Anthony Illingworth, Robin Hogan , Ewan O

1
CloudNET evaluating the clouds in seven
operational forecast models

• Anthony Illingworth, Robin Hogan , Ewan OConnor,
  U of Reading, UK
• Nicolas Gaussiat Damian Wilson, Malcolm Brooks
  Met Office, UK
• Dominique Bouniol, Alain Protat Martial
  Haeffelin, CETP, France
• David Donovan, Gerd-Jan Zadelhoff, Henk
  Klein-Baltink KNMI, NL
• Adrian Tomkins, ECMWF, Charles Wrench, RAL
• Herman Russchenberg, Oleg Krasnov TUD, NL
• Jean-M Piriou Meteo France
• Pekka Ravilla, Vaisala, Finland. et al.

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The EU CloudNet project Since April
2001www.met.rdg.ac.uk/radar/cloudnet
www.cloud-net.org

• Aim to retrieve continuously the crucial cloud
  parameters for climate and forecast models
• Three sites Chilbolton (UK) Cabauw (NL) and
  Palaiseau (F)
• recently Lindenberg (D) and ARM sites (USA
  Pacific)
• To evaluate a number of operational models
• Met Office (mesoscale and global versions)
• ECMWF - Météo-France (Arpege)
• KNMI (Racmo and Hirlam)
• recently DWD Lokal Model and SMHI RCA model
• Crucial aspects
• Report retrieval errors and data quality flags
• Use common formats based around NetCDF allow all
  algorithms to be applied at all sites and
  compared to all models
• COULD USE THE APPROACH FOR CLOUDSAT/CALIPSO
  GLOBAL DATA

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The three original CloudNET sites
Cabauw, The Netherlands 1.2-GHz wind profiler
RASS (KNMI) 3.3-GHz FM-CW radar TARA (TUD) 35-GHz
cloud radar (KNMI) 1064/532-nm lidar (RIVM) 905
nm lidar ceilometer (KNMI) 22-channel MICCY
radiometer (Bonn) IR radiometer (KNMI)
SIRTA, Palaiseau (Paris), France 5-GHz Doppler
Radar (Ronsard) 94-GHz Doppler Radar
(Rasta) 1064/532 nm polarimetric lidar 10.6 µm
Scanning Doppler Lidar 24/37-GHz radiometer
(DRAKKAR) 23.8/31.7-GHz radiometer (RESCOM)
Chilbolton, UK 3-GHz Doppler/polarisation radar
(CAMRa) 94-GHz Doppler cloud radar
(Galileo) 35-GHz Doppler cloud radar
(Copernicus) 905-nm lidar ceilometer 355-nm UV
lidar 22.2/28.8 GHz dual frequency radiometer

• Core instrumentation at each site
• Radar, lidar, microwave radiometers, raingauge

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Cloud Parameterisation

• Operational models currently in each grid box
• typically two prognostic cloud variables
• Prognostic liquid water/vapour content
• Prognostic ice water content (IWC) OR diagnose
  from T
• Prognostic cloud fraction OR diagnosed from
  total water PDF
• Particle size is prescribed
• Cloud droplets - different for marine/continental
• Ice particles size decreases with temperature
• Terminal velocity is a function of ice water
  content
• Sub-grid scale effects
• Overlap is assumed to be maximum-random
• What about cloud inhomogeneity?
• How can we evaluate hence improve model clouds?

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Standard CloudNET observations (e.g. Chilbolton)

• Radar Lidar, gauge, radiometers

But can the average user make sense of these
measurements?
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Target categorization

• Combining radar, lidar and model allows the type
  of cloud (or other target) to be identified
• From this can calculate cloud fraction in each
  model gridbox

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Cloud fraction
Observations OCTOBER 2003 Met Office Mesoscale
Model ECMWF Global Model Meteo-France ARPEGE Mo
del KNMI Regional Atmospheric Climate Model
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What happened to the MeteoFrance Arpege model on
18 April 2003?
Modification of cloud scheme cloud fraction and
water content now diagnosed from total water
content.
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Evaluation of Meteo-France Arpege total cloud
cover using conventional synoptic observations.
? More rms Error

• Worse
• Bias
• ?

2000 2005 2000 2005
Changes to cloud scheme in 2003-2005 seem to have
made performance worse!
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CloudNET monthly profiles of mean cloud
fraction and pdf of values of cloud fraction v
model Jan 2003 Jan 2005
Objective CloudNET analysis shows a remarkable
improvement in model clouds.
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Equitable threat scores for cloud fraction

• Scores for cloud fraction gt 0.05 over Cabauw for
  seven models together with persistence and
  climatology.

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Skill versus forecast lead time

• Met Office best over
• Chilbolton
• DWD best over Lindenberg.

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ARM SITES NOW BEING PROCESSED VIA CLOUDNET
SYSTEMMANUS ARM SITE IN W PACIFIC. CLOUD
FRACTION
CEILOMETER ONLY HIGH CIRRUS IS OBSERVED BY MPL
LIDAR NOT YET CORRECT IN CLOUDNET
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TROPICAL CONVECTION MANUS ARM SITE IN W PACIFIC.
CLOUD FRACTION
OBSERVED HIGH CIRRUS NOT YET CORRECT IN
CLOUDNET
ECMWF MODEL - MODEL CONVECTION SCHEME
CONTINUALLY TRIGGERING - GIVES V LOW CLOUD
FRACTION IN TOO MANY BOXES.
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TODAYS TIMETABLE

• CLOUD OBSERVING STATIONS.
• RETRIEVAL ALGORITHMS
• Lunch
• COMPARISON WITH THE OPERATIONAL MODELS.
• MODELLERS PERSPECTIVE AND GENERAL DISCUSSION.
• SPECIFICATION FOR A CLOUD
• OBSERVING STATION.