W O R L D M E T E O R O L O G I C A L O R G A N I Z A T I O N

COMMISSION FOR INSTRUMENTS AND METHODS OF OBSERVATION

JOINT

CIMO EXPERT TEAM ON
SURFACE-BASED INSTRUMENT INTERCOMPARISONS
AND CALIBRATION METHODS
Fifth (reduced) Session

AND

INTERNATIONAL ORGANIZING COMMITTEE ON
SURFACE-BASED INSTRUMENT INTERCOMPARISONS

Fifth (reduced) Session

Vigna di Valle, Italy

17 September – 21 September 2007

FINAL REPORT

CONTENTS

Pages
Agenda / Ii
Executive summary / Iii
General summary of the workof the meeting / p.1- p.4
Annexes:
List of participants / ANNEX I
Report of the Site Manager / ANNEX II
Positionsofparticipating instruments and ancillary sensors / ANNEX III
Data analysis and Quality assurance / Quality Control / ANNEX IV

CIMO/OPAG-SURFACE/ET-SBII&CM-4/IOC-4/p. 1

AGENDA

1ORGANIZATION OF THE MEETING

1.1Openingof themeeting

1.2Adoption of the agenda

1.3Working arrangements for the meeting

2REPORT OF THE CHAIRMAN

3 FIELD INTERCOMPARISON OF RAINFALL INTENSITY (RI) GAUGES,
VIGNA DI VALLE, ITALY

3.1Report of theField Site Manager on the site final preparation

3.2Report of the Laboratory Site Manager

3.3Data Processing, analysis methodology and QC of data

3.4Visit to the Intercomparison site and evaluation of site preparation

3.5Evaluation test for data acquisition system

3.6Expert team data exchange; daily supervision of Intercomparison field

4WORK PLAN

5DRAFT REPORT OF THE MEETING

6CLOSUREOFTHE MEETING

CIMO/OPAG-SURFACE/ET-SBII&CM-4/IOC-4/p. 1

EXECUTIVE SUMMARY

This report provides a summary of the fifth (reduced) session of the Joint Expert Team on Surface-Based Instrument Intercomparisons and Calibration Methods (ET) and International Organizing Committee on Surface-Based Instrument Intercomparisons (IOC). The session was organized as an on-site final inspection meeting prior to the official start of the WMO Intercomparison of Rainfall Intensity Gauges that will be performed in Vigna di Valle (Italy) from October 2007 for about 12 months.

The ET/IOC inspected and fully approved the intercomparison site, the data acquisition and data archiving. The ET/IOC also agreed on data processing procedures and discussed the analysis methodology proposed by Data Analysis Expert. Data QC procedures were finalized.

The Data Analysis Expert has to resign her task due to other preoccupations. The ET has to search for a new expert.

The WMO Intercomparison of Rainfall Intensity Gauges in Vigna di Valle (Italy) will officially start on 1. October 2007.

CIMO/OPAG-SURFACE/ET-SBII&CM-5/IOC-5/General Summary, p. 1

GENERAL SUMMARY

  1. ORGANIZATION OF THE MEETING
  2. Opening of the meeting
  3. The fifth (reduced) session of the Joint Meeting of the Expert Team on Surface-Based Instrument Intercomparisons and Calibration Methods (ET) and the International Organizing Committee on Surface-Based Instrument Intercomparisons (IOC) was held in the Italian Meteorological Service Centre of Meteorological Experimentation (ReSMA), Vigna di Valle, Italy, from 17 September to 21 September 2007. Mr Michel Leroy, the Chairman of the ET, opened the session. Col. Daddario, Director of ReSMA, welcomed the participants. Col. Pagano, representing the Permanent Representative of Italy with WMO, officially welcomed the participants on the second day of the meeting. The list of participants is given in Annex I.
  4. Adoption of the agenda
  5. The ET/IOC adopted the Agenda for the meeting, which is reproduced at the beginning of this report.
  6. Working arrangements for the meeting
  7. The working hours and tentative timetable for the meeting were agreed upon. It was agreed that the ET/IOC meeting would be chaired by Mr Leroy, chair of ET-SBII&CM.
  8. REPORT OF THE CHAIRMAN
  9. Mr Leroy gave a short report of the ET’s activities related to the WMO Temperature and Humidity Screen Intercomparison in Ghardaia, Algeria. Many difficulties arose with customs procedures, leading to a delay for the start of the intercomparison. During last summer, some technical contacts were kept between ONM (Office National de la Météorologie) of Algeria and Météo-France, but no news and no answers to questions about the status of preparation were received since August.
  10. FIELD INTERCOMPARISON OF RAINFALL INTENSITY (RI) INSTRUMENTS, VIGNA DI VALLE, ITALY
  11. Report of the Field Site Manager on the site final preparation
  12. Mr Vuerich, the Site Manager of the Field Intercomparison (SM-FI) gave a summary of the most important steps during the preparation phase of the field intercomparison (see ANNEX II). He stressed that documents that were created to inform participants about shipment and custom procedures as well as a list of answers to frequently asked questions have proven to be very successful. All documents have been additionally published on the CIMO website for download. An invitation to manufacturers to assist the installation turned out to be very effective and helpful. The SM-FI suggested the ET to adopt these procedures for future WMO intercomparisons.
  13. The SM-FI listed up logistic activities that had been necessary, such as transportation and mutual visits of experts in Genoa and Vigna di Valle. Many problems could also be addressed during telephone conferences and were consequently solved.
  14. Due to the variety of interfaces and data telegrams of the rain gauges the time for implementation into the data acquisition systems took longer than expected. Although described in detail in questionnaires and informative letters some interfaces did not correspond to ET’s requirements. In all cases solutions could be found.
  15. The SM-FI informed on the status of the preparation and installation of instrumentation on the intercomparison field. According to the agreed plan an evaluation phase has been performed from August to September, when first instruments had been implemented into the data acquisition system and further ones were gradually added.
  16. The SM-FI stated that all instruments and ancillary sensors are installed except for the instrument from Ukraine (position 19) which is still missing without further notice of the participant or manufacturer (see. Annex III). WMO Secretariat will be asked by the PL to inform the participant officially that the deadline for participation will pass by the end of September.
  17. As agreed by ET telephone conference (20.07.07) Position 20 (Vaisala PWD22) had to be exchanged with position 12 (ARG1000, Env. Meas.) due to the fact that company Vaisala required that the instrument has to be mounted at 2m height instead of the standard 1 m height chosen for this intercomparison field. Finally, a compromise was found with Vaisala for a 1.8 m height (see Annex III).
  18. SM-FI explained details of electrical installations on the intercomparison field, ancillary sensors and the implemented 4-fold pit containing the reference rain gauges.
  19. All available documentation on instruments such as manuals, transfer functions and simple data telegrams are provided for the ET on a preliminary ftp server. WMO will be asked by PL to provide space and restricted access on their ftp server. If available all files will be shifted there. SM-FI will check again if all documentation especially for the rain gauges used in the pit is complete and available in paper and/or in electronic form.
  20. The programming of the Data Acquisition (DAQ) system has been finalized and tested during the meeting. All transfer functions provided by manufacturers are programmed into the data logger. Therefore RI values in [mm/h] are already recorded in this stage.
  21. The data are stored in the data loggers memory and additionally in extra memory cards inserted in the logger. In combination with several UPS’s this will assure an uninterrupted operation of the DAQ system.
  22. The raw data of rain gauges and ancillary sensors are generally recorded every 10s. These data are used for optimal time synchronization during data reduction. The DAQ system additionally produces 1-minute data in real time containing additional diagnostic data which are useful for QC procedures.
  23. A set of ancillary data, requested during the last meeting, and derived values such as means, standard deviations etc. are provided by the system. Furthermore all data output by the rain gauges is recorded, with the exception of THIES Laser Precipitation Monitor where particle and velocity spectra are discarded to simplify the data acquisition process. This has been agreed by company THIES (e-mail to PL).
  24. SM-FI stated that all necessary maintenance of instruments will be done according to operating instructions given by participants. Instruments will be checked daily and nominated contact persons representing the participant will be called immediately in case of faults that cannot be corrected by routine maintenance. Routine calibration checks will be performed according to participant’s specific instructions. All catchment type rain gauges will be checked every 3 months by means of a field calibrator to be provided by SM-LI.
  25. All maintenance actions, observations and occurrences that do or presumably could affect the functionality of the instruments will be noted in a dedicated Intercomparison Logbook (notes on paper) by local staff.
  26. In addition to the paper logbook all of the above information that does or did affect the functionality of an instrument will be copied to an electronic logbook (e-log) in a fixed (machine readable) format. The e-log will contain information on start time, end-time, instrument ID and a fixed keyword describing the incident (examples: calibration, emptying, disconnected, manual interaction). The final set of keywords will be defined by SM-FI. This e-log will be taken into account automatically during the QC of data.
  27. The SM-FI’s proposal to invite all participants to an on-site meeting in early spring 2008 was welcomed by the ET. It was agreed that the invitation should be officially addressed by WMO. On this occasion, information on the data availability and practical experience with instruments could be given to participants. It would also allow participants to check the state of their instruments and confirm that they are properly operated.
    The formerly agreed data policy has to be respected, i.e. no data will be given to participants before the end of the intercomparison. During this visit instruments must not be changed because no changes to instruments are allowed during the whole intercomparison in order to provide homogeneous data.
  28. SM-FI underlined that the period of the intercomparison could easily be extended to 24 months if necessary. All related questions (customs, etc…) have already been solved.
  29. Report of the Laboratory Site Manager
  30. Mr Lanza informed on first results of the Laboratory phase performed at DICAT laboratory of University of Genoa, Italy. All laboratory tests are finished for the first instruments and the spare instruments are currently tested. He stressed that one aim of the laboratory phase is to help to distinguish between weather related effects and instrumental effects in the evaluation of the field intercomparison data.
  31. Mr. Lanza stated that the calibration is performed in stationary conditions and values are derived from long-term means. For lower intensities applied during the laboratory calibration the standard deviation can exceed WMO limits while the mean is within these limits.
  32. SM-LI apologised that due to temporal reduction in staff the report could not be provided on this meeting. A preliminary report of calibrations of the first batch of instruments will be provided by SM-LI as soon as possible. Calibration of the second batch of instruments (spares) will therefore be delayed. In case of urgent need to replace an instrument by a spare, the SM-LI assured that calibration of the respective instrument will be performed immediately.
  33. Data Processing, analysis methodology and QC of data
  34. The ET set up a scheme for time synchronization and the generation of 1-min data. Details are given in Annex IV.
  35. Transfer functions for all instruments were deployed and are applied in the data logger (see 3.1.9). PL has to clarify a comment on the transfer function given by company Lambrecht.
  36. It has been decided to evaluate the step response not only for weighing rain gauges but also for tipping bucket rain gauges. Special consideration has to be given to those rain gauges that are used as reference. All of them apply internal algorithms that are not made public. In order to be used as a reference the response of these instruments to applied RI has to be well known.
  37. Laboratory data was evaluated with averaging time intervals of 1, 5, 10 and 15 minutes. The differences in the resulting standard deviations were minor for averaging times of 10 and 15 minutes. Decision was taken that only 1 minute and 10 minute averaging times should be used for evaluation and display in graphs.
  38. Rain events containing hail will be evaluated but special note will be taken for the interpretation of the results. Pure solid precipitation will not be evaluated.
  39. Visit to the Intercomparison site and evaluation of site preparation
  40. The ET stated that the Intercomparison site has been prepared perfectly and in accordance with the proposals and decisions described in section 3.2 of the protocol of the 3rd ET meeting.
  41. Evaluation test for data acquisition system
  42. The SM-FI demonstrated the full functionality of the data acquisition system. Raw data of all rain gauges and ancillary data are stored with a time resolution of 10s and 1min. The system provides fail safe operation due to several UPS systems and local backup storage on memory cards within the datalogger next to the field. Data is transferred to a PC that is equipped with 2 external USB harddisk for a full backup of the raw data files.
  43. During the time of the meeting, the SM-LI generated a constant flow with a field calibrator, for each catching type instrument, in order to check the installed instrument and the software of the datalogger, for each of these instruments. Few minors software problems were solved during this test, which proved the functionality of the DAQ.
  44. Expert team data exchange; daily supervision of Intercomparison field
  45. The SM-FI has implemented an ftp server that can be accessed by all members of the ET for download of sequential 1 min data files grouped and named as daily files. The previously committed plan to install a RDB could not be realized. The data analysis expert indicated that an RDB was not necessary for her evaluations. The PL will investigate if there is a further need for the implementation of such an RDB and if it could be developed and installed at another place.
  1. WORK PLAN
  2. The official start of the Field Intercomparison of Rainfall Intensity Gauges will be on 1.10.2007.
  3. SM-FI organizes an on-site meeting for all participants in early spring 2008. The invitation should be officially addressed by WMO.
  4. SM-LI will draft as soon as possible a report of the calibration phase for the first set of instruments that are now installed in the field.
  5. SM-LI will consequently continue calibration of the remaining spare instruments to be provided to SM-FI.
  6. SM-LI will provide SM-FI with an appropriate device for field calibration of all catchment type rain gauges by the end of 2007.
  7. DRAFT REPORT OF THE SESSION
  8. The PL drafts a report of the meeting. Final report will be disseminated for further comment, if any, within 2 weeks time.
  9. CLOSURE OF THE SESSION
  10. The session was closed on 21 September 2007 at 12.15 h.

CIMO/OPAG-SURFACE/ET-SBII&CM-5/IOC-5/General Summary, p. 1

ANNEX I

List of participants

Dr Eckhard LANZINGER
Project Leader / Deutscher Wetterdienst
Frahmredder 95
22393 Hamburg
Germany
Tel.: +49 40 6690 2455
Fax: +49 40 6690 2499
E-mail:
Michel LEROY
chairman ET/IOC-SBII / Météo-France
DSO/DOS
BP 202
78195 Trappes CEDEX
France
Tel.: +33 1 3013 6405
Fax.: +33 1 3013 6020
E-mail:
Prof. Luca LANZA / DICAT – Department of Construction, Environmental and Architectural Engineering
University of Genova
Via Montallegro, 1 16145 Genova
Italy
Tel.: +39 010 353 2123
Fax: +39 010 353 2481
E-mail:
Dr Luigi STAGI
Site Manager for the Laboratory Intercomparison / DICAT – Department of Construction, Environmental and Architectural Engineering
University of Genova
Via Montallegro, 1 16145 Genova
Italy
Tel.: +39 010 353 2482
Fax: +39 010 353 2481
E-mail:
Dr Emanuele VUERICH
Site Manager for the Field Intercomparison / Italian Air Force Met Service - Experimentation Centre of Met Instrumentation
Via Braccianese km18
00062 Vigna di Valle, Bracciano
Rome
Italy
Tel.: +3906 99801013
Tel.: +3906 9988 7701
Fax: +3906 9987 297
E-mail:
Dr Fabio MALASPINA
Site Manager for the Field Intercomparison responsible for QA/QC / Italian Air Force Met Service - Experimentation Centre of Met Instrumentation
Via Braccianese km18
00062 Vigna di Valle, Bracciano
Rome
Italy
Tel.: +3906 99801013
Tel.: +3906 9988 7701
Fax: +3906 9987 297
E-mail:
Dr Annalisa MOLINI
Invited expert / DICAT – Department of Construction, Environmental and Architectural Engineering
University of Genova
Via Montallegro, 1 16145 Genova
Italy
Tel.: +39 010 353 2485
Fax: +39 010 353 2481
E-mail:
Dr Paolo PAGANO / Italian Meteorological Service
Aeroporto F. Baracca – Centocelle
Via di Centocelle 301
I-00175 Rome
Italy
Tel.: +390624002470
Fax: +390624401359
E-mail:
WMO Secretariat
7 bis, avenue de la Paix
CH-1211 Geneva 2
Switzerland / WWW website

CIMO/OPAG-SURFACE/ET-SBII&CM-5/IOC-5/General Summary, p. 1

ANNEX II

REPORT OF THE SITE MANAGER RESPONSIBLE FOR THE FIELD INTERCOMPARISON

See two presentations combined in file “FI-RI_Intercomparison site presentation.pdf”.

ANNEX III

POSITIONS OF PARTICIPATING INSTRUMENTS AND ANCILLARY SENSORS

See file “INSTRUMENTS POSITIONS_sept2007.ppt”

ANNEX IV

DATA ANALYSIS AND QUALITY ASSURANCE/QUALITY CONTROL

See attached report in file“WMO_DM_REPORT_2_SEPTEMBER2007_LOWRES.pdf”