WMO Intercomparison of Instruments and methods for the Measurement of Solid Precipitation and
Snow on the Ground, WMO-SPICE: Pre-SPICE Studies
R. Rasmussen(1) ,R. Nitu (2),B. Baker(3),E Lanzinger (4),D Yang(7),C Smith(7),Y.A. Roulet (5),B Goodison((15) ,H Liang(6),F Sabatini(8),J Kochendorfer (3),M Wolff(9) ,J Hendrikx (10), E Vuerich(11),L Lanza(12),P. Joe(2),O Aulamo(13),V Vuglinsky(14) , Michael Earle(2) ,Jeffery Hoover(2), S Landolt(1)
(1) National Center for Atmospheric Research, Boulder, USA, [email protected] (2) Environmemt Canada, Toronto, Canada, [email protected] , 3) NOAA Air Resources Laboratory, Oak Ridge, TN, 37830 ,4)Deutscher Wetterdienst, Hamburg, Germany,(5)Météo Suisse,PAYERNE, Switzerland, (6)China Meteorological Administration, BEIJING, China. 7)Environment Canada, Saskatoon, Canada . (8) CNR-IBIMET, Institute of Biometeorology, Florence, Italy, (9)Norwegian Meteorological Institute,Oslo, Norway, (10)Montana State University, Montana, U.S.A., (11) Italian Met Service – Air Force, Centre of Meteorological Experimentations, Vigna di Valle (Rome) Italy, 12) DICAT - Department of Civil, Environmental and Territorial Engineering, University of Genoa , GENOVA Italy , 13) Finnish Meteorological Institute, Arctic Research Centre, Sodankyla , (14) State Hydrological institute,St.Petersburg, Russian Federation, (15) World meteorological Organization, EC-PORS, GCOS, Geneva Switzerland
National Center for Atmospheric Research
Updraft generated upstream of gauge
Challenge to Measuring Snowfall
Theriault et al. 2011
Data from single alter GEONOR gauge at Marshall (box plots)
Model results (lines) from Fluent simulation of flow past single Alter GEONOR with snowflake trajectory modeling
Sing
le A
lter G
EON
OR
Due to updraft, snowgauges significantly undercatch
Key goal of Pre-SPICE: Establish Field Reference Systems for SPICE
• Need to establish a recognized field reference using automatic gauges to calculate the undercatch as a function of wind speed (transfer function).
– Proposed configuration: DFIR shield surrounding a Weighing Gauge (WG)
– Develop transfer functions to characterize the proposed reference against the WMO Secondary Reference (Tretyakov gauge inside DFIR);
• Options for the configuration of a Filed Reference using WG:– Type of WG: proposed Geonor T-200, OTT Pluvio 2;
– Configuration of WG: ▪ heated/non-heated; ▪ wind shield:
– DFIR,
– Double Alter, Belfort Double Alter.
Instruments and Site Focus for Pre-SPICE
– A WMO secondary field reference, using a manual Tretyakov gauge installed in a DFIR, was used in Canada and Finland.
– A DFIR shield surrounding an automatic precipitation weighing gauge was configured and assessed as a field working reference in Canada (CARE and Bratt’s Lake), Finland (Jokioinen), Norway (Haukeliseter), and USA (Boulder),(DFAR)
– In Switzerland, the focus of the pre-SPICE experiment was the assessment of the heating of a weighing gauge, in alpine conditions, in the presence of large amounts of snowfall.
– A laboratory calibration of the instruments considered for use as part of the working field reference was performed at the Precipitation Intensity Lead Centre in Genoa (Italy). This focused on the testing of the weighing gauges at temperatures representative of the winter operating conditions.
Week long meeting was held the week of June 11th in Boulder, Colorado to review the results of the Pre-SPICE testing
Current reference for snowfall observations are manual
Primary Reference (Valdai, Russia)Only one!
Bush Gauge
DRAFT – Page 11 – April 18, 2023
Secondary Reference: DFIR surrounding a Tretyakov precipitation gauge
• WMO Solid Precipitation Measurement Inter-comparison (WMO CIMO IOM Report No. 67, WMO/TD-No. 872, 1998 http://www.wmo.int/pages/prog/www/IMOP/publications/IOM-67-solid-precip/WMOtd872.pdf)
– Recommended : “The Double Fence Intercomparison Reference (DFIR) should be accepted as a secondary reference for the (manual) measurement of solid precipitation;” (section 6.1.2)
– (DFIR): “The octagonal vertical double-fence inscribed into circles 12 m and 4 m in diameter, with the outer fence 3.5 m high and the inner fence 3.0 m high surrounding a Tretyakov precipitation gauge mounted at a height of 3.0 m.”( section 2.2.2)
Double Fence Intercomparison Reference
Federal Department of Home Affairs FDHAFederal Office of Meteorology and Climatology MeteoSwiss
Pre-SPICEWinter 2011-2012
11.6.2012
Set-up and some results from Weissfluhjoch/Davos
Testing at Davos, Switzerland by MeteoSwiss
- Impact of heating on OTT Pluvio2 200 cm2 gauge with Tretyakov shield
Summary of Testing at Switzerland Impact of heating unshielded OTT Pluvio2 200 cm2 gauge
1. For prevailing alpine conditions, measurement is difficult with an unheated gauge: snow can induce mechanical effects on the sensor, with possible formation of ice or snow bridges between the housing and the weighing elements.
2. Heating of the ring is mandatory to ensure good quality measurements in Alpine winter conditions with high snow amount.
3. No under-catch due to the heating.
18/04/23Finnish Meteorological Institute 18
Jokioinen: Pre-SPICE field
60° 48' 50.44" N, 23° 29' 51.40” E, 104 m, from the sea level
Measurements 19.02.2012 – 30.04.2012
Manual measurements only once every day at 0600 UTC
Compared manual measurement in DFIR with Tretyakov shield and can with automated measurement in DFIR with OTT Pluvio2 gauge
18/04/23Finnish Meteorological Institute 21
Results from testing in Finland:
The daily precipitation amount from the automated gauge in the DFIR compared well with the manual measurement from the Tretyakov can also in a DFIR.
Suggests that can use an automated gauge in a DFIR as a reference for SPICE (DFAR).
Summary of results from the Canadian contribution to Pre-SPICE
Rodica Nitu, Paul Joe, Daqing Yang, Craig Smith, Michael Earle, Jeff Hoover, Jim Waller, Faisal Boudala
Pre-SPICE Workshop
Boulder, Colorado
June 11, 2012
Toward the definition of a SPICE field reference
Page 23 – April 18, 2023
Measurements from two field sites Centre for Atmospheric Research
Experiments (CARE) Egbert, Ontario
CARE
Bratt’s Lake
Bratt’s Lake (BL) Bratt’s Lake, Saskatchewan
Canada
Bratt’s
LakeCARE
Instruments at the Canadian CARE site
Tretyakov manual gauge in DFIR
Geonor T-200 heated (DFIR)
Pluvio 2 (Belfort Double Alter)
Geonor T-200 in BDA
Summary of Catch Efficiency vs. Wind SpeedGeonor T-200B w/ wind shields
0.00
0.20
0.40
0.60
0.80
1.00
1.20
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0
Wind Speed (m/s)
Ca
tch
Eff
icie
nc
y
DF SA DA Yang et al (1993)
The Bratt’s Lake Precipitation Intercomparison Facility
Heated Geonor gauge (CRN heating)
Unheated Geonor gauge
Bratt’s Lake, Saskatchewan:Under test:
Unheated Geonor in a DFIRHeated Geonor (using the CRN heating algorithm), in a DFIR
Page 26 – April 18, 2023
Rim heating has a positive impact on the gauge performance (accuracy, improved catch), both GEONOR T-200 or OTT PLUVIO2.
Both GEONOR T-200 and OTT PLUVIO2 performed well in terms of accuracy
Either GEONOR T-200 or OTT PLUVIO2 acceptable at weighing gauge for Field Reference
Summary of Canadian Pre-SPICE testing
DRAFT – Page 27 – April 18, 2023
Marshall (Boulder, CO USA) site with DFIR and Alter shielded snow guages
Summary of Pre-SPICE Results from Marshall Field Site, USA
1. Gauge performance in Small DFIR and standard DFIR similar in terms of accuracy.
2. Provided estimate of the performance of various wind shield types.
3. Noted the importance of heating the entire collection tube of the GEONOR T-200 gauge.
4. Noted that the current OTT PLUVIO2 heating algorithm may not be sufficient for heavy, wet snow conditions (dumps occurred in this situation).
Test site Haukeliseter, NorwayPre-SPICE Data
Mareile Wolff, Ketil Isaksen, Ragnar BrækkanNorwegian Meteorological Institute, Oslo, Norway
Norwegian Meteorological Institute met.no
Summary
Identified the need for improved identification of the onset and offset of weak precipitiation events- Suggested use of a precipitation detector, yes/no sensor, video camera
Blowing snow needs to be taken into account in open, high alpine sites
WMO-CIMO LEAD CENTRE“BENEDETTO CASTELLI”
ON PRECIPITATION INTENSITYITALY
Laboratory tests of SPICE reference instruments
2nd WMO SPICE, Boulder ,CO, USA, 11-15 June 2012 32
Conclusions 3/3
34
The dynamic tests show that both gauges are able to reproduce likely real world events with comparable performance;The results from laboratory tests open the way for possible improvements of their accuracy and precision (including low intensities, the interest for SPICE)The Lead Centre is currently conducting additional tests.
Matteo Colli from the U. of Genoa is currently visiting NCAR and testing the GEONOR T-200 gauge with the NCAR snow machine for heater performance for various snowfall rate and temperature conditions (snow capping elimination).
R1: DFIR + Tretyakov gauge (manual measurements) + Tretyakov shield designated in the 1989-1993 intercomparison as secondary field reference WMO/TD-872/1998);
R2: DFIR + automatic weighing gauge (AWG) + shield
Shield will be an Alter shield Either GEONOR T-200 or OTT
PLUVIO2 acceptable as the weighing gauge
Both gauges will be heated with the CRN heating algorithm (heat between +2 and -5 C, every 24 hours otherwise)
A capacitive precipitation detector will be used to detect the presence of precipitation
Working Field Reference for Precipitation Amount
As agreed during the Boulder Meeting June 2012
R3: An automatic weighing gauge in a (small) windshield paired with an unshielded gauge
- The Working Field Reference System type R3 consists of a pair of identical automatic weighing gauges heated in the same manner, one being unshielded and the second installed with a single Alter Shield. The configuration of the Alter shield is specified by the SPICE IOC. Gauge type: GEONOR T-200 or OTT PLUVIO2
- A capacitive precipitation detector will
be used to detect the presence of precipitation.
Working Field Reference for Precipitation Amount
As agreed during the Boulder Meeting June 2012
+A +
Thank You!
http://www.wmo.int/pages/prog/www/IMOP/reports/2011/Joint_ET-II_IOC-SPICE.pdf
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