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, rasmus@ucar.edu (2) Environmemt Canada, Toronto, Canada,
Rodica.nitu@ec.gc.ca , 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
How well
are we
measuring
snow?
Challenge to Measuring Snowfall
Updraft generated upstream of gauge
National Center for Atmospheric Research
Single Alter GEONOR
Due to updraft, snowgauges significantly undercatch
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
Theriault et al. 2011
Challenges to Measuring Snowfall
Capping of gauge
National Center for Atmospheric Research
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)
Week long meeting was held the week of June 11th in
– In Switzerland, the focus of the pre-SPICE experiment was the
Boulder,
Colorado to review the results of the Preassessment of the heating of a weighing gauge, in alpine
SPICE
testing
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.
Current reference for snowfall
observations are manual
Bush Gauge
Primary Reference (Valdai, Russia)
Only one!
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-solidprecip/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
DRAFT – Page 11 – April-8-15
Cross
section of
DFIR shield
Federal Department of Home Affairs FDHA
Federal Office of Meteorology and Climatology MeteoSwiss
Pre-SPICE
Winter 2011-2012
Set-up and some results from
Weissfluhjoch/Davos
11.6.2012
Testing at Davos, Switzerland by
MeteoSwiss
- Impact of heating on OTT Pluvio2 200 cm2
gauge with Tretyakov shield
21.02.2012
Title of presentation | Subtitle
Author
15
Schematic of ice bridging inside the
OTT PLUVIO2
Title of presentation | Subtitle
Author
16
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.
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
Finnish Meteorological Institute
08/04/2015
18
Rain
Both gauges in DFIR
Finnish Meteorological Institute
08/04/2015
19
Snow
Both gauges in DFIR
Finnish Meteorological Institute
08/04/2015
20
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).
Finnish Meteorological Institute
08/04/2015
21
Summary of results from the Canadian
contribution to Pre-SPICE
Toward the definition of a SPICE field reference
Rodica Nitu, Paul Joe, Daqing Yang, Craig Smith, Michael Earle,
Jeff Hoover, Jim Waller, Faisal Boudala
Pre-SPICE Workshop
Boulder, Colorado
June 11, 2012
Measurements from two field sites
 Centre for Atmospheric Research
Experiments (CARE)
CARE
 Egbert, Ontario
 Bratt’s Lake (BL)
 Bratt’s Lake, Saskatchewan
Bratt’s Lake
Canada
Bratt’s
Lake
CARE
Page 23 – April-8-15
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
The Bratt’s Lake Precipitation Intercomparison Facility
Summary of Catch Efficiency vs. Wind Speed
Geonor T-200B w/ wind shields
1.20
Catch Efficiency
1.00
0.80
0.60
0.40
0.20
DF
DA
SA
Yang et al (1993)
0.00
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)
Heated Geonor gauge (CRN heating)
Unheated Geonor gauge
Bratt’s Lake, Saskatchewan:
Under test:
Unheated Geonor in a DFIR
Heated Geonor (using the CRN
heating algorithm), in a DFIR
Summary of Canadian Pre-SPICE testing
 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
Page 26 – April-8-15
Marshall (Boulder, CO USA) site with
DFIR and Alter shielded snow guages
DRAFT – Page 27 – April-8-15
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, Norway
Pre-SPICE Data
Mareile Wolff, Ketil Isaksen, Ragnar Brækkan
Norwegian Meteorological Institute, Oslo, Norway
Haukeliseter
59°48.71’N, 7°12.86’E, 991m
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
Norwegian Meteorological Institute met.no
WMO-CIMO LEAD CENTRE
“BENEDETTO CASTELLI”
ON PRECIPITATION INTENSITY
ITALY
Laboratory tests of SPICE
reference instruments
2nd WMO SPICE, Boulder ,CO, USA, 11-15 June 2012
32
Experiment setup
Temperature tests
Gauges in the cold
chamber
Set-up for OTT
Set-up for Geonor
33
Conclusions 3/3
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).
34
Deutscher Wetterdienst
TI 23 - Sensorik
Reference Systems for SPICE
- LWE Precipitation Amount
Working Field Reference for Precipitation Amount
As agreed during the Boulder Meeting June 2012
 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.
A
++
How well
are we
measuring
snow?
Hopefully, after SPICE
a lot better!
Thank You!
http://www.wmo.int/pages/prog/www/IMOP/reports/2
011/Joint_ET-II_IOC-SPICE.pdf
rasmus@ucar.edu