with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can...
Transcript of with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can...
![Page 1: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/1.jpg)
Mountain Micrometeorology Modeling with WRF
Alex Anderson-ConnollyFotini Chow
![Page 2: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/2.jpg)
Motivation
● Air quality forecast
● Wind farm siting
● Weather predictione.g. cold pools
Photo Credit: Spencer Garn, ksl.com
![Page 3: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/3.jpg)
● perform large-eddy permitting simulations over Granite Peak○ stable flows○ mesoscale/microscale interactions
● investigate limitations of WRF○ 10 m resolution? 100 m? ○ 30 deg slope? 45 deg?
● improve fidelity of LES over complex terrain
Modeling goals
![Page 4: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/4.jpg)
Overview● Modeling
challenges○ Terra incognita○ High resolution
inputs○ Slope aspect ratio
● Comparisons to observations
● Future work
![Page 5: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/5.jpg)
Grid nesting across the gray zone● Nesting past terra
incognita
● 9 km -> 3 km -> 1 km -> 333 m -> 111 m ….
from Wyngaard (2004)
![Page 6: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/6.jpg)
Nest past gray zone
Goal:
on mesoscale domains, d01 and d02, parameterize all turbulence
![Page 7: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/7.jpg)
Nest past gray zone
Goal:
on LES domain, d03, resolve most turbulence
![Page 8: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/8.jpg)
d01(6.3 km)
d02(2.1 m)
d03(100 m)
dx, dy 6.3 km 2.1 km 100 m
nx, ny 100 pts 100 pts 190 pts
dz (121 lvls) ~55 m to ~175 m
dt 30 s 10 s 0.2 s
grid nest ratio
1 3 21
time step ratio
1 3 50
one-way nesting
Nest past gray zoneThree Domains near Great Salt Lake
Large nest ratios bypass the terra incognita (gray zone)
![Page 9: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/9.jpg)
High res inputs: Topography ⅓ arcsecond topography from National Elevation Dataset
wrf out-of-the-box: 30s
![Page 10: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/10.jpg)
High res inputs: Topography ⅓ arcsecond topography from National Elevation Dataset
max slope: 45 deg
wrf out-of-the-box: 30s
max slope: 30 deg
High res topographic input recreates complex terrain and leads to greater slopes
![Page 11: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/11.jpg)
High res inputs: Land coverwrf out-of-the-box:
30s NLCD Landuse
1s land use from NLCD Additional land use categories:
Lava, Playa & White Sand(as in Massey et al. 2014)
![Page 12: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/12.jpg)
soil type resolution is not increased, lava and white sand have been added
Example Soil type level
Input d01(6.3 km)
d02(2.1 km)
d03(100 m)
Topo 30 s(~1 km)
3 s(~100 m)
⅓ s(~10 m)
Land Cover
30 s(~1 km)
1 s(~30 m)
1 s(30 m)
Soil type 30 s(~1 km)
30 s(~1 km)
30 s(~1 km)
High res inputs: Soil type
![Page 13: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/13.jpg)
High res configurationsSW with topographic shading no topographic shading
WRF can include effects of shadows, important in complex terrain
![Page 14: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/14.jpg)
XY contour of SW rad
during IOP 6, 02 MDT 10/14/’12 - 02 MDT 10/15/’12
![Page 15: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/15.jpg)
Terrain following coordinatespressure based vertical coordinates
non-orthogonal grids lines
![Page 16: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/16.jpg)
Slope aspect ratio
true derivative, d/dx, is bounded by single cell
metric term errors arise, but will stay bounded
![Page 17: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/17.jpg)
Slope aspect ratio
![Page 18: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/18.jpg)
Slope aspect ratio
slope < arctan(b * dz/dx)
b ~ 1 to 5
Mahrer 1984
![Page 19: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/19.jpg)
Comparison with observations
![Page 20: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/20.jpg)
PWD78 on East Slope
not resolving dips in T2 during cold pool sloshing
not resolving quick drop in temperature as shadow front passes at ~1800 to 1900 MDT
Time [hrs since 00 MDT 10/14]
Temp. [deg C]
Surface time series - east slope
![Page 21: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/21.jpg)
MS44 in valley to the east
no cold pool leads to largemagnitudes of error
Problem: Mesoscale solution is recreated on LES domain
Possible Solutions:● larger LES domain● finer vertical resolution● lateral boundary perturbations
Time [hrs since 00 MDT 10/14]
Temp. [deg C]
Surface time series - valley
![Page 22: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/22.jpg)
Small scale featuresAre we resolving small scale motion on the LES domain?
At night time, lee waves are resolved
![Page 23: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/23.jpg)
Small scale featuresAre we resolving small scale motion on the LES domain?
During day time, thermal cells resolved
![Page 24: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/24.jpg)
XZ contour of vertical velocity
during IOP 6: 02 MDT 10/14/’12 -02 MDT 10/15/’12
Day: thermal plumes resolved
Night: lee waves resolved
![Page 25: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/25.jpg)
XY contour of vertical velocity
during IOP 6:02 MDT 10/14/’12 -
02 MDT 10/15/’12
Day: thermal plumes resolved
Night: lee waves resolved
![Page 26: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/26.jpg)
Conclusions Successes: WRF can run at 100 meters resolution over steep terrain,
~45 deg max slope, without blowing up if i) vertical resolutions are sufficiently coarse and ii) time steps are sufficiently small
Grey zone issues can be avoided through a nested approach
Take Home Message: WRF-LES can resolve the small scale features of mountain micrometeorology
![Page 27: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/27.jpg)
Ongoing challenge: better agreement with surface observations, sloshing, temperature biases. May need to develop turbulence on LES domain with● Larger domain● Improved vertical resolution● Lateral boundary perturbations
while considering● Computational costs ->● Slope aspect ratios
Take Home Message:Difficulty resolving near surface variables, for a practical computational cost and without violating slope aspect stability limits, makes a good case for IBM-WRF.
Future work
![Page 28: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/28.jpg)
Acknowledgments
ONR MURI MATERHORN
Thanks to Massey et al. for land cover data!
![Page 29: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/29.jpg)
![Page 30: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/30.jpg)
PBL closures
MYJ vs
YSU
For complex terrain, MYJ (local scheme) outperforms YSU (non-local)
Time [hrs since 00 MDT 10/14]
Temp. [deg C]
![Page 31: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/31.jpg)
LES closures
TKE 1.5 vs
TKE 1.5 and MYJ
Time [hrs since 00 MDT 10/14]
Temp. [deg C]
![Page 32: with WRF Mountain Micrometeorology Modeling Fotini Chow ...dynamics/materhorn/PDF... · WRF-LES can resolve the small scale features of mountain micrometeorology . Ongoing challenge:](https://reader035.fdocuments.net/reader035/viewer/2022062506/5f759f31347cf3713b4a06ed/html5/thumbnails/32.jpg)
PBL vs LESPBL domains’ solutions for surface variables are recreated on LES domain