Vegetation Greening Offsets Urbanization‐Induced Fast Warming in Guangdong, Hong Kong, and Macao Region (GHMR)

Abstract

 The effect of urbanization on the surface air temperature (SAT) decreases over time as regional vegetation greening increases. The urbanization effect on the land surface temperatures (LST) from the long time series of satellite retrievals remains significant. The anthropogenic heat was found to have a limited influence on SAT, but more significant and tangible effects on LST.

Modeling and Preliminary Analysis of the Impact of Meteorological Conditions on the COVID-19 Epidemic

“…PLSR analysis extracts the variables with the strongest explanatory power for the dependent variable by decomposing and filtering the data information, thus effectively overcoming the undesirable effects of multiple correlations of variables in system modeling. The PLSR model performs well in the separation of the influence of the external forcings on surface air temperature and precipitation [40][41][42]. Unlike the traditional MLR analysis method, it first obtains the standardized matrices of the independent and dependent variables through standardization, then performs principal component analysis on the independent variables, extracts the principal component corresponding to the largest eigenvalue that is most closely related to the dependent variable and the corresponding load vector, and uses this principal component to regress with the dependent variable to find the respective residual matrices; then performs similar processing on the residual matrices, and so on analogously.…”

Comparisons of the Urbanization Effect on Heat Stress Changes in Guangdong during Different Periods

“…In the PLSR analysis, thermal comfort indices were set as dependent variables, while seasonal averages of RH, PRE, SSD, WIN, LSTd, LSTn, and EVI and annual averages of AHF and DEM were set as independent variables. It should be noted that the environment within a 5 km radius of the weather station would affect the recording of atmospheric variables in field observations [53][54][55]. To reduce the uncertainty of driving factor analysis, the average value of satellite observations (EVI, LST, and AHF) in a buffer zone within a 5 km radius around each station were used in the PLSR analysis.…”

“…The contribution rate of urbanization to the summer direct thermal comfort indices is close to one-third of the total warming from 1979-2018 (Table 2), which is consistent with the contribution rate of urbanization warming to the mean temperature (32.03%), while the contribution rate of urbanization to UTCI is significantly higher (50%). However, from 2004 to 2018, the greening in Guangdong Province has a mitigating effect on urbanization warming [55]. Therefore, to investigate whether urbanization contributes significantly to the thermal comfort indices warming during the greening period, we also use the AMR approach to quantify the effect of urbanization on the four thermal comfort indices from 2004-2018 (greening mitigated warming in this period) (Table 2, see also Figure 5).…”

“…The urbanization effect on changes in the physiological index still reaches significant levels and needs to be considered. However, from 2004 to 2018, the greening in Guangdong Province has a mitigating effect on urbanization warming [55]. Therefore, to investigate whether urbanization contributes significantly to the thermal comfort indices warming during the greening period, we also use the AMR approach to quantify the effect of urbanization on the four thermal comfort indices from 2004-2018 (greening mitigated warming in this period) (Table 2, see also Figure 5).…”

“…A 10% decrease in relative humidity (from 85% to 75%) at 28 • C can result in a decrease of approximately 0.72-1.5 • C in the four thermal indices, while a 1 • C decrease in air temperature at a certain relative humidity can result in a decrease of approximately 1-2.3 • C in the four thermal indices. Accordingly, the direct thermal comfort indices are marginally more sensitive to air temperature changes than relative humidity, which may lead to urbanization having exactly the same effect on the direct thermal comfort indices as air temperature [22,26,29,55]. In the context of continuous urbanization and climate change, the sensitivity of thermal comfort indices to temperature changes remains higher than that of relative humidity even in coastal areas with high relative humidity [35].…”