- tbm - topographical boundary layer model dr. o. liechti [email protected]
TRANSCRIPT
Analysen & Konzepte • Dr. O. Liechti • CH-8404 Winterthur
A&K
- tBM -
topographical boundarylayer model
Dr. O. Liechti
Analysen & Konzepte • Dr. O. Liechti • CH-8404 Winterthur
A&K
Short Range Forecasting Methods
of Fog, Visibility, and Low Clouds
•Phase I Inventory•Phase II Research & Development•Phase IIIDissemination
COST Action 722
Analysen & Konzepte • Dr. O. Liechti • CH-8404 Winterthur
A&K
Phase II Research & Development
•WG I Initial Data•WG II Models•WG III Statistical Methods
Analysen & Konzepte • Dr. O. Liechti • CH-8404 Winterthur
A&K
WG I Initial data
CDG radiosonde
CDG remote sensing
ZRH stations in complex topography
ZRH model aircraft
local vertical profiles
Analysen & Konzepte • Dr. O. Liechti • CH-8404 Winterthur
A&K
WG II Models
D GM - LM - PAFOG
F ARPEGE - ALADIN - COBEL/ISBA
CH EZMW - aLMo - COBEL/ISBA
EZMW - aLMo - tBM
GFS - NMM - NMM
3D - 2D - 1D
Analysen & Konzepte • Dr. O. Liechti • CH-8404 Winterthur
A&K
Weather Conditions for Industrial Snow
fog/stratus
frost
inversion
calm
wind
-8 -6 -4 -2 00
100
200
300
400
500
temperature [°C]
height [mGND]
2.6 g/kg
LWC 0.2 g/kg
hu
mid
ity
te
mp
era
ture
2.4 g/kg
pools of cold air
locally enhanced snow grains
Analysen & Konzepte • Dr. O. Liechti • CH-8404 Winterthur
A&K
Zurich Airport Winterthur
Analysen & Konzepte • Dr. O. Liechti • CH-8404 Winterthur
A&K
SoundingPayerne midnight
noon
9. Jan. 2002
-20 -15 -10 -5 0 5
500
1000
1500
2000
T [degC]
z [mMSL]
2002 01 09 12z
T 12z
T 00z
Wind
-20 -15 -10 -5 0 5
500
1000
1500
2000
T [degC]
z [mMSL]
2002 01 09 00z
T 00z
Wind
[KT]
[KT]
20 10 0 10 20
20 10 0 10 20
IR radiative cooling
Analysen & Konzepte • Dr. O. Liechti • CH-8404 Winterthur
A&K
-8 -6 -4 -2 00
100
200
300
400
500
temperature [C]
height [mGND]
condensation
nocturnal cooling rates
–0.6°C/h–0.1°C/h
clear skyfog/stratus
nocturnal cooling rates
Analysen & Konzepte • Dr. O. Liechti • CH-8404 Winterthur
A&K
Stratus
0
100
200
300
400
500
600
700
500
600
700
800
900
1000
1100
Cases with Industrial Snow
height [mGND]
Top
Base
altitude [mMSL]
Source: MeteoSwiss
Lägern
Hörnli
Uetliberg
• low stratus
• white frost
• calm
Industrial Snow
mo
rnin
g
fog
fog
gy
days
Analysen & Konzepte • Dr. O. Liechti • CH-8404 Winterthur
A&K
thermodynamics of low stratus
• radiative loss of heat
• surface cooling
• convection
• supersaturation, condensation
• snow grains (locally enhanced)
Analysen & Konzepte • Dr. O. Liechti • CH-8404 Winterthur
A&K
simulation of pooling cold air
• IR radiative flux• convection• topographical volume effect• local circulation through differential
cooling
topographical boundary layer model (tBM)
Analysen & Konzepte • Dr. O. Liechti • CH-8404 Winterthur
A&K
0 50
500
1000
0 50 0 50 0 50 100
500
1000
A
%
m/M
B C D
AB
C
D
m/M
%%%
volume effect
local winds (2-D)
convection (1-D)
radiation (SW, LW)
topographical boundary layer model (tBM)tBM for Zurich airport
Analysen & Konzepte • Dr. O. Liechti • CH-8404 Winterthur
A&K
area-elevation-distributions for the areas A, B, C, D
tBM simulation (2-dim, 24 hrs)
Analysen & Konzepte • Dr. O. Liechti • CH-8404 Winterthur
A&K
A
B
C
D
T [C]
0 50
500
1000
0 50
0 50
0 50 100
500
1000
tBM simulation (2-dim, 24 hrs) pu
re top
og
raph
ical effect !
Analysen & Konzepte • Dr. O. Liechti • CH-8404 Winterthur
A&K
A
B
C
D
h [mMSL]
0 50
500
1000
0 50
0 50
0 50 100
500
1000
tBM simulation (2-dim, 24 hrs) pu
re top
og
raph
ical effect !
Analysen & Konzepte • Dr. O. Liechti • CH-8404 Winterthur
A&K
models in COST 722
model topo z-Mix x-Mix soil
COBEL flat shear –– 1d-ISBA
PAFOG flat shear –– Bewuchs
tBM V(z) convection circulation 0d
NMM flat parametr. circulation 1d
--> comparison @ Paris CDG 03/04/05