Analysis of the Urban Heat Island Effect in Shijiazhuang, China Using Satellite and Airborne Data

Abstract

Abstract:The urban heat island (UHI) effect resulting from rapid urbanization generally has a negative impact on urban residents. Shijiazhuang, the capital of Hebei Province in China, was selected to assess surface thermal patterns and its correlation with Land Cover Types (LCTs). This study was conducted using Landsat TM images on the mesoscale level and airborne hyperspectral thermal images on the microscale level. Land surface temperature (LST) was retrieved from four scenes of Landsat TM data in the summer days to analyze the thermal spatial patterns and intensity of surface UHI (SUHI). Surface thermal characteristics were further examined by relating LST to percentage of imperious surface area (ISA%) and four remote sensing indices (RSIs), the Normalized Difference Vegetation Index (NDVI), Universal Pattern Decomposition method (VIUPD), Normalized Difference Built-up Index (NDBI) and Biophysical Composition Index (BCI). On the other hand, fives scenes of airborne TASI (Thermal Airborne Spectrographic Imager sensor) images were utilized to describe more detailed urban thermal characteristics of the downtown of Shijiazhuang city. Our results show that an obvious surface heat island effect OPEN ACCESSRemote Sens. 2015, 7 4805 existed in the study area during summer days, with a SUHI intensity of 2-4 °C. The analyses reveal that ISA% can provide an additional metric for the study of SUHI, yet its association with LST is not straightforward and this should a focus in future work. It was also found that two physically based indices, VIUPD and BCI, have the potential to account for the variation in urban LST. The results concerning on TASI indicate that diversity of impervious surfaces (rooftops, concrete, and mixed asphalt) contribute most to the SUHI, among all of the land cover features. Moreover, the effect of impervious surfaces on LST is complicated, and the composition and arrangement of land cover features may play an important role in determining the magnitude and intensity of SUHI. Overall, the analysis of urban thermal signatures at two spatial scales complement each other and the use of airborne imagery data with higher spatial resolution is helpful in revealing more details for understanding urban thermal environments.Keywords: urban heat island (UHI); land cover types (LCTs); impervious surface area (ISA); thermal airborne spectrographic imager (TASI)

An Assessment of Urban Surface Energy Fluxes Using a Sub-Pixel Remote Sensing Analysis: A Case Study in Suzhou, China

“…Biases of 5.59 and 10.80 were achieved for the low-medium density impervious surface areas and the high-density impervious surface areas, respectively. Compared to the results of our previous studies that were based on simple spectral mixture analyses [54,55], the results achieved in this study were acceptable. …”

“…In addition, integrating the urban heat energy with VFC and ISA% with appropriate intervals may yield interesting findings. Therefore, on the basis of prior studies that examined the urban thermal environment [54,63,64], a zonal analysis was performed to examine the mean value of LST and heat flux on an increment of vegetation coverage from 0.1-1 and with an increment of ISA% from 10-100. The correlations between LST and VFC and ISA% are illustrated in Figure 7.…”

“…To evaluate the accuracy of the predicted abundance images of vegetation cover and impervious surfaces using MESMA (see Figure 4a,b), following our previous studies [54,55], 100 sample plots were randomly selected, and the corresponding reference values were obtained from a Google Earth™ image from 12 May 2010. As illustrated in Figure 5, the regression analysis showed a relationship with an R 2 of 0.85 and a slope of 0.96 regarding the VFC.…”

Evaluating an Enhanced Vegetation Condition Index (VCI) Based on VIUPD for Drought Monitoring in the Continental United States

“…Narrowband hyperspectral data-based VIUPD has been proven to be sensitive to spectral operations and was more sensor-independent than the other 11 vegetation indices, including the NDVI and EVI [23]. VIUPD also showed great potential to discern variations in urban LST when it was used to analyze the urban heat island effect in Shijiazhuang, China [24]. VIUPD was also applied to the inversion of crop chlorophyll content, and was found to have greater accuracy and stability when estimating the chlorophyll content of winter wheat than the NDVI, the triangle vegetation index (TVI), and the ratio of modified transformed chlorophyll absorption ratio index [25].…”

An Unmanned Airship Thermal Infrared Remote Sensing System for Low-Altitude and High Spatial Resolution Monitoring of Urban Thermal Environments: Integration and an Experiment

“…Although an airborne platform with a thermal infrared multispectral scanner, such as with a thermal airborne spectrographic imager (TASI), can provide better spatial resolution than satellites, the exorbitant price, operational technicality, and high maintainance costs limit its application widely [23][24][25][26]. In this case, this paper developed UALTIRSS and its experimental method for observing micro-scale thermal environments with high-resolution data.…”