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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

Summary

Clouds are the single greatest source of uncertainty in predicting future climate change. My research explores the fundamental physics of how warm clouds and precipitation form using a combination of measurements (both remotely sensed and in situto improve model microphysics parameterizations. My teaching aims to encourage critical numeracy and engage learners with the fundamentals of climate science as well as the societal implications of our interactions with the environment.

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

Research Experience

Oct 2016Present

Advanced Study Program Postdoctoral Fellow

National Center for Atmospheric Science, 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
  • Developing methodology to compare aircraft cloud measurements with high resolution model output using size-resolved microphysics 
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 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 Presentation" 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)

Refereed Publications

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,” accepted to Q. J. R. Meteorol. Soc.

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,” accepted to J. Appl. Meteor. Climatol. 

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

Works in Progress

M. K. Witte , T. L. Yuan, and P. Y. Chuang, “Improved agreement between in situ measurements and MODIS retrievals
of cloud effective radius in east Pacific marine stratocumulus,” to be submitted to Geophys. Res. Lett. 

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 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,"   to be submitted to Mon. Wea. Rev.

M. K. Witte , A. Dzambo, H. Yu, J. Tian, A. T. Lesage, E. Luke, W. Szyrmer and P. Kollias, "Early radar-based detection of drizzle in stratiform clouds," to be submitted to JGR:Atmos

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. 

Selected Conference Presentations

M. K. Witte, H. Morrison, A. Bansemer, J. B. Jensen, and A. Gettelman, "Scaling and multifractality of drizzle and cloud water in marine stratocumulus," poster presentation, EGU General Assembly, Vienna, Austria, 24 April 2017

M. K. Witte, P. Y. Chuang and G. Feingold, " Implementation of a high spectral resolution bin microphysics scheme in large eddy simulations of marine stratocumulus," poster presentation, AGU Fall Meeting, San Francisco, CA, 14 December 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, 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, 30 June 2010

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. 
    • GRADUATE STUDENT 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 homework in addition to leading 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.

Professional Memberships

American Geophysical Union

American Meteorological Society

References

Research Skills

Cloud probe instrumentation

Optical array probes, phase Doppler interferometry

Matlab
Data analysis
Large eddy simulation

Specializing in cloud microphysics schemes with a focus on bin microphysics

Fortran
Python