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Table 1 Mann-Kendall statistics of annual total illuminance in typical Chinese climate regions

From: The trend of natural illuminance levels in 14 Chinese cities in the past 50 years

Cities Z value Average annual total value (108 lx) Trend Q′ Regression equation R2value
Beijing -5.571 90.9 Decrease -0.37 y = -0.37x + 826.38 0.663
Changchun -1.477 86.13 Decrease -0.06 y = 0.06x + 206.2 0.045
Erenhot -2.18 106.2 Decrease -0.098 y = -0.098x + 301.04 0.02
Guangzhou -2.71 80.3 Decrease -0.17 y = -0.174x + 426.14 0.138
Heihe 0.078 78.4 Increase 0.0036 y = -0.123x + 71.3 0
Urumchi -3.04 91.1 Decrease -0.123 y = -0.123x + 335.52 0.21
Xi'an -3.7 83.3 Decrease -0.31 y = -0.31x + 704.6 0.276
Xining -4.215 105.6 Decrease -0.28 y = -0.28x + 662.4 0.238
Yushu -1.3 113.9 Decrease -0.19 y = -0.19x + 500.9 0.1
Fuzhou -0.044 83.5 Decrease -0.0026 y = 0.003x + 88.7 0
Kunming 2.357 102.8 Increase 0.188 y = 0.19x -270.4 0.11
Shanghai -2.56 86.1 Decrease -0.14 y = -0.14x + 369.8 0.16
Changsha -3.69 76.9 Decrease -0.26 y = -0.26x + 602.7 0.28
Chongqing -3.96 63 Decrease -0.24 y = -0.24x + 547.8 0.34