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Petrified Forest National Park Trends Analysis
The tables and figures below show the trends analysis results for 20% worst, middle 60% and 20% best days at PEFO1 based on light extinction coefficient data from 1994 to 2003. A significant increase trend in aerosol light extinction coefficients is found in 20% worst days, caused by increase in nitrate, OMC, soil and CM extinctions. Sulfate extinctions decreased significantly in the worst days. No significant trends are found for total aerosol light extinction in middle 60% and 20% best days. Significant increase in nitrate light extinctions is found in middle 60% days as well.

Table 1. Number of valid measurements used in the trends analysis
Site Year StartDate EndDate NoMeas
PEFO1 1994 1/1/1994 12/31/1994 90
PEFO1 1995 1/4/1995 12/30/1995 93
PEFO1 1996 1/3/1996 12/21/1996 83
PEFO1 1997 1/1/1997 12/31/1997 84
PEFO1 1998 1/3/1998 12/30/1998 83
PEFO1 1999 1/2/1999 12/29/1999 99
PEFO1 2000 1/1/2000 12/29/2000 90
PEFO1 2001 1/1/2001 12/30/2001 100
PEFO1 2002 1/2/2002 12/31/2002 115
PEFO1 2003 1/3/2003 12/29/2003 115
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)
PEFO1 1994 23.79 8.90 1.05 5.48 3.28 1.14 3.93
PEFO1 1995 25.87 11.06 0.98 6.70 3.40 1.11 2.63
PEFO1 1996 25.06 9.70 1.16 6.12 2.84 1.17 4.06
PEFO1 1997 26.01 8.86 1.57 5.56 2.96 1.91 5.14
PEFO1 1998 29.10 11.95 1.21 8.84 3.40 0.89 2.80
PEFO1 1999 28.65 6.92 1.61 8.97 3.74 1.75 5.65
PEFO1 2000 27.70 7.93 2.22 8.11 2.92 1.52 5.00
PEFO1 2001 22.29 7.57 1.54 5.12 2.49 1.65 3.92
PEFO1 2002 55.78 7.35 2.34 27.70 6.09 2.79 9.51
PEFO1 2003 41.45 7.49 1.87 10.53 3.21 2.99 15.36
               
Slope (1/Mm/Year)   1.075 -0.309 0.111 0.562 0.021 0.181 0.697
S-Value   21 -23 31 19 1 25 23
P-Value   0.036 0.023 0.002 0.054 0.500 0.014 0.023

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)
PEFO1 1994 16.13 5.74 1.06 4.07 2.60 0.65 2.02
PEFO1 1995 14.52 4.90 1.05 3.61 2.44 0.70 1.82
PEFO1 1996 14.88 4.82 0.86 3.48 1.98 0.94 2.79
PEFO1 1997 16.12 6.30 0.98 3.64 2.15 0.77 2.28
PEFO1 1998 16.30 5.31 1.00 4.49 2.25 0.71 2.55
PEFO1 1999 15.16 5.23 0.95 4.31 2.16 0.76 1.76
PEFO1 2000 15.88 4.87 1.30 4.88 2.25 0.69 1.90
PEFO1 2001 13.88 4.79 1.42 3.13 1.73 0.76 2.05
PEFO1 2002 15.91 5.08 1.91 3.22 2.08 1.14 2.48
PEFO1 2003 18.02 4.87 1.73 4.56 2.12 0.95 3.77
               
Slope (1/Mm/Year)   0.160 -0.078 0.107 0.048 -0.043 0.022 0.086
S-Value   7 -15 21 5 -19 19 11
P-Value   0.300 0.108 0.036 0.364 0.054 0.054 0.190

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)
PEFO1 1994 8.97 2.83 1.04 2.16 1.17 0.41 1.35
PEFO1 1995 8.64 2.57 1.01 2.05 1.47 0.45 1.10
PEFO1 1996 8.44 2.50 1.02 2.08 1.34 0.36 1.14
PEFO1 1997 9.51 2.82 0.58 2.74 1.52 0.51 1.35
PEFO1 1998 9.41 3.00 0.79 2.32 1.16 0.41 1.73
PEFO1 1999 9.20 2.75 0.60 2.61 1.50 0.53 1.20
PEFO1 2000 8.24 2.58 0.77 2.30 1.42 0.30 0.86
PEFO1 2001 8.33 2.89 1.10 1.61 1.20 0.40 1.13
PEFO1 2002 8.54 2.73 0.96 1.77 1.44 0.54 1.11
PEFO1 2003 8.90 2.46 0.76 2.63 1.66 0.32 1.07
               
Slope (1/Mm/Year)   -0.051 -0.012 -0.011 0.005 0.019 -0.001 -0.031
S-Value   -9 -7 -9 1 11 -1 -17
P-Value   0.242 0.300 0.242 0.500 0.190 0.500 0.078

Page last updated 30 March 2005