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Denali National Park Trends Analysis
The tables and figures below show the trends analysis results for 20% worst, middle 60% and 20% best days at DENA1 based on light extinction coefficient data from 1994 to 2003. No significant trend is observed for aerosol light extinction coefficients in 20% worst days. But the nitrate extinction increased significantly in the worst days. Significant decrease trend is found for aerosol light extinction coefficients in both middle 60% and 20% best days. Sulfate,  LAC and CM extinction decreased significantly in the middle 60% days. In the 20% best days, the extinction coefficients of all chemical components decreased.

Table 1. Number of valid measurements used in the trends analysis 
Site Year StartDate EndDate NoMeas
DENA1 1994 1/1/1994 12/24/1994 93
DENA1 1995 1/4/1995 12/30/1995 92
DENA1 1996 1/3/1996 12/21/1996 95
DENA1 1997 1/11/1997 12/31/1997 89
DENA1 1998 1/7/1998 12/30/1998 82
DENA1 1999 1/2/1999 12/29/1999 71
DENA1 2000 1/1/2000 9/23/2000 75
DENA1 2001 3/2/2001 12/30/2001 100
DENA1 2002 1/5/2002 12/31/2002 116
DENA1 2003 1/3/2003 12/29/2003 118
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)
DENA1 1994 18.24 8.23 0.32 5.74 1.53 0.26 2.15
DENA1 1995 15.23 8.84 0.32 2.12 1.38 0.35 2.21
DENA1 1996 15.99 6.55 0.34 4.92 1.58 0.32 2.28
DENA1 1997 23.12 6.81 0.56 9.65 2.70 0.21 3.21
DENA1 1998 12.76 4.47 0.52 3.91 1.34 0.19 2.32
DENA1 1999 16.63 5.57 1.09 4.80 1.46 0.31 3.40
DENA1 2000 29.21 5.85 1.20 17.87 2.89 0.21 1.20
DENA1 2001 16.08 5.37 0.79 6.16 1.47 0.52 1.78
DENA1 2002 25.87 7.60 0.85 13.55 2.14 0.38 1.35
DENA1 2003 16.12 6.21 0.52 6.61 1.57 0.18 1.02
               
Slope (1/Mm/Year)   0.143 -0.225 0.066 0.596 0.023 -0.004 -0.125
S-Value   9 -13 25 17 9 -3 -13
P-Value   0.242 0.146 0.014 0.078 0.242 0.431 0.146

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)
DENA1 1994 7.74 3.47 0.35 1.54 0.66 0.17 1.54
DENA1 1995 7.69 3.27 0.35 1.28 0.96 0.18 1.65
DENA1 1996 8.68 3.38 0.36 1.72 0.90 0.17 2.15
DENA1 1997 8.75 2.95 0.39 1.97 0.87 0.15 2.42
DENA1 1998 6.72 2.72 0.31 1.64 0.66 0.21 1.18
DENA1 1999 8.59 3.31 0.50 2.43 0.89 0.21 1.24
DENA1 2000 6.82 2.86 0.42 2.14 0.54 0.10 0.75
DENA1 2001 5.89 2.79 0.41 1.29 0.55 0.17 0.68
DENA1 2002 5.66 2.73 0.35 1.22 0.55 0.15 0.66
DENA1 2003 5.89 2.86 0.36 1.36 0.55 0.11 0.64
               
Slope (1/Mm/Year)   -0.264 -0.071 0.006 -0.020 -0.039 -0.006 -0.132
S-Value   -25 -25 5 -3 -23 -15 -31
P-Value   0.014 0.014 0.364 0.431 0.023 0.108 0.002
 

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)
DENA1 1994 3.68 1.52 0.35 0.74 0.32 0.10 0.66
DENA1 1995 3.64 1.55 0.35 0.57 0.34 0.11 0.72
DENA1 1996 4.14 1.48 0.24 0.97 0.42 0.09 0.95
DENA1 1997 4.04 1.33 0.26 1.07 0.60 0.08 0.70
DENA1 1998 3.12 0.92 0.10 0.98 0.42 0.09 0.61
DENA1 1999 3.78 1.24 0.13 0.86 0.41 0.17 0.97
DENA1 2000 2.42 0.87 0.15 0.79 0.25 0.05 0.31
DENA1 2001 2.11 1.21 0.13 0.27 0.29 0.06 0.15
DENA1 2002 1.68 0.89 0.14 0.21 0.14 0.04 0.25
DENA1 2003 1.55 0.79 0.10 0.33 0.12 0.03 0.18
               
Slope (1/Mm/Year)   -0.282 -0.081 -0.027 -0.067 -0.027 -0.008 -0.073
S-Value   -31 -35 -23 -17 -23 -29 -23
P-Value   0.002 0.000 0.023 0.078 0.023 0.005 0.023

Page last updated 30 March 2005