Table 1 Principal component factors and corresponding representative indicators

From: Diversified evolutionary patterns of surface urban heat island in new expansion areas of 31 Chinese cities

Factor

Definition

Representative Indicators

FAC 1

Economy-dominated

GDP_ M (−0.86*), DEM (0.84*), Lon (−0.81*), GDP_R (0.71*)

FAC 2

Climate-dominated

Prep (0.91*), Lat (−0.87*), Tem (0.86*)

FAC 3

Industry-dominated

PSI (0.91*), PTI (−0.89*), Light_R (0.82*)

FAC 4

Population-dominated

PD_M (0.79*), Light_M (0.79*), Grey_M (0.73*)

FAC 5

Population-industry-dominated

PD_R (0.88*), PPI (−0.86*)

FAC 6

Landscape-dominated

Green_R (−0.77*), Grey_R (0.75*)

FAC 7

Water-dominated

Blue_M (0.82*)

  1. *represents the significance at 0.01 level (two-tailed). DEM, average DEM of urban expansion area; Prep, multi-year average precipitation of urban expansion area; Tem, multi-year average temperature of urban expansion area; Lat, latitude of the city center; Lon, longitude of the city center; Grey_M and Blue_M, average area proportion of gray/blue space in urban expansion area in 2000 and 2018, respectively; Grey_R and Green_R, change rate of area proportion of gray/green space in urban expansion area from 2000 to 2018, respectively; PD_M, Light_M, and GDP_M, average population density, nighttime light intensity and GDP in urban expansion area in 2000 and 2018, respectively; PD_R, Light_R, and GDP_R, the change rate of population density, nighttime light intensity and GDP in urban expansion area from 2000 to 2018, respectively; and PPI, PSI, and PTI, the proportion of primary, secondary and tertiary industrial output of the city in 2018, respectively.
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