Transformative Urban Changes of Beijing in the Decade of the 2000s

Alessandro Sorichetta,Son V Nghiem,Catherine Linard,Marco Masetti,Andreas Richter

doi:10.3390/rs12040652

Abstract

The rapid economic growth, the exodus from rural to urban areas, and the associated extreme urban development that occurred in China in the decade of the 2000s have severely impacted the environment in Beijing, its vicinity, and beyond. This article presents an innovative approach for assessing mega-urban changes and their impact on the environment based on the use of decadal QuikSCAT (QSCAT) satellite data, acquired globally by the SeaWinds scatterometer over that period. The Dense Sampling Method (DSM) is applied to QSCAT data to obtain reliable annual infrastructure-based urban observations at a posting of ~1 km. The DSM-QSCAT data, along with different DSM-based change indices, were used to delineate the extent of the Beijing infrastructure-based urban area in each year between 2000 and 2009, and assess its development over time, enabling a physical quantification of its urbanization which reflects the implementation of various development policies during the same time period. Eventually, as a proxy for the impact of Beijing urbanization on the environment, the decadal trend of its infrastructure-based urbanization is compared with that of the corresponding tropospheric nitrogen dioxide (NO2) column densities as observed from the Global Ozone Monitoring Experiment (GOME) instrument aboard the second European Remote Sensing satellite (ERS-2) between 2000 and 2002, and from the SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY aboard of the ESA’s ENVIronmental SATellite (SCIAMACHY /ENVISAT) between 2003 and 2009. Results reveal a threefold increase of the yearly tropospheric NO2 column density within the Beijing infrastructure-based urban area extent in 2009, which had quadrupled since 2000.

Highlights

The rapid economic growth, the exodus from rural to urban areas, and the associated extreme urban development that occurred in China in the decade of the 2000s have severely impacted the environment in Beijing, its vicinity, and beyond
The Dense Sampling Method (DSM)-QSCAT data, along with different DSM-based change indices, were used to delineate the extent of the Beijing infrastructure-based urban area in each year between 2000 and 2009, and assess its development over time, enabling a physical quantification of its urbanization which reflects the implementation of various development policies during the same time period
The Intergovernmental Panel on Climate Change (IPCC) Working Groups (WG) II and III recognize that a large fraction of greenhouse gases from power generation, industry, transportation, and consumption can be attributed to human settlements [1]

Summary

Introduction

The Intergovernmental Panel on Climate Change (IPCC) Working Groups (WG) II and III recognize that a large fraction of greenhouse gases from power generation, industry, transportation, and consumption can be attributed to human settlements [1]. An innovative approach for consistently and quantitatively assessing infrastructure-based urbanization over space (i.e., horizontal and vertical urbanization/urban growth) and time, and its impact on the environment, is demonstrated for Beijing as a case study (Figure 1) Such an approach is based on the use of (i) decadal level L1B Ku-Band (at the frequency of 13.4 GHz and wavelength of 2.24 cm) radar backscatter data, collected by the SeaWinds scatterometer aboard the QuikSCAT satellite ( referred to as QSCAT data) [28], and (ii) decadal tropospheric nitrogen dioxide (NO2) column densities, retrieved from the Global Ozone Monitoring Experiment (GOME) spectrometer on the European Remote Sensing Satellite 2 (ERS-2) [29,30] and the SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY) aboard the European Space Agency’s (ESA) ENVIronmental SATellite (ENVISAT) [31]. Beijing is surrounded by three other highly populated, urbanized, and industrialized provinces, with four large cities having between 3.3 and 9.1 million inhabitants [7], which are considered significant contributors in the deterioration of Beijing’s air quality [8,37,38]

QSCAT Data and Dense Sampling Method for Urban Observations

Findings

Surface Change Indices