-wise 3x3 cofactor matrix. In order to compute
the epoch-wise covariance matrix for the positions these cofactors need to
be multiplied by the square of the a posteri RMS value found in line 4 of the
header.
Releases
========
RL01: - Orbits for 01-Apr-2002 (day 02/091) to 31-Oct-2017 (day 17/304) for
GRACE-A and 04-Sep-2017 (day 17/247) for GRACE-B.
- Based on RL02 GRACE GPS and attitude data.
- GPS data not screened for ionosphere-induced artifacts.
- Reference frames (defined by GNSS products):
- 02/091-15/158: IGb08 (EGSIEM-REPRO)
- 15/159-17/028: IGb08 (CODE operational IGS products)
- 17/029-17/304: IGS14 (CODE operational IGS products)
- Kinematic orbit positions not screened for outliers.
- When using these GRACE kinematic orbits, please cite them using the
following reference:
Arnold, Daniel; Jäggi, Adrian (2020). AIUB GRACE kinematic orbits,
release 01. Published by Astronomical Institute, University of Bern.
URL: http://www.aiub.unibe.ch/download/LEO_ORBITS/GRACE;
DOI: 10.48350/158372