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
Overview
 Goal
 What
is CI, and how we define it?
 Model configuration and tools
 Preliminary results/findings
Convection Initiation (CI)
 Requirements:
 Reflectivity
minutes
(Gremillion & Orville 1999)
 Observed
 42
≥ 35 dBZ at the -10 °C isotherm for 30
CI objects:
Radars in Central US (111 to 93 W, 27 to 50 N)
 Warning
Decision Support System -- Integrated
Information (WDSS-II)
 Tracking
 Used
Algorithm
(V. Lakshmanan 2009,2010)
in both observed and modelled CI
WRF Configuration
WRF
V3.4.1
15-3km
Nest, Thompson MP, RRTMG LW & SW
Five - 30 member Convective Allowing Ensembles
Varying
15
PBL scheme
hour simulations (15-06z)
Modifications
isotherm
to interpolate Reflectivity to -10 °C
PBL Schemes
Five
PBL Schemes used:
 Non-Local
ACM2
YSU
(Asymmetric Convective Model 2)
(Yonsei University)
 Local
MYJ
(Mellor-Yamada-Janjic)
QNSE
(Quasi-Normal Scale Elimination)
MYNN2.5
(Mellor-Yamada-Nakanishi-Niino level 2.5)
3 Cases
 May
19-20, 2013
 Deep
 SW
 May
trough
flow into Plains
31-June 1, 2013
 Initiation along boundaries
 500mb cutoff low
 Westerly
 June
winds into the plains
8-9, 2013
 Ridge
 NW
in Pacific NW
flow into the Central Plains.
 Minimal
initiation
Forecast Verification
Verified
against observed CI
Domain
18z
5
– 2000 J/kg CAPE field
RAP (13km) 00 hour analysis
Time and Space bins
40
km/1 hour
80
km/1.5 hour
120
km/2 hour
160
km/2.5 hour
200
km/3 hour
(Van Klooster and Paul J. Roebber 2009) – Figure 1
Forecast Verification
Brier
Skill Score
Performance Diagram
POD
vs SR (1-FAR)
Bias (Blue)
Critical Success Index (Black)
(Roebber 2009)
Performance Diagram
40 km/1 hour
80 km/1.5 hour
Performance Diagram
40 km/1 hour
80 km/1.5 hour
CAPE < 2000 J/kg
CI Overproduction
(19-20 May 2013 Example)
Observed
ACM2
MYJ
MYNN2.5
QNSE
YSU
Conclusions
 Forecasts
overproduce initiation events
Overproduce
PBL
 In
in areas of less instability
schemes too energetic??
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.

Ariel E. Cohen, Steven M. Cavallo, Michael C. Coniglio, and Harold E. Brooks, 2015: A Review of Planetary Boundary
Layer Parameterization Schemes and Their Sensitivity in Simulating Southeastern U.S. Cold Season Severe Weather
Environments. Wea. Forecasting, 30, 591–612.

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.

Gremillion M.S. and R.E. Orville 1999: Thunderstorm characteristics of cloud-to-ground at the Kennedy 146 Space
Center, Florida: A study of lightning initiation signatures as indicated by the WSR-88D. 147 Wea. Forecasting, 14,
640-649.

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