Surface-Based Instrument Intercomparisons and Calibration Methods Activity Report Draft recommendations

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Commission for Instruments and Methods of
ObservationFourteenth SessionGeneva, 7 14
December 2006

• Surface-Based Instrument Intercomparisons and
  Calibration MethodsActivity Report Draft
  recommendations
• Michel Leroy Chair of the ET-SBIICM

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Organization and Preparation of surface-based
intercomparisons

• Terms of reference
• Laboratory intercomparison of rainfall intensity
  (RI) measuring instruments.
• Combined intercomparison of thermometer
  screens/shields, in conjunction with humidity
  measurements, in various climatic regions

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Laboratory intercomparison of RI instruments

• Following recommendations of an expert meeting in
  Bratislava (2001) and CIMO XIII, first step
  before a field intercomparison.
• International Organizing Committee established.
• Three laboratories
• DIAM, University of Genoa, Italy De Bilt, KNMI,
  the Netherlands Trappes, Météo-France.
• 4 meetings for the laboratory intercomparison
• Trappes (2003), Genoa (2005), De Bilt (2005),
  Geneva (2005)

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Laboratory Intercomparison

• Project Manager Prof. Luca Lanza.
• 15-Sept-2004 ? 15-Sept-2005
• Catching type instruments.
• 19 (pairs) of instruments, divided in 3 groups.
• Shift of instruments between laboratories.
• Final Report available from the CIMO/IMOP Website
  since January 2006.

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Outcomes of laboratory intercomparison

• Each laboratory used its own testing device,
  based on constant flow and weighing.
• Proposal of a standardized procedure for
  laboratory calibration of catchment type rainfall
  intensity gauges. Draft Rec. 4.2/1
• To be included in CIMO guide.
• Some tipping-bucket rain gauges with proper
  correction software and some weighing gauges
  satisfy the WMO RI requirement over limited RI
  ranges (5 2 2000 mm/h)

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WMO Field Intercomparison of Rainfall Intensity
Instruments

• The laboratory Intercomparison was a first step,
  easier to handle than a field test.
• Not all instrument types available on the market
  were tested in laboratory.
• Looking for a possible site, Vigna di Valle,
  Italy (Italian Meteorological Service, ReSMA) was
  selected.
• August 2007 ? August 2008

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Field Intercomparison

• Call for instruments (March 2006)
• 24 instruments of different measuring principles
  were selected (54 proposed !).
• Reference based on a set of high quality devices,
  inserted in a pit gauge.
• Draft Rec. 4.2/2 Procedure and reference
  instruments for field rainfall intensity
  intercomparisons

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WMO Combined Intercomparison of Thermometer
Screens/Shields, in conjunction with Humidity
Measuring Instruments

• Looking for a possible site in harsh conditions,
  Ghardaïa, Algeria was selected.
• Desert region
• Jan. 2007 ? Jan. 2008
• Instruments calibration before and after

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Screens Hygrometers Intercomparison

• Call for instruments (March 2006)
• 16 screens/shields types (29 proposed) and 11
  hygrometers types(17 proposed) were selected.
• Reference Thygan
• Data analysis
• International Organizing Committee
• ISO standard 17714 (draft)

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Intercomparisons

• Heavy load for the organizing country
• Heavy load for the ET and IOC members
• That explains the possible time delays in
  organizing an Intercomparison.
• Successful participation of HMEI, in proposing
  instruments to be tested (directly or in
  conjunction with a WMO member).
• Any help for intercomparisons ?

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Future Intercomparisons

• Field RI Vigna di Valle, Italy 2007-2008
• Screens/humidity Ghardaïa, Algeria 2007-2008
• Intercomparisons in harsh climate conditions
  artic, desert, tropical, marine, urban ?
• Intercomparison of Present Weather Sensors ?