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Mikael K. Witte

  • National Center for Atmospheric Research, PO Box 3000, Boulder, CO 80307
  • (650)238-4885

Postdoctoral Fellow in Cloud Microphysics


Clouds are the single greatest source of uncertainty in predicting future climate change. My research explores the physics of clouds and precipitation as multiscale phenomena using a combination of measurements (both remotely sensed and in situ), theory and numerical models. This work is used to improve microphysics parameterizations, understand the influence of cloud-aerosol-precipitation interactions on climate and investigate the coupling of clouds and atmospheric circulationacross a range of scales. Overall, I seek to advance fundamental understanding of atmospheric physics through synergistic use of observations, models and theory.



PhD, Earth and Planetary Sciences

University of California, Santa Cruz

Dissertation title: Observational and modeling studies of collision-coalescence in marine stratocumulus

Dissertation advisor: Dr. Patrick Y. Chuang


BA, Physics and Mathematics

St. Olaf College

Graduated magna cum laude  with honors in physics

Works in Progress

M. K. Witte , H. Morrison, A. Bansemer, J. B. Jensen and A. Gettelman, "On the covariability of cloud and rain water as a function of length scale,"  to be submitted to J. Atmos. Sci., Sept. 2018

M. K. Witte  and J. B. Jensen, "Terminal fall velocities of hydrated sea salt particles and evidence for in-cloud transport of giant cloud condensation nuclei," in prep for J. Geophys. Res.: Atmos.

J. B. Jensen and  M. K. Witte , "A comparison of aircraft observed and GCCN modeled autoconversion rates in VOCALS marine stratocumulus," in prep for Science

Works in Peer Review

M. K. Witte , O. Ayala, L. P. Wang, G. Feingold and P. Y. Chuang, “Comparison of observed and simulated drop size spectra from LES with bin microphysics,” in revision,  Mon. Wea. Rev. 

Refereed Publications

M. K. Witte , T. Yuan, P. Y. Chuang, S. Platnick, K. G. Meyer, G. Wind and H. H. Jonsson, "MODIS retrievals of cloud     effective radius in marine stratocumulus exhibit no significant bias,”  in press, Geophys. Res. Lett., doi:10.1029/2018GL079325.

H. Morrison,  M. K. Witte , G. H. Bryan, J. Y. Harrington and Z. J. Lebo, "Spurious broadening of modeled cloud droplet spectra using bin microphysics in an Eulerian spatial domain," in press, J. Atmos. Sci., doi:10.1175/JAS-D-18-0055.1.

J. Rémillard, A. M. Fridlind, A. S. Ackerman, G. Tselioudis, P. Kollias, D. B. Mechem, H. E. Chandler, E. Luke, R. Wood,     M. K. Witte, P. Y. Chuang, and J. K. Ayers, “Use of cloud radar Doppler spectra to evaluate stratocumulus drizzle size distributions in large-eddy simulations with size-resolved microphysics,” J. Appl. Meteor. Climatol.,  56:3263-3283, 2017, doi:10.1175/JAMC-D-17-0100.1.

M. K. Witte , O. Ayala, L. P. Wang, A. Bott, and P. Y. Chuang, “Estimating collision-coalescence rates from in situ observations of marine stratocumulus,” Q. J. R. Meteorol. Soc., 143:2755-2763, 2017, doi:10.1002/qj.3124.

M. K. Witte , P. Y. Chuang and G. Feingold, "On Clouds and Clocks," Atmos. Chem. Phys.14:6729-6738, 2014, doi:10.5194/acp-14-6729-2014.

M. M. Dummer, K. Johnson,  M. K. Witte , W. K. Hogan, and M. Hibbs-Brenner, "Computed radiography imaging based on high-density 670-nm VCSEL arrays," Proc. SPIE. 7557, Multimodal Biomedical Imaging V, 75570H, 2010.

Research Experience

Oct 2018

Joint Institute for Regional Earth System Science and Engineering Postdoctoral Scholar

University of California Los Angeles/Jet Propulsion Laboratory, Pasadena, CA

I will be working with Drs. Joao Teixeira, Kay Suselj and Matt Lebsock on coupling a scale-aware cloud microphysics parameterization to the JPL eddy diffusivity-mass flux scheme

Oct 2016Oct 2018

Advanced Study Program Postdoctoral Fellow

National Center for Atmospheric Research, Boulder, CO

The Advanced Study Program provides fellows with the opportunity to pursue independent research of their choosing. In addition to external collaborations, my projects included:

  • Analyzing high frequency aircraft observations and large eddy simulations of shallow marine clouds to quantify the structure of cloud and drizzle liquid water across spatial scales
  • Formulating a stochastic statistical emulator to generate synthetic liquid water fields for a scale-aware microphysics parameterization
  • Studying aerosol effects on mixed phase precipitation formation as part of the Southern Ocean Clouds, Radiation, and Aerosol Transport Experimental Study (SOCRATES) using aircraft in situ measurements of cloud particles, sea salt and ice-nucleating particles
Jul 2016Sep 2016

Junior Research Specialist

University of California, Santa Cruz, CA
  • Performed large eddy simulations of near-coastal marine stratocumulus to examine the role of turbulence in precipitation formation
  • Analyzed microphysical measurements taken off the coasts of California and Chile for comparison with satellite retrievals of droplet effective radius to identify biases in the satellite retrieval algorithm
Jun 2012Jun 2016

PhD Dissertation Research

University of California, Santa Cruz, CA
  • Processed and analyzed microphysical, turbulent, and thermodynamic measurements from the 2008 Physics of Stratocumulus Tops (POST) flight campaign
  • Developed a quasi-inverse method for retrieving collision-coalescence rates from aircraft microphysical measurements, implemented in Matlab
  • Extensively modified the bin microphysics scheme of RAMS-LES to incorporate an inhomogeneous entrainment mixing scheme, a turbulent collection kernel and a high spectral resolution collision-coalescence subroutine
Jul 2015

ARM Summer Training and Science Applications Workshop

National Weather Center, Norman, OK, USA
  • Participated in a summer school with lectures on various remote sensing instruments (Doppler radar, lidar, radiometers, etc.) and engaged in original small group work
  • Voted "Best Project" by workshop instructors for work on early diagnosis of drizzle onset in marine stratocumulus using vertically-pointing Doppler radar

DYNAMO Field Project Assistant

Diego Garcia, British Indian Ocean Territory

DYNAMO was a multinational tropical meteorology experiment to study the Madden-Julian Oscillation which took place during Nov-Dec 2011. As part of the project, I was responsible for the following:

  • Calibrated and maintained DMT CIP, PIP, and CAS instruments over 12 research flights with the NOAA P3 "Miss Piggy"
  • Processed and analyzed microphysical measurements, including a rewrite of the CIP/PIP processing scripts

Graduate Research Assistant

University of California, Santa Cruz, CA

Prior to beginning dissertation research, I worked on a number of small projects:

  • Worked with Professor Ian Faloona (University of California, Davis) to set up an off-grid atmospheric monitoring site at Chews Ridge near Carmel Valley, CA
    • Designed and purchased monitoring instruments (O3, CO, and aerosol) as well as electronic, electrical, and cooling equipment subject to the constraints of low power consumption and small physical footprint
    • Calibrated and installed instruments on-site
  • Analyzed large eddy simulation output to characterize the life cycle of shallow cumulus clouds, resulting in a refereed publication (see below)
  • Performed a principal component analysis on microphysical, dynamic, and thermodynamic measurements from multiple field campaigns to yield insights into precipitation formation in marine stratocumulus

Electronics Design Intern

Vixar, Inc., Plymouth, MN
  • Designed and tested circuit boards for novel applications of vertical-cavity surface-emitting lasers (VCSELs), including fabrication of a prototype digital radiography device which resulted in a refereed conference proceedings publication (see above)

Teaching and Mentoring Experience

      • Mentored a group of 6 international graduate students on synthesis of models and observations to solve scientific problems. My responsibilities as a mentor included:
        • Gaining familiarity with several datasets related to the CSET field campaign prior to the Colloquium (remote sensing and in situ measurements from aircraft and relevant visualization software; satellite and meta-data from the NCAR/EOL Field Catalog; large eddy simulation output of preselected case studies)
        • Providing scaffolding to the students as they decided on research questions to pursue and which combinations of observations and model outputs were most relevant to their questions 
        • Serving as resident expert for all groups on large eddy simulation, microphysical parameterizations and pdf-based parameterizations for the CAM model
      • Supported an undergraduate researcher in learning scientific computing with Matlab, including algorithm design, automated handling of large data sets and visualization techniques and plotting
      • Served as a mentor for undergraduate researchers in the Chuang lab. Responsibilities included teaching basic scientific computing and algorithm design and leading a reading group on stratocumulus dynamics. 
      • Environmental Geology, Summer 2012
        • Taught 20 undergraduate students, both earth science majors and others, as instructor of record. Designed and implemented curriculum, delivered lectures, and assigned and graded reading and homework assignments as well as a cumulative assessment task.
    • INSTRUCTOR/PARTICIPANT, ISEE Professional Development Program
      • EarthWEST, Spring-Summer 2014
        • Designed and taught a 3-day, inquiry-based workshop to ~30 incoming community college transfer students focused on topics in earth science. Students chose a component of the carbon cycle to investigate (silicate weathering, biomass burning, ocean acidification) and were tasked with identifying and quantifying a climate feedback related to their chosen topic.
      • The Atmosphere, Winter 2011, 2013 and 2015
        • Taught discussion sections of a calculus-based atmospheric science overview course. Refreshed students on basic fluid mechanics and thermodynamics and graded and helped develop weekly problem sets.
      • Fundamentals of Environmental Science, Winter 2014
        • Led discussion sections of an introductory course for first-year students focused on teaching numeracy (the mathematical equivalent of literacy), providing a broad background on the climate system and exploring how human actions affect that system.
      • Mathematics in the Earth Sciences, Fall 2012
        • Evaluated assignments and led discussion sections on a wide range of mathematical topics, from linear algebra to differential equations. Guest taught lectures on ordinary differential equations.
      • Introductory Physics Laboratory: Electricity and Magnetism, Summer 2012
        • Provided instruction in the laboratory, evaluated lab notebooks, and led a discussion section.
      • Introduction to Weather and Climate, Spring 2012
        • Taught discussion sections of a general education meteorology course. Topics included dimensional analysis, climate change, and basic atmospheric thermodynamics and chemistry.
      • Planetary Discovery, Winter 2010
        • Graded homework and led discussion sections of an introductory planetary science course.

      • Analytical Physics I, 2005-2007
        • Introduced groups of 10-20 first-year undergraduate physics majors to the laboratory setting and taught the basics of lab notebook usage, error propagation, basic programming in Python, and introductory calculus-based classical and wave mechanics.

Selected Oral Presentations

Invited seminar, Brookhaven National Laboratory, Upton, NY, 19 July 2018

Invited seminar, Jet Propulsion Laboratory, Pasadena, CA, 13 March 2018

Oral presentation, NCAR Cloud Physics Discovery Day, Boulder, CO, 27 November 2017

EOL/MMM Joint Seminar, NCAR, Boulder, CO, 5 September 2017

Physics/Environmental Studies Depts. joint seminar, Saint Olaf College, Northfield, MN, 8 March 2017

Dept. of Atmos. Sci. seminar, University of Wyoming, Laramie, WY, 7 February 2017

Seminar,  Lawrence Berkeley National Laboratory, Berkeley, CA, 12 September 2016

Oral presentation, 17th International Conference on Clouds and Precipitation, Manchester, UK, 28 July 2016

Oral presentation, AGU Fall Meeting, San Francisco, CA, 18 December 2014

Oral presentation, 14th AMS Conference on Cloud Physics, Boston, MA, 7 July 2014

Oral presentation, AGU Fall Meeting, San Francisco, CA, 7 December 2012

Awards and Honors

  • Campus-wide Outstanding Teaching Assistant, University of California, Santa Cruz, 2013
  • Best Project, "Detecting the Onset of Drizzle using ARM Observations and a Steady-State 1-D Column Model,"  ARM Summer Training and Science Applications workshop, 2015

Professional Service

Reviewer, Journal of the Atmospheric Sciences,  2017 - Present

Reviewer, Atmospheric Chemistry and Physics,  2017 - Present

Reviewer, Atmospheric Measurement Techniques,  2018 - Present

Reviewer, Journal of Geophysical Research: Atmospheres,  2018 - Present

Chair, Precipitation Physics and Boundary Layer Stratiform Clouds oral sessions, 15th AMS Conference on Cloud Physics, 2018

Professional Memberships

American Geophysical Union

American Meteorological Society

European Geosciences Union

Research Skills

Large eddy simulation

My specialty is cloud microphysics schemes with a focus on bin microphysics and upscaling of bulk schemes.

Airborne cloud instrumentation

Optical array probes, phase Doppler interferometry, and holography.

Scientific computing

I am fluent in Matlab, Python, and Fortran. I also have experience with Maple, Mathematica, NCL, Perl and R.

Data analysis

My expertise is in automated analysis and visualization of large datasets from aircraft and model output. 

High performance computing

I run parallelized large eddy simulation models and have experience with programming both distributed and shared memory parallelization approaches.

Professional References

Dr. Hugh Morrison, Senior Scientist, National Center for Atmospheric Research,  [email protected]

Dr. Jørgen Jensen, Scientist III, National Center for Atmospheric Research,  [email protected]

Dr. Patrick Chuang, Professor, University of California Santa Cruz,  [email protected]