Contribution of Urban Surface Expansion to Regional Warming in Beijing, China

2017 ◽  
Vol 56 (6) ◽  
pp. 1551-1559 ◽  
Author(s):  
Deming Zhao ◽  
Jian Wu
Keyword(s):  
Urban Areas ◽  
Dynamical Downscaling ◽  
Urban Surface ◽  
Anthropogenic Activity ◽  
Regional Warming ◽  
Considerable Uncertainty ◽  
Surface Areas ◽  
Surface Expansion ◽  
Urban Surface Expansion ◽  
Beijing China

AbstractThe contribution of urban surface expansion to regional warming as detected from meteorological observational station data may vary with considerable uncertainty because of the spatial heterogeneity of such data—a situation that promotes a requirement for numerical model-based investigations. Satellite-based images from 1980 to 2016 that have fine resolution over three city clusters and that display the urban surface expansion in China from rapid economic development and anthropogenic activity were used to perform 37-yr nested dynamical downscaling using the Weather Research and Forecasting (WRF) Model. The urban surface areas in Beijing, China, expressed marked expansion in the last 37 years. The contribution of urban surface expansion to regional warming was approximately 22% of the overall warming in Beijing and was stronger in the plains areas of Beijing (42%). The contributions to land-use grids that changed from nonurban (in 1980) to urban (in 2016; N2U) were much stronger than those to grids that were classified as urban in both time periods (U2U), which were closer to the values of urban areas (including N2U and U2U) because of the intense increase in urban surface areas. Urban-related warming expressed marked annual variation and was greater in the warm seasons and smaller in the cold seasons. The greater increase in surface air temperature (SAT) minimum and the weaker SAT maximum accounted for the decreased diurnal temperature range.

scholarly journals Modelling Daily Mean Surface Air Temperature Calculated from Different Methods and Its Impact on Urban-Related Warming Evaluations over Guangzhou and Shenzhen Using the WRF Model

Atmosphere ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 48
Author(s):  
Deming Zhao ◽  
Jian Wu
Keyword(s):  
Air Temperature ◽  
Diurnal Cycle ◽  
Climate Model ◽  
Dynamical Downscaling ◽  
Spatial Scales ◽  
Wrf Model ◽  
Surface Air Temperature ◽  
Urban Surface ◽  
Surface Expansion ◽  
Urban Surface Expansion

The impacts of urban surface expansion, based on satellite-derived data displaying urban surface expansion in China at different spatial scales from 1980 to 2016, were investigated using nested dynamical downscaling methods with the Weather Research and Forecasting (WRF) regional climate model at a 3.3-km resolution over a city and city cluster scale. Urban-related warming, based on daily mean surface air temperature at 2 m (SAT), calculated from the averages of four time records each day (00, 06, 12, and 18 h UTC, T4) and averages of SAT maximum (Tmax) and minimum (Tmin) (Txn), was evaluated. Differences in urban-related warming contributions calculated using T4 and Txn were small, whereas annual mean SAT and trends calculated using Txn were respectively and significantly larger and smaller than those calculated using T4 over Guangzhou and Shenzhen, excluding the trends over middle-northern Shenzhen. The differences in annual mean SAT calculated using T4 and Txn are attributed to nonlinear or asymmetric variations with time for the diurnal cycle of SAT. Meanwhile, differences in trends between T4 and Txn are interpreted as a strong trend for Tmin and a weak one for Tmax, which mitigated the trend for Txn. The impacts on the evaluations of urban-related warming contributions calculated from different methods were the largest over the areas classified as urban surfaces in both time periods (U2U), especially during intense urban-surface-expansion periods between 2000 and 2016. The subregional performances in the changes in annual mean SAT, trends, and urban-related warming are attributed to urban-surface-expansion, which induced varied changes in the diurnal cycle due to asymmetric warming during the daytime and nighttime over different subregions.

scholarly journals The Influence of Urban Surface Expansion in China on Regional Climate

2017 ◽  
Vol 30 (3) ◽  
pp. 1061-1080 ◽  
Author(s):  
Deming Zhao ◽  
Jian Wu
Keyword(s):  
East Asia ◽  
Eastern China ◽  
Urban Land Use ◽  
Radiation Budget ◽  
Urban Surface ◽  
Eastern Coast ◽  
Total Cloud Amount ◽  
Surface Expansion ◽  
Urban Surface Expansion ◽  
The Impact

Abstract Incorporating satellite-based urban surface data for the 1980s, 1990s, 2000s, and 2010s in China, contributions to regional warming, and changes in the precipitation due to urban surface expansion were explored using the nested Fifth-generation Pennsylvania State University–NCAR Mesoscale Model version 3.7 (MM5V3.7) with urban effects considered. The impact on surface air temperature at 2 m (SAT) due to urban surface expansion between the 1980s and the 2010s revealed that annual urban-related warming was lower over East Asia (0.031°C) and China (0.075°C) but higher in eastern China (0.14°C), which experienced dramatic urbanization. Greater warming could be detected over urban surface areas in the three city clusters [Beijing–Tianjin–Hebei (BTH) and the Yangtze and Pearl River deltas (YRD and PRD, respectively)], which reached 1.06°, 0.84°, and 0.92°C, respectively. Urban-related warming was not limited to a single city or city clusters but extended over a SAT-increased belt that covered the eastern coast of China. Further analysis showed that urban-surface-expansion-induced changes in albedo and the total cloud amount contributed to the changes in the radiation budget, which resulted in strong surface radiative forcings in the urban surface (14.5, 11.2, and 11.7 W m−2 for BTH, YRD, and PRD, respectively). However, significant differences could be detected for the transition from nonurban to urban land use compared to those that were classified as urban in both time periods because of the varied albedo changes. The urbanization-related warming, especially in the city cluster areas, also had a further effect on the large-scale circulation and precipitation. The precipitation was weakened in northeastern and northern China but intensified in eastern and southern China, which resulted in the strengthened precipitation over China (0.016 mm day−1, 0.65%) and East Asia (0.011 mm day−1, 0.28%). Therefore, subregional characteristics with marked seasonal, interannual, and decadal variations were detected for the influence of the urban surface expansion.

scholarly journals Long-term effects of land use/land cover change on surface runoff in urban areas of Beijing, China

2013 ◽  
Vol 8 (1) ◽  
pp. 084596 ◽  
Author(s):  
Zhongchang Sun ◽  
Xinwu Li ◽  
Wenxue Fu ◽  
Yingkui Li ◽  
Dongsheng Tang
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Land Cover Change ◽  
Surface Runoff ◽  
Urban Areas ◽  
Land Use Land Cover ◽  
Long Term Effects ◽  
Effects Of Land Use ◽  
Beijing China

scholarly journals Temporal–Spatial Patterns of Relative Humidity and the Urban Dryness Island Effect in Beijing City

2017 ◽  
Vol 56 (8) ◽  
pp. 2221-2237 ◽  
Author(s):  
Ping Yang ◽  
Guoyu Ren ◽  
Wei Hou
Keyword(s):  
Relative Humidity ◽  
Urban Areas ◽  
Late Summer ◽  
Beijing City ◽  
Near Surface ◽  
Suburban Areas ◽  
Island Effect ◽  
Different Seasons ◽  
Autumn And Winter ◽  
Beijing China

AbstractHourly datasets obtained by automatic weather stations in Beijing, China, are developed and employed to analyze the spatial and temporal characteristics of relative humidity (RH) and urban dryness island intensity (UDII) over built-up areas. A total of 36 stations inside the sixth ring road are considered as urban sites, while six stations in suburban belts surrounding the built-up areas are taken as reference sites. Results show that the RH is obviously smaller in urban areas than in suburban areas, indicating the effect of urbanization on near-surface atmospheric moisture and RH. A further analysis of relations between RH and temperature on varied time scales shows that the variations in RH in the urban areas are not due solely to changes in temperature. The annual and seasonal mean UDII are high in central urban areas, with the strongest UDII values occurring in autumn and the weakest values occurring in spring. The diurnal UDII variations are characterized by a steadily strong UDII stage from 2000 to 0800 LT and a minimum at 1500 or 1600 LT. The rapid shifts of UDII from high (low) to low (high) occur during the periods 0800–1600 LT (1600–2000 LT). The occurrence time of the peaks varies among different seasons: the peaks appear at 0700, 2100, 2000, and 0800 LT for spring, summer, autumn, and winter, respectively. Further analysis shows that large UDII values appear in the evenings and early nights in late summer and early to midautumn and that low UDII values mainly occur in the afternoon hours of spring, winter, and late autumn.

Assessing the seasonal variability of shallow underground waters quality from a volcanic – sedimentary formation during El Niño event in Panama

2021 ◽  
Author(s):  
Mario Luis Miranda Montenegro ◽  
Ana Garcia ◽  
Raizha Batista ◽  
Obdulia de Montilla ◽  
Arkin Tapia ◽  
...  
Keyword(s):  
Drinking Water ◽  
El Niño ◽  
Urban Areas ◽  
El Nino ◽  
Anthropogenic Activity ◽  
Human Populations ◽  
Ph Values ◽  
El Niño Event ◽  
Geological Conditions ◽  
Groundwater Reserves

Abstract Providing drinking water to growing populations has become a worldwide concern. Therefore, in many countries some groundwater reserves are now being used to supply drinking water in remote urban areas. The state of these groundwater reserves is strongly influenced by the local geological conditions. Furthermore, climate change has caused a decrease in the periodicity of environmental conditions such as rainfalls, a key driver in replenishing these reserves. In 2019, the weak El Niño event affected the rainfall pattern, as well as physical and chemical quality of shallow ground waters in Panama. Within this study, the northwestern central region of Panama groundwaters have been systematically characterized during El Niño 2018 – 2019 event. Our results indicate that changes in values of physicochemical parameters such as alkalinity, pH and conductivity are related to changes in the amount of rainfall reported in the region starting from dry season (DS) to the rainy season (RS). Chloride was recorded as an indicator of anthropogenic activity and/or the effect of human populations on specific sites in the aquifer recharge zones. Lead (Pb2+), Zinc (Zn2+), Manganese (Mn2+), and Copper (Cu2+) concentrations in the groundwater were evaluated during the DS and RS 2019. Recorded data indicates sub – lethal concentrations of Pb2+, Zn2+, Mn2+ were associated to changes in alkalinity values of groundwater during the DS. While during the RS, a decrease in pH values favored the dissolution of Cu2+ and Zn2+. Our findings suggest that seasonal rainfall deficits modify shallow underground water alkalinity and pH values, inducing the redissolution of Pb2+, Zn2+, Mn2+, Cu 2+and exposing populations to sub – lethal concentrations of those microelements.

scholarly journals Monitoring of snow surface near-infrared bidirectional reflectance factors with added light-absorbing particles

2019 ◽  
Vol 13 (6) ◽  
pp. 1753-1766 ◽  
Author(s):  
Adam Schneider ◽  
Mark Flanner ◽  
Roger De Roo ◽  
Alden Adolph
Keyword(s):  
Near Infrared ◽  
Bidirectional Reflectance ◽  
Nondestructive Technique ◽  
Snow Albedo ◽  
Considerable Uncertainty ◽  
Clear Sky ◽  
Surface Areas ◽  
Microphysical Properties ◽  
Sky Conditions

Abstract. Broadband snow albedo can range from 0.3 to 0.9 depending on microphysical properties and light-absorbing particle (LAP) concentrations. Beyond the widely observed direct and visibly apparent effect of darkening snow, it is still unclear how LAPs influence snow albedo feedbacks. To investigate LAPs' indirect effect on snow albedo feedbacks, we developed and calibrated the Near-Infrared Emitting and Reflectance-Monitoring Dome (NERD) and monitored bidirectional reflectance factors (BRFs) hourly after depositing dust and black carbon (BC) particles onto experimental snow surfaces. After comparing snow infrared BRFs to snow specific surface areas (SSAs), we found that both measured and modeled snow infrared BRFs are correlated with snow SSA. These results, however, demonstrate a considerable uncertainty of ±10 m2 kg−1 in the determination of snow SSA from our BRF measurements. The nondestructive technique for snow SSA retrieval that we present here can be further developed for science applications that require rapid in situ snow SSA measurements. After adding large amounts of dust and BC to snow, we found more rapid decreasing of snow BRFs and SSAs in snow with added LAPs compared to natural (clean) snow but only during clear-sky conditions. These results suggest that deposition of LAPs onto snow can accelerate snow metamorphism via a net positive snow grain-size feedback.

scholarly journals Validation and Comparison of MODIS C6.1 and C6 Aerosol Products over Beijing, China

2018 ◽  
Vol 10 (12) ◽  
pp. 2021 ◽  
Author(s):  
Xinpeng Tian ◽  
Qiang Liu ◽  
Xiuhong Li ◽  
Jing Wei
Keyword(s):  
Optical Properties ◽  
Urban Areas ◽  
Surface Characteristics ◽  
Complex Surface ◽  
Deep Blue ◽  
Spatial Coverage ◽  
Moderate Resolution ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Beijing China ◽  
Better Than

The operational Moderate Resolution Imaging Spectroradiometer (MODIS) Aerosol Products (APs) have provided long-term and wide-spatial-coverage aerosol optical properties across the globe, such as aerosol optical depth (AOD). However, the performance of the latest Collection 6.1 (C6.1) of MODIS APs is still unclear over urban areas that feature complex surface characteristics and aerosol models. The aim of this study was to validate and compare the performance of the MODIS C6.1 and C6 APs (MxD04, x = O for Terra, x = Y for Aqua) over Beijing, China. The results of the Dark Target (DT) and Deep Blue (DB) algorithms were validated against Aerosol Robotic Network (AERONET) ground-based observations at local sites. The retrieval uncertainties and accuracies were evaluated using the expected error (EE: ±0.05 + 15%) and the root-mean-square error (RMSE). It was found that the MODIS C6.1 DT products performed better than the C6 DT products, with a greater percentage (by about 13%–14%) of the retrievals falling within the EE. However, the DT retrievals collected from two collections were significantly overestimated in the Beijing region, with more than 64% and 48% of the samples falling above the EE for the Terra and Aqua satellites, respectively. The MODIS C6.1 DB products performed similarly to the C6 DB products, with 70%–73% of the retrievals matching within the EE and estimation uncertainties. Moreover, the DB algorithm performed much better than DT algorithm over urban areas, especially in winter where abundant missing pixels were found in DT products. To investigate the effects of factors on AOD retrievals, the variability in the assumed surface reflectance and the main optical properties applied in DT and DB algorithms are also analyzed.

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