239
Modeling Snowmelt Runoff under Climate Change Scenarios
average of model simulations of the years 2020–2039, and the “2080” period is the
average of model simulations of the years 2070–2089. Each change scenario was
represented by a percentage change to monthly precipitation and a degree change
to monthly temperature for the 12 months of the year, relative to the corresponding
months of the base period simulation.
Collectively, these results provided a range of moisture scenarios covering dry,
average, and wet for each of two time periods for a total of six different scenarios
presented in Table 10.4. As indicated earlier, the GCM output represents a monthly
average and does not indicate how daily or interannual variability can change. One
TABLE 10.4
Idaho GCM Output for Selected Models
Wet
Middle
Dry
Canadian (cccma.t63)
NCAR (PCM)
NOAA (gfdl0)
Precipitation
(%)
Temperature
(°C)
Precipitation
(%)
Temperature
(°C)
Precipitation
(%)
Temperature
(°C)
2030 (2020–2039)
January
–15.99
1.21
–2.33
0.99
–6.51
0.32
February
23.16
1.93
4.43
0.77
–10.87
1.37
March
13.28
1.21
0.75
0.73
1.19
1.95
April
11.63
0.85
–0.12
0.47
11.80
1.03
May
21.03
1.44
7.41
0.79
1.62
0.21
June
18.01
0.61
7.99
0.83
–17.70
0.15
July
–2.92
0.88
–4.43
1.11
–32.36
3.17
August
15.95
0.44
3.92
0.90
–47.88
3.51
September
9.26
0.01
–17.01
1.28
0.38
1.68
October
17.15
1.10
13.87
0.80
–3.71
1.95
November
22.37
0.49
–3.92
0.55
0.81
1.51
December
22.83
1.71
–4.19
1.03
–1.82
1.20
Annual
12.93
0.99
1.16
0.86
–7.64
1.50
2080 (2070–2089)
January
4.52
3.38
6.95
3.84
–10.69
3.34
February
37.30
4.40
14.12
3.60
6.60
4.61
March
24.66
2.58
9.35
1.64
14.44
3.98
April
36.00
2.58
10.85
1.51
19.35
2.98
May
20.94
3.33
11.00
1.60
2.38
2.10
June
–6.83
2.85
11.79
2.50
–26.66
2.83
July
–9.16
3.08
–4.90
2.97
–50.35
7.50
August
–7.66
2.44
8.13
2.82
–47.16
8.52
September
16.70
2.50
–29.77
3.30
–40.71
5.48
October
13.25
3.04
12.96
2.26
–18.14
4.28
November
36.41
2.10
1.46
1.99
6.71
3.68
December
23.48
3.93
–3.90
2.72
31.55
3.25
Annual
17.41
3.02
5.32
2.56
–6.75
4.38
Modeling Snowmelt Runoff under Climate Change Scenarios
average of model simulations of the years 2020–2039, and the “2080” period is the
average of model simulations of the years 2070–2089. Each change scenario was
represented by a percentage change to monthly precipitation and a degree change
to monthly temperature for the 12 months of the year, relative to the corresponding
months of the base period simulation.
Collectively, these results provided a range of moisture scenarios covering dry,
average, and wet for each of two time periods for a total of six different scenarios
presented in Table 10.4. As indicated earlier, the GCM output represents a monthly
average and does not indicate how daily or interannual variability can change. One
TABLE 10.4
Idaho GCM Output for Selected Models
Wet
Middle
Dry
Canadian (cccma.t63)
NCAR (PCM)
NOAA (gfdl0)
Precipitation
(%)
Temperature
(°C)
Precipitation
(%)
Temperature
(°C)
Precipitation
(%)
Temperature
(°C)
2030 (2020–2039)
January
–15.99
1.21
–2.33
0.99
–6.51
0.32
February
23.16
1.93
4.43
0.77
–10.87
1.37
March
13.28
1.21
0.75
0.73
1.19
1.95
April
11.63
0.85
–0.12
0.47
11.80
1.03
May
21.03
1.44
7.41
0.79
1.62
0.21
June
18.01
0.61
7.99
0.83
–17.70
0.15
July
–2.92
0.88
–4.43
1.11
–32.36
3.17
August
15.95
0.44
3.92
0.90
–47.88
3.51
September
9.26
0.01
–17.01
1.28
0.38
1.68
October
17.15
1.10
13.87
0.80
–3.71
1.95
November
22.37
0.49
–3.92
0.55
0.81
1.51
December
22.83
1.71
–4.19
1.03
–1.82
1.20
Annual
12.93
0.99
1.16
0.86
–7.64
1.50
2080 (2070–2089)
January
4.52
3.38
6.95
3.84
–10.69
3.34
February
37.30
4.40
14.12
3.60
6.60
4.61
March
24.66
2.58
9.35
1.64
14.44
3.98
April
36.00
2.58
10.85
1.51
19.35
2.98
May
20.94
3.33
11.00
1.60
2.38
2.10
June
–6.83
2.85
11.79
2.50
–26.66
2.83
July
–9.16
3.08
–4.90
2.97
–50.35
7.50
August
–7.66
2.44
8.13
2.82
–47.16
8.52
September
16.70
2.50
–29.77
3.30
–40.71
5.48
October
13.25
3.04
12.96
2.26
–18.14
4.28
November
36.41
2.10
1.46
1.99
6.71
3.68
December
23.48
3.93
–3.90
2.72
31.55
3.25
Annual
17.41
3.02
5.32
2.56
–6.75
4.38