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. 9, 2016 | 2:00 PM | Room 5600

Ascent in a nocturnal low-level jet

Dr. Alan Shapiro - School of Meteorology

It has long been recognized that nocturnal low-level jets (LLJs) can provide thermodynamic and dynamical support for nocturnal convection over the Great Plains. However, the relation between a LLJ and many occurrences of convective initiation (CI), particularly involving elevated CI in regions removed from obvious frontal boundaries or other mesoscale structures, remains elusive. In such cases CI often happens in association with a LLJ, but it is not clear if the LLJ is a causative agent or if the LLJ and CI arise independently from nocturnal boundary layer processes and simply occur within overlapping domains at similar times.

A theory is presented for the vertical motion induced by a class of spatially variable LLJs. The theory does not address CI per se, but makes a case for how a nocturnal LLJ associated with (i) horizontally varying free-atmosphere geostrophic winds and (ii) horizontally varying buoyancy can force broad zones of mesoscale ascent within and above the atmospheric boundary layer (ABL), thus creating a favorable environment for CI.

We consider the development of a LLJ from the sudden relaxation of the frictional constraint in the ABL around sunset (mechanism proposed by Blackadar, but augmented with a buoyancy effect arising from a differentially heated surface). The governing equations are the linearized Boussinesq equations of motion, thermal energy, and mass conservation equation. Horizontal variations in the free-atmosphere geostrophic wind or ABL buoyancy, as accounted for in the initial (sunset) conditions. The sensitivity of the solution is explored with respect to the free-atmosphere Brunt-Vaisala frequency, Coriolis parameter, ABL depth, and the amplitude and lateral wavelength of the free-atmosphere geostrophic wind or ABL buoyancy variations. A laterally varying buoyancy is much more effective than a laterally varying free-atmosphere geostrophic wind in generating vertical motion, inducing vertical displacements of 500 m to 1 km within 6 h of sunset.

Upcoming Seminars

9/16 - Dr. Nathan Dahl (University of Miami): Simulated near-surface behavior of tornado-like vortices in a Fiedler chamber with resolved turbulence

Past Seminars

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