Corrected and calibrated accelerometer observations
Citation: Leibniz University Hannover. (2021). SW_ACCxCAL_2_. European Space Agency. https://swarmhandbook.earth.esa.int/catalogue/SW_ACCxCAL_2_
Product types: SW_OPER_ACCACAL_2_, SW_OPER_ACCBCAL_2_, SW_OPER_ACCCCAL_2_
Authored by: Leibniz University Hannover - https://ror.org/0304hq317
Creation year: 2021
Thematic areas: Thermosphere, Acceleration measurements
Applicable missions: Swarm
Applicable spacecraft: Swarm-A, Swarm-C
Time series of corrected and calibrated acceleration, including all corrections and calibration parameters
(delivered separately)
| Variable | Units | Description | Dim | Type |
|---|---|---|---|---|
| time | CDF Epoch (UTC time) | Epoch of observation (UTC) | 1 | CDF_EPOCH |
| a_cal | m/s^2 | Calibrated linear acceleration (X, Y, Z) | 3 | CDF_DOUBLE |
| a_stp | m/s^2 | Step correction for linear accelerations | 3 | CDF_DOUBLE |
| a_tmp | m/s^2 | Temperature correction for linear accelerations | 3 | CDF_DOUBLE |
| a_gg | m/s^2 | Gravity gradient correction for linear accelerations | 3 | CDF_DOUBLE |
| a_ca | m/s^2 | Centrifugal acceleration correction for linear accelerations | 3 | CDF_DOUBLE |
| a_aa | m/s^2 | Angular acceleration correction for linear accelerations | 3 | CDF_DOUBLE |
| s | (m/s^2)/(m/s^2) | Scale factor (time series) for linear accelerations | 3 | CDF_DOUBLE |
| b | m/s^2 | Bias for linear accelerations | 3 | CDF_DOUBLE |
| a_spk | m/s^2 | Spike correction for linear accelerations | 3 | CDF_DOUBLE |
| a_jit | m/s^2 | Voltage jitter correction for linear accelerations | 3 | CDF_DOUBLE |
| a_rh | m/s^2 | Resonant harmonics correction for linear accelerations | 3 | CDF_DOUBLE |
| flag_cor | - | Flag indicating which corrections are applied (combination of corrections is coded in the binary system) | 1 | CDF_UINT2 |
| flag_val | - | Validity flag: 0 = nominal data; 1 = anomalous data | 1 | CDF_UINT2 |
| flag_thr | - | Flag indicating on thrusters’ activity: 0 = inactivated; 1 = activated | 1 | CDF_UINT2 |
| Product identifier | ACCxCAL_2_ |
| Definition | Time series of corrected and calibrated acceleration, including all corrections, flags, and calibration parameters |
| Input Data | ACCx_PR_1B, ACCxPOD_2_, ACCx_FMi2, ACCxDISi2_, MODx_SC_1B, SC_xDYN_1B |
| Input Time Span | 24 hours |
| Spatial representation | Three-dimensional time series along satellite orbit |
| Time representation | UTC |
| Units | m/s2 for accelerations, unitless for scale factors and flags |
| Resolution | 64 bit double precision floating point format |
| Quality indicator | Validation report ACCxVAL_2_
Global attribute "DAILY_QUALITY_INDEX" of Type CDF_REAL, which ranges from 1.0 (good data quality) to 5.0 (bad data quality) |
| Data volume | Up to 5 MB per day |
| Output Data | CDF file with corrected and calibrated accelerations from the accelerometer, all corrections and calibration parameters, and flags; sampling rate is 1 Hz (accelerations are at original measurement epochs in the associated product ACCx_PR_1B) |
| Output time span | 1 day |
| Update rate | 3 months |
| Latency | 1 month |
| Notes | All accelerations are provided in the CRF (x-direction is roughly along-track, y-direction is roughly cross-track, z-direction is roughly nadir).
Calibration was performed against non-gravitational accelerations from POD that are contained in product ACCxPOD_2_, combined with force models that are contained in the product ACCx_FMi2_. Information on data quality and validity and on composition of the validity flag “flag_val” is available in the metadata of the cdf-file. Early versions of this product will contain only along-track acceleration data. |
More details about the corrections and associated flag values can be found in the CDF global attributes.
Variable "flag_cor" assembles corrections: flag a_xxx = 1 (correction applied) or flag a_xxx = 0 (correction not applied), and is coded in the binary system:(flag a_stp = 1)*2^0 + (flag a_tmp = 1)*2^1 + (flag a_gg = 0)*2^2 + (flag a_ca = 0)*2^3 + (flag a_aa = 0)*2^4 + (flag a_spk = 1)*2^5 + (flag a_jit = 1)*2^6 + (flag a_rh = 0/1)*2^7
Related experimental (EXPT) products can be found in the Swarm dissemination server in the directory: Advanced/Accelerometer_Data
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