Monthly gravity field of the Earth
Thematic areas: Geodesy/Gravity
Applicable missions: Swarm
Applicable spacecraft: Swarm-A, Swarm-B, Swarm-C
Monthly average of Earth's gravity field, i.e. with an implicit epoch located at the middle of the calendar month
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| Product identifier | EGF_SHA_2_ |
| Definition | Monthly gravity field of the Earth |
| Input data | GPSA_RO_1B, GPSB_RO_1B, GPSC_RO_1B, STRAATT_1B, STRBATT_1B, STRCATT_1B |
| Input time span | 1 calendar month |
| Spatial representation | Spherical harmonic coefficients |
| Time representation | Monthly average of Earth's gravity field, i.e. with an implicit epoch located at the middle of the calendar month |
| Units | See output data |
| Resolution | 12 significant digits in scientific notation |
| Uncertainty | Typically 1-2 mm geoid height or 1-2 cm Equivalent Water Height discrepancy w.r.t. GRACE over land areas during low solar activity periods, considering Gaussian smoothing with 750km spherical cap radius |
| Quality indicator | RMS over ocean areas that are 6 degrees away from coast lines, after removing long-term trend, annual and semi-annual variations estimated from monthly un-weighted averages of numerous GRACE models (AIUB02, CSR05, GRGS03, ITSG14, GFZ05a, JPL05 and TNJ01) |
| Data volume | 20 Kb |
| Data format | ASCII file with Stokes Coefficients following the ICGEM-format (http://icgem.gfz-potsdam.de/ICGEM-Format-2011.pdf) |
| Output data | Degree, order, cosine coefficient, sine coefficient (columns 5 and 6 set to zero) |
| Output time span | 1 calendar month |
| Update rate | Quarterly |
| Latency | 5 months |
| Notes | - Stokes coefficients available up to degree 40 - No smoothing applied - GRACE comparison indicates that there is little useful geophysical signal above roughly degree 12, i.e. it suggest the signal-to-noise ratio drops below 1 at those degrees and above - Further product details in Swarm ITT1.1 TN-01 |
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