Transcript ICAM__3_Sept_E_Crosmanx

Toward Improved NWP Simulations
of Utah Basin Cold Air Pools
Erik Crosman1, John Horel1, Chris Foster1, Erik Neemann1
1University
of Utah
Department of Atmospheric Sciences
Photo: Sebastian Hoch
12.5
33rd Conference on Alpine Meteorology 31 Aug – 4 Sept 2015, Innsbruck, Austria
Complex Range of European Valley Cold Pools
Highlighted this Week!
• Passy Valley cold pool project and modeling (Alexander Paci and Chantal
Staquet, France)
• Italian Alps high resolution cold pool modeling and particulate matter
distribution (Elena Tomasi and Lorenzo Giovannini, Italy)
• Fog formation in a valley (Sian Lane, UK)
• Shallow and subgrid cold pools (Peter Sheridan, UK)
• Idealized heat/mass/energetics (Ganbriele Arduini and Daniel Leukauf,
UK/Austria)
Recent Utah Wintertime Cold Pool Research
Uintah Basin (O3):
Uintah Basin Wintertime Ozone Study
(UBWOS)
Salt Lake Valley (PM2.5):
The Persistent Cold Air Pool Study (PCAPS)
The Bingham Canyon Mine Experiment
Overview and Air Quality: Silcox et al. 2012; Young 2013; Lareau et al. 2013
Whiteman et al. 2014; Whiteman and Hoch 2015; Young and Whiteman 2015
Large-Scale Dynamics: Lareau et al. 2013; Lareau and Horel 2014; Lareau and Horel
2015
Numerical Modeling and Local Forcing: Wei et al. 2013; Lu and Zhong 2014;
Neemann et al. 2014. Lareau and Horel 2015; Crosman and Horel 2015a,b
Complex Utah Basins
Cache
Valley
Great Salt Lake
Basin 1300 m
Salt Lake
Valley
3200 m
Utah
Valley
25 km
4000 m
Uintah Basin
Basic Weather Features Associated with Cold Air
Pools: Fairly Well Simulated with NWP
Warmer air aloft
H
High pressure
Cold air pool
Light winds
Pollutants
Critical Weather Details Associated with Poor
Winter Air Quality: Difficult to Simulate
Improper Surface State
Turbulent Mixing
Clouds
Transport
Depth of
polluted layer
Transport
Pollution concentrations
Surface fluxes
Critical Weather Details Associated with Poor
Winter Air Quality: Difficult to Simulate
Inadequate boundary-layer and cloud
parameterizations
Turbulent Mixing
Clouds
Transport
Depth of
polluted layer
Transport
Pollution concentrations
Snow Cover and Land Use
Improving Cold Air Pool Simulations in the
Weather Research and Forecasting Model (WRF)
Grid spacing = 12 km
--Surface state and
Grid spacing = 4 km
Grid spacing 250 m
Grid spacing
= 1.3 km
initialization
--Boundary-layer
physics
MYJ PBL (mesoscale)
No PBL (LES)
RRTMG radiation
NOAH LSM
Thompson microphysics
Improve Snow Cover Initialization
•Thin, tenous snow pack in
Utah Basins (< 5-10 cm)
•Snow physics models
undeveloped for shallow
snowpack
•Ice fog deposition
•Spatially inhomogeneous
snow fall and melt rates
0-5 cm
Simulating Snow Effects Better
Albedo
Before
correction
Depth
After
correction
Vegetation
Mean 2-m Temperatures Sensitivity to Snow Cover
Salt
Lake
Valley
-4.5 °C
-2.0 °C
SNOW
No Snow
Neemann et al. 2014
Uintah
Basin
-2.1 °C
-9.7 °C
-7.7 °C
°C
-12
-6
-10
-4
-8
-2
-6
0
-4
2
-2
4
0
6
2
8
11
Improve Land Use Specification
•Default USGS Land Use outdated
•NLCD 2011 Implemented
--40% increase in urban area
--30% decrease in lake
surface
•Additional changes required based
on satellite imagery (frozen lake,
dry lake) and surface albedo
measurements
•Allow albedo to increase ~15% in
urban environment
•Correctly specify lake temperature
Default WRF
After modifications
Temperature Difference NLCD2011 vs
USGS
Improve Cloud Specification
Liquid Clouds vs. Ice
Clouds
Over the entire model run,
liquid clouds produced an
average of 7-20 W/m2 more
longwave energy than ice
clouds in the Uintah Basin
Neemann et al. (2015)
14
FDDA (nudging) impacts on WRF-CMAQ model performance in
simulating
winter O3 formation in Uintah Basin
Trang Tran1, Huy Tran1, Erik Crosman2
Improve Turbulent Mixing: Large-Eddy Simulation of CAP
Depth
Ɵ PBL: YSU
ΔX 1335 m
Duration
CAP too shallow
Ɵ PBL: none
LES ΔX 250 m
PCAPS Ɵ observations
Clouds
Physics
Important
To verify
vertical
profiles
Crosman
and Horel
(2015)
LES: ΔX = 0.250 km
Great
Salt
Lake
PBL: YSU ΔX = 1.33 km
10
Salt
Lake
Valley
5
2-m
Temp
0 (ᵒC)
Great
Salt
Lake
Salt
Lake
Valley
-5
Toxic soup continues…
Time to exercise!
12
9
Wind
6 Speed
(m s-1)
3
0
sltrib.com
Summary and Future Work
• Surface state, snow cover, and land use specification
critical for simulating Cold Air Pools (CAPs)
• CAP simulations also sensitive to turbulent mixing and
cloud algorithms
• Simulations have been applied to a range of CAPs to
better understand meteorological evolution and
processes
• More advancements in NWP of CAPs are needed
Photo: Sebastian Hoch
Impact of Great Salt Lake on Temperature and Low Clouds
warm lake LAKE+3
cold lake LAKE-3
Cloud
water
Salt
Lake
Valley
Low clouds and fog
after ~2 days
2400
1280
2m
temp
(⁰C)
Elevation (m)
(g kg)
3500
Great
Salt
Lake
WRF CAP Sensitivity to Land Use
9 Day Average 2-m Temperature Difference
USGS minus NLCD