method for calculating the amount of accumulated snow transported during a single blizzard
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Method for Calculating the Amount of Accumulated Snow Transported during a Single Blizzard. 15th International Road Weather Conference February 5th - 7th, 2010 in Québec City, Canada. Masaru Matsuzawa 1 , Yasuhiko Ito and Masayo Ueda - PowerPoint PPT PresentationTRANSCRIPT
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
Method for Calculating the Amount of Accumulated Snow Transported during
a Single Blizzard
Masaru Matsuzawa1, Yasuhiko Ito and Masayo Ueda
1 The Civil Engineering Research Institute for Cold Region, Public Works Research Institute, JAPAN
Email: [email protected]
15th International Road Weather ConferenceFebruary 5th - 7th, 2010 in Québec City, Canada
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
1. Introduction
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
Background to the study
More than 100 vehicles stalled in the Kushiro/Nemuro district on March 31 and April 2, 2008.
How often do such blizzards occur?
Naganuma
Kushiro/Nemuro district
Approximately 140 vehicles were trapped in accumulated snow on National Route 274 in Naganuma near Sapporo on February 23 and 24, 2008.
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
Purpose of the study■Indexes to represent blizzard intensity ・ Maximum amount of accumulated snow (Fukuzawa et al., 2000) ・ Frequency of blizzards (Ishimoto, 1987)There are no indexes to represent the intensity of a single blizzard.
■Purpose of the studyDevelopment of an index to represent the intensity of a single blizzard•A single blizzard was defined.•The total transport rate of blowing snow during a single blizzard were calculated for the aforementioned cases.•The probability period for replication of the total transport rate of blowing snow was found.
} Blizzard intensity for the year
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
Contents1. Introduction2. Study Method3. Results4. Improvement of the method for
estimating the maximum transport rate of blowing snow
5. Conclusion
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
2. Study Method
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
Relationship between the transport rate Relationship between the transport rate of blowing snow Q and wind velocityof blowing snow Q and wind velocity
Definition of the transport rate of blowing snow Q:Definition of the transport rate of blowing snow Q:Mass of snow blown particles that passes through a particular unit
width perpendicular to the wind direction during a fixed time [g/(ms)][g/(ms)]
Relation between the transport rate of blowing snow Q and wind Relation between the transport rate of blowing snow Q and wind velocityvelocity (Kobayashi D. (1972))
Q=0.03VQ=0.03V1133
[g/(ms)][g/(ms)] ・・・ (1)
Where, V1 is the wind velocity at a height of 1 m.
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
Conditions required for the occurrence of blowing snow
• Conditions required for the occurrence of blowing snow during snowfall (Takeuchi et al., 1986)
• Blizzard conditions were assumed when either set of the following criteria were satisfied:
1: An air temperature of < -2°C, a wind velocity of > 5.0 m/s and a snow depth of > 1 cm
2: An air temperature of < 0.5°C, a wind velocity of > 7.5 m/s and a snow depth of > 1 cm
: low drift snow: intermittent high drift snow: continuous high drift snow
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
Definition of a single blizzardConditions required for blowing snow occurrence1.1. An air temperature of < -2°C, a wind velocity of > 5.0 An air temperature of < -2°C, a wind velocity of > 5.0
m/s and a snow depth of > 1 cmm/s and a snow depth of > 1 cm2.2. An air temperature of < 0.5°C, a wind velocity of > An air temperature of < 0.5°C, a wind velocity of >
7.5 m/s and a snow depth of > 1 cm7.5 m/s and a snow depth of > 1 cm
• A blizzard was considered to have ended when the above necessary conditions for blowing snow occurrence were not satisfied for six consecutive hours.
• The period between the start and end of a blizzard was defined as a single event.
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
Estimation of the transport rate of blowing snow Q and probability of replication
Q=0.03VQ=0.03V1133
[g/(ms)][g/(ms)] ・・・ (1)
The total value from the beginning to the end of a blizzard. Total transport rate of a single blizzard: Qsum [kg/m]
The probability of replication was calculated using Iwai’s method on the assumption that the annual maximum values for Qsum follow the logarithmic normal distribution.
AMeDAS: Automated Meteorological Data Acquisition System
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
3. Results
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
Case of Naganuma• Total transport rate of blowing snow Qsum
Naganuma AMeDAS (wind velocity, air temperature) and Eniwa-Shimamatsu AMeDAS (snow depth) data from the 23 winters from November 1981 to April 2004 were used.The results were compared with the transport rate of blowing snow on February 23 and 24, 2008.
Sapporo
Naganuma*Qsum was converted to a volume value on the assumption that the snowcover density was 350 kg/m3.
Period Qsum [m3/m]*Feb. 12 – 18, 1991 8.6March 8 – 9, 2003 5.0Feb. 23 – 24, 2008 4.6
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
Case of NaganumaProbability period for replication of the blizzard in February 2008:Approx. 10 years
1
10
100
1000
1.0 10.0 100.0 Pro
babi
lity
perio
d of
repl
icat
ion
(yrs
)
Transport rate of blowing snow (m3/m)
February 23 – 24, 2008, 4.6 m3/m
Case of the Kushiro/Nemuro districtAttoko AMeDAS (wind velocity, air temperature and snow depth) Data from the 18 winters from November 1986 and April 2004 were used.The probability period for replication of Qsum between March 31 and April 2, 2008 was more than 1,000 years.
Sapporo
Attoko
1
10
100
1000
0.1 1.0 10.0
Pro
babi
lity
perio
d of
repl
icat
ion(
yrs)
Transport rate of blowing snow (m3/m)
March 31 – Apr. 2, 2008, 4.4 m3/m
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
4. Improvements of the method for estimating the maximum transport
rate of blowing snow
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
Problem
•The 10-year probability of replication seemed too large for Naganuma, which experienced a severe blizzard in February 2008.
•Weather conditions in February 1991, March 2003 and February 2008 were reviewed.
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
Weather conditions during blizzardsFebruary 15 – 18, 1991
-20
-15
-10
-5
0
5
02468
101214161820
1:00
7:00
13:0
0
19:0
0
1:00
7:00
13:0
0
19:0
0
1:00
7:00
13:0
0
19:0
0
1:00
7:00
13:0
0
19:0
0
Tem
pera
ture
(C)
Suns
hine
Dur
ation
(h)
Prec
ipita
tion
(mm
) W
ind
Spee
d (m
/s)
Precipitation (mm) Sunshine Duration (h)
Wind Speed (m/sec) Temperature ( C゚)
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
Weather conditions during blizzards
March 7 – 10, 2003
-20
-15
-10
-5
0
5
02468
101214161820
1:00
7:00
13:0
0
19:0
0
1:00
7:00
13:0
0
19:0
0
1:00
7:00
13:0
0
19:0
0
1:00
7:00
13:0
0
19:0
0
Tem
pera
ture
(C)
Suns
hine
Dur
ation
(h)
Prec
ipita
tion
(mm
) W
ind
Spee
d (m
/s)
Precipitation (mm) Sunshine Duration (h)
Wind Speed (m/sec) Temperature ( C゚)
There was an almost total lack of precipitation.
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
Weather conditions during blizzards
February 21 – 24, 2008
-20
-15
-10
-5
0
5
02468
101214161820
1:00
7:00
13:0
0
19:0
0
1:00
7:00
13:0
0
19:0
0
1:00
7:00
13:0
0
19:0
0
1:00
7:00
13:0
0
19:0
0
Tem
pera
ture
(C)
Suns
hine
Dur
ation
(h)
Prec
ipita
tion
(mm
) W
ind
Spee
d (m
/s)
Precipitation (mm) Sunshine Duration (h)
Wind Speed (m/sec) Temperature ( C゚)
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
Improvement of the method for estimating the total transport rate of blowing snow Qsum
• Blizzards are unlikely to occur when there is no fresh snow on the surface. There may be some overestimation regarding the transport rate of blowing snow when there is no snowfall.
• The total snowfall over a distance of 300 m on the windward side from 24 hours before the onset to the end of the blizzard was considered the maximum amount for Qsum.
• This value was defined as the maximum possible transport rate of blowing snow Qmax.
The total transport rate of blowing snow Qsum was calculated again on the assumption that:
Qmax = 300 x total snowfall Qsum≦Qmax
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
0
1
2
3
4
5
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8
9
10
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
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1994
1995
1996
1997
1998
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2001
2002
2003
2004
2008
Max
imum
val
ue o
f the
tot
al a
mou
nt o
f bl
owin
g sn
ow (m
3 /m
)
Annual maximum values for the total amount of blowing snow Qsum
Qsum in March 2003 became smaller.Qsum in February 1991 > Qsum in February 2008
Before Improvement
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
4. Conclusion
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
Conclusion• The probability period was approximately 10 years for Qsum in Naganuma
on February 23 and 24, 2008, and more than 1,000 years for that in Attoko on March 31 and April 2, 2008.
• The calculation method for the total transfer rate of blowing snow was corrected. The results indicated that the probability period of replication for the blizzard in Naganuma in February 2008 was approximately 30 years.
• Qsum was still lower in February 2008 than that in February 1991 in Naganuma.
We intend to conduct a more detailed examination of this calculation method for the transfer rate of blowing snow in the future.
Civil Engineering Research Institute for Cold Region, PWRI, JAPANhttp://www2.ceri.go.jp
Thank you for your attention!