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Lassen Volcanic National Park Trends Analysis
The tables and figures below show the trends analysis results for 20% worst, middle 60% and 20% best days at LAVO1 based on light extinction coefficient data from 1994 to 2003. Overall, there is no significant  trend in aerosol light extinction in 20% worst days. A peak in OMC and LAC extinction is observed in 1999, No significant trend is found for the middle 60% days, and a decrease trend is found for 20% best days. 

Table 1. Number of valid measurements used in the trends analysis
Site Year StartDate EndDate NoMeas
LAVO1 1994 1/1/1994 12/31/1994 87
LAVO1 1995 1/21/1995 12/9/1995 78
LAVO1 1996 1/10/1996 12/25/1996 82
LAVO1 1997 1/4/1997 12/31/1997 89
LAVO1 1998 1/3/1998 12/30/1998 80
LAVO1 1999 1/13/1999 12/29/1999 86
LAVO1 2000 1/1/2000 12/26/2000 101
LAVO1 2001 1/4/2001 12/30/2001 112
LAVO1 2002 1/2/2002 12/31/2002 105
LAVO1 2003 1/3/2003 12/26/2003 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)
LAVO1 1994 27.31 8.53 1.09 10.98 3.27 1.15 2.30
LAVO1 1995 24.36 8.35 1.16 9.04 3.25 0.82 1.74
LAVO1 1996 24.06 7.92 1.72 8.99 3.03 0.75 1.65
LAVO1 1997 22.51 6.57 1.77 7.99 2.52 0.65 3.01
LAVO1 1998 36.55 8.16 2.16 16.71 5.72 1.20 2.60
LAVO1 1999 67.37 7.80 4.04 37.69 13.29 0.93 3.62
LAVO1 2000 25.78 7.24 3.37 9.25 3.25 0.62 2.05
LAVO1 2001 30.77 8.56 4.75 10.91 2.93 1.46 2.16
LAVO1 2002 35.60 7.63 3.90 16.37 3.02 1.42 3.26
LAVO1 2003 29.85 7.44 3.79 13.55 3.12 0.64 1.33
               
Slope (1/Mm/Year)   0.828 -0.103 0.356 0.422 -0.017 -0.002 0.050
S-Value   11 -15 33 11 -7 -1 1
P-Value   0.190 0.108 0.001 0.190 0.300 0.500 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)
LAVO1 1994 13.23 3.79 1.22 4.42 1.48 0.57 1.75
LAVO1 1995 13.08 4.26 1.24 4.25 1.68 0.51 1.14
LAVO1 1996 11.52 3.33 1.07 4.06 1.34 0.37 1.34
LAVO1 1997 11.06 3.77 1.15 3.55 1.19 0.31 1.09
LAVO1 1998 15.38 4.46 0.92 6.20 1.87 0.30 1.64
LAVO1 1999 13.93 3.87 1.25 5.05 1.72 0.40 1.64
LAVO1 2000 13.36 4.17 1.18 4.91 1.61 0.37 1.13
LAVO1 2001 12.43 4.75 1.24 3.54 1.22 0.58 1.10
LAVO1 2002 12.74 3.81 1.49 4.19 1.27 0.64 1.34
LAVO1 2003 11.21 3.46 1.27 4.18 1.30 0.39 0.61
               
Slope (1/Mm/Year)   -0.115 0.007 0.020 -0.027 -0.024 0.004 -0.051
S-Value   -9 3 17 -9 -9 3 -17
P-Value   0.242 0.431 0.078 0.242 0.242 0.431 0.078

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)
LAVO1 1994 6.12 1.61 1.59 1.78 0.55 0.14 0.46
LAVO1 1995 5.53 1.67 1.28 1.34 0.52 0.19 0.52
LAVO1 1996 4.55 1.31 0.83 1.45 0.42 0.07 0.46
LAVO1 1997 5.16 1.64 0.33 1.70 0.46 0.11 0.91
LAVO1 1998 4.36 0.91 0.28 2.03 0.49 0.07 0.58
LAVO1 1999 4.52 1.52 0.32 1.54 0.67 0.11 0.35
LAVO1 2000 4.61 1.93 0.61 1.25 0.50 0.10 0.24
LAVO1 2001 3.17 1.12 0.42 0.71 0.52 0.15 0.26
LAVO1 2002 3.24 1.23 0.41 0.90 0.38 0.09 0.23
LAVO1 2003 2.52 0.91 0.28 0.83 0.37 0.05 0.08
               
Slope (1/Mm/Year)   -0.360 -0.058 -0.109 -0.104 -0.009 -0.006 -0.044
S-Value   -33 -17 -23 -23 -15 -15 -27
P-Value   0.001 0.078 0.023 0.023 0.108 0.108 0.008

Page last updated 30 March 2005