Dr. Mike Larsen
Office: J.C. Long 217
Lab: Lightsey 336
Phone: (843) 953-2128
Full CV: (PDF)
CV formatted for T&P (in progress): (PDF)
Dr. Larsen's Spring 2016 Schedule: (PDF)
- Current Courses (Spring 2016) -Honors Physics II/Honors Physics II Lab (HONS 158/158L)
Research Seminar (PHYS 419)
- About Me -The academic basics can be found if you check out one of my CVs to the left. A more comprehensive biography (you must be bored) can be found here.
- Students Currently Working in the Larsen Atmospheric Physics Lab -Kensley Burriss -- Studying the rain microphysics of erosion.
Katelyn O'Dell -- Studying meteorological aspects of rainfall spatial and temporal variability.
Joshua Teves -- Examining raindrop size distribution spatial variability.
- Research Interests -I have quite a few varied research interests, most related loosely to the field of Atmospheric Microphysics. If there is an underlying theme, it would probably be "how discreteness matters in the atmosphere". In other words, rain comes down in drops -- when, how, and why does this matter? Some of the basic problems I'm working on are briefly summarized below.
1. Spatial and Temporal Variability in Rainfall -- This is the central question we are currently studying in my lab. I study how rainfall variables (e.g. accumulations, raindrop size distributions, and bulk rainfall quantities that related to the size distributions) vary in space and time.
Everyday experience suggests that rainfall is extremely variable; who doesn't have experience waiting to run to your car after leaving a shop during a rainstorm because you think the rain might "let up a little" in the next few minutes? However, most of our tools used to measure rainfall (e.g. radar, weather station rain gauges, etc.) only give information about rain every few minutes and often do not contain any spatial information on scales less than a few city blocks in size. We know rainfall varies substantially on spatial and temporal scales shorter than this, but the nature of that variability is poorly understood. We're working on this and would like to ultimately use the information on small spatial scales to tell us things about processes related to rainfall (e.g. erosion) and about the large scale structures and evolution of the storm.
1.a. The investigation of temporal and spatial variability in rainfall has allowed us to acquire some instrumentation that has opened up some other related areas of inquiry. In particular, we have recently completed some work confirming the existence of "super-terminal raindrops" (drops that fall faster than they would in still air due to the balance of gravitational and drag forces). We have also started to investigate questions associated with sampling variability in natural rain. The investigation of these and other related phenomena support the overall effort of understanding rainfall microstructure, but form separate interesting science questions on their own.
2. Radiative Transfer through Correlated Random Media -- I study how light propagates through clouds and other systems when there is statistical structure more complicated than "perfect spatial randomness". Some of the ideas we deal with are subtle, but ultimately the idea is straightforward enough to understand. As a simplified example, let's say you have 100 trees in two 1 acre fields -- in one of the fields, the trees are placed perfectly randomly within the field. In the second field, the trees are put together in clumps. Which field can you see further through (on average)? If you think about it for a second, you might realize that though there are places in the second field where we can't see very far at all, there are other areas (without any trees) where we can see all the way through. Mathematically (vie Jensen's inequality), we can show that you see further (on average) through the "clumpy forest".
In our lab, we use computer simulations to see if the amount of light making it through the "forest" can be linked back to the statistical structure of the "clumpiness". Although this is not the main area of emphasis in our lab right now, I find this problem fascinating and we have been fortunate enough to get some pretty awesome computer hardware to attack this problem. (Including using some GPU computing techniques).
(Topics 3-6 below are of interest to me, but not areas that I'm actively working in right now. At some time, I hope to return to these problems -- once I get the right students and/or funding.)
3. Aerosol Mixing -- There is a long history of research into atmospheric turbulence and wind patterns in the boundary layer of the atmosphere. The behavior of pseudo-passive scalars (i.e. aerosols, or airborne particulates) and how they behave due to the forcing of the statistically structured turbulent wind patterns, however, is not nearly as well understood. Using some basic tools from stochastic geometry, we hope to find a way to describe the statistical structure of aerosols as they mix due to ambient wind flow patters.
4. Stochastic Geometry -- Several of the problems we study involve using some relatively obscure mathematical tools that inter-relate simple statistical properties of geometric structures. (The field of stochastic geometry). There are a number of tools developed for use in these types of studies, but many need a little bit of "tweaking" before they are suitable for use in practical applications for analysis within atmospheric physics. Although this is vague, we work on developing some of these "tweaks".
5. Wavelet Analysis of Atmospheric Variables -- The Fourier transform is an extremely useful tool in many areas of Physics, but ultimately has some limitations when dealing with finite data sets. We believe that use of wavelet analysis may make identification of transient phenomena in atmospheric time-series easier to identify and interpret.
6. Effects of Finite Sampling and Dead-Time on Statistical Inference -- The assumption of perfect spatial and temporal randomness (a.k.a. Poisson statistics) are ubiquitous in the natural sciences. However, this assumption is often made where it is not necessarily appropriate. (Even in the cases where we think a system must be perfectly random -- say radioactive decay -- often show non-Poisson effects when examined closely; for example, the Quantum Zeno Effect). Some of our work deals with what you can infer when the underlying statistics really aren't Poissonian in nature.
We actually have much, much more than this going on in our lab (including projects on Monte Carlo simulation of discrete spatial systems, environmental radiation monitoring, fabrication of instruments designed to measure atmospheric particulates individually, and studies associated with the physics of correlated spatial structures and how they effect radar returns), but chances are few people have read this far. If you're interested in what we're doing or (better yet) might be interested in joining us, contact Dr. Larsen and he'll be glad to talk to you about our ongoing research.
- Alumni from the Larsen Atmospheric Physics Lab -(If you see your name here, I'd love to hear back from you and get an update on where you are and what you're doing! Lots of the information below is from googling, and I just don't know how much of it is accurate.)
Tobin Barrett (2010-2012) -- Studied radar returns to identify evidence of the urban heat island effect. (Working at Earthpack)
Josh Beck (2009-2010) -- Studied single raindrop detection techniques with focus on image edge detection. (Appears to have gotten a Masters Degree at UNL; unsure of what he is doing now)
Phil Boehner (2010-2012) -- Studied computational stochastic geometry and computational simulations of radiative transfer. Primarily worked with the CUDA computing environment. (Obtained his masters degree. Ph.D. student in the Department of Scientific Computing at Florida State University. Graduate Research Assistant.)
Clarissa Briner (2011-2012) -- Studied how statistical measures change when sampling a 3d system with a semi-1d transect. (Obtained her masters degree. PH.D. Student at the University of Colorado Boulder; working on turbulent combustion ["reconstructing Lagrangian trajectories from flow fields of pre-mixed flames"]).
Susanna Brylawski (2011-2012) -- Studied a means to make a relative humidity sensor using deliquescence. (Graduated from College of Charleston; artist and lamp designer).
Dawn Carrillo (2008-2010) -- Studied environmental radiation. (Unknown)
Jose Carrillo (2008-2010) -- Studied environmental radiation. (Unknown)
Michael Chute (2012-2013) -- Studied aerosol mixing. (Civil Engineer with Flatiron)
Erin Deck (2011) -- Studied whether clouds can be used as an indicator of regional climate change. (Unknown)
Benjamin Fullerton (2009-2010) -- Studied mechanical methods of detecting raindrops one drop at a time. (Manager at Menard's)
Joerael Harris (2011-2014) -- Studied rainfall DSD variability. (Tutoring at Trident Technical College; enrolling in a M.Sc. program for pure math at College of Charleston)
David Hayes (2009-2010) -- Studied radiative transfer in correlated random media, worked on constructing an ad hoc cluster computing system. (Software Development Partner at Black Brick Software)
Timothy Hayward (2013-2014) -- Explored tests to determine if a given data-set is statistically stationary and fractal properties of measured rainfall. (Enrolled in Physics Ph.D. program at William and Mary).
Cassidy Jenks (2013-2014) -- Studied different methodologies of measuring rainfall one drop at a time. (Unknown)
Robert Lemasters (2013-2015) -- Studied raindrop arrival timeseries statistics, including pair correlation functions and fractal scaling. (Enrolled in Physics Ph.D. program at Emory).
Kyle McClary (2008-2010) -- Studied acoustical methods of detecting rainfall one drop at a time. Also studied the effects of ethanol blends on engine wear. (Precision Farming Consultant at Green Line Equipment, Grand Island, NE)
Joshua Moravec (2010) -- Studied spatial properties of gamma ray bursts. (Software Quality Engineer at Hudl)
Joseph Niehaus (2010-2011) -- Studied dose-response models for airborne pathogens. (Enrolled in Atmospheric Sciences Ph.D. program at Michigan Technological University)
Matt Noffke (2008-2010) -- Studied scaling properties of rainfall fluctuations and helped to develop some methods to detect rainfall one drop at a time. (Lab Assistant at SynTech)
Alexis Payne (2013-2015) -- Studied changes in the turbulent inertial subrange in the day/night transition within the surface layer. (Intern at Northrup Grumman).
Danielle Policarpio Wolf (2009-2010) -- Studied capacitive properties of conductive fabrics. (Academic Tutor at Austin Learning Center and Operations/Strategy for Steve Wolf Designs)
David Ruwadi (2011) -- Studied whether clouds can be used as an indicator of regional climate change. (Graduated from College of Charleston; seeking Internship in Entertainment and Technology)
Grant Saltzgaber (2007-2010) -- Studied rainfall accumulation variability, scale-invariant properties of rainfall. (Obtained his masters degree. Attending University of Nebraska Medical Center)
Adrian Sanabria-Diaz (2009-2010) -- Studied wavelet decomposition of sounds for acoustical fingerprinting. (Consultant for PHYND Technologies, Inc.)
Cameron Self (2010-2011) -- Studyied the temporal behavior of wind in the atmospheric boundary layer. (Tropical Meteorologist at ImpactWeather)
Jenn Smaroff (2010-2011) -- Studied spatial properties of tornado outbreaks. (Unknown)
Conor Smith (2010-2011) -- Studied different methods of measuring rainfall one drop at a time and developed techniques to make "calibration" raindrops. (Ph.D. Student in the Applied Marine Physics program at Miami University. Studying small-scale surface currents.)
Dr. Aaron Steele (2008-2009) -- Studied wind in the atmospheric boundary layer and radiative transfer through correlated random media. (Completed M.S. at Miami University of Ohio, completed Ph.D. in Computer Science and Engineering at Notre Dame. Do not know what he is doing now.)
Annie Steele (2013-2014) -- Explored a way to build an affordable rain velocimeter. (Unknown)
Jeremy Stromer (2009) -- Studied optical properties of Lyotropic Chromonic Liquid Crystals (Enrolled in Ph.D. program at the University of Connecticut; working on Atomisitic simulations of nanostructure evolution for energy technologies.)
Derek Tuck (2014-2015) -- Developed a prototype rain velocimeter. (Unknown).