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Global Earth Gravity Field Supply Chain
EGV (Essential Geodetic Variable) Level: 3 — Global · Physical | Date: September 2026 | Version: 5.1
Reference: EGV White Paper V7.0 (GGOS — Global Geodetic Observing System, January 2026) · Guiding Principles v4.6 · 1st Joint Development Plan (JDP)
Major revisions:
- v5.1 — Replaced two raw filename references (the v5.0 entry below, and the
[^jpl-workforce]footnote) with working links to the hosted portal (un-ggce.merchantsofmalta.com). Part of a sweep across the whole deliverable set for the same issue, per the user's request. - v3.4 — Renamed the per-capability "Phase 1/2/3" priority tag to "Horizon 1/2/3", matching the framework used throughout Work Assignment 1b.
- v3.6 — Added the Capability Evidence Trail (confirmed / asserted / considered / queued), extending the method piloted on the Satellite Orbits annex.
- v3.7 — Corrected a spatial-resolution error: degree/order 2190 gravity models' 5 arc-minute grid spacing had been mischaracterised as "approximately five kilometres," conflating an angular grid spacing with a linear distance (correct equivalent: approximately 9 km at the equator).
- v3.9 — Incorporated previously-unaddressed 2025 Los Angeles wildfire and NASA JPL workforce-reduction evidence into the Tier 1–2 narrative and Evidence Trail (Confirmed count 16 → 14 of 16).
- v4.0 — Corrected the explanation for the Training and Education capability's 1.70 → 1.25 correction, traced via git history to State of Geodesy 2026's own originally-published figure rather than the rubric-derived convention the note had attributed it to.
- v5.0 — Converted from the retired five-tier structure to nine real functions (F1...F9), following Work Assignment 2 v5.0's precedent and its own external validation pass (full findings). Tier 0 splits into F1 (Satellite Gravimetry Mission Operations) and F2 (Terrestrial, Airborne & Marine Acquisition) — the two acquisition streams share the same PPTD basis (not yet separately assessed by State of Geodesy 2026) but face materially different risks, GRACE-FO mission continuity for F1 versus geographic coverage gaps for F2, and are kept as one function no longer. Tier 1's satellite and surface archives combine into F3 (Dual-Stream Archiving & Collation). Tier 2 splits three ways: satellite processing becomes F4 (Satellite Gravity Processing, Level-2), surface processing becomes F6 (Surface Gravity Anomaly Harmonization) — sharing F4's PPTD basis — and the COST-G time-variable combination description embedded in Tier 2's and Tier 3's prose is consolidated into a newly separated F5 (Time-Variable Gravity Combination, COST-G/AIUB Bern). The prior grouping treated all combination work as one "Geoid Model Development" function; the real pipeline runs two organisationally distinct combination services on different cadences — COST-G's operational monthly combination (F5) and the decade-scale static ultra-high-degree combination, now F7 (Ultra-High-Degree Global Combination, NGA/GFZ/TU Munich) — with materially different institutional redundancy: F5's multiple-independent-centres-feeding-one-service model is, in its own right, the most structurally sound element of this entire supply chain, a finding the prior bundled structure did not surface distinctly. Tier 4 splits into F8 (Geoid Model Evaluation & Benchmark Validation) and F9 (Model Archiving & Dissemination, ICGEM) — validation and distribution are organisationally distinct activities the prior structure combined. F5 and F8 carry no currently-scored capability — genuine coverage gaps, not silently absorbed into F7 or F9. Matching Work Assignment 2 v4.0/v6.0's precedent, removed the retired Tier Risk Score / PPTD Gap × Step Criticality apparatus and the per-capability Horizon 1/2/3 tag throughout — PPTD scores are shown as descriptive context only. Corrected the PPTD averaging convention to exclude not-applicable dimensions rather than scoring them 0, per Work Assignment 1b v7.0 Annex A.2 — Equipment Calibration and Maintenance's average moves from 2.50 to 3.33 (Data excluded) and Training and Education's from 1.25 to 1.67 (Data excluded), the same two corrections already applied to the other three converted annexes. Also carried Metadata Management forward into F3, which Work Assignment 2's own summary table for F3 currently omits (it lists only Data Quality Management, Data Preservation, and Data Sharing) — this annex's own Tier 1 table has always scored it, and the "16 of 58" capability count this document has carried since v3.6 already included it; flagged for Work Assignment 2 to reconcile rather than silently dropped here.
Subsequent versions applied editorial and terminology consistency fixes only unless otherwise noted above.
PPTD (People, Process, Technology, Data) scores: State of Geodesy 2026 — A baseline maturity assessment (UN-GGCE, 16 March 2026)[^sog2026]
Audience
This document serves two readerships: (1) UN-GGCE leadership and technical counterparts already familiar with this engagement; and (2) UN-GGCE staff and Member State stakeholders new to this specific analysis. Readers new to the engagement should read this Purpose & Reading Guide; the function-by-function detail that follows supports the summary findings reported in the Work Assignment 2 and Work Assignment 3 reports.
Purpose & Reading Guide
This is one of five technical workflow descriptions supporting Work Assignment 2 of the UN-GGCE Global Geodesy Supply Chain Assessment (Terms of Reference 2). It maps, function by function, how the Global Earth Gravity Field models are produced — the institutions involved, the capabilities each step depends on, and where the production chain is most exposed to failure.
Companion Documents
Readers new to this engagement should start with the Critical Product Mapping Report (Work Assignment 2), which maps this product's functions to capabilities, organisations and information artifacts at summary level; the Investment Prioritization and Risk Rubric (Work Assignment 1b), which defines the risk-scoring method; and the EGV Data Levels and Supply Chain Tiers appendix (Work Assignment 1 Appendix), which explains the underlying data-level structure this document's functions are keyed to.
Overview
The Global Earth Gravity Field is a Level 3 Essential Geodetic Variable within the physical subdomain of the GGOS EGV framework. It encompasses Global Gravity Field Models (GGM) — mathematical representations of the Earth's gravitational potential expressed as spherical harmonic series. These models define the geoid: the equipotential surface of the Earth's gravity field that best approximates global mean sea level. The geoid is the physical reference surface against which all height measurements worldwide are ultimately compared and unified. Realising a globally consistent, centimetre-accurate geoid is the prerequisite for a unified global height reference system and is identified in UN General Assembly Resolution 69/266[^unga69266] as a foundational element of sustainable development.
The supply chain producing this EGV is bifurcated at its most fundamental level. Dedicated satellite gravimetry missions — principally GRACE-FO (a joint mission of NASA, the National Aeronautics and Space Administration, and GFZ, the German Research Centre for Geosciences), the ESA (European Space Agency) GOCE mission (which operated from 2009 to 2013), and the earlier CHAMP mission — provide continuous, homogeneous, global coverage of the long-to-medium wavelength components of the gravity field. These missions sense gravity through orbital perturbations and, in GOCE's case, direct gravity gradiometry measurements. They constitute the only practical means of obtaining global gravity coverage with uniform accuracy. Surface gravity observations — terrestrial gravimeter networks, airborne gravity surveys over mountainous and polar terrain, and shipborne campaigns over the ocean — provide the high-frequency, short-wavelength detail that satellite missions cannot resolve. These two data streams must be combined to produce the ultra-high-degree spherical harmonic models that underpin operational geoid modelling. The combination is technically complex, computationally intensive, and depends on institutional capacity concentrated in a very small number of organisations worldwide.
The EGV White Paper V7.0 (GGOS, January 2026) formalises two changes directly relevant to this supply chain. First, the former "Level 0" stratum is redesignated as the Basis level, encompassing Geodetic Infrastructure and Geodetic Standards and Conventions. Second, a new Level 1 EGV — Geodetic Observations — is introduced; it includes satellite gravity gradiometry, gravimetry, and atomic clock frequencies as observable quantities. Upstream of the Level 3 Global Earth Gravity Field, this supply chain therefore draws from Level 1 Geodetic Observations (satellite and surface gravity measurements) and passes through the Level 2 EGV Land and Marine Gravity Data (standardised gravity anomalies). V7.0 also introduces two new Level 3 EGVs — Regional Reference Frames and Regional Gravity Field Model — that depend directly on the outputs of this pipeline. Those downstream EGVs are noted as co-produced variables outside the scope of this supply chain description.
Co-Produced EGVs
| EGV | Level | Mechanism |
|---|---|---|
| Sea Level and Sea Surface | 3 | Essential for computing Mean Dynamic Topography from satellite altimetry; the geoid provides the reference surface |
| Terrestrial Water Storage | 3 | Time-variable gravity directly observes mass transport — groundwater depletion, aquifer recharge, and river basin hydrological change |
| Ice Sheets | 3 | GRACE-FO monthly gravity solutions directly measure ice mass change in Greenland and Antarctica |
| Regional Reference Frames | 3 | Regional geoid models underpin physical height systems; new in EGV White Paper V7.0 |
| Regional Gravity Field Model | 3 | Regional densification of global gravity models for national and sub-continental surveying applications; new in EGV White Paper V7.0 |
Governance
| Institution | Role | Risk Level |
|---|---|---|
| International Gravity Field Service (IGFS / IAG — International Association of Geodesy) | Coordinates the collection, validation, and distribution of gravity data and models under the IAG umbrella | Medium |
| Bureau Gravimétrique International (BGI) | Archives and distributes surface and absolute gravity data on a largely voluntary, in-kind basis | Medium |
| ICGEM (International Centre for Global Earth Models; GFZ Potsdam, Germany) | Collects, evaluates, and distributes global gravity field models through a publicly accessible, FAIR (Findable, Accessible, Interoperable, Reusable)-compliant portal | Low |
| COST-G (IAG Combination Service for Time-variable Gravity Fields; AIUB, Bern, Switzerland) | Independently combines monthly time-variable gravity fields from multiple satellite analysis centres | Medium |
| NASA's Jet Propulsion Laboratory (JPL) / CSR (Centre for Space Research, University of Texas) / GFZ | Primary GRACE-FO science analysis centres; producers of the definitive monthly Level-2 gravity solutions | High |
The Risk Level column above is a separate, qualitative institutional judgement about each organisation's structural position in the supply chain.
Supply Chain
Note on PPTD tables below: averages exclude not-applicable dimensions (marked N/A) rather than scoring them 0, per Work Assignment 1b v7.0 Annex A.2. Dimensionality (how many of the four dimensions apply) is shown alongside each average. ⚠ flags a capability whose corrected average falls below 2.5.
F1 — Satellite Gravimetry Mission Operations
Data level: Basis → Level 1 EGV (Geodetic Observations — Geodetic Physical Observations) — raw gravity measurements from satellite missions.
Satellite gravimetry missions — GRACE-FO (2018–present, NASA/GFZ), GOCE (2009–2013, ESA), and CHAMP (2000–2010, GFZ) — sense gravity through precision measurements of inter-satellite range-rate (GRACE-FO), gravity gradients (GOCE), or orbital perturbations (CHAMP). These missions provide the only means of achieving consistent, continuous, globally uniform gravity field sampling at long and medium wavelengths. Their data forms the homogeneous backbone without which a physically meaningful global geoid cannot be realised. The GRACE-FO mission is particularly critical for time-variable gravity: it produces monthly solutions that directly quantify changes in terrestrial water storage, ice mass loss, and ocean bottom pressure at spatial scales of several hundred kilometres.
The most acute systemic risk at this function is the absence of a confirmed, funded successor to the GRACE-FO mission. GRACE-FO's nominal operational lifetime and the budgetary timelines of its successor — provisionally designated GRACE-C or its equivalent — leave a credible gap scenario in which time-variable gravity monitoring is interrupted for a period of years. This risk is formally identified as WA3 Gap 6 within the present engagement. An interruption comparable to the 11-month gap between the end of GRACE and the launch of GRACE-FO (2017–2018) would degrade the temporal continuity of all downstream EGVs that depend on monthly gravity solutions, including Terrestrial Water Storage and Ice Sheets. No surface-based network (F2) can substitute for the global coverage provided by a satellite gravimetry pair.
Risk: High — GRACE-FO has no confirmed funded successor mission, creating a satellite gravimetry continuity risk that would degrade time-variable gravity monitoring across multiple downstream EGVs (WA3 Gap 6). (Principle 5: Minimum Capability Maturity) recommends that formalised national backing for mission-critical space infrastructure be demonstrated before it can be classified as a reliable supply chain input, and no Member State or agency has yet provided such formalisation for a successor gravimetry mission.
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| Gravity Data Acquisition and Storage | 2.00 | 4.00 | 4.00 | 3.00 | 4 of 4 | 3.25 |
| Ground-Based Asset Management | 3.00 | 2.00 | 2.00 | 3.00 | 4 of 4 | 2.50 |
| Equipment Calibration and Maintenance | 4.00 | 3.00 | 3.00 | N/A | 3 of 4 | 3.33 |
Note on this table: shared PPTD basis with F2 below — not yet separately assessed per stream.
(Source: State of Geodesy 2026, re-verified against the live capability-maturity graph 2026-08-29)
F2 — Terrestrial, Airborne & Marine Acquisition
Data level: Basis → Level 1 EGV (Geodetic Observations — Geodetic Physical Observations) — raw gravity measurements from surface campaigns.
Surface gravity campaigns complement the satellite record by providing the short-wavelength, high-resolution measurements that satellite missions cannot resolve. Terrestrial gravimeter networks — operated by national mapping agencies, geological surveys, universities, and in some cases commercial entities for resource exploration — form the densest component. Airborne gravimetry is deployed to cover mountainous terrain, remote polar regions, and areas where ground access is impractical. Shipborne surveys contribute to marine coverage, particularly in polar and shallow-water areas not sampled by satellite radar altimetry. Together, these sources are essential for bringing global geoid models to the centimetre accuracy required by practical surveying and vertical datum unification.
The spatial distribution of surface gravity data is profoundly uneven. High-density coverage exists across North America, Western Europe, Australia, and parts of East Asia. Across large areas of Sub-Saharan Africa, parts of South and Central Asia, the Amazon basin, and much of the polar regions, surface gravity campaigns are sparse or entirely absent. This distributional inequity is a structural limitation that directly prevents accurate local geoid modelling in precisely those developing regions where improved height reference systems would have the greatest development impact — a failure against (Principle 1: Geographic Distribution for Technical Performance), which recommends that observatory distribution be driven by the technical demands of EGV products. Data densification in these regions requires coordinated investment in both instrumentation and observation campaign capacity.
Risk: High — Surface gravity coverage is extremely uneven globally, with entire regions of the developing world sparse or absent from the record. Unlike F1, this function has no single-point mission-continuity risk, but its geographic distribution gap is a direct and unresolved failure against (Principle 1: Geographic Distribution for Technical Performance).
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| Gravity Data Acquisition and Storage | 2.00 | 4.00 | 4.00 | 3.00 | 4 of 4 | 3.25 |
| Ground-Based Asset Management | 3.00 | 2.00 | 2.00 | 3.00 | 4 of 4 | 2.50 |
| Equipment Calibration and Maintenance | 4.00 | 3.00 | 3.00 | N/A | 3 of 4 | 3.33 |
Note on this table: shared PPTD basis with F1 above — see note there. These averages reflect a blend of satellite- and surface-relevant evidence and do not yet separately capture F2's own, more severe, geographic coverage gap described in the narrative above.
(Source: State of Geodesy 2026, re-verified against the live capability-maturity graph 2026-08-29)
F3 — Dual-Stream Archiving & Collation
Data level: Level 1 EGV (Geodetic Observations) — calibrated gravity anomalies and Level-1b satellite mission data ingested to archives.
Satellite gravity data flows through dedicated institutional archives operated by the sponsoring space agencies. GRACE-FO Level-1b data and Level-2 monthly solutions are distributed through NASA's Physical Oceanography Distributed Active Archive Centre (PO.DAAC) and the GFZ data portal. ESA's GOCE data products remain accessible through ESA's Earth Online infrastructure. These archives are mature, maintained, and generally FAIR-compliant, reflecting the data management standards of major civil space agencies. Their continuity is nonetheless contingent on sustained national space agency budgets and on the active maintenance of archive infrastructure that was designed for specific mission timescales.
PO.DAAC operates from the Jet Propulsion Laboratory (JPL) campus in Pasadena, California, which experienced a documented six-day network and power disruption during the January 2025 Los Angeles wildfires.[^jpl-wildfire] No GRACE-FO archive outage attributable to the wildfires has been documented. The event demonstrates a physical single-site vulnerability shared by JPL-hosted infrastructure generally.
Surface gravity data is collated by the Bureau Gravimétrique International (BGI) on a largely voluntary, in-kind basis. Member nations contribute data according to bilateral agreements and national policies. The result is an archive of highly variable completeness and quality: dense and well-documented for some regions, absent or fragmentary for others. BGI performs quality checking and standardisation, but its capacity to impose consistent data standards across contributing nations is limited by the voluntary nature of the arrangement and the absence of a formal, legally binding data sharing obligation for Member States.
A structural data access gap persists across this function. A significant fraction of historical terrestrial gravity data — particularly measurements collected during resource exploration activities by oil and gas companies, and gravity surveys conducted by national military or intelligence agencies — remains restricted or classified. This data is commercially or strategically sensitive, and its owners have neither the legal obligation nor the institutional incentive to share it through international channels. The practical consequence is that BGI's archive underrepresents the actual density of historical gravity measurements in several regions, including parts of the Middle East, the former Soviet Union, and areas of active hydrocarbon production. This structural restriction is incompatible with the FAIR data principles recommended under JDP Objective 1.2 and does not meet the recommended target under (Principle 4: Technical Interoperability and Data Accessibility); it would benefit from sustained diplomatic and policy engagement at the intergovernmental level under (Principle 3: Centralised Accountability through Multilateral Governance).
Risk: Medium — Variable quality in surface gravity archives; significant historical data remains restricted or privately siloed, preventing FAIR compliance and limiting the accuracy of geoid models in data-sparse regions.
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| Data Quality Management | 2.00 | 2.00 | 1.00 | 3.00 | 4 of 4 | 2.00 ⚠ |
| Metadata Management | 2.00 | 2.00 | 1.00 | 3.00 | 4 of 4 | 2.00 ⚠ |
| Data Preservation | 2.00 | 2.00 | 2.00 | 2.00 | 4 of 4 | 2.00 ⚠ |
| Data Sharing | 3.00 | 4.00 | 2.00 | 3.00 | 4 of 4 | 3.00 |
Note on this table: Metadata Management is carried here per this document's own established scoring (see v5.0 changelog note above) though Work Assignment 2's current summary table for F3 omits it — flagged for reconciliation there. Data Sharing is shared with F9's table below.
(Source: State of Geodesy 2026, re-verified against the live capability-maturity graph 2026-08-29)
F4 — Satellite Gravity Processing (Level-2)
Data level: Level 1 → Level 2 EGV (Land and Marine Gravity Data, satellite stream) — calibrated satellite-derived monthly Level-2 solutions.
GRACE-FO Level-1b data is processed into monthly static gravity solutions independently by three primary analysis centres: the Centre for Space Research (CSR) at the University of Texas at Austin, NASA's Jet Propulsion Laboratory (JPL), and the GFZ German Research Centre for Geosciences in Potsdam. Each centre applies its own independently developed algorithms, software, and background model choices. This algorithmic diversity is a recognised strength of the system: independent solutions enable cross-validation and reduce the risk that a systematic error in any single processing chain propagates undetected into the official products; the combination of these independent solutions into a single evaluated product is COST-G's function, described separately at F5.
JPL's total workforce fell by approximately 25% across four rounds of layoffs in 2024–2025, including DOGE-related reductions beginning February 2025.[^jpl-workforce] No degradation in JPL's GRACE-FO Level-2 solution delivery attributable to these reductions has been documented. The reduction concentrates additional capacity risk in one of only three institutions capable of producing an independent GRACE-FO solution.
The global pool of professionals possessing the theoretical background and practical experience required to perform geoid model development is both limited and, on the evidence of declining academic programme enrolments, actively contracting. The capability maturity assessment scores Training and Education at 1.67, reflecting a genuine capacity constraint shared with F6 below. This is a structural risk that compounds over time: as the cohort of practitioners who produced EGM2008 and similar models approaches retirement, the institutional knowledge required to produce their successors is concentrated in an ever-smaller group of individuals, not adequately captured in documentation or reproducible workflows.
Software diversity exists across satellite processing, with multiple independently developed processing packages in use (including proprietary tools at NGA (National Geospatial-Intelligence Agency), GFZ, and TU Munich (Technical University of Munich), and open-source or research codes at various universities). Where a national agency's processing capability depends on a single specialist or a bespoke tool maintained by one individual, that agency's contribution to the global network is contingent on that individual's continued availability — a key-person risk formally identified in the capability maturity model under Geodetic Software and Tools. (Principle 5: Minimum Capability Maturity) applies directly: entities that cannot demonstrate workforce resilience and succession documentation should not be designated as primary providers in the production chain.
Risk: High — Satellite Level-2 processing is concentrated in exactly three institutions, one of which (JPL) sustained a substantial 2024–2025 workforce reduction; the global pool of professionals capable of this work is limited and decreasing, a structural succession risk shared with F6.
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| Gravity Data Processing and Analysis | 3.00 | 3.00 | 2.00 | 3.00 | 4 of 4 | 2.75 |
| Geodetic Software and Tools | 2.00 | 3.00 | 1.00 | 2.00 | 4 of 4 | 2.00 ⚠ |
| Training and Education | 2.00 | 1.00 | 2.00 | N/A | 3 of 4 | 1.67 ⚠ |
Note on this table: shared PPTD basis with F6 below — not yet separately assessed per stream.
(Source: State of Geodesy 2026, re-verified against the live capability-maturity graph 2026-08-29)
F5 — Time-Variable Gravity Combination (COST-G)
Data level: Level 2 → Level 3 EGV transition (time-variable component) — the combined monthly time-variable gravity solution.
COST-G, the IAG's Combination Service for Time-variable Gravity Fields, hosted at AIUB (Astronomical Institute, University of Bern, Switzerland), coordinates and produces the combined monthly time-variable gravity solution. It independently receives solutions from CSR, JPL, GFZ (F4), and additional contributing centres, applies a rigorous weighting and combination procedure, and releases a single evaluated combined product. This governance model — multiple independent contributing centres feeding a single coordination service — is the most structurally sound element of the entire gravity supply chain. The diversity of contributing algorithms means that no single organisation's processing failure will disrupt the combined time-variable product.
No capability in the current 58-capability State of Geodesy 2026 model is scored specifically against this function. This is a genuine coverage gap, not a function with a low score — the maturity evidence that exists for gravity processing (F4/F6's Gravity Data Processing and Analysis, Geodetic Software and Tools, Training and Education) describes the contributing analysis centres, not COST-G's own combination operation at AIUB. Matching Work Assignment 2's own treatment of this same gap, it is flagged here rather than silently absorbed into F4's or F7's tables.
Risk: Low, structurally — the multiple-independent-centres-feeding-one-service architecture is a genuine resilience strength, the strongest in this document. No capability data exists to support a numeric rating; the qualitative finding is nonetheless positive and is stated as such rather than left as "not assessed."
(No capability table — see note above.)
F6 — Surface Gravity Anomaly Harmonization
Data level: Level 1 → Level 2 EGV (Land and Marine Gravity Data, surface stream) — standardised gravity anomalies.
National geodetic agencies, university research groups, and specialist commercial consultancies process surface, airborne, and shipborne gravimetry data into standardised gravity anomalies — free-air and Bouguer reductions applied to raw observed gravity values referenced to the international gravity formula. This processing work is largely decentralised and depends on the capacity of individual national institutions. The methodological standards, software toolchains, and quality control practices applied vary significantly across agencies, with well-resourced national mapping agencies in Europe, North America, and Australia maintaining high standards, while many developing-country agencies lack the specialist personnel or software licences required to process their own national data to international standards.
The training and knowledge-fragility risk described at F4 applies with equal or greater force here: the specialist capacity gap is particularly acute among developing-country agencies attempting to process their own national surface gravity data to international standards without dedicated personnel or software licences.
Risk: High — Surface gravity anomaly harmonization is largely decentralised across national institutions of widely varying capacity; the capacity challenge is particularly acute in developing countries and represents a structural succession risk shared with F4.
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| Gravity Data Processing and Analysis | 3.00 | 3.00 | 2.00 | 3.00 | 4 of 4 | 2.75 |
| Geodetic Software and Tools | 2.00 | 3.00 | 1.00 | 2.00 | 4 of 4 | 2.00 ⚠ |
| Training and Education | 2.00 | 1.00 | 2.00 | N/A | 3 of 4 | 1.67 ⚠ |
Note on this table: shared PPTD basis with F4 above — see note there.
(Source: State of Geodesy 2026, re-verified against the live capability-maturity graph 2026-08-29)
F7 — Ultra-High-Degree Global Combination
Data level: Level 3 EGV (Global Earth Gravity Field) — ultra-high-degree spherical harmonic gravity field models combining satellite and surface data.
This function is the central scientific achievement of the supply chain: the merger of the spatially homogeneous but spectrally limited satellite-only gravity models (F4) with the high-resolution but spatially heterogeneous surface gravity anomaly datasets (F6). The resulting ultra-high-degree spherical harmonic models — of which the Earth Gravitational Model 2008 (EGM2008, developed by NGA to degree and order 2190) and its successor candidate XGM2019 (TU Munich/GFZ, degree 2190) are the most operationally significant — encode the gravity field at a 5 arc-minute grid spacing (approximately 9 km at the equator), the standard EGM2008/XGM2019 convention for a degree/order 2190 model. These models are used to compute geoid undulations at any point on Earth, providing the physical height reference that underpins all precision surveying, civil engineering, oceanography, and vertical datum work globally.
The production of a high-degree combined static model is a decade-scale institutional undertaking of extraordinary complexity, structurally distinct from F5's operational monthly cadence. EGM2008 required the integration of satellite data from GRACE, marine altimetry-derived gravity anomalies, and terrestrial gravity datasets from more than a hundred countries, processed over several years with proprietary algorithms at NGA and with extensive international collaboration. No global geodetic institution other than NGA (USA), GFZ (Germany), and TU Munich (Germany) currently possesses the combination of data access, computational resources, specialist personnel, and institutional mandate required to produce a comparable model. The subsequent generation — dependent on GOCE data for its high-frequency satellite contribution — has advanced the state of the art but has not substantively broadened the institutional base capable of leading such an effort.
This institutional concentration creates a knowledge management risk that is assessed as critical. The Knowledge Management capability is scored at 1.25 — reflecting limited documentation of combination workflows, no centralised knowledge repositories accessible to the broader community, and key dependencies on individuals approaching retirement. Were a leading combination centre to lose institutional mandate or funding, the geodetic community would have no clear succession arrangement to maintain the production of next-generation ultra-high-degree models. (Principle 3: Centralised Accountability through Multilateral Governance) recommends that a designated body hold formal accountability for the continuation of ultra-high-degree model production. The absence of a transition plan for this capability also conflicts with (Principle 6: Transparency, Monitoring and Performance Assurance), which recommends that systemic vulnerabilities be proactively identified and communicated to Member States.
Risk: Medium — Ultra-high-degree model computation is an infrequent, institutionally concentrated undertaking; the knowledge required to produce successor models is concentrated in very few agencies globally and is inadequately documented or transferred. This is the most organisationally exposed function in this workflow.
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| Geodetic Data Products | 2.00 | 3.00 | 3.00 | 3.00 | 4 of 4 | 2.75 |
| Research and Development Prototyping | 3.00 | 3.00 | 3.00 | 3.00 | 4 of 4 | 3.00 |
| Knowledge Management | 1.00 | 2.00 | 1.00 | 1.00 | 4 of 4 | 1.25 ⚠ |
| Research and Development Planning | 2.00 | 1.00 | 2.00 | 1.00 | 4 of 4 | 1.50 ⚠ |
(Source: State of Geodesy 2026, re-verified against the live capability-maturity graph 2026-08-29)
F8 — Geoid Model Evaluation & Benchmark Validation
Data level: Level 3 EGV (pre-dissemination) — independent validation of candidate models before publication.
Validation of gravity models is conducted both internally — through residual analysis against independent surface gravity data and GPS-levelling comparisons — and externally through independent computation by research groups using alternative software implementations. The geodetically relevant quality indicator for a combined global model is the standard deviation of geoid undulation residuals against GPS-levelling benchmarks, a metric that has improved progressively from approximately one metre (EGM96) to approximately 0.2 metres globally (EGM2008) to below 0.1 metres in well-surveyed regions with high-resolution input data. This validation work is coordinated by IGFS/IAG Commission 2, national geodetic agencies, and academic evaluation teams, working from ICGEM's (F9) published comparison and evaluation reports.
No capability in the current 58-capability model is scored against this function. This is a genuine coverage gap, not a function with a low score — despite real, substantive validation activity described above, no dedicated evaluation/validation capability currently exists in the State of Geodesy 2026 model to measure it. Matching Work Assignment 2's own treatment of this same gap, it is flagged here rather than silently absorbed into F7's or F9's tables.
Risk: Not assessed — no capability data exists to support a numeric risk rating, despite substantive, real validation activity being documented above. The absence of any scored capability for this function is itself a finding.
(No capability table — see note above.)
F9 — Model Archiving & Dissemination
Data level: Level 3 EGV (validated Global Earth Gravity Field models) — published gravity field models distributed via ICGEM.
The International Centre for Global Earth Models (ICGEM), hosted and operated by GFZ Potsdam, functions as the definitive global clearinghouse for gravity field model evaluation and distribution. ICGEM maintains a comprehensive catalogue of global and regional gravity field models, provides interactive online calculation services that allow users to compute geoid undulations, gravity anomalies, gravity disturbances, and other gravity field functionals directly from spherical harmonic coefficients at user-specified locations and resolutions, and publishes the model comparison and evaluation reports produced at F8. The service is publicly accessible without registration and conforms to FAIR data principles.
The principal risk at this function is structural. ICGEM's operation is funded through GFZ's institutional budget, which is in turn supported by the German Federal Ministry of Education and Research and the Helmholtz Association. There is no formal multilateral service level agreement governing ICGEM's continued operation, no formal succession arrangement designating an alternative host institution, and no pooled international funding mechanism that would sustain the service in the event of a GFZ budget reduction or institutional restructuring. As with other IAG Services that rely on in-kind contributions from host institutions, this arrangement has functioned well historically but does not meet the standard of formalised operational continuity recommended under JDP Objective 1.1 and (Principle 3: Centralised Accountability through Multilateral Governance). (Principle 6: Transparency, Monitoring and Performance Assurance) recommends that ICGEM's operational status be subject to formal monitoring and that a designated successor institution be identified and agreed before any disruption occurs.
Risk: Low — ICGEM provides a robust, FAIR-compliant distribution mechanism; the principal gap is its dependence on GFZ institutional funding with no formal global SLA, succession plan, or pooled funding arrangement.
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| Geodetic Services | 2.00 | 2.00 | 2.00 | 2.00 | 4 of 4 | 2.00 ⚠ |
| Data Distribution | 2.00 | 2.00 | 1.00 | 3.00 | 4 of 4 | 2.00 ⚠ |
| Data Sharing | 3.00 | 4.00 | 2.00 | 3.00 | 4 of 4 | 3.00 |
Note on this table: Data Sharing is shared with F3's table above — the same underlying score applies to both functions, not a duplicated assessment.
(Source: State of Geodesy 2026, re-verified against the live capability-maturity graph 2026-08-29)
Capability Evidence Trail
Applying the confirmed/asserted/considered/queued method piloted on the Satellite Orbits annex. Every capability that appears in this document's function tables — 16 of the 58-capability model (Data Sharing shared across F3 and F9; Ground-Based Asset Management, Equipment Calibration and Maintenance, and Gravity Data Acquisition and Storage each shared across F1 and F2; Training and Education, Geodetic Software and Tools, and Gravity Data Processing and Analysis each shared across F4 and F6) — is classified below by how it got its score. This is the starting draft the Technical Product Working Group is expected to confirm or challenge.
Confirmed — cited directly in this annex's function tables, at the shared State of Geodesy 2026 baseline, with no product-specific departure asserted (14 of 16 capabilities currently in this document):
- F1/F2 (3, shared): Gravity Data Acquisition and Storage, Ground-Based Asset Management, Equipment Calibration and Maintenance
- F3 (3, of 4 — see Considered below for the fourth): Data Quality Management, Metadata Management (flagged separately as omitted from Work Assignment 2's current F3 summary — see F3 above), Data Sharing
- F4/F6 (3, shared): Gravity Data Processing and Analysis, Geodetic Software and Tools, Training and Education
- F7 (3, of 4 — see Considered below for the fourth): Geodetic Data Products, Research and Development Prototyping, Research and Development Planning
- F9 (2, net new beyond F3's shared Data Sharing): Geodetic Services, Data Distribution (flagged separately as excluded from the retired Gap calculation — carried forward here for record only)
Asserted — none. No capability in this annex currently carries a product-specific numeric departure from the shared baseline.
Considered and not asserted — evidence exists but doesn't cleanly support a departure (2 of 16):
- Data Preservation (F3, avg 2.00) — PO.DAAC, the primary GRACE-FO Level-1b/Level-2 archive, operates from the same Jet Propulsion Laboratory campus that experienced a documented six-day network and power disruption during the January 2025 Los Angeles wildfires.[^jpl-wildfire] No GRACE-FO archive outage attributable to the wildfires has been documented. This is real, specific evidence of a physical single-site vulnerability; a confirmed archive-level impact would be needed to move the score, and a Technical Product Working Group member closer to PO.DAAC's actual disruption record could establish whether one occurred.
- Knowledge Management (F7, avg 1.25) — JPL, one of only three primary GRACE-FO analysis centres, lost approximately 25% of its total workforce across four rounds of layoffs in 2024–2025, including DOGE-related reductions beginning February 2025.[^jpl-workforce] Specific, sourced, and lands directly on one of the institutions this capability depends on. Already the joint-lowest score in the document; this evidence corroborates the baseline.
Queued — evidenced in this annex's prose, not yet added to any function table, not yet dimension-level rated (4 capabilities):
- Mandate — F7: "No global geodetic institution other than NGA (USA), GFZ (Germany), and TU Munich (Germany) currently possesses the combination of data access, computational resources, specialist personnel, and institutional mandate required to produce a comparable model." This annex has no Governance & Strategy capability evidenced anywhere (also noted in Work Assignment 2's own Principle 3 findings for this product) — this sentence is the closest thing to direct evidence for one.
- Funding and Investment — F1: the absence of a "confirmed, funded successor to the GRACE-FO mission" (WA3 Gap 6); F9: ICGEM's dependence on GFZ's institutional budget with "no pooled international funding mechanism."
- Legal Framework — F3: restricted or classified historical gravity data with "neither the legal obligation nor the institutional incentive to share it," and "no formal, legally binding data sharing obligation for Member States."
- Disaster Recovery and Supply Chain Continuity — F9: ICGEM has "no formal succession arrangement designating an alternative host institution" and does not meet "the standard of formalised operational continuity."
If asked why these four aren't scored yet: the honest answer is the same one Satellite Orbits gave — scoring them properly means the same per-dimension check the rest of this table went through.
Workflow Diagram
JDP Alignment
| Pipeline Element | Gap | JDP Objective |
|---|---|---|
| GRACE-FO successor (F1) | No confirmed funded successor mission; a multi-year gap in satellite gravimetry would degrade time-variable gravity monitoring across multiple downstream EGVs (WA3 Gap 6) | 1.3 — Formalised national backing for critical capabilities |
| Surface gravity coverage (F2) | Extremely sparse in developing regions; hinders accurate geoid modelling locally and prevents vertical datum unification in areas of greatest development need | 1.2 — Modernised infrastructure and data sharing |
| Gravity data access (F3) | Historical data siloed or classified by national security and commercial interests; FAIR non-compliant; requires diplomatic and policy engagement to resolve | 1.2 — FAIR data principles adoption |
| Professional capacity (F4/F6) | Declining number of professionals capable of geoid model development; Training and Education scored at 1.67; inadequate succession documentation | 1.4 — Succession planning and capacity building |
| Ultra-high-degree combination (F7) | Institutional concentration in three agencies globally; Knowledge Management scored at 1.25 with no clear succession arrangement | 1.4 — Succession planning and knowledge transfer |
| Model distribution at ICGEM (F9) | Effective but hosted voluntarily by GFZ with no formal global operational SLA, no designated successor institution, and no pooled international funding | 1.1 — SLAs and MoUs (Memoranda of Understanding) for critical functions |
[^sog2026]: United Nations Global Geodetic Centre of Excellence, 2026, State of Geodesy 2026: A Baseline Maturity Assessment, Bonn, Germany, https://www.un.org/globalgeospatial/sites/default/files/2026-05/stateofgeodesy.pdf [^unga69266]: UN General Assembly, 2015, Resolution 69/266: A Global Geodetic Reference Frame for Sustainable Development, https://undocs.org/A/RES/69/266 [^jpl-wildfire]: International GNSS Service, IGSMAIL-8553 (9 January 2025) https://lists.igs.org/pipermail/igsmail/2025/008549.html and IGSMAIL-8555 (15 January 2025) https://lists.igs.org/pipermail/igsmail/2025/008551.html: network and power disruption at NASA Jet Propulsion Laboratory due to the January 2025 Los Angeles wildfires; primary systems restored after six days. [^jpl-workforce]: JPL workforce reduction of approximately 1,500 positions (~25% of total workforce) across four rounds of layoffs, 2024–2025, including DOGE-related reductions beginning February 2025. SpaceNews; CalTech; LAist (as compiled in Reference Verification, §3).