MeteoSwiss acceptance procedure for automatic weather stations (AWSCheck)

1. MeteoSwiss acceptance procedure for automatic weather stations (AWSCheck) J. Fisler, M. Kube, E. Grüter and B. Calpini

2. Overview • Introduction • Goals • Motivation • Methods • Results • Summary • Outlook

3. Introduction • Siting classifications change over time (usually to the worse) • Quality of data can decrease over time • More factors than siting classification influence data quality: • High quality instruments • Regular calibration of instruments • Proper maintenance • Periodic monitoring of weather stations and factors influencing data quality is crucial! 1997 1973 1985 1976

4. Goal MeteoSwiss wants to develop a procedure that is able to determine the quality of measurement data based on an assessment of the corresponding automatic weather station. The result should be simple and easy to understand (e.g. good, acceptable, bad).

5. Motivation • MeteoSwiss includes data of partner stations (both public and private sector): Is their data reliable? • Create a quality label for MeteoSwiss’ own stations • Higher credibility of extreme values • Increase awareness for measurement data quality • Responsibility as national weather service to follow WMO recommendations (CIMO guide) • Collect metadata about weather stations

6. Methods Operator = Meteorological service, e.g. MeteoSwiss or private company Auditor = Neutral third-party organization conducting assessment Cycle repeated every 5 years!

7. Step 1: Pre-Analysis • When? Some weeks or months before audit on site • Who? Auditor • What? Based on documents provided by operator: • Does AWS meet requirements to be certified? • What instruments are installed? • How is maintenance done? • History documentation? • …

8. Step 2: Audit on site • When? One day visit every five years • Who? Auditor and operator together • What? For each instrument auditor and operator fill out questionnaire at the location of the AWS. As a result, AWSCheck gives a first assessment for the installed instruments using the categories green, yellow and red

9. Step 2: Audit on site - Questionnaire

10. Step 3: Post-Analysis • When? After one year (then: yearly reports) • Who? Operator • What? Statistics on performance of instrument: • Measurement and transmission interval 10min? • Downtime of an instrument below 3 days? • Data availability above 96%? • Data delivery time? • …

11. Methods: The challenge of mountainous terrain in Switzerland In mountainous terrain it is not possible to strictly follow CIMO recommendations: • Measurement height: Due to high snow level instruments are installed above 2m. To respect this AWSCheckallows measurement heights of up to 3m for mountain stations. • Topography: The Leroy siting classification defines a flat terrain without any obstacles. In mountain regions or in steep valleys some of the Leroy criteria cannot be met. Therefore AWSCheck allows higher Leroy classes at sites considered as “special topography”. • More adaptations for Switzerland are listed in the paper! • It’s a Swiss procedure adaptable for other countries!

12. Results of acceptance procedure Each instrument is rated using the following categories: Fully compliant All WMO/CIMO requirements fulfilled Climatology Meteorology Warnings Compliant Most requirements fulfilled Climatology Meteorology Warnings Not compliant Some important WMO requirements not fulfilled! Be aware of the limitations and use data with caution. Climatology Meteorology Warnings

13. Results: Site classification examples Compliant Not Compliant Fully Compliant Not Compliant

14. Summary • Procedure to determine measurement data quality based on an assessment of weather station. • Three steps: pre-analysis, audit on site, post-analysis. • Labels instruments as fully compliant, compliant and not compliant. • Applied every five years to ensure that label is still valid. • Audits carried out by a neutral third party organization

15. Outlook • Implementation of step 3 (post-analysis) into the MeteoSwiss data warehouse. • Assessment by METAS (national agency of the International Bureau of Weights and Measures) of 40 MeteoSwiss and partner stations in 2013 • Based on the results of the assessments AWSCheck will be further optimized • Development of App for smartphones and tablets

16. References (excerpt) • DWD (2001). Richtlinien für automatische Klimastationen. Offenbach, Deutscher Wetterdienst. • Kube, Marlen, Stocker, Catherine (2012). Qualitätssicherung von Messstationen. Fachkonzept SMN3, Version 0.6. • WMO (2010a). WMO Guide to Meteorological Instruments and Methods of Observation. Geneva, World Meteorological Organization. WMO-No. 8 (2008 edition, Updated in 2010). • WMO (2010b). Commission for Instruments and Methods of Observation – Report of the Fifteenth session. Helsinki 2-8 September 2010. WMO-No. 1064. • Furthermoremanyscientists, climatologists, meteorologists, hydrologists, databaseexperts, techniciansandmaintenancestaffmembershavebeenconsulted.

17. Contact Federal Office of Meteorology and Climatology MeteoSwiss Joël Fisler Krähbühlstrasse 58 CH-8044 Zürich Tel. +41 44 256 94 33, Mobile +41 79 875 32 37 joel.fisler@meteoswiss.ch http://www.meteoswiss.admin.ch

18. Questions