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Mikael K. Witte

  • National Center for Atmospheric Research, PO Box 3000, Boulder, CO 80307
  • +1(650)238-4885

Postdoctoral Fellow in Cloud Microphysics

Summary

Clouds are the single greatest source of uncertainty in predicting future climate change. My research explores the fundamental 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 understand the influence of cloud-aerosol-precipitation interactions on climate and improve microphysics parameterizations for models across a range of scales, from large eddy simulations to operational forecasting to global climate models.

My teaching encourages critical numeracy and engages learners with the fundamentals of atmospheric and climate science as well as the societal implications of our interactions with the environment through quantitative reasoning and inquiry-based methods.

Education

20092016

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

20042008

BA, Physics and Mathematics

St. Olaf College

Graduated magna cum laude  with honors in physics

Works in Progress

M. K. Witte , O. Ayala, L. P. Wang, G. Feingold and P. Y. Chuang, “Can turbulent collision-coalescence improve simulations of marine stratocumulus?” to be submitted to Atmos. Chem. Phys.,  November 2017 

H. Morrison,  M. K. Witte , G. H. Bryan, J. Y. Harrington and Z. J. Lebo, "Spurious broadening of bin model droplet spectra from condensational growth and spatial advection errors," to be submitted to J. Atmos. Sci., November 2017

M. K. Witte , H. Morrison, A. Bansemer, J. B. Jensen and A. Gettelman, "On the covariance of cloud and rain water as a function of length scale,"  in prep for  J. Atmos. Sci.

M. K. Witte , N. Guy, D. P. Jorgensen, and P. Y. Chuang, "In situ airborne observations of rain drop distributions during DYNAMO,"   in prep for Mon. Wea. Rev.

J. P. Perkins and  M. K. Witte , "Effects of topography and atmospheric boundary layer flow on the abrasion of planetary canyon systems,"  in prep for Geophys. Res. Lett.

Refereed Publications

M. K. Witte , T. L. 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,”  submitted to Geophys. Res. Lett. 

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,” in press, J. Appl. Meteor. Climatol., 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., 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 2016Present

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, current projects include:

  • Analyzing high frequency aircraft observations 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
  • Operating the AutoGNI (Giant Nuclei Impactor) instrument as part of the Southern Ocean Clouds, Radiation, and Aerosol Transport Experimental Study in Hobart, AUS
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
20112013

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 CDP 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
20092012

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
20082009

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 below)

Teaching Experience

  • UNIVERSITY OF CALIFORNIA, SANTA CRUZ
    • UNDERGRADUATE RESEARCH MENTOR, 2011-2016
      • 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. 
    • INSTRUCTOR
      • 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.
    • TEACHING ASSISTANT
      • 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.
  • SAINT OLAF COLLEGE

    • LABORATORY TEACHING ASSISTANT
      • 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 Presentations

M. K. Witte, "Scaling analysis of cloud and rain liquid water," E OL/MMM Joint Seminar, NCAR, Boulder, CO, 5 September 2017

M. K. Witte, "Collision-coalescence and precipitation formation in marine stratocumulus," Dept. of Atmos. Sci. seminar, University of Wyoming, Laramie, WY, 7 February 2017

M. K. Witte, " Precipitation formation in large eddy simulations of marine stratocumulus,"  seminar,  Lawrence Berkeley National Laboratory, Berkeley, CA, 12 September 2016

M. K. Witte, P. Y. Chuang, O. Ayala and L. P. Wang, "Turbulence-microphysics feedbacks in LES of marine stratocumulus," oral presentation, 17th International Conference on Clouds and Precipitation, Manchester, UK, 28 July 2016

M .K. Witte, P. Y. Chuang, L. P. Wang and O. Ayala, “What controls drizzle initiation? Insights from a comparison of large-eddy simulations with observations,” oral presentation, AGU Fall Meeting, San Francisco, CA, 18 December 2014

M. K. Witte, P. Y. Chuang, O. Ayala and L. P. Wang, “Applying an inverse method to estimate collision-coalescence rates from aircraft observations,” oral presentation, 14th AMS Conference on Cloud Physics, Boston, MA, 7 July 2014

M. K. Witte, P. Y. Chuang, G. Feingold and H. Jiang, “A small cumulus cloud clock from in situ measurements,” oral presentation, AGU Fall Meeting, San Francisco, CA, 7 December 2012

M. K. Witte, D. L. Rossiter and P. Y. Chuang, “Principal component analysis of marine stratocumulus drizzle and other in situ observations,” poster presentation, 13th AMS Conference on Cloud Physics, Portland, OR 30 June 2010

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

2017 - Present, Reviewer, Journal of the Atmospheric Sciences

2017 - Present, Reviewer, Atmospheric Chemistry and Physics

Professional Memberships

American Geophysical Union

American Meteorological Society

European Geosciences Union

Research Skills

Cloud probe instrumentation

Optical array probes, phase Doppler interferometry

Scientific computing

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

Large eddy simulation

My specialty is cloud microphysics schemes with a focus on bin microphysics.

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 both distributed and shared memory parallelization approaches.

Professional References

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

Dr. Graham Feingold, Research Scientist, NOAA Earth System Research Laboratory,  [email protected]

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

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