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Jian Yao, Ph.D.

Associate professor
Department of Earth and Atmospheric Sciences

Education

  • Ph.D. in Physics, University of Colorado Boulder, 2014
  • M.Sc. in Physics, University of Colorado Boulder, 2012
  • B.Sc. in Physics (minor: Microelectronics), Nanjing University, 2009

Research Interests

  • Global Positioning System (GPS) & Global Navigation Satellite System (GNSS)
  • Positioning, Navigation and Timing (PNT)
  • Satellite orbit determination and its applications in thermosphere density sensing
  • Time and frequency metrology

Labs and Facilities

Publications and Media Placements

Publications

  • Jian Yao*, Jan-Peter Weiss, Tzu-Wei Fang, Eric Sutton, and Tim Fuller-Rowell, “Sensing thermospheric density using COSMIC-2 satellite GNSS data,” Proceedings of the 2023 Institute of Navigation GNSS+ Meeting, pp. 3217-3226, 2023.
  • Jian Yao*, Jan-Peter Weiss, and Teresa VanHove, “Impacts of high rate GNSS satellite clock estimation on radio occultation bending angle retrievals: preliminary report,” Proceedings of the 2023 Institute of Navigation International Technical Meeting (ITM), pp. 995 – 1001, 2023.
  • Thomas Parker*, Victor Zhang, Gerard Petit, Jian Yao, Roger Brown, and James Hanssen, “A three-cornered hat analysis of instabilities in two-way and GPS carrier phase time transfer systems,” Metrologia, vol. 59, pp. 035007, 2022.
  • Jeffrey Sherman*, Ladan Arissian, Roger Brown, Matthew J Deutch, Elizabeth Donley, Vladislav Gerginov, Judah Levine, Glenn Nelson, Andrew Novick, Bijunath Patla, Tom Parker, Benjamin Stuhl, Jian Yao, William Yates, Michael Lombardi, Victor Zhang, and Douglas Sutton, “A Resilient Architecture for the Realization and Distribution of Coordinated Universal Time to Critical Infrastructure Systems in the United States,” NIST Technical Note 2187, 2021.
  • Jian Yao*, Sungpil Yoon, Steve Hilla, Bryan Stressler, and Mark Schenewerk, “GPS satellite clock observation based on globally-distributed atomic clock networks,” GPS Solutions, vol. 25, pp. 1-10, 2021.
  • Kyle Beloy, Martha I Bodine, Tobias Bothwell, Samuel M Brewer, Sarah L Bromley, Jwo-Sy Chen, Jean-Daniel Deschênes, Scott A Diddams, Robert J Fasano, Tara M Fortier*, Youssef S Hassan, David B Hume*, Dhruv Kedar, Colin J Kennedy*, Isaac Khader, Amanda Koepke*, David R Leibrandt, Holly Leopardi*, Andrew D Ludlow, William F McGrew, William R Milner, Nathan R Newbury, Daniele Nicolodi, Eric Oelker, Thomas E Parker, John M Robinson, Stefania Romisch, Stefan A Schäffer, Jeffrey A Sherman, Laura C Sinclair*, Lindsay Sonderhouse, William C Swann, Jian Yao, Jun Ye, and Xiaogang Zhang*, “Frequency ratio measurements with 18-digit accuracy using a network of optical clocks,” Nature, 591, 564-569, 2021.
  • Holly Leopardi*, Kyle Beloy, Tobias Bothwell, Samuel Brewer, Sarah L Bromley, Jwo-Sy Chen, Scott A Diddams, Robert Fasano, Youssef Hassan, David Hume, Dhruv Kedar, Colin J Kennedy, David Leibrandt, Andrew Ludlow, William McGrew, William Milner, Daniele Nicolodi, Eric Oelker, Thomas Parker, John M Robinson, S Romisch, Jeffrey Sherman*, Lindsay Sonderhouse, Jian Yao, Jun Ye, Xiaogang Zhang, and Tara Michele Fortier*, “Measurement of the 27Al+ and 87Sr absolute optical frequencies,” Metrologia, vol. 58, pp. 015017, 2021.
  • Martha I Bodine*, Jean-Daniel Deschênes, Isaac H Khader, William C Swann, Holly Leopardi, Kyle Beloy, Tobias Bothwell, Samuel M Brewer, Sarah L Bromley, Jwo-Sy Chen, Scott A Diddams, Robert J Fasano, Tara M Fortier, David B Hume, Druv Kedar, Colin J Kennedy, Amanda Koepke, David R Leibrandt, Andrew D Ludlow, William F McGrew, William Milner, Daniele Nicolodi, Eric G Oelker, Thomas E Parker, John M Robinson, Jeffrey A Sherman, Jian Yao, Jun Ye, Xiaogang Zhang, Nathan R Newbury, and Laura C Sinclair, “Optical atomic clock comparison through turbulent air,” Phys. Rev. Research, 2, 033395, 2020.
  • Jian Yao*, Sungpil Yoon, Steve Hilla, and Mark Schenewerk, “The reverse precise-point-positioning processing for GPS satellite clock observation,” Proceedings of the 7th International Colloquium on Scientific and Fundamental Aspects of GNSS, 2019.
  • William R. Milner*, John M. Robinson, Colin J. Kennedy, Dhruv Kedar, Tobias Bothwell, Jeffrey A. Sherman, Dan G. Matei, Thomas Legero, Uwe Sterr, Fritz Riehle, Holly Leopardi, Tara M. Fortier, Jian Yao*, Jun Ye*, and Eric Oelker*, “Demonstration of a time scale based on a stable optical carrier,” Physical Review Letters, vol. 123, pp. 173201, 2019. This paper was selected as an Editors’ Suggestion and Featured in Physics paper.
  • Jian Yao*, Jeffrey Sherman, Tara Fortier, Holly Leopardi, Thomas Parker, William McGrew, Xiaogang Zhang, Daniele Nicolodi, Robert Fasano, Stephan Schaeffer, Kyle Beloy, Joshua Savory, Stefania Romisch, Chris Oates, Scott Diddams, Andrew Ludlow, and Judah Levine, “Optical-clock-based time scale,” Physical Review Applied, vol. 12, pp. 044069, 2019. This paper was selected as an Editors’ Suggestion paper.
  • Youssef Hassan, William McGrew, Xiaogang Zhang, Robert Fasano, Daniele Nicolodi, Kyle Beloy, Wesley Brand, Stephan Schaffer, Roger Brown, Jian Yao, Jeffrey Sherman, Thomas Parker, Holly Leopardi, Tara Fortier, and Andrew Ludlow*, “Updates on Yb optical lattice clocks at NIST,” Bulletin of the American Physical Society, 2019.
  • William McGrew, Xiaogang Zhang, Holly Leopardi, Robert Fasano, Daniele Nicolodi, Kyle Beloy, Jian Yao, Jeffrey Sherman, Stephan Schaffer, Joshua Savory, Stefania Romisch, Chris Oates, Thomas Parker*, Tara Fortier*, and Andrew Ludlow*, “Towards the optical second: verifying optical clocks at the SI limit,” Optica, vol. 6, pp. 448-454, 2019.
  • Jian Yao*, Jeffrey Sherman, Tara Fortier, Thomas Parker, Judah Levine, Joshua Savory, Stefania Romisch, William McGrew, Xiaogang Zhang, Daniele Nicolodi, Robert Fasano, Stephan Schaeffer, Kyle Beloy, and Andrew Ludlow, “Progress on incorporating an optical clock into a time scale at NIST: simulations and preliminary real-data analysis,” Invited paper, NAVIGATION, vol. 65, pp. 601-608, 2018.
  • Jian Yao*, Thomas Parker, Neil Ashby, and Judah Levine, “Incorporating an optical clock into a time scale,” IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 65, no. 1, pp. 127-134, 2018.
  • Jian Yao*, Thomas Parker, and Judah Levine, “JY1 time scale: a new Kalman-filter time scale designed at NIST,” Measurement Science and Technology, vol. 28, pp. 115004/1-8, 2017.
  • Jian Yao*, Thomas Parker, and Judah Levine, “The development of a new Kalman-filter time scale at NIST,” Proceedings of the 48th Institute of Navigation PTTI Meeting, pp. 18-25, 2017.
  • Jian Yao*, Michael A. Lombardi, Andrew N. Novick, Bijunath Patla, Jeff A. Sherman, and Victor Zhang, “The effects of the January 2016 UTC offset anomaly on GPS receivers monitored at NIST,” Proceedings of the 48th Institute of Navigation PTTI Meeting, pp. 155-163, 2017.
  • Zhiheng Jiang*, Victor Zhang, Tom Parker, Jian Yao, Yi-Jiun Huang and Shinn-Yan Lin, “Accurate time transfer with indirect TWSTFT links,” Proceedings of the 48th Institute of Navigation PTTI Meeting, pp. 243-255, 2017.
  • Marc Weiss*, Lee Cosart, James Hanssen, and Jian Yao, “Precision time transfer using IEEE 1588 over OTN through a commercial optical telecommunications network,” Proceedings of the 2016 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication (ISPCS), 2016.
  • Jian Yao*, and Judah Levine, “A study of GPS carrier-phase time transfer noise based on NIST GPS receivers,” Journal of Research of NIST, pp. 372-388, 2016.
  • Zhiheng Jiang*, Yi-Jiun Huang, Wen-Hung Tseng, Shinn-Yan Lin, Miho Fujieda, Sung Hoon Yang, and Jian Yao, “Experience of TWSTFT SDR – BIPM Analysis,” BIPM TM260, 2016.
  • Jian Yao*, and Judah Levine, “Long-term GPS carrier-phase time transfer noise: a study based on seven GPS receivers at NIST,” Proceedings of the 2016 IEEE International Frequency Control Symposium (IFCS), pp. 249-253, 2016.
  • Jian Yao*, Marc Weiss, Charles Curry, and Judah Levine, “GPS jamming and GPS carrier-phase time transfer,” Proceedings of the 47th Institute of Navigation PTTI Meeting, pp. 80-85, 2016.
  • Marc Weiss*, Jian Yao, Lee Cosart, and James Hanssen, “Ethernet time transfer through a U.S. commercial optical telecommunications network, part 2,” Proceedings of the 47th Institute of Navigation PTTI Meeting, pp. 107-115, 2016.
  • Jian Yao*, Judah Levine, and Marc Weiss, “Toward continuous GPS carrier-phase time transfer: eliminating the time discontinuity at an anomaly,” Journal of Research of NIST, pp. 280-292, 2015.
  • Jian Yao*, Ivan Skakun, Zhiheng Jiang, and Judah Levine, “A detailed comparison of two continuous GPS carrier-phase time transfer techniques,” Metrologia, vol. 52, pp. 666-676, 2015.
  • Victor Zhang*, Thomas Parker, and Jian Yao, “Long-term uncertainty in time transfer using GPS and TWSTFT techniques,” Proceedings of the 2015 IEEE IFCS-EFTF Conference, pp. 723-727, 2015.
  • Jian Yao*, Ivan Skakun, Zhiheng Jiang, and Judah Levine, “Comparison of two continuous GPS carrier-phase time transfer techniques,” Proceedings of the 2015 IEEE IFCS-EFTF Conference, pp. 655-661, 2015.
  • Jian Yao, “Continuous GPS carrier-phase time transfer,” Ph.D. thesis, University of Colorado at Boulder, 2014.
  • Jian Yao*, and Judah Levine, “GPS measurements anomaly and continuous GPS carrier-phase time transfer,” Proceedings of the 46th Institute of Navigation PTTI Meeting, pp. 164-169, 2014.
  • Jian Yao*, and Judah Levine, “An improvement of RINEX-Shift algorithm for continuous GPS carrier-phase time transfer,” Proceedings of the 27th Institute of Navigation GNSS+ Meeting, pp. 1253-1260, 2014.
  • Jian Yao*, and Judah Levine, “A new algorithm to eliminate GPS carrier-phase time transfer boundary discontinuity,” Proceedings of the 45th Institute of Navigation PTTI Meeting, pp. 292-303, 2013.
  • Jian Yao* and Judah Levine, “GPS carrier-phase time transfer boundary discontinuity investigation,” Proceedings of the 44th Institute of Navigation PTTI Meeting, pp. 317-326, 2012.
  • Marc Weiss*, Jian Yao and Jiaqi Li, “In search of a new primary GPS receiver for NIST,” Proceedings of the 44th Institute of Navigation PTTI Meeting, pp. 179-186, 2012.
* labels the corresponding author(s).

Media and Reports

  • In 2023, Digital Locations, Inc interviewed me on Positioning, Navigation, and Timing (PNT). Here is the Podcast. It was also reported by Yahoo Finance.
  • In 2021, President's FY 2021 Budget Request to Congress — NIST (Page 20) reported my research on time scales. It says "NIST scientists demonstrated the first next generation ‘time scale’ — a system that incorporates data from multiple atomic clocks to produce a single highly accurate timekeeping signal for distribution.”
  • In 2021, NIST news and a LinkedIn blog reported my co-authored paper "A Resilient Architecture for the Realization and Distribution of Coordinated Universal Time to Critical Infrastructure Systems in the United States." This work was also mentioned in 2021 Commerce Accomplishments. It says "NIST recommended steps to boost resilience of U.S. timekeeping."
  • In 2021, NPR news, Nature podcast and AAAS news reported my co-authored paper "Frequency ratio measurements at 18-digit accuracy using an optical clock network." 
  • In 2019, APS news and NIST news reported my corresponding-authored paper "Demonstration of a time scale based on a stable optical carrier."
  • In 2019, ScienceDaily reported my co-authored paper "Towards the optical second: Verifying optical clocks at the SI limit."
  • In 2017, phys.org news reported my first-authored paper "Incorporating an Optical Clock into a Time Scale."
  • In 2017, Wikipedia on Leap Second mentioned my first-authored paper "The effects of the January 2016 UTC offset anomaly on GPS receivers monitored at NIST." This blog discussed the paper in details.
  • In 2016, NIST news and phys.org news reported my co-authored paper "Precision Time Transfer using IEEE 1588 over OTN through a Commercial Optical Telecommunications Network."

Honors and Awards

  • Trusted Reviewer, IOP Publishing, 2023.
  • NIST Distinguished Associate Award, U.S. Department of Commerce, 2019.
  • Outstanding Reviewer Awards, IOP Measurement Science and Technology, 2018.
  • Student Representative, IEEE Ultrasonics, Ferroelectrics, and Frequency Control (UFFC) Society, 2013-2015.
  • Best Student Paper, 45th Institute of Navigation Precise Time and Time Interval (PTTI) Meeting, 2013.
  • Best Student Paper, 44th Institute of Navigation Precise Time and Time Interval (PTTI) Meeting, 2012.

Professional Organizations and Associations

  • Scientific Committee, POD-Derived Thermospheric Density Workshop, 2024.
  • Editorial Board, IOP Measurement Science and Technology, since 2024 January.
  • Session Chair, Institute of Navigation International Technical Meeting (ITM) & Precise Time and Time Interval Meeting (PTTI), 2024 & 2022 & 2019 & 2017.
  • Scientific Committee, European Frequency and Time Forum (EFTF), since 2023 September.
  • Committee, UCAR’s University Community Programs (UCP) Strategic Planning Project, 2022-2024
  • Editorial Advisory Board, GPS Solutions, since 2018.
  • Panelist, American Institute of Aeronautics and Astronautics (AIAA) Rocky Mountain Annual Technical Symposium, 2023.
  • Editor, Special Issue “Timekeeping in Space: Technology, Practice, Promise, and Benefits”, GPS Solutions (Impact Factor: 5.222), 2021-2023.
  • General Co-Chair, IEEE GNSS+R Workshop, 2023.
  • Committee, National Institute of Standards and Technology (NIST) Physical Measurement Laboratory (PML) Internal Awards Program, 2021.
  • Technical Program Committee, IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication (ISPCS), 2017 & 2016.
  • Technical Program Committee, IEEE International Frequency Control Symposium, 2016.
  • Reviewer for journals such as GPS Solutions, NAVIGATION, IEEE Transactions on Instrumentation and Measurement, Metrologia, IOP Measurement Science and Technology, Remote Sensing, Elsevier, Algorithms, Artificial Satellites, IEEE Industrial Electronics Magazine.