Sensitivity of PBL Parameterization on

Ensemble Forecast of Convection Initiation

Bryan Burlingame

M.S. Graduate Research Assistant

University of Wisconsin-Milwaukee

burling6@uwm.edu

http://derecho.math.uwm.edu/~bmburlin/

Clark Evans - UWM

Paul Roebber - UWM

Ryan Torn – SUNY Albany

Glen Romine - UCAR

OverviewGoalWhat is CI, and how we define

it?Model configuration and toolsPreliminary results/findings

Convection Initiation (CI)Requirements:

Reflectivity ≥ 35 dBZ at the -10 C isotherm for 30 minutes (Gremillion & Orville 1999)

Observed CI objects:42 Radars in Central US (111 to 93 W, 27 to 50

N)Warning Decision Support System -- Integrated

Information (WDSS-II)Tracking Algorithm (V. Lakshmanan 2009,2010)

Used in both observed and modelled CI

WRF Configuration

WRF V3.4.115-3km Nest, Thompson MP, RRTMG LW & SWFive - 30 member Convective Allowing EnsemblesVarying PBL scheme

15 hour simulations (15-06z)Modifications to interpolate Reflectivity to -10 C

isotherm

PBL SchemesFive PBL Schemes used:

Non-LocalACM2 (Asymmetric Convective Model 2)YSU (Yonsei University)

LocalMYJ (Mellor-Yamada-Janjic)QNSE (Quasi-Normal Scale Elimination)MYNN2.5 (Mellor-Yamada-Nakanishi-Niino level 2.5)

3 CasesMay 19-20, 2013

Deep trough SW flow into PlainsInitiation along boundaries

May 31-June 1, 2013 500mb cutoff lowWesterly winds into the plains June 8-9, 2013Ridge in Pacific NWNW flow into the Central

Plains. Minimal initiation

Forecast VerificationVerified against observed CI

Domain – 2000 J/kg CAPE field18z RAP (13km) 00 hour analysis

5 Time and Space bins40 km/1 hour80 km/1.5 hour120 km/2 hour160 km/2.5 hour200 km/3 hour

(Van Klooster and Paul J. Roebber 2009) – Figure 1

Forecast Verification

(Roebber 2009)

Brier Skill ScorePerformance Diagram

POD vs SR (1-FAR)Bias (Blue)Critical Success Index (Black)

Performance Diagram40 km/1 hour

80 km/1.5 hour

Performance Diagram CAPE < 2000

J/kg40 km/1 hour

80 km/1.5 hour

CI Overproduction (19-20 May 2013 Example)Observed

QNSE

MYJACM2

YSUMYNN2.5

ConclusionsForecasts overproduce initiation events

Overproduce in areas of less instabilityPBL schemes too energetic??

In area of high probability of convective occurrence:All forecasts verified well within 80km / 1 hour

References Adam J. Clark, Michael C. Coniglio, Brice E. Coffer, Greg Thompson, Ming Xue, and Fanyou Kong, 2015: Sensitivity of

24-h Forecast Dryline Position and Structure to Boundary Layer Parameterizations in Convection-Allowing WRF Model Simulations. Wea. Forecasting, 30, 613–638.

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Michael C. Coniglio, James Correia Jr., Patrick T. Marsh, and Fanyou Kong, 2013: Verification of Convection-Allowing WRF Model Forecasts of the Planetary Boundary Layer Using Sounding Observations. Wea. Forecasting, 28, 842–862.

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V. Lakshmanan, K. Hondl, and R. Rabin, “ An efficient, general-purpose technique for identifying storm cells in geospatial images,'' J. Ocean. Atmos. Tech., vol. 26, , no. 3, pp. 523-37, 2009

 V. Lakshmanan and T. Smith, “ An objective method of evaluating and devising storm tracking algorithms,'' Wea. and Forecasting, pp. 721-729, vol. 29 no. 3, 2010. 

Paul J. Roebber, 2009: Visualizing Multiple Measures of Forecast Quality. Wea. Forecasting, 24, 601–608

Sara L. Van Klooster and Paul J. Roebber, 2009: Surface-Based Convective Potential in the Contiguous United States in a Business-as-Usual Future Climate. J. Climate, 22, 3317–3330