GV for Snowfall GV for Snowfall Retrieval Research Retrieval Research David Hudak David Hudak Paul Joe Paul Joe Environment Environnement Canada Canada 2nd International GPM Ground Validation Workshop, 27-29 September, Taipei, Taiwan
Jan 29, 2016
GV for Snowfall GV for Snowfall Retrieval ResearchRetrieval Research
David HudakDavid Hudak
Paul JoePaul Joe Environment EnvironnementCanada Canada
2nd International GPM Ground Validation Workshop, 27-29 September, Taipei, Taiwan
Ref: WMO Publication No. 9 Volume ARef: WMO Publication No. 9 Volume A
All active Synoptic Stations north of 50 N
90° N
75° N
60° N
45° N
247729 Oct 200129 Oct 2001
POSS OccurrencePOSS Occurrence(1 minute data)(1 minute data)
•Surface obs•Doppler XBand•Derived Snowrates•Minutely•Snow only•Typed by observer•1 winter of data
YEV=Inuvik 68°NYUL=Montreal 45°N
Vertical Profile AnalysisVertical Profile AnalysisFort Simpson (62Fort Simpson (62°°N)N) Montreal (45°N)(45°N)
Quantifying Snow Gauge Errors
Systematic errors:
WIND (temperature) wetting loss evaporation loss non-zero trace
capping of gauge orifice
blowing snow
Goodison et al
0
20
40
60
80
100
120
0 1 2 3 4 5 6 7 8 9
Wind speed at gauge height (m/s)
Rat
io o
f gau
ge c
atch
to th
e D
FIR
(%)
Canadian Nipher NWS 8" AlterNWS 8" unsh Hellmann unshTretyakov
WMO Intercomparison Study Results
Catch Efficiency vs Wind for the 4 most widely used gauges
Precipitation Occurrence Sensing System (POSS)
•Doppler •Mie Scattering•Terminal Velocity
•XBand •Bistatic•Continuous Wave
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2POSS Estimate/DFIR
0
0.1
0.2
0.3
0.4
0.5
Re
lati
ve
fre
qu
en
cy
Egbert,O nt. Sept 1997-Feb 200459 observations (tw ice daily)so lid precip ita tion onlyT<0C ; D FIR >=1 m m
R PR PV
POSS Research Applications Quantitative Precipitation Estimation (QPE)
• Solid precipitation rate validation using the Double Fence Intercomparison Reference (DFIR)
Under over
POSS Research ApplicationsQPE Snow Density
0.0 0.10.02 0.04 0.06 0.08 0.20
Average density (gcm -3)
1
2
0.90.8
0.7
0.6
0.5
0.4
0.3
0.2
PO
SS
(RP
)/D
FIR
E gbert, O nt. Sept1997 to Feb 200454 observations (tw ice daily)R P m ethod assum ing snow density=0.1 gcm -3
Tem p. <0 C ; W ind<20kts; D FIR >0.1m m
0.01 0.10.02 0.04 0.060.08 0.2
A verage density (gcm -3)
0.6
0.8
1
1.2
1.4
Ave
rag
e m
ode
velo
city
(m
s-1
)
Egbert, O nt. Sept1997 to Feb 200446 observations (tw ice daily)Tem p. <0 C ; W ind<10kts; D FIR >0.1m m
1 minute snow water equivalent precipitation rate
Hot plate insensitive
18:00 19:00 20:00 21:00 22:00 23:00 0:00Time
0
1
2
3
4
Sn
ow
f al l
wa
ter
eq
uiv
ale
ntp
r ec i
pi ta
ti on
r ate
( mm
h-1)
AIRS2 Mirabel SnowEnding: 031218 00:00Observer total amount= 4.8 mm
Hot Plate1(5.23 mm)Hot Plate2 (4.69 mm)POSS (5.18 mm)
POSS Research ApplicationsAirport Vicinity Icing and Snow Advisor (AVISA)
NCAR/DRI Hot Plate
Centre fo Atmospheric Research ExperimentsCentre fo Atmospheric Research ExperimentsEC field project deployment suite
Penn StateSpectrometer
Wind Profiler
HotPlates
X-bandRadar
Univ. of AlaskaW-bandRadar
McGill Univ.
Video Disdrometer
10m met towerRadiation sensorsVisibility meterCeilometer
MW Radiometer
POSS
W-band:
•Nadir and Vertical-up: Z, LDR, Vd
•Vertical-up – side: Polarimetric, Vd
•Nadir-Side: Polarimetric, Doppler
•Nadir – Nadir-aft – Dual-Doppler
•Side – Side-forward – Dual-Doppler
X-band:
•Nadir and vertical-up – Single polarization
•Side - Polarimetric
NRC Airborne W/X – band radar (NAWX)
Fully Polarimetric and Doppler W-band: Five ports – Electronic switching X-band: Two ports - Electronic switching
CONVAIR-580 CLOUD MICROPHYSICS (cntd)
C a n a d a
Standard PMS 2D Imagery
800 um
6400 um
Under-wing particle probes
POSS Research ApplicationsPrecipitation Typing
Doppler Spectral Mode Analysis
RAIN SNOW
Mixed SNOW & RAIN
YHMYKF
King City C-band Dual Polarized radar
ZR-IP-S
Correlation Coefficient ρhv
C-band Polarization parameters
Correlation Coefficient ρhv
Differential Reflectivity ZDR
Reflectivity Z
Specific Differential Phase kdp