AGU 100

100+ Advances in Geodesy in Celebration of AGU's Centennial (1919-2019)

To celebrate the AGU Centennial, the Geodesy Section is recognizing compelling advances in geodesy in the last 100 years including:
• Science – research advances in understanding Earth and Earth processes
• Technology – advanced in instruments, field work, hardware and other technological endeavors
• Data – advances in computation, data analysis, data management, and software
• Education – advances in education (formal or informal) or education research
• Broader Impacts – advances in applied science, science management, community engagement, and societal benefits

Submissions accepted through the start of AGU 2019 Annual Meeting.
Please submit your advances via email to the AGU Geodesy Section Centennial Committee (Vicki Childers, Tim Dixon, and Linda Rowan) at with subject heading "100 Advances in Geodesy".

1923 – 1950s: Development of the two-pendulum gravimeter by F. A. Vening Meinesz, and his subsequent use of it to measure gravity at sea. Showed the association of gravity anomalies with ocean trenches. Bruins & Scholte, (1967). Tech Adv, 12 
1932 Lucien LaCoste develops his relative gravimeter to measure gravity on the Earth. Clark, R.D. (1984). Lucien LaCoste. In: The Leading Edge 3(12):24 Technology Adv 30
1932-1933: International Polar Year, Collaboration to understand atmospheric phenomena, especially electrical geophysical phenomena, over the poles, advanced radio science & tech. 27 observing sites, used new tech, e.g. radiosondes. Impact Adv 10 
1940. John Randall and Harry Boot design a lightweight cavity magnetron, a type of vacuum tube that generates microwaves. Their device produced high-powered 10 cm wavelength pulses and stimulated rapid improvements in radar technology. Tech Adv 101
1942. Austrian-American actress Hedy Lammar and George Antheil patent frequency-hopping and donate it to the US Navy to assist the allied war effort. The technique is the basis of spread spectrum technology used today in GPS/GNSS. Tech Adv 102
1950 - Ohio State University’s Department of Geodetic Science begins its degree program. Over the next 70+ years, it would go on to train many of the top geodesists around the world and carry out innovative research projects in geodesy. Cloud, J. (2000). Crossing the Olentangy River: The Figure of the Earth and the Military- Industrial-Academic-Complex, 1947}1972 Stud. Hist. Phil. Mod. Phys., Vol. 31, No. 3, pp. 371}404, 2000. Merchant, D. (1969). History of the Department Geodetic Science at The Ohio State University. Ed Adv 103
1955: Gold showed mass redistribution on the surface or in the interior of Earth would result in a reorientation of the body w/respect to spin axis orientation. Subsequent studies of true polar wander advance understanding of Earth. Gold 1955, Sci Adv 67 
1957-1958: International Geophysical Year Global geophysics @ poles. 1st satellites, Sputnik 1, Sputnik 2, Explorer 1, & Vanguard 1. Disc: van Allen radiation belts & mid-Atlantic ridge spreading center. Led to Antarctica Treaty;World Data Systems. Imp Adv 33 
1958. Development of the Mogi model for volcano deformation. Kiyoo Mogi realized a mathematical model developed by N. Yamakawa, 1955 could be used to model the deformation at a volcano caused by pressure changes. K. Mogi 1958. Tech Adv 104
1958: Dislocation theory to model earthquake deformation After realization that subduction eqs could be caused by dynamic fast slip on large faults, Steketee, 1958, Green's function method to simulate surface displacements on a semi-infinite elastic med. Data Adv 15 
1958: Triangulated deformation msts. on either side of faults - before & after earthquakes, along w/focal depths, to confirm the coincidence of seismically-detected eqs. & faults. Obs. of central tenet of elastic rebound theory, K. Kasahara 1958. Sci Adv 94  
1959: Publication showing that the Earth is "Pear-shaped" by O'Keefe et al., 1959: Astronomical Journal, 64.
1960: Book About the Rotation of the Earth "The Rotation of the Earth: A Geophysical Discussion" by W. H. Munk and G. L. McDonald--as an advance in education, a systematic survey of Earth orientation measurements & causes. Education Advance 5 
1963: First solution was given for a world wide geodetic datum and gravity field. Kaula, 1963: JGR.
1963-1999: Free-fall absolute gravimeters 4 geodesy. Portable, absolute freefall gravimeter - invented in 1960s Faller 1963 & used in 1990s Niebauer et al. 1995: allows ~2 microGal accuracy in accel. gravity & allows realization of a ~1 cm geoid. Tech Adv 48 
1964: Book About Dislocation Theory Basis for modeling geodetic obs of plate motions & understanding eq size & frequency. Methods used in geodesy, geophys, geochem, etc... Elementary Dislocation Theory, Weertman, Johannes; Julia R. Weertman (1964) Ed Adv 26 
1964: Satellite Laser Ranging, SLR & Lunar Laser Ranging, LLR, use short-pulse lasers & optical receivers & timing electronics to measure distance from ground to satellites & moon. Measure positions, motions, orbits, gravity, orientation. Broader Imp. Adv 74  
1965-1972: Recognizing the geometry of megathrust earthquakes using ground displacement measurements following the 1960 Valdivia and 1964 Alaska earthquakes: Plafker 1965 and Palfker 1972, Sci Adv 29 
1967 Heiskanen and Moritz publish their textbook in Physical Geodesy, the classic text that generations of geodesists read in graduate school and beyond. Heiskanen, W. A., & Moritz, H. (1967). Physical Geodesy. San Francisco: W.H. Freeman and Company. Education Adv 105
1970-1972: Used signal processing tools to extract an isostatic Green's Function (GF) from topographic and gravity data. Showed local isostasy, could be extracted from GFs. Dorman & Lewis 1970, Lewis & Dorman 1970, Dorman & Lewis 1972. Data Adv 65  
1971+: Repeat microgravity used to measure aquifer specific yield and map aquifer storage changes. Montgomery, E. L. 1971, Determination of coefficient of storage by use of gravity measurements, Phd, Uni. Arizona; Pool & Eychaner, 1995. Data Adv 73  
1973: Geodetic data along the San Andreas fault between Parkfield & San Francisco, CA re‐examined to estimate the current relative movement, 32 ± 5 mm/yr for the period 1907–1971, betw American & Pacific plates. Savage & Burford, 1973 Sci Adv 46 
1976: Mission to Earth: Landsat Views the World Picture Book. 4 years after launch of 1st Landsat, published compendium of Landsat scenes showing Earth's surface from a perspective never before presented; Ed Adv 22 
1976: USGS scientists published “ERTS-1, a new window on our planet”, showing the first step in using remote-sensing techniques for inventory and management of Earth 's resources and measuring changes. Ed Adv 36 
1977: Multibeam Echosounder - mapping seafloor. Developed for US Navy, then sci in 1970s. Multibeam data transformed our vision of processes acting on seafloor & of geomorphic features associated with mass-wasting & volcano-tectonic processes. Tech Adv 52  
1978: Seasat, 1st Earth-orbiting satellite for remote sensing of Earth's oceans with 1st spaceborne synthetic-aperture radar (SAR). Demonstrated global monitoring of oceanic phenomena & determined requirements for ocean remote sensing. Tech Adv 68  
1978-present: Synthetic aperture radar space missions to measure Earth deformation & changes. NASA, SeaSAT, 1978 & ESA, ERS, C-band 1991-2000, 1995-2001 opened a new era in space-based geodesy (InSAR). Gabriel et al. 1989. Technology advance, part of 100 Advances 2 
1980-1991: Angular momentum changes in atmosphere balanced by equal & opposite changes in angular momentum of solid Earth. Rotation of Earth & other planets provide info abt atmos. & core. Hide et al. 1980; Hide&Dickey 1991. Sci Adv 53  
1981: Computed luni-solar forced nutations of an elliptical, rotating, self-gravitating, elastic, hydrostatically prestressed & oceanless Earth. Corrected astrometric data for the nutation of Earth, so other effects can be studied. Wahr, 1981. Tech Adv 60  
1984: Adoption of Fourier Transforms to Geoid Modeling. Recognized Stokes integral & TC integral as "convolution integrals" could transform to frequency domain so FT could solve integral fast & advanced geoid modeling. Sideris 1984, Schwarz et al. 1990, Data Adv 61  
1984+: Formation & ongoing work of @UNAVCO by @NSF_GEO. Originally University NAVSTAR Consortium to share GPS receivers etc. to measure plate motion using nascent GPS constellation. UNAVCO, now non-profit to support research using geodesy. Broader Imp 79  
1985: Development of a Terrestrial Reference Frame using space geodesy data from VLBI, LLR, SLR & Doppler/TRANSIT for science & societal applications, Boucher and Altamimi, 1985; First tweet of 100 Advances in Geodesy over history of AGU 1919-2019; 1 
1988: Defining the Characteristic Signal of Reflected GNSS Around an Antenna. Georgiadou & Kleusberg 1988, showed that interference patterns have a characteristic frequency that depends on the height of the antenna above the reflecting surface. Tech Adv 70  
1988 Creation of the North American Vertical Datum of 1988. Zilkoski, David B; Richards, John H.; Young, Gary M. (1992) Results of the General Adjustment of the North American Vertical Datum of 1988. In Surveying and Land Information Systems, 52(3), 133-149. Broader Imp Adv 106
1988+: TANGO project, regional GPS experiment - European & North American, Azores Archipelago network, Described complex tectonics betw/North American, Eurasian & Nubian plates, Bastos et al. 1991; More than 20y of GPS obs now - increase precision. Sci Adv 96  
1988-1990: Regional GPS campaign and collaboration to measure geodynamics of Central and South America called CASA UNO (25 orgs., 13 countries, 43 GPS receivers, 590 days of data). Kellogg & Dixon 1990. Sci Adv 98  
1989: Differential interferometric radar pioneers Differential interferometric radar from 1978 L-band radar satellite to detect vertical motions caused by soil swelling. Gabriel et al., (1989) Tech Adv 23 
1989 Development of the first geocentric datum. Schwarz, Charles R. ed. (1989) North American Datum of 1983. NOAA Professional Paper NOS 2. National Geodetic Survey, Charting and Geodetic Services, National Ocean Service. Rockville, MD. Broader Imp Adv 107
1989-1992: Nascent GPS-based obs of regional geodynamics in California. Helped define plate tectonics, fault processes advance techniques etc... Dong & Bock, 1989 & Larsen & Reilinger, 1992. Sci Adv 58  
1990- 2002: Steadiness of plate motion on different timescales observed by geodesy. Plate motions over tens to millions of yrs similar. Similarity shows viscous asthenosphere damps out episodic motions. Smith etal. 1990, Gordon&Stein1992, Sella etal. 2002 Sci Adv 93  
1990: Measuring coseismic slip during the 1989 Loma Prieta, California earthquake with GPS. Lisowski et al., 1990. Sci Adv 78  
1991: Alaska Satellite Facility at Geophysical Institute at the University of Alaska Fairbanks. Mission to make remote-sensing data accessible for polar processes, wetlands, glaciers, sea ice, climate change, permafrost, & flooding. Broad Imp Adv 76  
1992: Measuring Precipitable Water Vapor With GNSS Bevis et al. (1992) suggested that GPS zenith delays, estimated by geodesists, could be used to study variations in PWV in the troposphere. Now measure PWV w/GNSS to understand atmos. Tech Adv, 9 
1992: Sidereal Filtering - data analysis tech advanced by Genrich & Bock (1992) - using the repeating ground track of GPS satellites, to create a multipath error profile from the day before an eq & apply profile to pos. estimates on day of. Tech Adv, 16 
1992-1993: GPS obs. of extension in a volcanic zone in northeast Iceland related to a major rifting event thru a series of intrusions & extrusions 10 y before. Foulger et al,1992 & Heki et al. 1993, Sci Adv. 21 
1993: Differential interferometric radar has widen our eyes to see our dynamic Earth. Including a mapping of the 1992 Landers earthquake surface displacements, Massonnet et al., 1993. Sci Adv 64  
1993: Satellite radar interferometry to measure flow velocities & grounding-line positions of Rutford Glacier, Antarctica, advance tech. & understanding of ice stream dynamics; Goldstein et al. 1993. Sci Adv 100  
1994: Determining crustal motion in central/east Mediterranean from campaign SLR msmts, showed west motion of Anatolian Block relative to Eurasia, Smith et al. 1994, Sci Adv 86  
1994: GNSS Earth Observation Network (GEONET) in Japan, Dense array 1300+ sites, 20 km spacing. Obs. earthquakes & Earth processes - research & societal benefits. Sagiya T. 2004. "The first decade of GEONET: 1994–2003" Impact Adv, 17 
1994+:Global models (NUVEL-1, DeMets et al 1990 & NUVEL-1A, DeMets et al, 1994) describing geologically current motion btw 12 assumed-rigid plates by inverting data, such as ocean floor magnetic anomalies, transform faults & eq. slip vectors, over 3–5 MY. Sci Adv 83  
1994-now, International Global Navigation Satellite Systems Service (IGS). Organizes a network of GNSS sites to improve satellite orbits & clocks to adv knowledge of Earth’s reference frame & its changes. Dow et al. 2009, Imp Adv 24 
1995: Estimate plate motions: Pacific, North American, Eurasian, Australian, African, Antarctic & South American from GPS. Adv knowledge of major plate motions, relation to crustal dynamics & to other Earth processes Argus&Heflin; Larson&Freymueller, 1995. Sci Adv, 18 
1995+: Glacial isostatic adjustment (GIA) is large & measurable by space gravity & Global Positioning System (GPS) msmts can separate GIA from present-day ice-mass balance. James & Ivins 1995, Sci Adv 80  
1995-1996: Estimation of plate motion from southern France to Turkey w/combination of SLR & GPS, shows a microplate in south Greece & the Aegean Sea, & sense of motion across North Anatolian fault. Noomen et al. 1996, Sci Adv 55  
1995-1997: Early GPS campaigns provided obs. of geodynamics of the Mediterranean region, identifying plate processes, hazards & advances techniques. Straub & Kahle, 1995, Noomen et al. 1996, Reilinger et al. 1997. Sci Adv 95  
1997-2001: Development of GNSS radio occultation technique to understand atmosphere, enhance weather models for a better atmospheric predictions. Kursinski et al. 1997, Hajj et al. 1998, Wickert et al. 2001. Tech Adv 82  
1999: Geodesy shows difference btw plate boundary & intraplate earthquakes. At plate boundaries, GPS data show strain accumulating via earthquake cycle. GPS data for New Madrid seismic zone find no or little strain accumulating. Newman et al. 1999 Sci Adv 71  
1999: The International VLBI Service for Geodesy & Astrometry (IVS) supports global Very Long Baseline Interferometry (VLBI) components. Advance reference frame, tectonic plates, gravity, length of day, atmospheric models, etc... Broad Imp Adv 81  
2000-2010: CHAMP Satellite Mission to Understand Earth’s Gravity & Magnetic Field - Challenging Mini-satellite Payload (CHAMP) simultaneously highly precise gravity & magnetic field measurements for the first time., Impact Adv 20 
2000-now: GNSS-based rapid assessment of large earthquakes & seismogenic tsunamis. Improvements in positioning accuracy & speed enable rapid magnitude & slip characteristics for earthquake warning. Murray et al. 2018. Tech Adv 45 
2001: Measuring snow loads with High Density GNSS Network, Heki (2001) measured the water load, mostly in the form of snow in the mountainous regions of Japan using the dense GNSS network, GEONET. Can extract variability over time. Tech Advance, 8 
2001: Measuring water loads with GNSS. van Dam et al. (2001) observed water loads in vertical component time series from nascent IGS network using models to quantify effects of groundwater, snowpack, & soil moisture. Tech Adv 66  
2001: Spatially dense space geodetic obs. of interseismic def. as predictive tool for future eq. hazards. High-res. maps of surface velocities constrain slip rates, interseismc coupling, extent of seismic layer, stress accum.. Peltzer et al. 2001 Sci Adv 90  
2001: Two-thirds of the Chandler wobble caused by fluctuating pressure on the seabed, caused by changes in the circulation of the oceans caused by variations in temperature, salinity, and wind. Gross 2001. Sci Adv 77  
2001-2003: Discovery of Episodic Tremor & Slip (ETS) using geodesy & seismology changed the understanding of fault slip behavior. Started new research direction & new discoveries. Dragert et al,, 2001; Obara 2002; Rogers&Dragert 2003, Science Advance, 3 
2002: Geodetic detection of extensive damage zones on major crustal faults reducing elastic moduli. Direct observational constraints on the extent of damage & the degree of softening of rocks made possible with InSAR. Fialko et al. 2002, Sci Adv 89  
2002: Geodetic detection of the shallow coseismic slip deficit. Smaller amplitude of near-surface slip compared to slip in the middle of seismic layer, Simons et al. 2002. Sci Adv 92  
2002: Widespread active volcanic deformation of remote central Andes volcanic arc documented using InSAR surveys, Pritchard and Simons, 2002. Sci Adv 75  
2002-2014: Development & Utilization of the International Terrestrial Reference Frame (ITRF) for science & societal applications. 30+y R&D devoted to ITRF, for the benefit of Earth science applications, Altamimi et al., 2016. Imp Adv 37 
2002-2017: GRACE mission; Tandem satellites that's changed the way we study Earth's gravitational forces & the Earth system, the Gravity Recovery and Climate Experiment, or GRACE, advanced study of changes in waters, ice sheets & solid Earth. Imp Adv 28 
2003 - 2004: Revelation of timescales of variability of ice streams and glaciers from minutes to millenia from geodetic and other data/modeling. Bindschadler et al., 2003, Scambos et al., 2004. Sci Adv 69  
2003: High Rate GPS Measurements of Seismic Displacements - Obs. of seismic motions by a geodetic GPS receiver during the 2002 Mw 7.9 Denali Fault earthquake (Larson et al. 2003). Surface waves visible at GPS site in Colorado. Sci Advance 7 
2004: Confirmation of Lense-Thirring Effect with Satellite Laser Ranging. Ciufolini & Pavlis 2004, confirmed twisting effect of spinning Earth on orbits of 2 satellites using Satellite Laser Ranging (SLR) data of Int. Laser Ranging Service. Sci Adv 57  
2004: High Rate GPS Measurements of Earthquake Slip History. Ji et al. 2004, produced 1st eq slip history using high-rate GPS positioning records for 2003 Mw 6.5 San Simeon earthquake. High-rate GPS positions combined w/seismic & GPS static offsets. Sci Adv 62  
An artist's drawing of one of NASA's Mars rover on the surface of Mars 2004: Mars rovers, Spirit & Opportunity, traversed 50km+ at accuracy of 1.5/1000. The geodetic long-distance localization & planetary surface mapping achieved a tech advancement within deep space infrastructure. Arvidson et al., 2004, Tech Adv 72  
2005: Formulation of the algorithm for computing rigorous orthometric heights was published. Orthometric heights can now be rigorously computed to an accuracy of a few centimeters in the worst case. Rigorous orthometric heights, Tenzer et al., 2005, Journal of Geodesy 79. 
2005 & 2013: Measure Volcanic Ash Plumes w/GNSS. Houlié et al. (2005) used carrier phase outliers in GNSS 4 ash plume in 2000 Miyakejima, Japan, . Larson (2013) measured ash plume 4 Redoubt eruptions using the GPS signal-to-noise ratio. Tech Adv 42 
2005-2010: Geodesy measures glacial isostatic adjustment (GIA). Observations provide new constraints of the rheology of the mantle & role of GIA in nucleating intraplate earthquakes. Calais et al, 2006; Sella et al., 2007; Argus et al., 2010 Sci Adv, 14 
2005-now: EarthScope Ed. grants 4 geohazards professional development 4 educators/responders. Teachers on the Leading Edge (TOTLE), Workshops, Cascadia EarthScope Eq & Tsunami Ed. Prog. (CEETEP), Alaska Native Geosci Learning Experience (ANGLE). Ed Adv 32 
2006: Gravitational effect of the pole tide (small ocean tide with an amplitude ~ 6 mm, only non-extraterrestrial effect) is easily detected by the superconducting gravimeter. H. Virtanen thesis, 2006. Tech Adv 87  
2006: High-Rate GPS 4 Rapid Estimate of Earthquake Magnitude (7+). Blewitt et al. 2006 analyzed high-rate positions for 38 IGS sites for Mw9.0 2004 Sumatra earthquake: an accurate magnitude could have been determined w/in 15 minutes. Tech Adv 35 
2006: High-Rate GPS for Rapid Estimate of Earthquake Magnitude (7+). Blewitt et al. (2006) showed GPS data can rapid determine magnitude for Mw9.0 2004 Sumatra earthquake. Could lead to better, quicker tsunami warning, Sobolev et al. 2007. Tech Adv 56  
2008: Measuring Soil Moisture with GNSS Reflections. GNSS-Interferometric Reflectometry soil moisture msmts, Larson et al. 2008, using satellite signal that reflects off ground. Provides info about hydrologic, climatic, & ecologic conditions. Tech Adv 63  
2009 -2013 ESA's Gravity field & steady-state Ocean Circulation Explorer (GOCE) mapping the geoid. Uses new technology in space to map Earth's gravity field in unprecedented detail. Imp Adv 41 
2009: Investigation of the Chandler Wobble with 163 years of data from IERS using 2 digital filters & 2 transforms; found 3 phase reversals 1850, 1920, 2005 that slow wobble; Malkin & Miller 2009. Data Adv 84  
2009: Measuring Snow Depth w/GNSS Interferometric Reflectometry (Larson et al. 2009). GNSS-IR snow depth & snow water equivalent (McCreight et al. 2014) measured for 220 sites over 10 y in the western U.S. & Canada (Larson, 2016). Tech Adv 34 
2010: GPS data measures relative & absolute plate motion. Shows today's velocities of major tectonic plates agrees w/estimates from other geologic & geophysical data, DeMets et al., 2010. Sci Adv 91  
2010: High-rate GPS Measurements of Slip Distribution for M8.8 Maule Earthquake. GPS measures > 5m horizontal & >1.7m vertical change, constrain rupture process. Delouis et al. 2010, Vigny et al. 2011. Sci Adv 51  
2010: Measuring Vegetation Water Content with GNSS Reflections. Small et al. 2010 measured vegetation water content w/GNSS-Interferometric Reflectometry. Use changes in reflection amplitudes of the frequency. Tech Adv 54  
2010: New Zealand’s network (GEONET) of 150+ cGPS sites records slow-slip events every 5 years with durations of 6 days to 1.5 years on Hikurangi Subduction Zone from decades of obs. Wallace & Beavan 2010. Sci Adv 99  
2011: Dense GPS obs. of 2011 Mw 9.1 Tohoku-Oki Earthquake Constrain Seismic Moment & Slip Distribution. 100s of high-rate GPS sites from GEONET recorded the 2011 Mw 9.1 Tohoku-Oki eq. Ground displacements of 6m plus moment & displ. Yue & Lay 2011. Sci Imp 40 
2012 – 2014: GPS helped anticipate/capture a large Mw=7.6 earthquake. GPS sites placed over the fault segment of a seismic region, captured the Nicoya, Costa Rica M=7.6 earthquake, Protti et al.,2014, anticipated by Feng et al., 2012. Impact Adv, 13 
2012: A Reconciled View of Ice Sheet Contrib. to Sea Level. Satellite altimetry, interferometry, & gravimetry data estimate mass balance of Earth’s polar ice sheets. Shepherd et al, 2012. Since 1992, ice sheets contributed 0.59 ± 0.20 mm/y. Sci Adv 59  
2012: Discoveries of new volcanic deformation, InSAR obs. of surface def. due to Altiplano-Puna Magma Body, revealed conjugate pattern of uplift surrounded by broader region of subsidence - “Sombrero uplift”. Fialko&Pearse 2012, Henderson&Pritchard 2013. Sci Adv 85  
2013: Measuring Sea Level with GPS Reflections GPS-Interferometric Reflectometry combined w/traditional GPS to track tides and measure absolute sea level. Larson et al. 2013a and 2013 b. Tech Adv 19 
2013-2014: Measuring Surface & Ground Water Changes w/SAR Through Land Changes. Borsa et al. 2014- CA drought, decrease in surface water & snow caused elastic uplift in Mtns. Chaussard et al. 2014 showed groundwater changes cause land changes Sci Imp 38 
2013-2014: Measuring Surface and Ground Water Changes with SAR to Determine Elastic Uplift of Mountain Ranges. Borsa et al., 2014, Chaussard et al. 2013 and 2014, Sci Adv 31 
2013-now: GEodesy Tools for Societal Issues (GETSI) project developed undergrad resources that feature geodetic data & quantitative skills applied to issues of climate change, natural hazards, & water resources. Ed Adv 44 
2014: First global surface velocity field and global strain rate model from geodetic data Kreemer, C., G. Blewitt and E.C. Klein 2014. A geodetic plate motion and Global Strain Rate Model. Geochemistry, Geophysics, Geosystems, 15(10): 3849-388 Sci Adv 49 
2014: Measuring Precipitable Water Vapor With GNSS in Real-Time. Can measure precipitable water vapor (PWV) in real-time with GNSS networks (Li et al. 2014). Use for weather forecasts Moore et al. (2015). Tech Adv 27 
2015 - 2018: Constraints on mantle/asthenosphere rheology from tidal periods & longer period phenomena from geodesy, Bos et al 2015; Peltier et al 2015; Qiu et al 2018; Sci Adv 25 
2015: Extremely High-Rate GPS Measurements (5 Hz) for Earthquake Motion Detections for Mw7.8 Gorkha Earthquake. Galetzka et al. 2015 GPS obs detected slip pulse, strong oscillations with 3–4s periods & basin resonance. Sci Adv 43 
2015: Measure Snow Accumulation & Ice Sheet Features w/GNSS Reflections. GPS-Interferometric Reflectometry (GPS-IR) in Greenland measure snow & firn density, Larson et al. 2015. GPS-IR in west Antarctica 10-year snow data, Siegfried et al. 2017. Tech Adv 50 
2015: Relativistic chronometric leveling. Height difference betw PTB Braunschweig (Germany) and Observatoire de Paris (France) - at 1400 km - confirmed w/accuracy of few decimeters using relativistic chronometric leveling. Lisdat et al. 2016. Tech Adv, 39 
2015-2018: Method for computing the deformation-induced topographic effect (DITE) in volcano geodesy. Corrects observed spatiotemporal gravity changes in volcanic regions for the effect of surface deformation to interpret residual gravity changes. Data advance, 4 
What is the difference between a hurricane watch and a warning? 2015-2019: A great advance is the use of satellite imaging geodesy for rapid global disaster response. Assessment of natural disasters (earthquakes, cyclones, tsunamis, etc) & inform preparedness/ response/mitigation, Barnhart et al. 2019, Impact Advance, 6 
2017: Dense postseismic GNSS data & models find sliver motion controlled by kinematic interplay betw megathrust & upper plate or fluids moving downdip, 2012 Mw7.6 Nicoya EQ, Hobbs et al. 2019 & Mexican SZ, Fasola et al., 2019 Sci Adv 88  
2018: Global surface velocity field model from geodetic data for understanding glacial isostatic adjustment Schumacher, et al. Global surface velocity field model from geodetic data for understanding glacial isostatic adjustment, 2018. Sci Adv 47 
2018: Understanding the Effects of Drought on Vegetation Via Direct Measurement of Water Content by GNSS Reflections, GNSS sites in California quantify changes in vegetation water content observed in 2012–2014 drought (Small et al. 2018). Sci Adv 11 
2019: International network of geodetic Very Long Baseline Interferometry (VLBI) radio telescopes provide global reference frame for radar satellite data (SAR), can now measure global sea level etc. Parker et al, 2019. Tech Adv 97  
2019: Demonstration that the two French geodesists, Delambre and Méchain, who "measured the Earth" at the end of the 18th century to provide the meter as the unit of length for the basis of the metric system, had done an excellent job having measured the Parisian meridian to an accuracy of 3.5 x 10-6. How gravity field shortened our metre, Vaníček & Foroughi, 2019, Journal of Geodesy, 93.

We would like to thank everyone that submitted a contribution to the 100 Advances in Geodesy, and those that submitted additional feedback to make this page a success. We look forward to new Advances in Geodesy as AGU moves into the next century, and recognize the thriving Geodesy community that continues to make these advances possible.