World Meteorological Organization Working together in weather, climate and water

WMO SPICE Solid Precipitation Intercomparison Experiment

- Overall results and recommendations

WMO: OBS www.wmo.int

WMO

CIMO-XVII Amsterdam, The Netherlands October 12-16 2018

Yves-Alain Roulet MeteoSwiss

SPICE Final Report Coordinator

Summary

• Project Mission and Deliverables

• Organization and participation

• (Some) Results

• (Some) Recommendations and Future work

SPICE Mission

• To provide guidance on the performance and use of modern automated systems measuring: total precipitation amount, especially when the precipitation

is solid snow depth and snowfall

Formigal, SPAIN

Participating Organizations

Instrument Providers

• Adolf Thies GmbH & Co KG • Belfort Instrument Company • Campbell Scientific Inc, Canada • Campbell Scientific Ltd. UK • CAE S.p.A. • Environmental Measurements LTD • Felix Technologies Inc. • Geonor AS • Hydrological Services America • MPS System • METEOSERVIS v.o.s. • NIMH – Bulgaria: Sutron • OTT Hydromet GmbH • Sommer GmbH& Co KG • Vaisala Oyj • Yankee Environmental Systems, Inc. • ZAMG (Austria)

Cover all major technologies: Precipitation Instruments:

Weighing Gauges; Tipping Bucket Gauges (heated); Non Catchment Type

Instruments (laser, optical, heat transfer)

Ultrasound and Laser snow

depth instruments

Snow Water Equivalent Instruments (gamma radiation, load cell)

WMO

Characterization of the performance

• Individual Instrument Performance Reports (IPRs): – Annexes to the Final Report – Developed by instrument model – No ranking!

• Strategy: – Multiple sites, multiple configurations – Use consistent reference system configurations on all sites

• Focus: – Ability to detect and measure precipitation (precipitating and non-

precipitating events) – Sustainability of performance throughout the assessment period

What is the issue?

Wind-induced precipitation undercatch

CE for weighing gauges

Tmax ≤ -2 °C

CE for tipping bucket

Tmax ≤ -2 °C

Transfer functions

CE for non-catchment type instruments

Tmax ≤ -2 °C

Manual and automatic snow on the ground measurements

Time series of the daily manual snow stake measurements and 1-minute SR50A measurements at CARE for 2013/14. The stake measurements are at the corners of the target with the SR50A measuring the snow in the middle of the target.

…and a lot more

Capping Heating

Noise

Target for SoG measurements

• Further assessments should be conducted for the field reference configurations recommended by SPICE, including in other climate regimes and over longer periods. To achieve this, it is recommended to set up “super sites”, with all references recommended in this report collocated, to allow for further assessment and characterization of their relative performance for different climate regimes, reporting intervals, operating conditions, and field limitations. This would support the need for traceability of observations in the absence of a primary standard.

• It is recommended to apply the methods and results from the SPICE project to national and regional precipitation data/measurements in various climatic regimes. Further work is needed to derive and use tailored transfer functions for specific environments, e.g. mountainous regions. Additionally, it is recommended that operational programs actively disseminate information on the availability of adjustment procedures that could be applied to raw (uncorrected) operational measurements of solid precipitation, and conduct targeted assessments of the impact of their application, as recommended by SPICE.

(Some) Conclusions and Recommendations (I)

• The potential for the operational use of non-catchment type sensors has been recognized. They are, for instance, less sensitive to high winds, which could make them more reliable for measurements at more exposed sites. In order to reach this goal, it is recommended that additional work be conducted to understand and improve the instrument specific internal algorithms, in a joint effort between manufacturers and the user communities.

• To the extent possible, all SPICE sites are encouraged to continue operating, and to make data available, together with all associated metadata (e.g. reflecting any modifications to the configuration over time, etc.). This will allow for the establishment of long-term datasets, which will open up additional avenues of research for meteorological, hydrological and climatological purposes. The satellite and radar communities could use these datasets as accurate and quality-controlled ground-truth information for verification and validation purposes.

(Some) Conclusions and Recommendations (II)

• Comprehensive data (and metadata) sets for further data mining • QC methodology • Up and running «super sites» with standard reference measurements • List of recommendations and best practices for solid precipitation and snow on the

ground measurements, and for automatic field reference systems • Several scientific publications • Lisaison CIMO / GCW (SPICE as demonstration project for GCW) • Characterization of the performance of existing, new, and emerging technologies and

their configurations • Input to update relevant chapters of the CIMO Guide • Guidance to Members on transition to automation from manual observations of solid

precipitation and snow depth measurements • Recommendations to manufacturers on instrument requirements and potential

improvements • Community of scientists, operational managers and manufacturers

Output / Legacy

• Continue developing transfer functions and model validation • Validate snow pack measurement new technologies to improve subseasonal and

seasonal forecasting of runoff • Assess further the event based methodology against fixed time observation (e.g. hourly

data) • Understand and reduce the scatter from transfer functions using CFD simulation • Collaborate with the manufacturers to better understand and improve the algorithms to

report precipitation accumulation using non-catchment type instruments • Possible intercomparison on non-catchment type instruments, as a follow up of a

EURAMET project on laboratory calibration (2020-22)

(Some) Future Work

Thank you for your attention!