Global Differential GPS System

In-orbit estimation of forces acting on GPS III spacecraft

Da Kuang, Yoaz E. Bar-Sever, Ant J. Sibthorpe, JPL/Caltech

Develops an empirical model (G3-SPM-2025) for solar radiation and related forces on GPS Block III satellites using in-orbit data. The model expresses forces as functions of the Earth-Spacecraft-Sun angle and orbit beta angle, improving upon the present model employed in the GipsyX/RTGx software at JPL. Demonstrates better performance in dynamic fit to multi-day sequences of precise orbit solutions, overlap of daily orbit determination solutions, and orbit predictions.
Journal of Geodesy (2026) 100:26

GNSS-based automated detection of the 2025 Kamchatka tsunami 30 minutes before landfall using GUARDIAN

C. Martire, W. Lu, P. Vergados, et al., JPL/Caltech

Demonstrates GUARDIAN's capability to automatically detect and provide early warning of the 2025 Kamchatka tsunami 30 minutes before coastal landfall using GNSS ionospheric observations, showcasing the operational effectiveness of real-time GNSS-based tsunami detection systems.
Natural Hazards 122, 391 (2026)

Detection of ionospheric disturbances with a sparse GNSS network in simulated near-real time Mw 7.8 and Mw 7.5 Kahramanmaraş earthquake sequence

F. Luhrmann, J. Park, W.K. Wong, Attila Komjathy, et al.

Detection and analysis of ionospheric disturbances following the February 2023 Kahramanmaraş earthquake sequence using a sparse GNSS network in simulated near-real time conditions.
GPS Solutions 29, 54 (2025)

The GUARDIAN system -- a GNSS upper atmospheric real-time disaster information and alert network

L. Martire, S. Krishnamoorthy, P. Vergados, Attila Komjathy, et al., JPL/Caltech

The GUARDIAN (GNSS Upper Atmospheric Real-time Disaster Information and Alert Network) system uses GNSS observations to detect and characterize ionospheric disturbances from natural hazards in near real-time, providing early warning capabilities for tsunamis and other geophysical events.
GPS Solutions 27, 32 (2023)

The Global Differential GPS (GDGPS) System: Architecture, Capabilities, and Operations

Yoaz Bar-Sever, Attila Komjathy, Anthony J. Mannucci, AJ Oria, JPL/Caltech

Comprehensive overview of the GDGPS system architecture, capabilities, and operational aspects.
JPL Open Repository (2022)

Analysis of a High Accuracy Service based on JPL's Global Differential GPS

Nacer Naciri, Yoaz Bar-Sever, Willy Bertiger, Sunil Bisnath, Attila Komjathy, Mark Miller, Larry Romans, Bela Szilagyi, Michele Vallisneri, JPL/Caltech

In the current global navigation satellite system (GNSS) context, with several constellations offering high accuracy services (HAS), we have evaluated a potential HAS for GPS based on JPL's Global Differential GPS (GDGPS) system. This HAS also provides corrections for Galileo and GLONASS.
NAVIGATION: Journal of the Institute of Navigation, Volume 72, Number 1

GipsyX/RTGx, a new tool set for space geodetic operations and research

Willy Bertiger, Yoaz Bar-Sever, Angie Dorsey, Bruce Haines, Nate Harvey, Dan Hemberger, Michael Heflin, Wenwen Lu, Mark Miller, Angelyn W. Moore, Dave Murphy, Paul Ries, Larry Romans, Aurore Sibois, Ant Sibthorpe, Bela Szilagyi, Michele Vallisneri, Pascal Willis, JPL/Caltech

GipsyX/RTGx is JPL's next generation software package for positioning, navigation, timing, and Earth science using measurements from large geodetic Global Navigation Satellite Systems (GNSS), Satellite Laser Ranging (SLR), and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), with Very Long Baseline Interferometry (VLBI) under development. The software facilitates combined estimation of geodetic and geophysical parameters using a Kalman filter approach on real or simulated data in both post-processing and in real-time. Applications include real-time orbit determination and ephemeris predictions, JPL's Global Differential GPS (GDGPS) System, precision post-processing GNSS orbit determination, Precise Point Positioning (PPP) with ambiguity resolution, operational orbit determination for LEO satellites, and multi-technique orbit determination for LEO.
Advances in Space Research 66 (2020) 469-489

GDGPS High Accuracy Products for Real-Time Applications: Supporting Public and Scientific Communities

Attila Komjathy, Group Supervisor, JPL/Caltech

Overview of GDGPS system status, operations centers transition, real-time public products for distribution, performance comparisons, standalone JPL prototype client, and GDGPS-based science products for natural hazard detection.
65th Meeting of the Civil GPS Service Interface Committee (CGSIC), April 2026

GDGPS products on NASA's EarthData

Official NASA EarthData portal providing access to JPL Global Differential GPS products for space geodesy applications.
NASA EarthData (2025)

GDGPS products on CDDIS

CDDIS (Crustal Dynamics Data Information System) archive of GDGPS daily accuracy POD clock correction products.
NASA CDDIS (2024)

NASA Researchers Test Novel Approach to Detect Tsunamis using GPS signals

UN-SPIDER coverage of NASA's innovative GNSS-based tsunami detection research using ionospheric observations.
UN-SPIDER (2023)

See NASA's GUARDIAN Catch a Tsunami

Recent JPL news feature showcasing GUARDIAN's real-time tsunami detection capabilities in action.
NASA/JPL News

NASA's GUARDIAN: Innovative GPS-Based Tsunami Detection System

SciTechDaily feature on the GUARDIAN system's capability to detect tsunamis using GPS ionospheric measurements.
SciTechDaily (2023)

NASA Researchers Detect Tsunamis by Their Rumble in the Atmosphere

Official NASA/JPL news feature on detecting tsunamis through atmospheric disturbances using GNSS technology.
NASA/JPL News

Scientists sent balloons into the stratosphere — and found a mystery

Washington Post coverage of stratospheric balloon research detecting atmospheric signals from natural phenomena.
The Washington Post (2023)

Scientists just detected an earthquake from a balloon and might be able to do it on Venus, too

Space.com article on detecting earthquakes using balloon-based sensors, with implications for Venus exploration.
Space.com (October 18, 2022)