Boundary Layer Seminar Series

OU BLISS sponsors seminars generally every other Friday from 3-4 pm in room 5600 of the National Weather Center. Members of BLISS, as well as outside guests, will speak on a variety of topics related to boundary layer research, including fieldwork, laboratory simulations, and more. All are welcome.

May 6 2015:

Paul Flanagan : The Dryline, Convective Initiation, and Rapid Evolution of Drought in Oklahoma During 2011

During the warm season of 2011, a rapid expansion of drought conditions (i.e., flash drought) occurred across eastern Oklahoma. In a matter of weeks, portions of the state transitioned from a rating by United States Drought Monitor (USDM) of no drought conditions to moderate/severe drought conditions. The goal of this study was to investigate the environmental feedbacks during the period spanning March-August 2011 and determine the role of surface conditions on the evolution of the dryline, convective initiation, and rapid drought development that occurred over the eastern region of Oklahoma. Results show that conditions over western Oklahoma continued to deteriorate during April and May, while eastern Oklahoma received below to normal temperatures and excessive rainfall. During the month of June extreme temperatures and wind anomalies forced a rapid depletion of soil moisture by evapotranspiration and flash drought occurred.

Analysis of the dryline during the period shows that on average dryline longitude was further to the east than the climatological normal. Overall, 17 dryline events were analyzed during the month of May accounting for 55% of the days in the month. Of these events, 13 produced convective clouds, with 7 of these producing precipitation. The dryline events that produced precipitation during May versus those that only produced convective clouds without precipitation were, on average, 1.7° further to the east. Preliminary model analyses, using the Weather Research and Forecasting (WRF) Advance Research (ARW) model were completed to diagnose the sensitivity of the dryline to surface conditions. Soil moisture sensitivity tests were completed on a select dryline case to investigate the role of the heterogeneous soil moisture field on the precipitation patterns produced by select drylines. The results demonstrated that the soil moisture conditions impacted the evolution of the dryline and convective initiation.

Other upcoming seminars:

Past Seminars

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