Federal Department of Home Affairs FDHA
Federal Office of Meteorology and Climatology MeteoSwiss
Conditional verification of
all COSMO countries:
first results
COSMO General Meeting, September 2012, Lugano
by the members of WG Verification
Objectives of conditional verification
 Contribute to COSMO model development
 Improve the understanding of forecast errors
 Identify possible sources of errors in COSMO
Conditional Verification | COSMO-GM 2012, Lugano
Vanessa Stauch, vanessa.stauch@meteoswiss.ch
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Feedback loop within COSMO
COSMO
operational application
and development
Physical aspects
(atmosphere and soil)
Data assimilation
Predictability and EPS
Conditional Verification | COSMO-GM 2012, Lugano
Vanessa Stauch, vanessa.stauch@meteoswiss.ch
Conditional verification
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Common conditional verification results
• overcast
Cloud cover
clearly stratifies the COSMO
T2M for
conditions
T2M for clear sky conditions
forecast error of T2M (no matter which
diagnostic)
• Under observed clear sky conditions, the mean
error has a pronounced daily cycle:
All models underestimate daytime T2M and
overestimate nighttime T2M
• Under observed overcast conditions, this
behaviour is not observed
Autumn
Spring 2012,
2011, ME and RMSE for many COSMO models
Conditional Verification | COSMO-GM 2012, Lugano
Vanessa Stauch, vanessa.stauch@meteoswiss.ch
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Searching for clues…
• Additional stratification to look at cases with stable
boundary layer → distinguish between dynamical and
radiation dominated processes
Conditional Verification | COSMO-GM 2012, Lugano
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COSMO-ME Conditional Verification
T2m when observed TCC ≤ 25%
COSMO-ME Conditional Verification
T2m when observed TCC ≤ 25% & wind speed ≤ 2 m/s
COSMO-7 Conditional Verification
T2m when forecast TCC ≤ 25%
COSMO-7 Conditional Verification
T2m when forecast TCC ≤ 25% & wind speed ≤ 2.5 m/s
Searching for clues…
• Additional stratification to look at cases with stable
boundary layer → distinguish between dynamical and
radiation dominated processes
→ in calm wind conditions, the underestimation of
the daily temperature amplitude is even more
pronounced
Conditional Verification | COSMO-GM 2012, Lugano
Vanessa Stauch, vanessa.stauch@meteoswiss.ch
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Nighttime overestimation
Conditional Verification | COSMO-GM 2012, Lugano
Vanessa Stauch, vanessa.stauch@meteoswiss.ch
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Stations on the Swiss plateau
T2M for clear sky
conditions at stations
with gph <800m
Conditional Verification | COSMO-GM 2012, Lugano
Vanessa Stauch, vanessa.stauch@meteoswiss.ch
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Searching for clues…
• Additional stratification to look at cases with stable
boundary layer → distinguish between dynamical and
radiation dominated processes
→ in calm wind conditions, the underestimation of
the daily temperature amplitude is even more
pronounced → overestimated thermal mixing?
Nighttime overestimation from insufficient
radiative cooling?
Daytime underestimation from underestimated
sensible heat flux? Wrong soil moisture?
Conditional Verification | COSMO-GM 2012, Lugano
Vanessa Stauch, vanessa.stauch@meteoswiss.ch
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Td, 2mT with dry or wet soil conditions
Fall
Winter
Spring
W_SO Water content of first soil layer(kg/m2) 1cm.
Td: Higher error in dry soil and larger underestimation
2mT: Higher error in wet soil and larger understimation
Fall
Winter
WG5 COSMO General Meeting, Lugano 2012
Spring
T2M with fcst soil moisture condition
ME, RMSE dry conditions
ME, RMSE wet conditions
ME, RMSE no conditions
Similar systematic error properties
as for cloud cover conditions, but
phase slightly shifted and different
data sample → new box opened…
Conditional Verification | COSMO-GM 2012, Lugano
Vanessa Stauch, vanessa.stauch@meteoswiss.ch
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Conclusions
 Conditional verification provides us with tools for analysing
complex COSMO model errors
 Use of intensive measurement sites will further help the
analyses (e.g. for clear sky temperature error,
measurements for sensible and latent fluxes, for
temperature and dewpoint error, measurements for soil
moisture)
 Suitable stratifications for precipitation still need to be
identified (e.g. appropriate time integrations for CAPE, so
far no success with weather classes)
 Tight interaction with WG3 and others
Conditional Verification | COSMO-GM 2012, Lugano
Vanessa Stauch, vanessa.stauch@meteoswiss.ch
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For parallel session
ADDITIONAL DISCUSSION
POINTS
Conditional Verification | COSMO-GM 2012, Lugano
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List of conditional verifications I
 2m temperature
•
Comparison between observation based cloud cover conditions and
forecast based cloud cover conditions
•
2 conditions: cloud cover and total cloud water column
•
2 conditions: cloud cover and wind speed
•
Condition on soil type: 1:ice, 2:rock, 3:sand, 4:loam (incl. sandy &
clay), 5:clay » bug on sample size reported
•
Condition on soil temperature: T_SO>=0°C, T_SO<0°C
•
Condition on soil water content: dry: W_SO<1m, wet: W_SO>3.5m
•
Condition on snow cover: W_SNOW>0mm, W_SNOW=0mm
•
Condition on grid point height: gph>800m, gph<=800m
•
Condition on GWTWS: annual
Conditional Verification | COSMO-GM 2012, Lugano
Vanessa Stauch, vanessa.stauch@meteoswiss.ch
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List of conditional verifications II
 10m wind speed
• Condition on Z0: Z0 < 20cm, Z0 > 1
• Condition on grid point height: gph>800m, gph<=800m
• Condition on GWTWS: annual
 Precipitation (6h)
•
Condition on CAPE: comparison between CAPE_con or
CAPE_mu
•
Condition on GWTWS: annual
 Dewpoint
•
Condition on soil moisture: dry: W_SO<1m, wet: W_SO>3.5m
Conditional Verification | COSMO-GM 2012, Lugano
Vanessa Stauch, vanessa.stauch@meteoswiss.ch
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CV precipitation
Ideas for distinction between convective (local) and large scale
(synoptic) precip:
 CAPE, convective time scale after Keil (= CAPE/Precip)
 Appropriate time period to associate with precip?
 Pressure drop?
Conditional Verification | COSMO-GM 2012, Lugano
Vanessa Stauch, vanessa.stauch@meteoswiss.ch
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Temperature and dewpoint
Ideas about soil moisture errors?
Weather type dependent verification: any success?
Conditional Verification | COSMO-GM 2012, Lugano
Vanessa Stauch, vanessa.stauch@meteoswiss.ch
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Weather type dependent verification
any success? New insights?
Conditional Verification | COSMO-GM 2012, Lugano
Vanessa Stauch, vanessa.stauch@meteoswiss.ch
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PREC06 with weather classes: FBI0.2
Conditional Verification | COSMO-GM 2012, Lugano
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PREC06 with weather classes: ETS0.2
Conditional Verification | COSMO-GM 2012, Lugano
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FF10M with grid point height
ME, RMSE all stations
ME, RMSE gp height > 800m
ME, RMSE gp height < 800m
Conditional Verification | COSMO-GM 2012, Lugano
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FF10M scatter plot
Winter 2012
Conditional Verification | COSMO-GM 2012, Lugano
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