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Glacier National Park Trends Analysis
The tables and figures below show the trends analysis results for 20% worst, middle 60% and 20% best days at GLAC1 based on light extinction coefficient data from 1994 to 2003. Overall, there is a significant increase trend in aerosol light extinction in 20% worst days, which is caused mainly by increase in nitrate light extinction. No significant trend is found for aerosol light extinction coefficients in middle 60% days, and a significant decrease trend is observed for the 20% best days caused by sulfate and CM.

Table 1. Number of valid measurements used in the trends analysis
Site Year StartDate EndDate NoMeas
GLAC1 1994 1/5/1994 12/31/1994 96
GLAC1 1995 1/4/1995 12/30/1995 97
GLAC1 1996 1/3/1996 12/28/1996 100
GLAC1 1997 1/1/1997 12/31/1997 100
GLAC1 1998 1/3/1998 12/30/1998 95
GLAC1 1999 1/2/1999 12/29/1999 100
GLAC1 2000 1/1/2000 12/29/2000 99
GLAC1 2001 1/1/2001 12/30/2001 100
GLAC1 2002 1/5/2002 12/31/2002 96
GLAC1 2003 1/3/2003 12/29/2003 101
Table 2. Trends analysis for 20% worst visibility days
Site Year Bep (1/Mm) Sulfate_Ext (1/Mm) Nitrate_Ext (1/Mm) OMC_Ext (1/Mm) LAC_Ext (1/Mm) Soil_Ext (1/Mm) CM_Ext (1/Mm)
GLAC1 1994 56.05 12.82 1.92 25.82 8.28 0.99 6.22
GLAC1 1995 48.15 11.77 1.89 19.43 7.24 0.96 6.85
GLAC1 1996 48.63 18.11 3.11 17.85 6.21 0.51 2.83
GLAC1 1997 47.30 16.42 5.65 14.62 5.20 0.59 4.80
GLAC1 1998 60.62 12.66 3.87 24.24 6.73 1.87 11.25
GLAC1 1999 59.20 12.57 3.26 19.93 5.86 2.34 15.25
GLAC1 2000 66.51 14.30 10.17 25.89 7.13 1.87 7.15
GLAC1 2001 66.30 11.34 9.06 31.44 7.71 1.56 5.18
GLAC1 2002 55.75 17.16 8.63 20.15 5.58 1.37 2.86
GLAC1 2003 66.80 13.85 10.39 27.99 6.40 1.42 6.75
               
Slope (1/Mm/Year)   1.690 -0.039 0.963 0.750 -0.105 0.058 0.005
S-Value   21 -1 31 17 -9 11 1
P-Value   0.036 0.500 0.002 0.078 0.242 0.190 0.500

Table 3. Trends analysis for middle 60% visibility days
Site Year Bep (1/Mm) Sulfate_Ext (1/Mm) Nitrate_Ext (1/Mm) OMC_Ext (1/Mm) LAC_Ext (1/Mm) Soil_Ext (1/Mm) CM_Ext (1/Mm)
GLAC1 1994 29.19 8.34 1.89 10.81 4.18 0.63 3.34
GLAC1 1995 24.77 9.05 1.87 7.04 3.73 0.41 2.66
GLAC1 1996 27.51 8.82 2.09 9.12 3.45 0.53 3.50
GLAC1 1997 25.05 8.29 1.70 8.16 3.12 0.43 3.35
GLAC1 1998 28.03 8.86 1.72 9.36 3.45 0.61 4.03
GLAC1 1999 24.62 6.65 1.41 8.73 3.50 0.53 3.80
GLAC1 2000 27.12 7.84 2.26 9.33 3.58 0.51 3.59
GLAC1 2001 24.91 7.88 2.49 8.06 3.04 0.68 2.76
GLAC1 2002 23.19 8.25 2.06 7.17 2.68 0.73 2.30
GLAC1 2003 25.62 7.24 2.10 9.31 3.32 0.69 2.95
               
Slope (1/Mm/Year)   -0.345 -0.148 0.029 -0.024 -0.094 0.026 -0.066
S-Value   -15 -21 11 -7 -21 19 -5
P-Value   0.108 0.036 0.190 0.300 0.036 0.054 0.364

Table 4. Trends analysis for 20% best visibility days
Site Year Bep (1/Mm) Sulfate_Ext (1/Mm) Nitrate_Ext (1/Mm) OMC_Ext (1/Mm) LAC_Ext (1/Mm) Soil_Ext (1/Mm) CM_Ext (1/Mm)
GLAC1 1994 13.94 5.41 1.94 3.61 1.24 0.23 1.51
GLAC1 1995 12.52 3.45 1.98 3.67 2.06 0.16 1.20
GLAC1 1996 12.39 4.30 1.40 3.62 1.84 0.18 1.05
GLAC1 1997 11.58 3.91 0.93 3.92 1.43 0.18 1.21
GLAC1 1998 12.38 3.53 0.96 4.45 2.09 0.16 1.20
GLAC1 1999 10.54 3.80 0.84 3.17 1.53 0.15 1.06
GLAC1 2000 10.77 3.84 0.97 3.59 1.42 0.14 0.81
GLAC1 2001 10.06 3.57 1.00 3.27 1.29 0.24 0.69
GLAC1 2002 9.08 3.18 0.88 2.68 1.33 0.25 0.76
GLAC1 2003 10.95 3.31 1.04 3.85 1.93 0.20 0.64
               
Slope (1/Mm/Year)   -0.470 -0.132 -0.087 -0.048 -0.020 0.001 -0.091
S-Value   -33 -23 -13 -9 -5 1 -33
P-Value   0.001 0.023 0.146 0.242 0.364 0.500 0.001

Page last updated 30 March 2005