On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m...
Transcript of On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m...
![Page 1: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/1.jpg)
Eidgenössisches Departement des Innern EDIBundesamt für Meteorologie und Klimatologie MeteoSchweiz
On the 2m temperature and dew point diagnostics in the
COSMO model
Matteo Buzzi and M.W. Rotach MeteoSwiss
![Page 2: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/2.jpg)
2On the 2m temperature diagnostics in the COSMO model | [email protected]
Overview
• Introduction• Surface layer• Operational 2m temperature and dew point diagnostics
• Possible sources of error• The role of subgrid scale orography
• Alternatives: new interpolation formulas or profiles• Case studies
• Intercomparison: verification results• Conclusions
![Page 3: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/3.jpg)
3On the 2m temperature diagnostics in the COSMO model | [email protected]
Surface layer
0
Inertial sublayer (ISL)
Roughness sublayer (RSL)
hcan
z*
0.1zi
Θ'w' sensible heat fluxQv'w' latent heat flux
Θ'w'surf or Qv'w'surf
constant turbulent fluxes
inconstant fluxes
NWP modelsfirst model layer
2m
z*= 2hcan
![Page 4: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/4.jpg)
4On the 2m temperature diagnostics in the COSMO model | [email protected]
COSMO 2m temperature and dew point diagnostics: 3 cases
T(ke), Q(ke)
H1=z0
0Ts,Qs
H2=z0+h(ke)
z0+h(ke-1) T(ke-1), Q(ke-1)
hcan
skin
laye
r!
EXP LOG LOG INTERP
( ) ⎟⎟⎠
⎞⎜⎜⎝
⎛ ++= H
lam
Htur
HlamH
turH
lamcan rrrrrRCh log
![Page 5: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/5.jpg)
5On the 2m temperature diagnostics in the COSMO model | [email protected]
2m temperature: possible sources of error
• Surface temperature:• soil model (surface energy balance, LH, SH, GF, SWbal, LWbal)
• Atmosphere temperature:• dynamics (e.g. advection), convection, turbulence scheme
• Interpolation profile in the diagnostics:• choice of “wrong” profile function
• Surface description:• Roughness length:
• canopy height
![Page 6: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/6.jpg)
6On the 2m temperature diagnostics in the COSMO model | [email protected]
COSMO-7 roughness length (7 km)[m]
![Page 7: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/7.jpg)
7On the 2m temperature diagnostics in the COSMO model | [email protected]
COSMO-7 roughness length: local and orographic component (7 km)
z0 = z0, loc + z0,oro
z0, loc z0,oro[m] [m]
hcan
![Page 8: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/8.jpg)
8On the 2m temperature diagnostics in the COSMO model | [email protected]
Unrealistic canopy height (7km)20.12.2006 6 UTC 20.12.2006 12 UTC [m]
exp profile is too often used!
hcan =z0, loc
0.1
( ) ⎟⎟⎠
⎞⎜⎜⎝
⎛ ++= H
lam
Htur
HlamH
turH
lamcan rrrrrRCh log
![Page 9: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/9.jpg)
9On the 2m temperature diagnostics in the COSMO model | [email protected]
Averaged diurnal cycle: 15.04.2007
z0,oro< 0.2 m 0.2 m < z0,oro< 0.5 m
COSMO-7 over the alpine region
![Page 10: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/10.jpg)
10On the 2m temperature diagnostics in the COSMO model | [email protected]
Phase error
26.07.2007 COSMO-7- Swiss SYNOP stations
![Page 11: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/11.jpg)
11On the 2m temperature diagnostics in the COSMO model | [email protected]
Comparison of different diagnosticsProblem:
2 m temperature is too close to the surface temperatureSolution:
introduction of a local roughness length and try others diagnostics0. Introduce a realistic hcan in operational diagnostics
• But inconsistent with resistances (option only possible if surface transfer scheme and turbulence scheme are called twice)
1. Use a simple logarithmic interpolation as used for wind (newlog)• But not consistent with RSL (z0,loc >0.2m)!
2. ECMWF IFS diagnostics (logarithmic interpolation based on Monin-Obuchov similarity) (ecmwf)• But not consistent with RSL (z0,loc >0.2m)!
3. New approach (new):• New logarithmic profile (as 1.) only for gridcells with z0,loc < 0.2m• z0,loc > 0.2m new RSL profiles independent from surface
temperature4. Diagnostics for a SYNOP garden (by Matthias R.) (dwdnew)
• But not consistent with RSL (z0,loc >0.2m)!5. As 4. but with z0,loc instead of typical SYNOP z0 (dwdnew z0loc)
![Page 12: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/12.jpg)
12On the 2m temperature diagnostics in the COSMO model | [email protected]
H2 = H(ke) + z0, loc + d
New profiles: general aspects
0
Inertial sublayer ISL
Roughness sublayer RSL
hcan
z*
0.1zi
Temperature
T*, ISL fluxes
hcan =z0, loc
0.1z* = 2hcan
d =23
hcan
Approach for large z0,loc: derive temperature and specific humidity profile from turbulent flux profiles and atmospheric values
First model atmospheric levelH2
d
T,QV,H0,LH0, Mo0
![Page 13: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/13.jpg)
13On the 2m temperature diagnostics in the COSMO model | [email protected]
New profiles: 3 cases
newlog
![Page 14: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/14.jpg)
14On the 2m temperature diagnostics in the COSMO model | [email protected]
New profiles: formulationdθdz
=θ*(z)
α ⋅ (z − z0, loc )
θ*(z) =w'θ '(z)u*(z)
=w'θ '(z)
u'w'(z)2 + v'w'(z)2( )1 / 4
θ(z) = θ(z*) −θ*(z)
α ⋅ (z − z0, loc )dz
z0
z
∫
θ*(z*)α ⋅ (z* − z0, loc )
= φhθ*
k(z* − d)⇒ α =
k(z* − z0, loc )φh (z* − d)
φh ( zL
)
Profile matching at z*
RSL: local scaling
Integration
ISLRSL
![Page 15: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/15.jpg)
15On the 2m temperature diagnostics in the COSMO model | [email protected]
Sensible heat flux and vertical temperature derivative
![Page 16: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/16.jpg)
16On the 2m temperature diagnostics in the COSMO model | [email protected]
Temperature and specific humidity
![Page 17: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/17.jpg)
17On the 2m temperature diagnostics in the COSMO model | [email protected]
Case studies and model settings
• 5 cases 24h forecast COSMO 7km (fairly good weather)• 20.12.2006, 15.04.2007, 18.06.2006, 26.07.2007,
15.10.2007• COMSO 3.20, Runge-Kutta, IFS Analysis as BC, COSMO
analysis as IC• Verification with SYNOP stations for the domain covering
the alpine region (COSMO-2) (for all 6 variants)
![Page 18: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/18.jpg)
18On the 2m temperature diagnostics in the COSMO model | [email protected]
Variants compared with operational diagnostics
1. Simple logarithmic interpolation as used for wind (newlog)
2. ECMWF IFS diagnostics (ecmwf)
3. New approach (new): RSL profiles z0,loc > 0.2m
4. Diagnostics for a SYNOP garden (dwdnew)
5. As 4. but with z0,loc instead of typical SYNOP z0 (dwdnew z0loc)
![Page 19: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/19.jpg)
19On the 2m temperature diagnostics in the COSMO model | [email protected]
Results: diurnal cycle 15.04.2007
![Page 20: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/20.jpg)
20On the 2m temperature diagnostics in the COSMO model | [email protected]
Averaged diurnal cycle: 15.04.2007
![Page 21: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/21.jpg)
21On the 2m temperature diagnostics in the COSMO model | [email protected]
Comparison of the vertical profiles
![Page 22: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/22.jpg)
22On the 2m temperature diagnostics in the COSMO model | [email protected]
Comparison of the vertical profiles
![Page 23: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/23.jpg)
23On the 2m temperature diagnostics in the COSMO model | [email protected]
Verification: SYNOP alpine region 2m temperature 20.12.2006
![Page 24: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/24.jpg)
24On the 2m temperature diagnostics in the COSMO model | [email protected]
Verification: SYNOP alpine region2m dew point (RMSE)
![Page 25: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/25.jpg)
25On the 2m temperature diagnostics in the COSMO model | [email protected]
2m temperature: results summary
RMSE[°C]
ME[°C]
STDEV ME[°C]
Operational 3.15 -0.86 3.03
new RSL 2.86 -0.62 2.79
newlog 2.74 -0.52 2.69
dwdnew 2.73 -0.44 2.70
dwdnew z0,loc 2.75 -0.56 2.69
ecmwf 2.74 -0.56 2.68
COSMO-7 verified on COMSO-2 domain (only 5 days)!
![Page 26: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/26.jpg)
26On the 2m temperature diagnostics in the COSMO model | [email protected]
Conclusions
• 2 m temperature and 2m dew point: multiple sources of error (soil, atmosphere, choice of the interpolation profile)
• Unrealistic canopy height (from subgridscale orography) is a significant source of error (choice between EXP and LOG profile)
• Operational diagnostics compared to 5 options based on local roughness length or on SYNOP garden
![Page 27: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/27.jpg)
27On the 2m temperature diagnostics in the COSMO model | [email protected]
Conclusions• Better verification results for all the 5 options:
• Phase shift improved• Cold bias in winter significantly reduced
but still important!• Logarithmic interpolation: the best results, BUT inconsistent
with the RSL (for z0,loc>0.2)!• The new RSL profiles perform comparably well and are
consistent with the RSL• Local roughness length necessary for diagnostics: should be
introduced in COSMO• Downscaling on a SYNOP garden:
• inconsistent with the mean gridbox conditions in the model• but gives better verification results (better SMA @ DWD)
![Page 28: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/28.jpg)
Eidgenössisches Departement des Innern EDIBundesamt für Meteorologie und Klimatologie MeteoSchweiz
Thank you for your attention!
![Page 29: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/29.jpg)
29On the 2m temperature diagnostics in the COSMO model | [email protected]
Verification: SYNOP Switzerland 2m temperature 20.12.2006
![Page 30: On the 2m temperature and dew point diagnostics in the COSMO … · 2016. 12. 20. · On the 2m temperature diagnostics in the COSMO model | matteo.buzzi@meteoswiss.ch 8 Unrealistic](https://reader033.fdocuments.in/reader033/viewer/2022060601/6055824767e24b136421deef/html5/thumbnails/30.jpg)
30On the 2m temperature diagnostics in the COSMO model | [email protected]
New profiles: turbulent fluxes
u'w' = c ⋅ u'w'ISLz − z0zs − z0
⎛ ⎝ ⎜
⎞ ⎠ ⎟
2
exp a(1−z − z0zs − z0
⎛ ⎝ ⎜
⎞ ⎠ ⎟
⎛
⎝ ⎜
⎞
⎠ ⎟
v'w' = c ⋅ v'w'ISLz − z0zs − z0
⎛ ⎝ ⎜
⎞ ⎠ ⎟
2
exp a(1−z − z0zs − z0
⎛ ⎝ ⎜
⎞ ⎠ ⎟
⎛
⎝ ⎜
⎞
⎠ ⎟
u'w'(z*) = u'w'ISL v'w'(z*) = v 'w'ISL ⇒ c =z * −z0zs − z0
⎛ ⎝ ⎜
⎞ ⎠ ⎟
−2
exp a(1−z * −z0zs − z0
⎛ ⎝ ⎜
⎞ ⎠ ⎟
⎛
⎝ ⎜
⎞
⎠ ⎟
Momentum fluxes
Kaster-Klein and Rotach (2004)
Sensible heat flux
w'θ ' = w'θ 'ISLz − z0zs − z0
⎛
⎝ ⎜
⎞
⎠ ⎟
2
exp −ch zs − zzs
⎛
⎝ ⎜
⎞
⎠ ⎟
⎛
⎝ ⎜
⎞
⎠ ⎟ z < zs
w'θ ' = w'θ 'ISL z ≥ zs Modified from Christen (2005)
ch=1.2
a=2