Dr. Stephen Guimond

Dr. Stephen Guimond

  • 301.614.5809
  • NASA/GSFC
  • Mail Code: 612
  • Greenbelt , MD 20771
  • Employer: UNIVERSITY OF MARYLAND BALTIMORE CO
  • Brief Bio

    For details about my current work click the following link:

    The Geophysical Fluid Dynamics (GFD) Group at UMBC

     

     

    Research Interests

    Remote sensing with a focus on airborne Doppler radar including designing algorithms for computing geophysical variables such as winds, latent heat and precipitation. Geophysical fluid dynamics with a focus on hurricanes, convection, turbulence and computational methods.

    Current Projects

    The Dynamics of Turbulent Buoyant Plumes

    With support from the Department of Energy/Los Alamos National Laboratory, I am modeling the dynamics of wildfire smoke plumes and their associated convection as well as interaction with the stratosphere using the NASA GEOS climate model. The goal is to understand the interaction of uncertain model parameters that dictate the rise rate, height and residence time of smoke plumes in the stratosphere. With an increased frequency and severity of recent wildfire events, we seek to understand the short and long term effects of these plumes on weather and climate.

    Understanding the Turbulent Dynamics of Convective Bursts and Tropical Cyclone Intensification Using Large Eddy Simulations and High-Order Numerics

    With support from the National Science Foundation, my group is studying the fundamental fluid mechanics of atmospheric convection and turbulence in hurricane intensification with advanced numerical methods from the applied mathematics community. The goal is to understand the production, dissipation and nonlinear transfer of energy across scales in a turbulent regime with large eddy simulations and turbulence-resolving remote sensing data. This work has important implications for NASA in the design of new remote sensing instruments and the study of the planetary boundary layer.

    The Physics of Precipitation Bands in Extra-Tropical Systems

    With support from NASA, I am studying multi-scale banded precipitation features in extra-tropical cyclones. Banded structures in extreme weather systems are generally turbulent perturbations to a balanced, background flow that can organize and concentrate variables such as moisture, momentum, and energy. The concentration of these variables can lead to multiple intense bands of mixed-phase precipitation that are difficult to measure, model and predict with significant consequences for society in the energy and travel industries. The current understanding of the physical processes controlling the formation and evolution of these precipitation bands and their representation/predictability in numerical models is limited. In this work, airborne and spaceborne remote sensing measurements along with large-eddy numerical simulations are being used to advance the understanding of the physics of banded structures in extra-tropical cyclones. The measurement aspect focuses on radar data collected during the Investigation of Microphysics and Precipitation for Atlantic Coast-Threatening Snowstorms (IMPACTS) field campaign along with supporting satellite data. The modeling aspect provides a testing ground for airborne simulation studies and a mechanistic understanding of the banded structures using a dynamical budget methodology.

    Understanding the Structure and Role of the Turbulent Boundary Layer in Hurricane Intensity Change

    With support from the Office of Naval Research, I am studying the fluid mechanics of the hurricane boundary layer with a focus on the characteristics of coherent turbulent structures and their dynamical role in the large-scale flow evolution using airborne radar measurements. The fundamental measurable in the planetary boundary layer is wind velocity and I have been computing 3D winds at very fine scale for use in understanding the role of turbulence in high Reynolds number flows such as hurricanes.

    Positions/Employment

    10/2020 - Present

    Associate Research Professor

    UMBC/JCET, Baltimore, MD
    8/2017 - 9/2020

    Assistant Research Professor

    UMBC/JCET, Baltimore, MD
    2014 - 2017

    Assistant Research Scientist

    University of Maryland/ESSIC, GSFC
    2012 - 2014

    Research Associate

    University of Maryland/ESSIC, GSFC
    2010 - 2012

    NASA Postdoctoral Fellow (NPP)

    Oak Ridge Associated Universities, GSFC

    Teaching Experience

    1. Tutoring student athletes in Meteorology classes at Florida State University
    2. Statistics and general Meteorology classes at Florida State University
    3. Synoptic/Dynamic Meteorology classes at the Naval Postgraduate School
    4. Dynamic Meteorology classes at the University of Maryland Baltimore County (UMBC)
    5. PHYS 499, research physics course at UMBC
    6. PHYS 440, computational physics course at UMBC (wavelets lectures)

    Education

    2010, Ph.D., Atmospheric Science, Florida State University

    2007, M.S., Atmospheric Science, Florida State University

    2004, B.S., Atmospheric Science, Iowa State University

    Professional Societies

    American Meteorological Society (AMS), 2004 - Present
    American Geophysical Union (AGU) – Atmospheric Sciences and Nonlinear Geophysics sections, 2015 - Present

    Professional Service

    Organizing Committee: 33rd Conf. on Hurricanes and Tropical Meteorology, 38th Conf. on Radar Meteorology & 32nd Conf. on Hurricanes and Tropical Meteorology

    Session Chair: 30th, 32nd, 33rd Conf. on Hurricanes and Tropical Meteorology and NASA Ocean Vector Winds Science Team meeting

    Mission Scientist: NASA East Pacific Origins and Characteristics of Hurricanes (EPOCH) field program, NASA Hurricane and Severe Storm Sentinel (HS3) field program

    Instrument Scientist: GOES-R field program, NOAA SHOUT field program

    Reviewer: Journal of the Atmospheric Sciences, Monthly Weather Review, IEEE, NASA postdoctoral program, QJRMS

    Editor: Remote Sensing journal, special issue on "High Winds and High Seas"

    Awards

    2017, Robert H. Goddard Science Team Award

         NASA Goddard Space Flight Center, High Altitude Radar Group

         "For excellence in instrument development, field deployments and data analysis"

    2016, Best Science Highlight

         NASA Goddard Space Flight Center, Earth Sciences Division (Atmospheres)

         "Developing clear, informative hurricane science"

    2014, Outstanding Performance (Software Development)

         NASA Goddard Space Flight Center, Earth Sciences Division (Atmospheres)

         "Developing wind retrieval algorithms for the HIWRAP radar"

    2013, Exceptional Scientific Achievement Award

         NASA Goddard Space Flight Center, Mesoscale Atmospheric Processes Laboratory

         "Developing wind retrieval algorithms for the HIWRAP radar"

    2006, Student Poster Award

         American Meteorological Society, 14th Conference on Satellite Meteorology

    Grants

    03/01/2017 Weather and Atmospheric Dynamics, NASA

    Understanding Hurricane Inner-Core Asymmetries and their Relationship to Convective Bursts and Storm Intensification using a Suite of NASA Data

    ; PI
    11/01/2018 Earth Venture Suborbital-3, NASA

    Investigation of Microphysics and Precipitation for Atlantic Coast-Threatening Snowstorms (IMPACTS)

    ; Co-I; ER-2 X-band Doppler Radar (EXRAD) wind retrievals and understanding the dynamics/thermodynamics of banded features in winter storms.
    09/01/2019 - 08/31/2021 Next Generation of Mesoscale Weather Observing Platforms, NOAA

    Real-time Observations of the Three-Dimensional Hurricane Boundary Layer Winds and Ocean Surface Vector Winds with an Imaging Airborne Profiler

    ; Co-PI
    03/27/2020 The Dynamics of Turbulent Buoyant Plumes , Department of Energy/Los Alamos National Laboratory
    PI
    08/01/2021 - 07/31/2024 Collaborative Research: Understanding the Turbulent Dynamics of Convective Bursts and Tropical Cyclone Intensification Using Large Eddy Simulations and High-Order Numerics, National Science Foundation (NSF)
    PI
    01/03/2022 - 01/03/2025 Understanding the Structure and Role of the Turbulent Boundary Layer in Hurricane Intensity Change, Office of Naval Research (ONR)
    PI

    Publications

    Refereed

    Guimond, S., J. Reisner, and M. Dubey. 2023. "The Dynamics of Megafire Smoke Plumes in Climate Models: Why a Converged Solution Matters for Physical Interpretations." Journal of Advances in Modeling Earth Systems (JAMES), 15 (e2022MS003432): [Full Text (Link)] [10.1029/2022MS003432]

    Guimond, S. 2023. "ER-2 X-band Radar (EXRAD) 3D Winds IMPACTS." NASA Global Hydrometeorology Resource Center DAAC, [http://dx.doi.org/10.5067/IMPACTS/EXRAD/DATA201]

    Protzko, D., S. Guimond, C. Jackson, et al. J. Sapp, Z. Jelenak, and P. Chang. 2022. "Documenting Coherent Turbulent Structures in the Boundary Layer of Intense Hurricanes through Wavelet Analysis on IWRAP and SAR Data." IEEE Transactions on Geoscience and Remote Sensing, (Submitted)

    Hasan, B., S. Guimond, M. Yu, S. Reddy, and F. Giraldo. 2022. "The Effects of Numerical Dissipation on Hurricane Rapid Intensification with Observational Heating." Journal of Advances in Modeling Earth Systems, 14 (8): [10.1029/2021MS002897]

    D'Angelo, G., S. Guimond, J. Reisner, D. Peterson, and M. Dubey. 2022. "Contrasting stratospheric smoke mass and lifetime from 2017 Canadian and 2019/2020 Australian megafires: Global simulations and satellite observations." Journal of Geophysical Research: Atmospheres, 127: [https://doi.org/10.1029/2021JD036249]

    Sroka, S., and S. R. Guimond. 2021. "Organized Kinetic Energy Backscatter in the Hurricane Boundary Layer from Radar Measurements." Journal of Fluid Mechanics, 924: A21 [10.1017/jfm.2021.632]

    Helms, C. N., M. L. Walker McLinden, G. M. Heymsfield, and S. R. Guimond. 2020. "Reducing Errors in Velocity-Azimuth Display (VAD) Wind and Deformation Retrievals from Airborne Doppler Radars in Convective Environments." Journal of Atmospheric and Oceanic Technology , 2251–2266 [https://doi.org/10.1175/JTECH-D-20-0034.1]

    Guimond, S. R. 2020. "Papers of Note: New Insight into Secondary Hurricane Eyewall Development from Airborne and Ground Radar." Bulletin of the American Meteorological Society, 101 (June): 471-472.

    Guimond, S. R., P. Reasor, G. M. Heymsfield, and M. McLinden. 2020. "The Dynamics of Vortex Rossby Waves and Secondary Eyewall Development in Hurricane Matthew (2016): New Insights from Radar Measurements." Journal of the Atmospheric Sciences, 77: 2349-2374 [10.1175/JAS-D-19-0284.1]

    Guimond, S. R. 2019. "Papers of Note: Coherent turbulence in Hurricane Rita (2005) during an eyewall replacement cycle." Bulletin of the American Meteorological Society, 100 (January): 18-20.

    Guimond, S. R., J. Zhang, J. Sapp, and S. Frasier. 2018. "Coherent Turbulence in the Boundary Layer of Hurricane Rita (2005) During an Eyewall Replacement Cycle." Journal of the Atmospheric Sciences, 75: 3071-3093 [10.1175/JAS-D-17-0347.1]

    Didlake, A. C., G. M. Heymsfield, P. D. Reasor, and S. R. Guimond. 2017. "Concentric Eyewall Asymmetries in Hurricane Gonzalo (2014) Observed by Airborne Radar." Monthly Weather Review, 145: 729 - 749.

    Guimond, S. R., J. M. Reisner, S. Marras, and F. X. Giraldo. 2016. "The Impacts of Dry Dynamic Cores on Asymmetric Hurricane Intensification." Journal of the Atmospheric Sciences, 73: 4661-4684 [10.1175/JAS-D-16-0055.1]

    Guimond, S. R., G. M. Heymsfield, P. D. Reasor, and A. C. Didlake. 2016. "The Rapid Intensification of Hurricane Karl (2010): New Remote Sensing Observations of Convective Bursts from the Global Hawk Platform." Journal of the Atmospheric Sciences, 73: 3617 - 3639 [10.1175/JAS-D-16-0026.1]

    Guimond, S. R., G. M. Heymsfield, P. D. Reasor, and A. C. Didlake. 2016. "The Rapid Intensification of Hurricane Karl (2010): New Remote Sensing Observations of Convective Bursts from the Global Hawk Platform." Journal of the Atmospheric Sciences, 73 (9): 3617-3639 [10.1175/jas-d-16-0026.1]

    Li, L., G. Heymsfield, J. Carswell, et al. D. H. Schaubert, M. L. McLinden, J. Creticos, M. Perrine, M. Coon, J. I. Cervantes, M. Vega, S. Guimond, L. Tian, and A. Emory. 2016. "The NASA High-Altitude Imaging Wind and Rain Airborne Profiler." IEEE Transactions on Geoscience and Remote Sensing, 54 (1): 298-310 [10.1109/tgrs.2015.2456501]

    Tian, L., G. M. Heymsfield, A. C. Didlake, S. Guimond, and L. Li. 2015. "Velocity–Azimuth Display Analysis of Doppler Velocity for HIWRAP." Journal of Applied Meteorology and Climatology, 54 (8): 1792-1808 [10.1175/jamc-d-14-0054.1]

    Didlake, A. C., G. M. Heymsfield, L. Tian, and S. R. Guimond. 2015. "The Coplane Analysis Technique for Three-Dimensional Wind Retrieval Using the HIWRAP Airborne Doppler Radar." J. Appl. Meteor. Climatol., 54 (3): 605–623 [10.1175/JAMC-D-14-0203.1]

    Guimond, S. R., L. Tian, G. M. Heymsfield, and S. J. Frasier. 2014. "Wind Retrieval Algorithms for the IWRAP and HIWRAP Airborne Doppler Radars with Applications to Hurricanes." Journal of Atmospheric and Oceanic Technology, 31 (6): 1189-1215 [10.1175/JTECH-D-13-00140.1]

    Braun, S. A., R. Kakar, E. Zipser, et al. G. M. Heymsfield, C. Albers, S. Brown, S. Durden, S. Guimond, J. Halverson, A. Heymsfield, S. Ismail, B. Lambrigtsen, T. Miller, S. Tanelli, J. Thomas, and J. Zawislak. 2013. "NASA's Genesis and Rapid Intensification Processes (GRIP) Field Experiment." Bulletin of the American Meteorological Society, 94 (3): 345-363 [10.1175/BAMS-D-11-00232.1]

    Godinez, H., J. Reisner, A. Fierro, S. Guimond, and J. Kao. 2012. "Determining Key Model Parameters of Rapidly Intensifying Hurricane Guillermo (1997) Using the Ensemble Kalman Filter." Journal of the Atmospheric Sciences, 69 (11): 3147-3171 [10.1175/JAS-D-12-022.1]

    Guimond, S., and J. Reisner. 2012. "A Latent Heat Retrieval and Its Effects on the Intensity and Structure Change of Hurricane Guillermo (1997). Part II: Numerical Simulations." Journal of the Atmospheric Sciences, 69 (11): 3128-3146 [10.1175/JAS-D-11-0201.1]

    Guimond, S. R., M. A. Bourassa, and P. D. Reasor. 2011. "A Latent Heat Retrieval and Its Effects on the Intensity and Structure Change of Hurricane Guillermo (1997). Part I: The Algorithm and Observations." J Atmos Sci, 68 (8): 1549–1567 [10.1175/2011JAS3700.1]

    Heymsfield, G. M., L. Tian, A. Heymsfield, L. Li, and S. R. Guimond. 2010. "Characteristics of Deep Tropical and Subtropical Convection from Nadir-Viewing High-Altitude Airborne Doppler Radar." Journal of the Atmospheric Sciences, 67 (2): 285-308 [10.1175/2009JAS3132.1]

    Guimond, S. R., G. M. Heymsfield, and T. Joseph. 2010. "Multiscale Observations of Hurricane Dennis (2005): The Effects of Hot Towers on Rapid Intensification." J. Atmos. Sci., 67 (3): 633-654 [10.1175/2009JAS3119.1]

    Wu, X., and S. R. Guimond. 2006. "Two- and three-dimensional cloud-resolving model simulations of the mesoscale enhancement of surface heat fluxes by precipitating deep convection." J Climate, 19: 139-149.

    Non-Refereed

    Guimond, S. R., S. Sroka, and D. Protzko. 2018. "A Large Eddy Simulation of Hurricane Intensification." 33rd Conference on Hurricanes and Tropical Meteorology, Amer. Meteor. Soc.. 17 pp. [Full Text (Link)]

    Brief Bio

    For details about my current work click the following link:

    The Geophysical Fluid Dynamics (GFD) Group at UMBC

     

     

    Publications

    Refereed

    Guimond, S., J. Reisner, and M. Dubey. 2023. "The Dynamics of Megafire Smoke Plumes in Climate Models: Why a Converged Solution Matters for Physical Interpretations." Journal of Advances in Modeling Earth Systems (JAMES) 15 (e2022MS003432): [Full Text (Link)] [10.1029/2022MS003432]

    Guimond, S. 2023. "ER-2 X-band Radar (EXRAD) 3D Winds IMPACTS." NASA Global Hydrometeorology Resource Center DAAC [http://dx.doi.org/10.5067/IMPACTS/EXRAD/DATA201]

    Protzko, D., S. Guimond, C. Jackson, et al. J. Sapp, Z. Jelenak, and P. Chang. 2022. "Documenting Coherent Turbulent Structures in the Boundary Layer of Intense Hurricanes through Wavelet Analysis on IWRAP and SAR Data." IEEE Transactions on Geoscience and Remote Sensing (Submitted)

    Hasan, B., S. Guimond, M. Yu, S. Reddy, and F. Giraldo. 2022. "The Effects of Numerical Dissipation on Hurricane Rapid Intensification with Observational Heating." Journal of Advances in Modeling Earth Systems 14 (8): [10.1029/2021MS002897]

    D'Angelo, G., S. Guimond, J. Reisner, D. Peterson, and M. Dubey. 2022. "Contrasting stratospheric smoke mass and lifetime from 2017 Canadian and 2019/2020 Australian megafires: Global simulations and satellite observations." Journal of Geophysical Research: Atmospheres 127 [https://doi.org/10.1029/2021JD036249]

    Sroka, S., and S. R. Guimond. 2021. "Organized Kinetic Energy Backscatter in the Hurricane Boundary Layer from Radar Measurements." Journal of Fluid Mechanics 924 A21 [10.1017/jfm.2021.632]

    Helms, C. N., M. L. Walker McLinden, G. M. Heymsfield, and S. R. Guimond. 2020. "Reducing Errors in Velocity-Azimuth Display (VAD) Wind and Deformation Retrievals from Airborne Doppler Radars in Convective Environments." Journal of Atmospheric and Oceanic Technology 2251–2266 [https://doi.org/10.1175/JTECH-D-20-0034.1]

    Guimond, S. R. 2020. "Papers of Note: New Insight into Secondary Hurricane Eyewall Development from Airborne and Ground Radar." Bulletin of the American Meteorological Society 101 (June): 471-472

    Guimond, S. R., P. Reasor, G. M. Heymsfield, and M. McLinden. 2020. "The Dynamics of Vortex Rossby Waves and Secondary Eyewall Development in Hurricane Matthew (2016): New Insights from Radar Measurements." Journal of the Atmospheric Sciences 77 2349-2374 [10.1175/JAS-D-19-0284.1]

    Guimond, S. R. 2019. "Papers of Note: Coherent turbulence in Hurricane Rita (2005) during an eyewall replacement cycle." Bulletin of the American Meteorological Society 100 (January): 18-20

    Guimond, S. R., J. Zhang, J. Sapp, and S. Frasier. 2018. "Coherent Turbulence in the Boundary Layer of Hurricane Rita (2005) During an Eyewall Replacement Cycle." Journal of the Atmospheric Sciences 75 3071-3093 [10.1175/JAS-D-17-0347.1]

    Didlake, A. C., G. M. Heymsfield, P. D. Reasor, and S. R. Guimond. 2017. "Concentric Eyewall Asymmetries in Hurricane Gonzalo (2014) Observed by Airborne Radar." Monthly Weather Review 145 729 - 749

    Guimond, S. R., J. M. Reisner, S. Marras, and F. X. Giraldo. 2016. "The Impacts of Dry Dynamic Cores on Asymmetric Hurricane Intensification." Journal of the Atmospheric Sciences 73 4661-4684 [10.1175/JAS-D-16-0055.1]

    Guimond, S. R., G. M. Heymsfield, P. D. Reasor, and A. C. Didlake. 2016. "The Rapid Intensification of Hurricane Karl (2010): New Remote Sensing Observations of Convective Bursts from the Global Hawk Platform." Journal of the Atmospheric Sciences 73 3617 - 3639 [10.1175/JAS-D-16-0026.1]

    Guimond, S. R., G. M. Heymsfield, P. D. Reasor, and A. C. Didlake. 2016. "The Rapid Intensification of Hurricane Karl (2010): New Remote Sensing Observations of Convective Bursts from the Global Hawk Platform." Journal of the Atmospheric Sciences 73 (9): 3617-3639 [10.1175/jas-d-16-0026.1]

    Li, L., G. Heymsfield, J. Carswell, et al. D. H. Schaubert, M. L. McLinden, J. Creticos, M. Perrine, M. Coon, J. I. Cervantes, M. Vega, S. Guimond, L. Tian, and A. Emory. 2016. "The NASA High-Altitude Imaging Wind and Rain Airborne Profiler." IEEE Transactions on Geoscience and Remote Sensing 54 (1): 298-310 [10.1109/tgrs.2015.2456501]

    Tian, L., G. M. Heymsfield, A. C. Didlake, S. Guimond, and L. Li. 2015. "Velocity–Azimuth Display Analysis of Doppler Velocity for HIWRAP." Journal of Applied Meteorology and Climatology 54 (8): 1792-1808 [10.1175/jamc-d-14-0054.1]

    Didlake, A. C., G. M. Heymsfield, L. Tian, and S. R. Guimond. 2015. "The Coplane Analysis Technique for Three-Dimensional Wind Retrieval Using the HIWRAP Airborne Doppler Radar." J. Appl. Meteor. Climatol. 54 (3): 605–623 [10.1175/JAMC-D-14-0203.1]

    Guimond, S. R., L. Tian, G. M. Heymsfield, and S. J. Frasier. 2014. "Wind Retrieval Algorithms for the IWRAP and HIWRAP Airborne Doppler Radars with Applications to Hurricanes." Journal of Atmospheric and Oceanic Technology 31 (6): 1189-1215 [10.1175/JTECH-D-13-00140.1]

    Braun, S. A., R. Kakar, E. Zipser, et al. G. M. Heymsfield, C. Albers, S. Brown, S. Durden, S. Guimond, J. Halverson, A. Heymsfield, S. Ismail, B. Lambrigtsen, T. Miller, S. Tanelli, J. Thomas, and J. Zawislak. 2013. "NASA's Genesis and Rapid Intensification Processes (GRIP) Field Experiment." Bulletin of the American Meteorological Society 94 (3): 345-363 [10.1175/BAMS-D-11-00232.1]

    Godinez, H., J. Reisner, A. Fierro, S. Guimond, and J. Kao. 2012. "Determining Key Model Parameters of Rapidly Intensifying Hurricane Guillermo (1997) Using the Ensemble Kalman Filter." Journal of the Atmospheric Sciences 69 (11): 3147-3171 [10.1175/JAS-D-12-022.1]

    Guimond, S., and J. Reisner. 2012. "A Latent Heat Retrieval and Its Effects on the Intensity and Structure Change of Hurricane Guillermo (1997). Part II: Numerical Simulations." Journal of the Atmospheric Sciences 69 (11): 3128-3146 [10.1175/JAS-D-11-0201.1]

    Guimond, S. R., M. A. Bourassa, and P. D. Reasor. 2011. "A Latent Heat Retrieval and Its Effects on the Intensity and Structure Change of Hurricane Guillermo (1997). Part I: The Algorithm and Observations." J Atmos Sci 68 (8): 1549–1567 [10.1175/2011JAS3700.1]

    Heymsfield, G. M., L. Tian, A. Heymsfield, L. Li, and S. R. Guimond. 2010. "Characteristics of Deep Tropical and Subtropical Convection from Nadir-Viewing High-Altitude Airborne Doppler Radar." Journal of the Atmospheric Sciences 67 (2): 285-308 [10.1175/2009JAS3132.1]

    Guimond, S. R., G. M. Heymsfield, and T. Joseph. 2010. "Multiscale Observations of Hurricane Dennis (2005): The Effects of Hot Towers on Rapid Intensification." J. Atmos. Sci. 67 (3): 633-654 [10.1175/2009JAS3119.1]

    Wu, X., and S. R. Guimond. 2006. "Two- and three-dimensional cloud-resolving model simulations of the mesoscale enhancement of surface heat fluxes by precipitating deep convection." J Climate 19 139-149

    Non-Refereed

    Guimond, S. R., S. Sroka, and D. Protzko. 2018. "A Large Eddy Simulation of Hurricane Intensification." 33rd Conference on Hurricanes and Tropical Meteorology, Amer. Meteor. Soc.. 17 pp. [Full Text (Link)]

                                                                                                                                                                                            
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