Yuyu Zhou

The University of Hong Kong | HKU · Department of Geography

The nighttime light (NTL) observations from Defense Meteorological Satellite Program/Operational Linescane System (DMSP/OLS) offer great potentials to study urban dynamics from regional to global scales, for more than two decades. In this paper, we presented a new approach to develop spatially and temporally consistent global urban maps from 1992 t...

Urbanization has caused environmental changes, such as urban heat islands (UHIs), that affect terrestrial ecosystems. However, how and to what extent urbanization affects plant phenology remains relatively unexplored. Here, we investigated the changes in the satellite-derived start of season (SOS) and the covariation between SOS and temperature (R...

To the Editor — Alongside the unparalleled changes in global climate, our home planet is experiencing an unprecedented period of urbanization, which is expected to continue across the next few decades. For plants, the impacts of urbanization, such as altered air quality, light regimes and water and nutrient availability, can induce large shifts in...

Information on urban built-up infrastructure is essential to understand the role of cities in shaping environmental, economic, and social outcomes. The lack of data on built-up heights over large areas has limited our ability to characterize urban infrastructure and its spatial variations across the world. Here, we developed a global atlas of urban...

Urban building height, as a fundamental 3D urban structural feature, has far-reaching applications. However, creating readily available datasets of recent urban building heights with fine spatial resolutions and global coverage remains a challenging task. Here, we provide a 150-m global urban building heights dataset around 2020 by combining the sp...

Ecosystem dynamics and ecological disturbances manifest as breakpoints in long-term multispectral remote sensing time series. Typically, these breakpoints are captured using univariate methods applied individually to each band, with subsequent integration of the results. However, multivariate analysis provides a promising way to fully incorporate t...

High-resolution urban climate modeling has faced substantial challenges due to the absence of a globally consistent, spatially continuous, and accurate dataset to represent the spatial heterogeneity of urban surfaces and their biophysical properties. This deficiency has long obstructed the development of urban-resolving Earth System Models (ESMs) a...

Land surface temperature (LST) derived from satellite observations and weather modeling has been widely used for investigating Earth surface-atmosphere energy exchange and radiation budget. However, satellite-derived LST has a trade-off between spatial and temporal resolutions and missing observations caused by clouds, while there are limitations s...

The gap between the projected urban areas in the current trend (UAC) and those in the sustainable scenario (UAS) is a critical factor in understanding whether cities can fulfill the requirements of sustainable development. However, there is a paucity of knowledge on this cutting-edge topic. Given the extensive and rapid urbanization in the United S...

Exposure to ambient fine particulate matter (PM2.5) poses a significant global health challenge. However, a major obstacle for epidemiological studies and risk assessment lies in the absence of high-resolution spatiotemporal exposure estimates. Here, we present an integrated framework to achieve accurate estimations of population exposure to PM2.5...

Urban evolutionary ecology is inherently interdisciplinary. Moreover, it is a field with global significance. However, bringing researchers and resources together across fields and countries is challenging. Therefore, an online collaborative research hub, where common methods and best practices are shared among scientists from diverse geographic, e...

Understanding the sensitivity of spring leaf-out dates to temperature (ST) is integral to predicting phenological responses to climate warming and the consequences for global biogeochemical cycles. While variation in ST has been shown to be influenced by local climate adaptations, the impact of biodiversity remains unknown. Here we combine 393,139...

Tracking long-term tidal flat dynamics is crucial for coastal restoration decision making. Accurately capturing the loss and gain of tidal flats due to human-induced disturbances is challenging in the micro-tidal areas. In this study, we developed an automated method for mapping the annual tidal flat changes in the micro-tidal areas under intense h...

With continuing global warming and urbanization, it is increasingly important to understand the resilience of urban vegetation to extreme high temperatures, but few studies have examined urban vegetation at large scale or both concurrent and delayed responses. In this study, we performed an urban-rural comparison using the Enhanced Vegetation Index...

Improved representation of urban processes in Earth System Models (ESMs) is a pressing need for climate modeling and climate‐driven urban energy studies. Despite recent improvements to its fully coupled Building Energy Model (BEM), the current Community Land Model Urban (CLMU) in the Community Earth System Model (CESM) lacks the infrastructure to m...

Urban evolutionary ecology is inherently interdisciplinary. Moreover, it is a field with global significance. However, bringing researchers and resources together across fields and countries is challenging. Therefore, an online collaborative research hub, where common methods and best practices are shared among scientists from diverse geographic, e...

Dust loading in West and South Asia has been a major environmental issue due to its negative effects on air quality, food security, energy supply and public health, as well as on regional and global weather and climate. Yet a robust understanding of its recent changes and future projection remains unclear. On the basis of several high-quality remot...

Remote sensing of urban environments has unveiled a significant shift from single-city investigations to the inclusion of multiple cities. Originated from the ideas of the Remote Sensing of Environment special issue entitled "Remote Sensing of the Urban Environment: Beyond the Single City," this paper offers a comprehensive examination of the state...

Climate change is causing widespread land surface greening in spring1–4, but the impacts of anthropogenic air pollution on these changes remain poorly understood. Using global ground and satellite observations of fine particulate matter ≤ 2.5 μm (PM2.5) from 2000 to 2020, here we show that PM2.5 concentration offsets global spring greening as indic...

A R T I C L E I N F O Keywords: Spring vegetation phenology urbanization urban heat island effect climates rural-urban ecosystem A B S T R A C T Cities have been considered ideal surrogates for evaluating ecological responses to climate warming. Although research has revealed that the urban heat island effect is not the only determinant that drives...

High levels of sulfur dioxide (SO2) due to human activities pose a serious air pollution issue in China, especially in urban agglomerations. However, limited research has investigated the impact of anthropogenic emissions on higher SO2 concentrations in urban regions compared to rural areas in China. Here, we analyzed the trends in SO2 concentratio...

Improved representation of urban processes in Earth System Models (ESMs) is a pressing need for climate modeling and climate-driven urban energy studies. Despite recent improvements to its fully coupled building energy model, the current Community Land Model Urban (CLMU) in the Community Earth System Model (CESM) lacks the infrastructure to model a...

Characterizing urban environments with broad coverages and high precision is more important than ever for achieving the UN's Sustainable Development Goals (SDGs) as half of the world's populations are living in cities. Urban building height as a fundamental 3D urban structural feature has far-reaching applications. However, so far, producing readil...

Climate, technologies, and socio-economic changes will influence future building energy use in cities. However, current low-resolution regional and state-level analyses are insufficient to reliably assist city-level decision-making. Here we estimate mid-century hourly building energy consumption in 277 U.S. urban areas using a bottom-up approach. T...

Understanding the sensitivity of spring leaf-out dates to temperature (S T ) is integral to predicting phenological responses to climate warming and the consequences for global biogeochemical cycles. While variation in S T has been shown to be influenced by local climate adaptations, the impact of biodiversity on phenological sensitivity remains un...

There is a lack of understanding of the complex spatiotemporal patterns of heat exposure during heat waves, and the impact of urbanization intensity and urban morphology on heat exposure in urban thermal environments. To address these issues, this study used mean radiant temperature (Tmrt) as an index to indicate human exposure to extreme heat, and...

The information of global spatially explicit urban extents under scenarios is important to mitigate future environmental risks caused by global urbanization and climate change. Although future dynamics of urban extent were commonly modeled with conversion from non-urban to urban extent using cellular-automata (CA)-based models, gradual changes of i...

The dynamics of built-up height are a crucial aspect of urban form, enabling the characterization of urban growth patterns and the attainment of sustainable development goals. While past studies have focused on urban extent mapping, little has been done to reveal changes in vertical structures in built-up areas. In this study, we reconstructed annu...

Investigation on the future impacts of climatic and environmental change on vegetation photosynthesis has been largely restricted to controlled field experiments, which can hardly be extended to global scale due to limited spatial, species and ecosystem coverages. However, in urban areas plants experience altered environments that mimic potential f...

Relative radiometric normalization (RRN) is a widely used method for enhancing the radiometric consistency among multi-temporal satellite images. Diverse satellite images enhance the information for observing the Earth’s surface and bring additional uncertainties in the applications using multi-sensor images, such as change detection, multi-tempora...

Radiometric consistency of multi-temporal satellite observations is affected by sensor stability and scene related issues. Relative radiometric normalization (RRN) is a widely-used method to reduce these radiometric differences, its performance depends on the accurate identification of representative pseudo-invariant features (PIFs). However, exist...

[[Fulltext at https://go.osu.edu/agai]]: Statistical crop modeling is pivotal for understanding climate impacts on crop yields. Choices of models matter: Linear regression is interpretable but limited in predictive power; machine learning predicts well but often remains a black box. To develop explainable artificial intelligence (AI) for exploring...

Nighttime light (NTL) remote sensing data offer unique capabilities to characterize both the extent and intensity of human activities and have been extensively used to understand urbanization since 1992. The recent proliferation of NTL sensors, algorithms, and products creates new opportunities to understand contemporary urbanization and the associ...

Urban greening (UG) affects local climate by altering surface energy balance, while long-term UG cooling potential, patterns, and contribution to curbing urban warming remain unclear. Here we designed an novel statistical model with universal applicability to evaluate the cooling potential of UG (CPUG) and created the first CPUG map for China. By e...

The information of global spatially explicit urban extents under scenarios is important to mitigate future environmental risks caused by global urbanization and climate change. Although future dynamics of urban extent were commonly modelled with conversion from non-urban to urban using cellular automata (CA) based models, gradual changes of impervi...

The cellular automata (CA) based models have been extensively used in urban sprawl modeling to support sustainable urban planning. However, in most existing urban CA models, only abrupt conversion (i.e., from non-urban to urban) was considered, whereas the difference in urbanization levels among different grids, as well as the nature of continuous...

Background: Studies on the health effects of heat are particularly limited in Texas, the U.S. state with the top ten highest number of annual heat-related deaths per capita from 2018 to 2020. This study aims to assess the effects of heat on all-cause and cause-specific mortality in 12 metropolitan statistical areas (MSAs) across Texas from 1990 to...

Urban vegetation, a harbinger of future global vegetation change, is controlled by complex urban environments. The urban-rural gradient in vegetation greenness trends and their responses to biogeochemical drivers (e.g. elevated atmospheric CO2 concentration and climate warming) and land-cover changes, however, remain unclear. Here we used satellite...

Near-surface air temperature (Ta) is a key variable in global climate studies. A global gridded dataset of daily maximum and minimum Ta (Tmax⁡ and Tmin⁡) is particularly valuable and critically needed in the scientific and policy communities but is still not available. In this paper, we developed a global dataset of daily Tmax⁡ and Tmin⁡ at 1 km re...

Unprecedented efforts to cut greenhouse gas (GHG) emissions show an urgent need to avoid the detrimental impact of climatic change, such as urban overheating. While different sources account for sizable GHG emissions, US residential building energy consumption accounts for about 50% of CO2 emissions. Therefore, residential buildings provide a signi...

Accurate estimation of forest aboveground biomass (AGB) is vital for informing ecosystem and carbon management. The Global Ecosystem Dynamics Investigation (GEDI) instrument—a new-generation spaceborne lidar system from NASA—provides the first global coverage of high-resolution 3D altimetry data aimed specifically for mapping Earth’s forests, but i...

Past two decades have witnessed a rapid urbanization process in China, with the urbanization ratio suddenly increasing from 30.9 % to 63.9 %. Physical urban areas (PUA) are fundamental indicators to monitoring and evaluating urbanization, which differ from administrative urban areas and are much complicated to identify, as PUA contain heterogeneous...

Very-high-resolution (VHR) land cover and land use (LCLU) is an essential baseline data for understanding fine-scale interactions between humans and the heterogeneous landscapes of urban environments. In this study, we developed a Fine-resolution, Large-area Urban Thematic information Extraction (FLUTE) framework to address multiple challenges faci...

Near-surface air temperature (Ta) is one of the key variables in a variety of studies such as hydrological modeling, assessment of heat waves, and energy modeling. Among existing methods, statistical algorithms are suitable for integrating auxiliary spatial data with station-based Ta data to produce gridded Ta over large areas. However, existing st...

Research on the evolutionary ecology of urban areas reveals how human-induced evolutionary changes affect biodiversity and essential ecosystem services. In a rapidly urbanizing world imposing many selective pressures, a time-sensitive goal is to identify the emergent issues and research priorities that affect the ecology and evolution of species wi...

Although several products of the global urban extent with fine resolutions (e.g. 30 m-38 m) have been developed, quantitative evaluations of these products across spaces and times are still missing, which is crucial to future urban growth modeling. Here, we analysed the discrepancy of six global fine resolution urban extent products across spaces a...

Near-surface air temperature (Ta) is a key variable in global climate studies. A global gridded dataset of daily maximum and minimum Ta (Tmax and Tmin) is particularly valuable and critically needed in the scientific and policy communities, but is still not available. In this paper, we developed a global dataset of daily Tmax and Tmin dataset at 1-...

Agriculture is a major water user, especially in dry and drought-prone areas that rely on irrigation to support agricultural production. In recent years, the over-extraction of groundwater, exacerbated by climate change, population growth, and intensive agricultural irrigation, has led to a drop in water levels and impacts the hydrological cycle. U...

In recent decades, nighttime light (NTL) images have been widely explored to portray human footprints. Most of the studies used monthly or yearly temporal composite NTL products as a solution for invalid observations due to cloud coverage and outlier signals. However, the impact of temporal compositing on NTL data and its applications remains large...

Spring phenology plays an essential role in climate change, terrestrial ecosystem, and public health. Field-based monitoring and understanding of changes in spring phenology for long periods and in large regions are challenging due to the limited in-site observations. Space-based remotely sensed observations offer great potentials for monitoring de...

Zipf’s law, characterizing the rank-size distribution of city size or population, has been widely applied in urban studies. Previous studies on Zipf’s law mainly focused on the spatial dimension of urban size and population, with limited consideration of its temporal dynamics. Here, we proposed a conceptual model to characterize the spatial sprawl...

The increasing heat stress from the combined effect of changes such as temperature and humidity in the context of global change receives growing concerns. However, there is limited information for future changes in heat stress, as well as its potential socioeconomic impact, under the intended nationally determined mitigation scenarios. This study e...

Aerosol loadings and their spatial distribution are among the most important atmospheric information needed for a range of applications such as air quality monitoring, climate research, and public health. A key measure of aerosol quantity is aerosol optical depth (AOD) and it has been routinely observed from space by Earth observing satellites/inst...

Artificial light at night (ALAN), an increasing anthropogenic driver, is widespread and shows rapid expansion with potential adverse impact on the terrestrial ecosystem. However, whether and to what extent does ALAN affect plant phenology, a critical factor influencing the timing of terrestrial ecosystem processes, remains unexplored due to limited...

Land surface temperature (LST) is one of the most important and widely used parameters for studying land surface processes. Moderate Resolution Imaging Spectroradiometer (MODIS) LST products (e.g., MOD11A1 and MYD11A1) can provide this information with moderate spatiotemporal resolution with global coverage. However, the applications of these data...

Understanding the spatiotemporal dynamics of global urbanization over a long time series is increasingly important for sustainable development goals. The harmonized nighttime light (NTL) time-series composites created by fusing multi-source NTL observations provide a long and consistent record of the nightscape for characterizing and understanding...

Anthropogenic heat (AH) emission from buildings is a key contributor to the urban heat island (UHI) effect. Although an improved understanding of spatiotemporal patterns of building AH is highly needed for mitigating UHI effect, such information is still limited in high spatiotemporal resolutions at the city level. In this study, a bottom-up city b...

Surface albedo is a key parameter in the surface energy balance and has been identified as a primary essential climate variable (ECV). Variations in surface albedo can be used as a diagnostic tool for local climate change. This is particularly true in urban areas, where the impacts of land cover conversion due to increasing anthropogenic demands ca...