Tab. 2 Parameters of PM2.5 maps

Linear regression model + interpolation of residuals Annual average
rural areas urban background
c (constant) 2.4 1.8
a1 (rural map of PM10) 0.66  
a2 (urban map of PM10)   0.69
range [km] 50 160
nugget 2 2
partial sill 2 6
weight IDW 1 1
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