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China is exposed to a wide range of natural hazards, and disaster losses have escalated over the past decade. Owing to the pressure from natural disasters, along with changes in climate, social conditions, and regional environment, assessment of social vulnerability (SV) to natural hazards has become increasingly urgent for risk management and sustainable development in China. This paper presents a new method for quantifying SV based on the projection pursuit cluster (PPC) model. A reference social vulnerability index (SVI) at the county level was created for the Yangtze River Delta area in China for 1995, 2000, 2005, and 2009. The result of social vulnerability assessment was validated using data of actual losses from natural disasters. The primary findings are as follows: (i) In the study area, the major factors that impact SVI are regional per capita GDP and per capita income. (ii) The study area was more vulnerable in 1995 than in later years. SV of the whole region had decreased over the study period. (iii) Most part of Shanghai and the southeast part of Jiangsu Province had been the least vulnerable within the region. From this least vulnerable zone to the periphery of the region, the situation deteriorated. The highest SVI values in all evaluated years were found in the northern, western, or southern tips of the Yangtze River Delta. [ABSTRACT FROM AUTHOR]

Understanding the dynamics of urbanization and induced environmental changes on a regional scale is essential for policy makers to address the growing challenges of local sustainability and global climate change. Choosing the Yangtze River Delta (YRD) region of China as a case study, this paper focuses on the long-term urbanization process, its consequences on the spatio-temporal changes on the landscape and associated carbon sources and sinks, and policy drivers behind these changes. Differing from previous research, this paper highlights a systematic analysis of the dynamic process and policies related to urbanization and associated environmental changes through the integration of interdisciplinary, region-based and data-intensive approaches. The results indicate that the urbanization of the YRD region experienced a three-staged trajectory from regressive during 1960–1978 to progressive but unbalanced development from 1978 to 2010. Landscape changes occurred at an unprecedented rate with the encroachment of urbanized terrain on cropland, cropland exploitation, and the reclamation of forest and water as the dominant types. Both carbon sources and sinks have increased significantly from 1995 to 2010, while the spatial net carbon intensity of built-up land shows a significant jump due to the faster growth of carbon emissions than the already astonishing expansion of urban land. Policy implications include improving the social welfare systems, strengthening ecological land conservation and urban sprawl control polices, and reforming the economic structure, especially in Jiangsu province, toward a low-carbon one. [ABSTRACT FROM AUTHOR]

Yangtze River Delta (YRD) region has experienced a remarkable urbanization during the past 30years, and regional climate change and air pollution are becoming more and more evident due to urbanization. Impacts of urban canopy on regional climate and air quality in dry- and wet-season are investigated in this paper, utilizing the Weather Research and Forecasting/Chemistry (WRF/Chem) model. Four regimes of urban canopy schemes with updated USGS land-use data in actual state of 2004 base on MODIS observations are examined: (1) SLAB scheme that does not consider urban canopy parameters (the control experiment in this paper); (2) a single-layer urban model with a fixed diurnal profile for anthropogenic heat (UCM); (3) multilayer urban canopy model (BEP-Building effect parameterization); (4) multilayer urban models with a building energy model including anthropogenic heat due to air conditioning (BEP+BEM). Results show that, compared with observations, the best 2-m temperature estimates with minimum bias are obtained with SLAB and BEP+BEM schemes, while the best 10-m wind speed predictions are obtained with BEP and BEP+BEM scheme. For PM10 and ozone predictions, BEP+BEM scheme predicted PM10 well during January, while the best estimate of PM10 is obtained with UCM scheme during July, BEP+BEM and SLAB schemes best estimated ozone concentrations for both the two months. Spatial differences of meteorological factors between canopy schemes and control scheme show that compared with SLAB scheme, BEP and BEP+BEM schemes cause an increase of temperature with differences of 0.5°C and 0.3°C, respectively, UCM scheme simulates lower temperature with decrease of 0.7°C during January. In July, all the canopy experiments calculates lower air temperature with reduction of 0.5°C–1.6°C. All the canopy experiments compute lower 10-m wind speed for both January and July. Decreases were 0.7m/s (0.8m/s) with UCM, 1.7m/s (2.6m/s) with BEP, and 1.8m/s (2.3m/s) with BEP+BEM schemes in January (July), respectively. For chemical field distributions, results show that, compared with SLAB scheme, UCM scheme calculates higher PM10 concentration in both January and July, with the differences of 22.3% (or 24.4μg/m3) in January, and 31.4% (or 17.4μg/m3) in July, respectively. As large as 32.7% (or 18.3 μg/m3) of PM10 increase is found over Hangzhou city during July. While 18.6% (or 22.1 μg/m3) and 16.7% (or 24.6 μg/m3) of PM10 decreases are fund in BEP and BEP+BEM schemes during January. Compared with control experiment during January, 6.5% (or 2.6ppb) to 10.4% (4.2ppb) increases of ozone are computed over mage-cities by canopy experiments. All the three canopy schemes predict lower ozone concentrations and as large as 30.2% (or 11.2ppb) decrease is obtained with UCM scheme, and 16.5% (6.2ppb) decrease with BEP scheme during July. The SLAB scheme is suitable for real-time weather forecast while multiple urban canopy scheme is necessary when quantify the urbanization impacts on regional climate. [ABSTRACT FROM AUTHOR]

Abstract: The spatial and temporal characters of tropospheric NO2 column over Yangtze River Delta (YZD) are analyzed using monthly averaged tropospheric NO2 column densities from GOME (1996-2002) and SCIAMACHY (2003-2010) measurements. In addition, with the NO2 column densities data and the land cover maps of YZD, the characters of NO2 concentration over different ecosystem have been analyzed. The results indicated that the tropospheric NO2 column densities in YZD increased distinctly from 1996 to 2010 and it showed distinct regional and seasonal variation characteristics. It has the highest concentration in winter while lowest in summer. It also presents zonal distribution and decreasing along the Yangtze River from eastern to western. Under the influence of the urbanization process, the highest NO2 column densities appeared at cities and metropolis which are located in the Shanghai, Nanjing as well as Hangzhou. Moreover the lowest column densities appeared at the forest areas which are in the south and west of Zhejiang province. The sharp increasing of appeared in water bodies, followed urban area and water bodies. The lowest increasing of NO2 column appeared in grassland. Furthermore, we inferred the ground-level NO2 concentration from the GOME and SCIAMACHY data in this paper. We compared with the dry plus of N deposition which inferred from the remote sensing data and the mass concentration of N dry deposition from the control experiments, they performed significant correlation (P<0.001), and have the high R value (R2=0.86). [Copyright &y& Elsevier]

Abstract: The Yangtze River Delta (YRD), one of China’s most developed, dynamic, densely populated and concentrated industrial area, is growing into an influential world-class metropolitan area and playing an important role in China’s economic and social development. The formation and the urbanization process of YRD are inseparable from climate change. This paper explores such interrelationship from two perspectives. On one hand, using historic data, we summarized the urbanization process in the YRD, and concluded that climate change has been shaping the Delta and its socioeconomic development. On the other hand, the urbanization process of the Delta has shaped its geography and built environment, which, however, are not adaptable to future climate change. Potential disruptive effects include large flooded land area, flood disasters, production and energy inefficiency, and other environmental threats. It is imperative to adopt policies and programs to mitigate and adapt to climate change in the fast urbanization process. [Copyright &y& Elsevier]

Urban land expansion is one of the most conspicuous aspects of urbanization and has profound impacts on regional climate change. Most studies, however, focus on its impacts on surface temperature, and possible effects on atmospheric humidity are less known. By examining the humidity changes in the Yangtze River Delta urban agglomeration of China during 1961–2014, we find a prominent urban dry island (UDI) effect in this urban agglomeration, as characterized by reduced humidity and increased vapor pressure deficit in the urban core area. In the past decades, the UDI effect has been significantly intensified by rapid urban land expansion. Urban expansion contributes to around half of the decrease in atmospheric humidity and the increase in vapor pressure deficit in urban areas. These effects are particularly stronger in wet hot summer and relatively weaker in cold dry winter. We suggest that the UDI effect should be considered in future urban planning, landscape design, and climate change assessment and mitigation. Plain Language Summary: The effect of urbanization on climate is an important concern in sustainability and climate change mitigation. While it is well known that urbanization has profound impacts on the urban heat island, much less is known about the impacts on atmospheric humidity, a key indicator in climate and hydrometeorology science. Here we show that a prominent urban dry island (UDI) effect, characterized by reduced humidity and enhanced vapor pressure deficit, appears in the Yangtze River Delta urban agglomeration of east China, one of the largest mega‐urban regions of the world. This UDI effect has been significantly intensified with increasing artificial built‐up surfaces and urban heat island. Urban expansion can contribute to nearly half of the decrease in atmospheric humidity and the increase in vapor pressure deficit in urban core areas. Key Points: An urban dry island effect is noticeable in the urban agglomeration of the Yangtze River Delta of east ChinaThe urban dry island effect has been significantly enhanced by rapid urban land expansion in the past several decadesUrban expansion contributes to around half of the decrease in atmospheric humidity and the increase in vapor pressure deficit [ABSTRACT FROM AUTHOR]

The Yangtze River Delta (YRD) is one of largest river deltas and metropolitan areas in the world with strong human interference, so it is vulnerable to extreme weather events. Based on daily precipitation dataset of 16 rain gauges in Yangtze River Delta and Mann-Kendall trend detection techniques, the trend in annual and seasonal precipitation extremes has been investigated in the period 1957-2013. Possible links between changes in extreme precipitation and monsoon indices have also been explored. The results show that: (1) the increasing trends of consecutive wet days, maximum daily precipitation, maximum 5-day precipitation and maximum precipitation amount in the past 57 years in YRD can be detected. Much attention should be paid to higher risk of flash flood in these areas, especially in big cities of Shanghai, Nanjing, Hangzhou and Ningbo. (2) Both precipitation days and amount of heavy events (defined as over 90th, 95th and 99th) exhibit overwhelming upward tendency in summer and winter throughout YRD. The summer is to meet with heavier precipitation events as result of larger increasing magnitude in heavy rain days and amounts in the past 57 years. So, high importance should be placed on the relief for flood in summer in the large cites. (3) There is an abrupt change point for extreme precipitation events, and increased annual total precipitation has impact on the upward tendency of heavy rainfall events in YRD on great scale. In addition, the significant correlations between indices (P90, P95, R90 and R95) and monsoon indices (East Asian Summer Monsoon Index and South Asia Summer Monsoon Index) indicate that extreme precipitation events are related to the EASMI and SASMI. Therefore, these properties of precipitation extremes are of great significance to the control of natural hazards in YRD with high degree of human activities and understanding the impact of climate change on hydrologic processes. [ABSTRACT FROM AUTHOR]

Located in the ‘Hot Summer Cold Winter’ climatic zone of China, the Yangtze River Delta area is one of the most challenging regions for providing occupant comfort in buildings, and effects of climate change in the next 100 years will make further increase in energy consumption. This article uses climate change data from HadCM3 to generate test reference years (TRYs) compiled for 2020s, 2050s and 2080s under various future scenarios for the cities of Ningbo, Shanghai and Hangzhou. Simulations were then conducted to see if effects of climate change can be contained or even reversed with improvements in building standards, and it was shown that energy consumption can be significantly reduced with building improvements, even in the face of climate change. [ABSTRACT FROM AUTHOR]

Based on the monthly mean values of 10 meteorological elements from 53 surface weather stations in the Yangtze Delta and its adjacent areas during 1961–1997, the part played by linear climate trends has been analyzed to explore the characteristics of the regional climate change. The results show that the annual air temperature, and maximum and minimum air temperatures, have all increased rapidly in the Yangtze Delta, but there has been a reverse trend in its adjacent areas, i.e., the air temperatures have gradually decreased. Thus the Yangtze Delta emerges as a regional heat island in relation to its adjacent areas. The regional heat island consists of several urban heat sub-islands in southern Jiangsu Province and northern Zhejiang Province, including Shanghai, Wuxi, Changshu, Nanjing, Hangzhou and Ningbo. It appears most obvious in winter and least obvious in summer. An intensity of the regional heat island is defined, and it is shown that the variation of the heat island is positively correlated to the economic development of the region, and is assumed to be related with the increased consumption of energy due to economic development. The results of a climatological analysis of the other annual meteorological elements have indicated the tendency that the soil temperature of the Yangtze Delta has a weak cooling process, its precipitation has evidently increased, sunshine duration and visibility have apparently decreased, and the trend centers appear mainly in the cities. All these phenomena imply that air pollution and aerosols increase with economic development, leading to a cooling mechanism, which in turn suppresses the enhancement of the heat island caused by increasing consumption of energy. On the other hand, an intensified heat island also makes convection and precipitation increase. For the adjacent areas whose economic development is less intense than the Yangtze Delta, a weak cooling appeared there because their heat island caused by increasing consumption of energy resources could not offset the cooling due to aerosols. It can be seen from satellite images that the increase of aerosols in the Yangtze Delta is more obvious than its adjacent areas. By use of a three-region nested mesoscale model, a series of simulations are made with no-forcing and forcing of the optical depth of aerosol and the heating due to energy consumption by human activities. The results of the analysis and the simulation coincide very well. The simulations support the above-mentioned mechanisms of the regional heat island in the Yangtze Delta of China. [ABSTRACT FROM AUTHOR]