Sciences and Exploration Directorate

Terence J Sabaka

(RSCH AST, SOLID EARTH GEOPHYSICAL STD)

Terence J Sabaka's Contact Card & Information.
Email: terence.j.sabaka@nasa.gov
Phone: 301.614.6493
Org Code: 61A
Address:
NASA/GSFC
Mail Code 61A
Greenbelt, MD 20771
Employer:
NASA

Brief Bio


Terence Sabaka has been working in geopotential research for over 37 years at GSFC. This includes modeling the near-Earth magnetic field and producing a suite of models known as "Comprehensive Models" that have been of great use to the scientific community. He has also included capabilities in the Geodetic Parameter Estimation (GEODYN) code and has provided guidance in general parameter estimation for Space Geodesy. He is also developing algorithms to produce gridded Level-3 products for the GEDI mission and algorithms for the fusion of data sets such as GEDI and ICESat-2. He is also involved in the computation of the probability of lasing for the Constraint Analysis Monitoring System (CAMS) for the ICESat-2 laser.

Research Interests


Geopotential Field Theory

Earth Science: Theory & Modeling

Studying magnetic and gravity fields through measurements made by satellites and ground surveys.


Inverse Theory

Earth Science: Theory & Modeling

Once measurements have been collected what is the best way to infer the states of geophysical parameters, such as spherical harmonic expansions of magnetic and gravity fields. This includes accounting for noise in the system, which is comprised not only of a zero-mean random part, but also systematic bias. He is also beginning to understand and apply Artificial Intelligence (AI) and Machine Learning (ML) via Neural Networks for the benefit of Space Geodesy problems of interest in the Lab.

Current Projects


Comprehensive Geomagnetic Field Modeling

Theory & Modeling

The theory behind Comprehensive Geomagnetic Field Modeling is to parameterize the major near-Earth magnetic field sources and subsequently co-estimate them so as to achieve optimal separation of sources.  This has been used to great success over the part two decades and has produced a suite of Comprehensive Models (CMs), which have been used extentsively by the community.  This algorithm is used to produce the primary line of Level-2 magnetic field products for the ESA Swarm mission.


Level-3 Gridded Land Surface Metrics for the Global Ecosystem Dynamics Investigation (GEDI) Mission

Theory & Modeling

The Global Ecosystem Dynamics Investigation (GEDI) Mission will measure vegatation canopy heights at non-uniform postions.  In order to deliver values on a regular grid, this information will need to be interpolated.  Possible methods for doing this include using Restricted Maximum Likelihood (REML) to first estimate the deterministic and stochastic parts of the signal in the GEDI data followed by Bayesian Kriging (BK) to interpolate this information to the regular grid centers.  BK is able to incorporate uncertainties in the REML step in order to optimally interpolate the signal and provide realistic error estimates of the interpolates.


Incorporation of Kalman Filtering/Smoothing into the Precise Orbit Determination and Geodetic Parameter Estimation (GEODYN) Program.

Theory & Modeling

The Precise Orbit Determination and Geodetic Parameter Estimation (GEODYN) Program currently assumes that the equations of motion are error-free.  However, many factors render this assumption invalid.  Therefore, a Kalman filtering/smoothing system is being developed for GEODYN in which process noise can be accounted for in the satellite dynamics leading to Dynamic Model Compensation via Gauss-Markov error processes.  This will also allow for dynamic error-covariance matrices to be produced that coincide with the orbits.

Positions/Employment


Research Geophysicist

NASA, Geodesy and Geophysics Laboratory, Code 61A - Goddard Space Flight Center

November 2016 - Present

Carries out research in geopotential modeling of the Earth, Moon, and other planets.  Supports magnetic and geodetic missions.


Research Geophysicist

NASA, Planetary Geodynamics Laboratory, Code 698 - Goddard Space Flight Center

June 2009 - November 2016

Carries out research in geopotential modeling of the Earth, Moon, and other planets. Supports magnetic and geodetic missions.


Research Geophysicist

Raytheon Corporation - Goddard Space Flight Center

March 1986 - June 2009

Carries out research in geopotential modeling of the Earth, Moon, and other planets. Supports magnetic and geodetic missions.

Education


1983 - BS (summa cum laude, geology) University of Akron
1986 - MS (geophysics) University of Akron
2003 - MS (applied mathematics) University of Maryland Baltimore County

Publications


Refereed

2021. "High‐spatial‐resolution mass rates from GRACE and GRACE‐FO: Global and ice sheet analyses." Journal of Geophysical Research: Solid Earth 126 (12): e2021JB023024 [10.1029/2021JB023024] [Journal Article/Letter]

2021. "Patched Local Lunar Gravity Solutions using GRAIL Data." Earth and Space Science 8 (11): e2021EA00169 [10.1029/2021ea001695] [Journal Article/Letter]

2021. "GRACE Fast Mascons From Spherical Harmonics and a Regularization Design Trade Study." Journal of Geophysical Research: Solid Earth 126 (8): [10.1029/2021jb022113] [Journal Article/Letter]

2021. "ICESat‐2 Constraint Analysis and Monitoring System (CAMS)." Earth and Space Science 8 (5): [10.1029/2020ea001497] [Journal Article/Letter]

2021. "Deriving Mercury geodetic parameters with altimetric crossovers from the Mercury Laser Altimeter (MLA)." Journal of Geophysical Research - Planets 126 (4): e2020JE006683 [Full Text] [10.1029/2020JE006683] [Journal Article/Letter]

2021. "International Geomagnetic Reference Field: the thirteenth generation." Earth, Planets and Space 73 (1): 49 [10.1186/s40623-020-01288-x] [Journal Article/Letter]

2021. "Geomagnetic secular variation forecast using the NASA GEMS ensemble Kalman filter: A candidate SV model for IGRF-13." Earth, Planets and Space 73 (1): 47 [10.1186/s40623-020-01324-w] [Journal Article/Letter]

2020. "CM6: a comprehensive geomagnetic field model derived from both CHAMP and Swarm satellite observations." Earth, Planets and Space 72 (1): 80 [10.1186/s40623-020-01210-5] [Journal Article/Letter]

2020. "Development of a Daily GRACE Mascon Solution for Terrestrial Water Storage." Journal of Geophysical Research: Solid Earth 125 (3): [10.1029/2019jb018468] [Journal Article/Letter]

2020. "High-resolution gravity field models from GRAIL data and implications for models of the density structure of the Moon’s crust." Journal of Geophysical Research: Planets 125 (2): [10.1029/2019JE006086] [Journal Article/Letter]

2019. "Water Storage Trends in High Mountain Asia." Frontiers in Earth Science 7 [10.3389/feart.2019.00235] [Journal Article/Letter]

2019. "Correction to: Regularization and error characterization of GRACE mascons." Journal of Geodesy 93 (9): 1399-1399 [10.1007/s00190-019-01286-2] [Journal Article/Letter]

2019. "Regularization and error characterization of GRACE mascons." Journal of Geodesy [10.1007/s00190-019-01252-y] [Journal Article/Letter]

2019. "Geodetic evidence that Mercury has a solid inner core." Geophysical Research Letters 46 (7): 3625-3633 [Full Text] [10.1029/2018gl081135] [Journal Article/Letter]

2018. "A comprehensive model of Earth’s magnetic field determined from 4 years of Swarm satellite observations." Earth, Planets and Space 70 (1): 130 [10.1186/s40623-018-0896-3] [Journal Article/Letter]

2017. "Recovery of Bennu's Orientation for the OSIRIS-REx Mission: Implications for the Spin State Accuracy and Geolocation Errors." Journal of Geodesy 91 (10): 1141-1161 [Full Text] [10.1007/s00190-017-1058-2] [Journal Article/Letter]

2017. "Evidence for a Low Bulk Crustal Density for Mars from Gravity and Topography." Geophysical Research Letters 44 (15): 7686–7694 [Full Text] [10.1002/2017GL074172] [Journal Article/Letter]

2017. "Joint inversion of satellite-detected tidal and magnetospheric signals constrains electrical conductivity and water content of the upper mantle and transition zone." Geophysical Research Letters 44 (12): 6074-6081 [10.1002/2017gl073446] [Journal Article/Letter]

2016. "Satellite tidal magnetic signals constrain oceanic lithosphere-asthenosphere boundary." Science Advances 2 (9): e1600798-e1600798 [10.1126/sciadv.1600798] [Journal Article/Letter]

2016. "Extracting ocean-generated tidal magnetic signals from Swarm data through satellite gradiometry." Geophysical Research Letters 43 (7): 3237-3245 [10.1002/2016gl068180] [Journal Article/Letter]

2015. "Lunar impact basins revealed by Gravity Recovery and Interior Laboratory measurements." Science Advances 1 (9): e1500852-e1500852 [Full Text] [10.1126/sciadv.1500852] [Journal Article/Letter]

2015. "International Geomagnetic Reference Field: the 12th generation." Earth Planet Sp 67 (1): 79 [10.1186/s40623-015-0228-9] [Journal Article/Letter]

2015. "Can we probe the conductivity of the lithosphere and upper mantle using satellite tidal magnetic signals?." Geophysical Research Letters 42 (9): 3233–3239 [10.1002/2015GL063540] [Journal Article/Letter]

2015. "CM5, a pre-Swarm comprehensive geomagnetic field model derived from over 12 yr of CHAMP, Ørsted, SAC-C and observatory data ." Geophys. J. Int. 200 (3): 1596-1626 [10.1093/gji/ggu493] [Journal Article/Letter]

2014. "Gravimetry measurements from space." Remote Sensing of the Cryosphere 231-247 [10.1002/9781118368909.ch10] [Article in Book]

2014. "High-resolution local gravity model of the south pole of the Moon from GRAIL extended mission data." Geophys. Res. Lett. 41 (10): 3367-3374 [Full Text] [10.1002/2014GL060178] [Journal Article/Letter]

2014. "GRGM900C: A degree-900 lunar gravity model from GRAIL primary and extended mission data." Geophys. Res. Lett. 41 (10): 3382-3389 [Full Text] [10.1002/2014GL060027] [Journal Article/Letter]

2013. "Use of the Comprehensive Inversion method for Swarm satellite data analysis." Earth Planets and Space 65 (11): 1201-1222 [10.5047/eps.2013.09.007] [Journal Article/Letter]

2013. "High-degree gravity models from GRAIL primary mission data." J. Geophys. Res.-Planets 118 1676-1698 [10.1002/jgre.20118] [Journal Article/Letter]

2013. "Antarctica, Greenland and Gulf of Alaska land ice evolution from an iterated GRACE global mascon solution." Journal of Glaciology 216 613-631 [10.3189/2013JoG12J147] [Journal Article/Letter]

2010. "International Geomagnetic Reference Field: the eleventh generation." Geophysical Journal International 183 (3): 1216-1230 [10.1111/j.1365-246X.2010.04804.x] [Journal Article/Letter]

2010. "Improving global mass flux solutions from Gravity Recovery and Climate Experiment (GRACE) through forward modeling and continuous time correlation." J. Geophys. Res. 115 (B11): B11403 [10.1029/2010JB007533] [Journal Article/Letter]

2010. "Mathematical properties relevant to geomagnetic field modeling." [Journal Article/Letter]

2010. "The magnetic field of the Earth's lithosphere." Space Science Reviews 155 (1-4): 95-127 [10.1007/s11214-010-9667-6] [Journal Article/Letter]

2010. "Measuring the Earth's magnetic field from space: Concepts of past, present and future missions." Space Science Reviews 155 (1-4): 65-93 [10.1007/s11214-010-9676-5] [Journal Article/Letter]

2010. "The CHAOS-3 geomagnetic field model and candidates for the 11th generation IGRF." Earth Planets and Space 62 (10): 719-727 [10.5047/eps.2010.07.003] [Journal Article/Letter]

2010. "Global mass flux solutions from GRACE: A comparison of parameter estimation strategies—Mass concentrations versus Stokes coefficients." J. Geophys. Res. Solid Earth 115 (B1): [Full Text] [10.1029/2009JB006546] [Journal Article/Letter]

2009. "CHAOS-2, a geomagnetic field model derived from one decade of continuous satellite data." Geophysical Journal International 179 (3): 1477-1487 [10.1111/j.1365-246x.2009.04386.x] [Journal Article/Letter]

2009. "Mercury's internal magnetic field: Constraints on large- and small-scale fields of crustal origin ." Earth and Planetary Science Letters 285 (3-4): 340-346 [10.1016/j.epsl.2008.12.017] [Journal Article/Letter]

2009. "CHAOS-2-a geomagnetic field model derived from one decade of continuous satellite data ." Geophysical Journal International 179 (3): 1477-1487 [Journal Article/Letter]

2009. "Constraining a numerical geodynamo model with 100 years of surface observations." Geophysical Journal International 179 (3): 1458-1468 [10.1111/j.1365-246X.2009.04376.x] [Journal Article/Letter]

2007. "Magnetic field gradients from the ST-5 constellation: Improving magnetic and thermal models of the lithosphere." Geophys Res. Lett 34 (24): L24306 [10.1029/2007GL031739] [Journal Article/Letter]

2007. "On induction effects of geomagnetic daily variations from equatorial electrojet and solar quiet sources at low and middle latitudes." Journal of Geophysical Research 112 (B10): B10102 [10.1029/2007jb004955] [Journal Article/Letter]

2007. "Age spot or youthful marking: Origin of Reiner Gamma." Geophysical Research Letters 34 (2): L02205 [10.1029/2006gl027794] [Journal Article/Letter]

2006. "CHAOS-a model of the Earth's magnetic field derived from CHAMP, Ørsted, and SAC-C magnetic satellite data." Geophysical Journal International 166 (1): 67-75 [10.1111/j.1365-246x.2006.02959.x] [Journal Article/Letter]

2006. "The Swarm End-to-End mission simulator study: A demonstration of separating the various contributions to Earth’s magnetic field using synthetic data." Earth, Planets and Space 58 (4): 359-370 [10.1186/bf03351934] [Journal Article/Letter]

2006. "3-D electromagnetic induction studies using the Swarm constellation: Mapping conductivity anomalies in the Earth’s mantle." Earth, Planets and Space 58 (4): 417-427 [10.1186/bf03351938] [Journal Article/Letter]

2006. "Enhancing comprehensive inversions using the Swarm constellation." Earth Planets and Space 58 (4): 371–395 [Full Text] [10.1186/BF03351935] [Journal Article/Letter]

2005. "Ionospheric and Induced Field Leakage in Geomagnetic Field Models, and Derivation of Candidate Models for DGRF 1995 and DGRF 2000." Earth Planets and Space 57 (12): 1191-1196 [Full Text] [10.1186/BF03351903] [Journal Article/Letter]

2005. "Balloon Geomagnetic Survey at Stratospheric Altitudes." Earth Observation with CHAMP 273-278 [10.1007/3-540-26800-6_43] [Article in Book]

2005. "New Parameterization of External and Induced Fields in Geomagnetic Field Modeling, and a Candidate Model for IGRF 2005." Earth Planets Space 57 (12): 1141-1149 [10.1186/BF03351897] [Journal Article/Letter]

2004. "Extending comprehensive models of the Earth's magnetic field with Ørsted and CHAMP data." Geophysical Journal International 159 (2): 521-547 [10.1111/j.1365-246x.2004.02421.x] [Journal Article/Letter]

2003. "The 9th-Generation International Geomagnetic Reference Field." Geophysical Journal International 155 (3): 1051-1055 [10.1111/j.1365-246X.2003.02102.x] [Journal Article/Letter]

2002. "A comprehensive model of the quiet-time, near-Earth magnetic field: Phase 3." Geophysical Journal International 151 (1): 32-68 [10.1046/j.1365-246X.2002.01774.x] [Journal Article/Letter]

2002. "Compatibility of high-altitude aeromagnetic and satellite-altitude magnetic anomalies over Canada." GEOPHYSICS 67 (2): 546-554 [10.1190/1.1468615] [Journal Article/Letter]

2001. "The orthogonalization of magnetic systems." Sensors and Actuators A: Physical 89 (3): 185-196 [10.1016/s0924-4247(00)00515-x] [Journal Article/Letter]

2000. "Ørsted Initial Field Model." Geophysical Research Letters 27 (22): 3607-3610 [10.1029/2000gl011930] [Journal Article/Letter]

2000. "An altitude-normalized magnetic map of Mars and its interpretation." Geophys. Res. Lett. 27 (16): 2449-2452 [10.1029/2000GL000072] [Journal Article/Letter]

2000. " Determination of the IGRF 2000 model." Earth Planets and Space 52 (12): 1175-1182 [Full Text] [10.1186/BF03352349] [Journal Article/Letter]

1997. "The missing dimension in Magsat and POGO anomaly studies." Geophysical Research Letters 24 (22): 2909-2912 [10.1029/97gl52978] [Journal Article/Letter]

1997. "The geomagnetic field 1900-1995, including the large-scale field from magnetospheric sources, and the NASA candidate models for the 1995 revision of the IGRF." Journal of Geomagnetism and Geoelectricity 49 (2-3): 157-206 [Full Text] [10.5636/jgg.49.157] [Journal Article/Letter]

1997. "Adjustment of UARS, POGS, and DE-1 satellite magnetic field data for modeling of Earth's main field." Journal of Geomagnetism and Geoelectricity 49 (2-3): 393-415 [Full Text] [Journal Article/Letter]

1997. "The geomagnetic field 1900-1995, including the large-scale field from magnetospheric sources, and the NASA candidate models for the 1995 revision of the IGRF." Journal of geomagnetism and geoelectricity 49 (2-3): 157-206 [Full Text] [10.5636/jgg.49.157] [Journal Article/Letter]

1996. "The near-Earth magnetic field from magnetospheric and quiet-day ionospheric sources and how it is modeled." Physics of the Earth and Planetary Interiors 98 (3-4): 235-267 [10.1016/s0031-9201(96)03190-1] [Journal Article/Letter]

1996. "International Geomagnetic Reference Field, 1995 revision Presented by IAGA Division V, Working Group 8." Physics of the Earth and Planetary Interiors 97 (1-4): 23-26 [10.1016/0031-9201(96)03139-1] [Journal Article/Letter]

1996. "Conjugate Gradient Analysis: A New Tool For Studying Satellite Magnetic Data Sets." Geophysical Research Letters 23 (5): 507-510 [Full Text] [10.1029/96GL00388] [Journal Article/Letter]

1992. "The Geomagnetic Field: 1970-1990 and the NASA Candidate Models for DGRF1985 and IGRF1990." Journal of geomagnetism and geoelectricity 44 (9): 745-767 [10.5636/jgg.44.745] [Journal Article/Letter]

1989. "Uncertainty estimates in geomagnetic field modeling." Journal of Geophysical Research 94 (B9): 12281 [10.1029/jb094ib09p12281] [Journal Article/Letter]

1988. "Definitive IGRF models for 1945, 1950, 1955, and 1960." Journal of geomagnetism and geoelectricity 40 (6): 645-702 [10.5636/jgg.40.645] [Journal Article/Letter]

Non-Refereed

2018. "A Large Solid Inner Core at Mercury." 49th Lunar and Planetary Science Conference (Virtual Meeting), 19-23 March 2018, The Woodlands, Texas Abstract # 6036 [Full Text] [Proceedings]

2018. "A high-resolution global map of lunar gravity from patched local solutions." Proceedings of the 49th Lunar and Planetary Science Conference, The Woodlands, Texas, U.S.A. March 19-23, 2018, Paper #2477 [Full Text] [Proceedings]

2018. "New Insights into Mercury’s Interior with the MESSENGER Mission." Proceedings of the 49th Lunar and Planetary Science Conference, The Woodlands, Texas, U.S.A., March 19-23, 2018. Paper # 1659 [Full Text] [Proceedings]

2017. "Recovery of Bennu's Orientation for the OSIRIS-REx Mission." Proceedings of the 48th Lunar and Planetary Science Conference, March 20-24, 2017, The Woodlands, Texas, U.S.A. Paper # 1989 [Full Text] [Proceedings]

2016. "A global degree and order 1200 model of the lunar gravity field using GRAIL mission data." Proceedings of the 47th Lunar and Planetary Science Conference, March 21-25, 2016, The Woodlands, Texas, U.S.A. Paper # 1484 [Full Text] [Proceedings]

2013. "Improved precision orbit determination of lunar orbiters from GRAIL-derived lunar gravity models." Spaceflight Mechanics 2013 (AAS/AIAA Spaceflight Mechanics Meeting, Feb. 10-14, 2013, Kauai, Hawaii), Advances in the Astronautical Sciences 148, Part II 1125-1141 [Proceedings]

2013. "Modeling and precise orbit determination in suport of gravity model development for the GRAIL mission." Spaceflight Mechanics 2013 (AAS/AIAA Spaceflight Mechanics Meeting, Feb. 10-14, 2013, Kauai, Hawaii), Advances in the Astronautical Sciences 148, Part II 1111-1123 [Proceedings]

2010. "Sources of the geomagnetic field and the modern data that enable their investigation." The Handbook of Geomathematics [Article in Book]

2009. "Mercury's Internal Magnetic Field from MESSENGER." 40th Lunar and Planetary Science Conference, 23-27 March 2009, The Woodlands, Texas Abstract # 1277 [Full Text] [Proceedings]

2008. " Interpreting magnetic anomaly signatures observed over the nearside lunar mare basins." NLSI Lunar Science Conference, 20-23 July 2008, NASA Ames Research Center Abstract #2105 [Full Text] [Proceedings]

2007. "Antipodal Seismic Effects of Lunar Basin-forming Impacts: Enhanced Magnetic and Geochemical Anomalies Peripheral to the South Pole-Aitken Basin." 38th Lunar and Planetary Science Conference, 12-16 March 2007, Houston, Texas, Abstract # 1381 [Full Text] [Proceedings]

2007. "The Reiner Gamma Albedo Marking on Earth's Moon: Old or Young." 38th Lunar and Planetary Science Conference, 12-16 March 2007, Houston, Texas Abstract # 1027 [Full Text] [Proceedings]

2006. "The Lunar Magnetic Field Environment: Interpretation of New Maps of the Internal and External Fields." 37th Lunar and Planetary Science Conference, 13-17 March 2006, Houston, Texas Abstract # 1933 [Full Text] [Proceedings]

2002. "Magnetic Spectra of Earth and Mars." 33rd Lunar and Planetary Science Conference, 11-15 March 2002, Houston, Texas Abstact # 1924 [Full Text] [Proceedings]

1991. "An initial analysis of the data from the Polar Orbiting Geophysical (POGS) Satellite." NASA-TM-104551 [Full Text] [Report]

1991. "Geomagnetic model investigations for 1980 - 1989: A model for strategic defense initiative particle beam experiments and a study in the effects of data types and observatory bias solutions." NASA-TM-104541 [Full Text] [Report]

1990. "Processing of DMSP magnetic data: Handbook of programs, tapes, and datasets." NASA-TM-100757 [Full Text] [Report]

1989. "Processing of DMSP magnetic data and its use in geomagnetic field modeling." NASA-TM-100750 [Full Text] [Report]