About

The University of Oklahoma group for Boundary Layer Integrated Sensing and Simulation (OU-BLISS) is a team of faculty and researchers with an interest in multi-faceted studies of the boundary layer. Through a variety of instrumentation and simulations, we seek to understand the dynamic nature of the lowest level of the atmosphere.

Please feel free to contact us with any questions!

PECAN

PECAN: Plains Elevated Convection At Night

OU-BLISS members participated in this large, intensive field project operating the CLAMPS platform to collect data before and during nighttime thunderstorms. Learn more »

LABLE

LABLE: Lower Atmospheric Boundary Layer Experiment

An on-going study by the OU-BLISS team in collaboration with the ARM Southern Great Plains research facility. Learn more »

People

Current Group Members

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Dr. Petra Klein

Professor
School of Meteorology

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Dr. Dave Turner

Scientist
National Severe Storms Laboratory

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Dr. Evgeni Fedorovich

Professor
School of Meteorology

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Dr. Alan Shapiro

Professor
School of Meteorology

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Dr. Phillip Chilson

Professor
School of Meteorology

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Dr. Jeremy Gibbs

Postdoctoral Research Associate
CIMMS, School of Meteorology

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Matt Carney

Instrumentation Tech
School of Meteorology

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Greg Blumberg

Ph.D. Student
School of Meteorology

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Elizabeth Smith

Ph.D. Student
School of Meteorology

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Josh Gebauer

M.S. Student
School of Meteorology

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Previous Group Members

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Dr. Jennifer Newman

Postdoctoral Research Associate

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Dr. Tim Bonin

Postdoctoral Research Associate

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Seminars

Next Seminar | Sept. 16, 2016 | 2:00 PM | Room 5600

Simulated near-surface behavior of tornado-like vortices in a Fiedler chamber with resolved turbulence

Dr. Nathan Dahl - University of Miami

The Fiedler chamber is an idealized framework developed for the purpose of studying tornado-like vortices within a closed domain. Its configuration allows direct comparison between the wind speeds and the theoretical maximum derived from the environmental potential energy, known as the "thermodynamic speed limit." With recent advances in computing power, this framework can be used to generate realistic, high-resolution flow structures in order to examine the processes governing tornado evolution at the very lowest levels of the atmosphere.

In an effort to bridge gaps between vortex theory and actual observations, we performed several high-resolution, three-dimensional large eddy simulations with fully-developed near-surface turbulence obtained through an "eddy injection" technique, which were used to analyze momentum budgets and the influence of various background conditions on vortex intensity and structure. The time-azimuthal mean winds from these simulations consistently and substantially exceeded the thermodynamic speed limit; furthermore, maximum 3-s wind gusts at 10 m height exceeded the EF-scale threshold for "violent" tornadoes (~74 m/s) even when the background vertical forcing was relatively modest, and gusts well in excess of 100 m/s were common. We also simulated observations from sensors impacted by translating vortex cores in an effort to quantify the errors associated with estimating maximum wind speeds from in situ data and damage surveys. Our current results are qualitatively similar to those obtained by Nolan (2014) for hurricanes but quantitatively show a much larger potential for error (over 40 m/s in some cases) due the transience and structural complexity of tornadoes.

Upcoming Seminars

TBA

Past Seminars

09/09/16 - Dr. Alan Shaprio: Ascent in a nocturnal low-level jet

05/05/16 - Brad Illsoton: Near Surface Atmospheric Impacts Resulting from a Developing Metropolitan Area

04/22/16 - Joshua Gebauer: The Role of the Nocturnal Low-Level Jet in Convection Initiation on 1-2 June 2015

04/15/16 - Jinxin Wang: A Study of Urban Heat Island Intensity Trends in the Dallas-Fort Worth Region during Wet and Dry Summers

04/01/16 - Greg Blumberg: Towards Understanding the Capabilities of High-Temporal Resolution Soundings in Convective Environments

03/25/16 - Dr. Sukanta Basu: Quasi-universal scaling of boundary-layer wind speeds in mesoscale regime

12/11/15 - Elizabeth Smith: WRF model study of the Great Plains low-level jet: effects of grid spacing and boundary layer parameterization

12/04/15 - Ethan Cook: Ekman Revisited: The case of the phantom PGF

11/06/15 - Dr. Phillip Chilson: CLOUD-MAP: Advancing Meteorology and Atmospheric Physics Through Unmanned Aerial Systems

10/15/15 - Dr. Jeremy Gibbs: Sensitivity of turbulence statistics in the lower portion of a numerically simulated stable boundary layer to parameters of the Deardorff subgrid turbulence closure model

09/18/15 - William Anderson: Large-eddy simulation of rough wall turbulence: effects of complex topography, evidence of inner-outer effects, and the role of turbulence in aeolian systems

08/26/15 - Cedrick Ansorge: Conditional analyses of the very stable boundary layer

05/06/15 - Paul Flanagan: The Dryline, Convective Initiation, and Rapid Evolution of Drought in Oklahoma During 2011

05/01/15 - William (Greg) Blumberg: Ground-Based Infrared Thermodynamic Sounders: A Fresh Look at the Enivornments Supporting Deep Convection

04/24/15 - Ethan Cook: A very basic model for velocity statistics of an Ekman-like neutral turbulent layer

04/10/15 - Jinxin Wang: Urban heat island of Dallas Fort-Worth during July 2011 North-Central Texas drought: WRF-SLUCM model verification and sensitivity study of UHI’s dependence on land-use category.

03/14/15 - Larissa Reames: Boundary Layer and Urban Scheme Performance for a nested 500m WRF simulation

03/07/15 - Jennifer Newman: Optimizing Lidar Scanning Strategies for Wind Energy Turbulence Measurements

01/16/15 - Dr. Alan Shapiro: A Unified Theory for the Great Plains Nocturnal Low-Level Jet

12/12/14 - Chiel van Heerwaarden: A comparison of heterogeneously heated convective boundary layers with fixed flux and fixed temperature boundary conditions

11/21/14 - Cedrick Ansorge: Study of Stabily Stratified Bounday Layers using Turbulent Ekman Flow

10/31/14 - Tim Bonin: Thermal and Turbulence Characteristics of the Southern Great Plains Nocturnal Boundary Layer

10/24/14 - Mike Buban: The formation of small-scale atmospheric vortices via horizontal shearing instability

10/17/14 - Dr. Alan Shapiro: On the lower boundary condition for pressure in numerical simulations of boundary layer flows driven by surface buoyancy variations

09/26/14 - Dr. Jeremy Gibbs: Step Brothers 2: Revisiting Surface Heat-Flux and Temperature Boundary Conditions in Models of Stably Stratified Boundary-Layer Flows

04/25/14 - Stephen Castleberry: Evaluation of a Microwave Radiometer Thermodynamic Retrieval Algorithm

04/18/14 - Charlotte Wainwright: Sampling the boundary layer with a sodar simulator

04/11/14 - Jinxin Wang: Urban effects on precipitation: a literature review and climatology study for Dallas-Fort Worth

04/04/14 - Kerstin Schaefer: Validation of the mesoscale transport and fluid model METRAS for Berlin based on a measurement campaign in summer 2012

03/28/14 - Nathan Anderson: Vertical Velocity Turbulence Profiles Measured by Two Horizontally Separated Doppler Lidars

02/21/14 - Larissa Reames: The WRF-simulated effects of the Oklahoma City urban area on its environment on the dynamics of a simulated supercell thunderstorm

02/14/14 - Dr. Alan Shapiro: New similarity model solutions for boundary-layer flows

01/31/14 - Dr. Petra Klein: Scaling of Mean Flow and Turbulence in the Urban Canopy Layer

01/17/14 - Jennifer Newman: Optimizing Lidar Scanning Strategies for Turbulence Measurements

12/2/13 - Dr. Robert M. Banta: Generalized Relationships in the Stable Boundary Layer Derived from High-Resolution Doppler Lidar and Instrumented Tower Data

11/15/13 - Subhashree Mishra: Raman Lidar Observations from the ARM Site in Darwin, Australia: A Water Vapor and Aerosol Climatology

11/08/13 - Kodi Monroe: Sensitivity of the modeled urban heat island to rooftop parameters

11/01/13 - Nathan Anderson: Vertical Velocity Turbulence Profiles Measured by Two Horizontally Separated Doppler Lidars

10/07/13 - Dr. Tristan Quaife: Integrating satellite data with models of the land surface

10/04/13 - Hayden Mahan: Impacts of Vegetation and Precipitation on Throughfall Heterogeneity in a Tropical Pre-Montane Transitional Cloud Forest

09/06/13 - Dr. Alan Shapiro: A Boundary-Layer Scaling for Turbulent Katabatic Flow

05/03/13 - Jennifer Newman: Using Ground-Based Measurements to Improve Wind Power Forecasts

04/19/13 - Greg Blumberg: Developing a Statistical Thermodynamic Retrieval for Ground-Based Infrared Spectrometers

04/05/13 - Tim Bonin: Observed Characteristics of Low-Level Jets During the Lower Atmospheric Boundary Layer Experiment

03/08/13 - Charlotte Wainwright: Virtually Sampling the Developing Boundary Layer

02/08/13 - Xiaoming Hu: Simulations of thet Low-Level Jet with WRF

01/25/13 - Dr. Petra Klein: Impact of the Low-Level Jet on Urban Heat Island Intensity and Nocturnal Ozone Concentrations in OKC

Publications