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d l l l d d fIndex calculation related to need for winter maintenanceT bjö GTorbjörn Gustavsson
KlimatorGöteborg SwedenGöteborg, Sweden
Example of winter index
‐for calculation of maintenance activities
NORIKS = Σ ( Tr + Tf + P+ DS)
Tr –Temperature rise indicates risk of hoar frost
Tf – Temperature fall indicates risk for ice formation.
P – Precipitation such as snow or sleet
DS – Drifting snow
Outline of presentationOutline of presentation
• Background– Areas
– Climate: today – future
I d• Index
• Variation in salting and plowingg p g
The regionsThe regions
Mean road temperature1st November to 31st March 1998‐2008
Area Road T (˚C) Air T (˚C)
S1 0.63 0.78
S2 ‐0.44 ‐0.24
S3 ‐4.52 ‐4.10
F1 ‐2.38 ‐2.39
F2 ‐4.05 ‐4.29
F3 ‐5.50 ‐5.50
Millimeters of water equivalent precipitation per seasonMillimeters of water equivalent precipitation per season
• Millimeters of water equivalent precipitation as snow per season
• Millimeters of water equivalent precipitation as rain per season
Precipitation extremesMean number of events per area and season, 1998 to 2008
Precipitation extremes
Area Precipitation 1‐3mm Precipitation 3‐6mm Precipitation 6‐9mm Precipitation >9mm
S1 36.31 1.99 0.20 0.03
S2 12.08 0.43 0.06 0.00
S3 9.66 0.18 0.01 0.00
F1 40.40 3.91 0.34 0.20
F2 46 83 5 46 0 67 0 23F2 46.83 5.46 0.67 0.23
F3 37.90 3.00 0.29 0.20
Mean winds1st November to 31st March 1998‐2008
Area Mean max wind (m/s) Mean wind (m/s)
S1 5.28 2.69
S2 4.51 2.27
S3 3.22 1.31
F1 4 33 1 82F1 4.33 1.82
F2 3.85 1.63
F3 3.59 1.51
Extreme windExtreme wind
Mean number of events per area and season from 1998 to 2008
Area Wind 10‐15m/s Wind 15‐20m/s Wind 20‐25m/s Wind 25‐30m/s Wind >30m/s
S1 641.35 93.45 11.23 1.44 0.17
S2 361.58 25.08 1.49 0.12 0.00
S3 147.51 14.97 0.81 0.02 0.00
F1 301.30 23.73 1.37 0.11 0.00
F2 193 43 7 92 0 20 0 00 0 00F2 193.43 7.92 0.20 0.00 0.00
F3 79.16 0.94 0.03 0.00 0.00
Historical observationsHistorical observationsWind extremesWind extremes Mean number of events per season
200
250
vents Wind 15‐20m/s
0
50
100
150
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
Mean nu
mbe
r of ev
10
15
20
25
30
umbe
r of events Wind 20‐25m/s
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007Season0
5
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
Mean nu
Season
6
7
ents Wind 25‐30m/s
0
1
2
3
4
5
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
Mean nu
mbe
r of eve
/
Mean S1
Mean S2
Mean S3
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007Season
0 2
0,3
0,4
0,5
0,6
0,7
umbe
r of events Wind over 30m/s
0
0,1
0,2
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
Mean nu
Season
Index calculationIndex calculationPloughing indices, subdivided according to WIND and TEMP• Index1 ‐ Number of occasions when the amount of snow > 1mm during 4h, T between ‐3 to +1°C, and the wind
velocity is between 0‐7m/s.
• Index2 ‐ Number of occasions when the amount of snow > 1mm during 4h, T between ‐3 to +1°C, and the wind velocity is between 7‐14m/svelocity is between 7‐14m/s.
• Index3 ‐ Number of occasions when the amount of snow > 1mm during 4h, T between ‐3 to +1°C, and the wind velocity is between >14m/s.
• Index4 ‐ Number of occasions when the amount of snow > 1mm during 4h, T < ‐3°C, and the wind velocity is b /between 0‐7m/s.
• Index5 ‐ Number of occasions when the amount of snow > 1mm during 4h, T < ‐3°C, and the wind velocity is between 7‐14m/s.
• Index6 ‐ Number of occasions when the amount of snow > 1mm during 4h, T < ‐3°C, and the wind velocity is g , , ybetween >14m/s.
Salting indices, subdivided in relation to type of situation• Index7 ‐ Number of occasions when it is/has been raining and the surface temperature < 0,5°C.
• Index8 ‐ Number of occasions when surface temperature between ‐6°C and 0°C, during 4h, and dew point > surface temperature.
• Index9 Number of occasions when surface temperature shifts from +1°C to 1°C• Index9 ‐ Number of occasions when surface temperature shifts from +1 C to ‐1 C.
IndicesIndicesSweden Finland
50
60
70
80
area
whe
n ou
ghing
Ploughing needed(Index 1‐6)
50
60
70
80
area whe
n ou
ghing
Ploughing needed(Index 1‐6)
0
10
20
30
40
50
umbe
r of events pe
r re was a need for plo
S1
S2
S3 0
10
20
30
40
umbe
r of events pe
rre was a need for plo
F1
F2
F3
0
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
Mean n
ther
Season
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007Mean n
ther
Season
200
300
400
500
600
of events pe
r area
a ne
ed fo
r salting Salting needed
(Index 7‐9)
S1200
300
400
500
600
vents pe
r area
ed
for plou
ghing Salting needed
(Index 7‐9)
F1
0
100
200
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
Mean nu
mbe
r o
whe
n there was
S2
S3 0
100
200
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
Mean nu
mbe
r of ev
whe
n there was a ne F1
F2
F3
Season
w
Season
70was
ces 1‐6) 2005‐2006 in S1 2005‐2006
20
30
40
50
60
70
f events whe
n there w
ughing
(mean of indi
0
10
601 611 633 634 646 647 1403 1407 1417 1425 1426 1427 1504 1513 1518 1523 1539 1542 1543 1601 1612 1620 1623 1625Num
ber of
a ne
ed fo
r plou
Station
New technique for calculating the need for maintenance activities
Model scenariosModel scenarios
ECHAM NCAR
AreaRoad T (˚C) Air T (˚C) Road T (˚C) Air T (˚C)Road T ( C) Air T ( C) Road T ( C) Air T ( C)
S10.89 1.03 1.06 1.21
S21.07 1.28 1.22 1.44
S31.19 1.58 1.38 1.86
F1F11.18 1.31 1.95 2.14
F21.20 1.37 2.11 2.41
F31.27 1.44 2.22 2.57
Echam temperature scenariosEcham temperature scenariosMean Road temperature change from the first 30year Mean Air temperature change from the first 30yearMean Road temperature change from the first 30year period (1980‐2010) to the last one (2025‐2055) according to the Echam scenario.
Mean Air temperature change from the first 30year period (1980‐2010) to the last one (2025‐2055) according to the Echam scenario.
Seasonal mean halfhours per area
Area
Percentual change (1980‐2010 to 2025‐2055)Index 1‐6 Ploughing
Percentual change(1980‐2010 to 2025‐2055) Index 7‐9 Salting
F1 ‐8.9% 3.0%
F2 ‐5.1% 11.8%
2 1% 12 4%F3 ‐2.1% 12.4%
S1 ‐9.6% ‐1.3%
S2 ‐18.6% 1.9%S2
S3 ‐4.5% 16.6%
Seasonal mean events per areaPercentual change (1980 2010 to 2025 2055)
Percentual change(1980 2010 to 2025 2055)
Area (1980‐2010 to 2025‐2055)Index 1‐6 Ploughing
(1980‐2010 to 2025‐2055)Index 7‐9 Salting
F1 ‐9.0% 3.4%
F2 5 3% 11 9%F2 ‐5.3% 11.9%
F3 ‐1.9% 12.2%
S1 ‐9.8% ‐2.1%
S2 15 7% 2 4%S2 ‐15.7% 2.4%
S3 ‐3.1% 16.7%
DATABASE FORDATABASE FOR FURTHER STUDIESFURTHER STUDIES
Echam scenarios extreme precipitation changes
E t i it ti h f th fi t thi t i d (1980 t 2010)Extreme precipitation changes from the first thirty year period (1980 to 2010) to the last thirty year period (2025 to 2055) in S1 region. Values are mean number of events (30 minute periods).
DATABASE FOR FURTHER STUDIES
SummarySummary
ib d h d li f diff• Described the road climate for 6 different areas
• Developed a winter index• Calculated index according to present andCalculated index according to present and future climate
• Calculated the change in maintenance need• Calculated the change in maintenance need (salting & plowing)
• Analyzed extreme wind and precipitation and calculated variations for the future