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Grand Canyon National Park (INGA1) Trends Analysis
The tables and figures below show the trends analysis results for 20% worst, middle 60% and 20% best days at INGA1 based on light extinction coefficient data from 1994 to 2003. Overall, there is no significant  trend in aerosol light extinction in 20% worst days. Nitrate and OMC extinctions increased significantly, while CM extinctions decreased significantly in the worst days. Aerosol light extinction coefficients decreased significantly in both middle 60% days and  20% best days. In the middle 60% days the decrease trend is due to decrease in sulfate and CM light extinction coefficients, and in the 20% best days it is due to nitrate and CM.

Table 1. Number of valid measurements used in the trends analysis
Site Year StartDate EndDate NoMeas
INGA1 1994 1/1/1994 12/31/1994 84
INGA1 1995 1/4/1995 12/30/1995 68
INGA1 1996 1/10/1996 12/28/1996 56
INGA1 1997 1/1/1997 12/27/1997 53
INGA1 1998 1/14/1998 11/28/1998 77
INGA1 1999 1/27/1999 12/22/1999 61
INGA1 2000 1/8/2000 12/29/2000 56
INGA1 2001 1/1/2001 12/6/2001 73
INGA1 2002 1/17/2002 12/31/2002 71
INGA1 2003 1/3/2003 12/29/2003 84
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)
INGA1 1994 28.13 9.90 1.12 7.46 2.72 1.67 5.26
INGA1 1995 28.89 10.03 1.18 7.26 2.44 1.69 6.29
INGA1 1996 24.35 6.90 1.14 6.57 1.93 2.87 4.95
INGA1 1997 39.02 13.50 1.74 7.70 2.02 1.77 12.29
INGA1 1998 29.09 9.14 1.23 9.53 2.86 1.64 4.69
INGA1 1999 27.98 5.83 1.40 10.85 3.85 1.82 4.23
INGA1 2000 31.41 7.70 3.74 10.74 2.68 2.54 4.00
INGA1 2001 32.26 8.12 2.40 12.44 3.46 2.27 3.58
INGA1 2002 25.18 7.76 2.46 6.04 1.77 2.51 4.63
INGA1 2003 38.84 6.12 2.58 19.83 3.76 1.71 4.84
               
Slope (1/Mm/Year)   0.561 -0.345 0.170 0.862 0.116 0.031 -0.210
S-Value   11 -17 33 21 9 11 -21
P-Value   0.190 0.078 0.001 0.036 0.242 0.190 0.036

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)
INGA1 1994 17.41 5.98 1.20 4.50 1.60 1.10 3.04
INGA1 1995 18.57 6.69 1.22 4.09 1.97 0.76 3.84
INGA1 1996 16.43 4.23 1.32 3.63 1.51 1.18 4.55
INGA1 1997 18.30 5.90 0.97 4.50 1.79 1.03 4.11
INGA1 1998 18.15 5.36 1.10 5.23 2.06 0.85 3.56
INGA1 1999 17.05 4.62 1.28 5.49 2.16 0.96 2.53
INGA1 2000 16.85 5.43 1.25 5.07 1.85 1.10 2.15
INGA1 2001 15.36 5.67 1.18 3.67 1.38 1.08 2.38
INGA1 2002 14.62 4.50 1.40 3.60 1.17 1.28 2.66
INGA1 2003 11.32 3.63 1.17 3.13 1.01 0.58 1.80
               
Slope (1/Mm/Year)   -0.565 -0.216 0.009 -0.077 -0.072 -0.001 -0.255
S-Value   -31 -21 3 -13 -15 -1 -25
P-Value   0.002 0.036 0.431 0.146 0.108 0.500 0.014

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)
INGA1 1994 9.05 3.09 1.44 1.99 0.73 0.32 1.48
INGA1 1995 9.51 2.38 1.32 2.27 1.03 0.42 2.09
INGA1 1996 7.99 1.84 1.17 2.14 0.96 0.49 1.40
INGA1 1997 9.64 2.97 0.71 2.28 1.20 0.29 2.18
INGA1 1998 8.30 2.26 0.68 2.50 0.88 0.37 1.61
INGA1 1999 10.67 3.25 0.53 3.75 1.27 0.53 1.34
INGA1 2000 7.51 2.31 0.44 2.19 1.18 0.33 1.08
INGA1 2001 8.51 3.61 0.69 1.88 0.97 0.53 0.83
INGA1 2002 6.36 2.47 0.69 1.37 0.68 0.28 0.86
INGA1 2003 4.94 1.62 0.45 1.46 0.55 0.20 0.66
               
Slope (1/Mm/Year)   -0.399 -0.031 -0.106 -0.065 -0.038 -0.013 -0.161
S-Value   -19 -3 -29 -11 -9 -9 -31
P-Value   0.054 0.431 0.005 0.190 0.242 0.242 0.002

Page last updated 30 March 2005