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  Contact Information

   Department of Earth & Environmental Systems
   600 Chestnut St.
  Science Building RM159
  Indiana State University
  Terre Haute, IN 47809

  Phone: (812)237-2255
  Fax: (812)237-8029


Home >>Research

 Research Overview     

I characterize myself as an environmental geographer who uses remote sensing, GIS, and spatial modeling methods and techniques to study urban environmental issues and ecosystems. My main research areas involve three broad themes: (1) urban remote sensing; (2) urban climatology and ecology; and (3) environmental sustainability.

The goals of my research include: improving our understanding of urban structures, environments, and ecosystems through remote sensing and GIScience; linking urban climate (heat islands) with urban ecology (landscape patterns and processes) across various spatial scales; and exploring human-environment interactions during the urbanization process in different geographical settings and stages from a local to a global scope. The ultimate goal is to obtain better knowledge about urban environments and global urbanization processes through remote sensing and GIScience for sustainable development.

My research is motivated by the following key issues and questions which are crucial to furthering our understanding about urban environments and urbanization processes worldwide:

  • In the twenty-first century there have been significant advances in remote sensor technology and image processing capacity, specifically high spatial-resolution, LiDAR, and hyperspectral sensing; however, these techniques have not been well integrated with more established aerial photography, multispectral and Radar remote sensing techniques, as well as unprecedented interest in on-line mapping, to serve as the catalyst for the development of urban remote sensing research and applications. How can all these technologies be integrated for better detection, interpretation, characterization, and modeling of urban structures and environments?
  • Urban landscapes are extremely heterogeneous, temporally dynamic, and spectrally diverse. Can a global model be developed for urban landscape space-time analysis that can account for urban morphologies in different geographical settings?
  • Human economic and social activities, animal behaviors, energy use, and demographic characteristics in cities at nighttime are distinct from those at daytime. What is the relationship between the daytime and nighttime urban environments and ecosystems? Can nighttime light remote sensing provide a linkage between them so that human‐environment interactions in urban areas can be better understood?
  • Land surface temperature (LST) data derived from satellite thermal infrared (TIR) imagery have been widely used in urban climate studies for analyzing LST patterns and modeling urban heat islands. However, LSTs and air temperatures can be very different, especially in summer daytime with clear skies and high solar loading. Can the intensity, location and shape of urban heat islands across various spatial scales be characterized and modeled from multi-temporal and multi-resolution TIR imagery? How can these parameters be connected with those derived from air temperature measurements?
  • Consistent time series LST data are of prime importance for assessing climate change of different temporal and spatial scales, as well as for analysis of the impact of urbanization on landscape thermal characteristics and the Earth’s surface energy balance. How can LSTs under cloudy skies be retrieved? Can we optimize satellite TIR data to develop a consistent time series when and where disturbance events, such as deforestation, forest degradation, desertification, or rapid urbanization, occur? Can the data gap be filled up due to sensor failure or low temporal revisit frequency of a sensor?
  • Studies of land use and land cover changes and their linkage with environmental parameters draw heavily upon landscape ecology. However, the effect of the spatial composition and structure of thermal landscapes on urban heat island process and surface energy fluxes have received much less attention. How can urban thermal landscapes be investigated as scale-dependent spatial patterns associated with biogeophysical processes? Can remote sensing TIR data from a variety of sensors with different spatial resolutions be combined and used for this purpose?
  • A characteristic change to the Earth’ surface associated with urbanization is the expansion of impervious surfaces, such as roads, driveways, sidewalks, parking lots, rooftops, and so on. Impervious surfaces have emerged not only as an indicator of the degree of urbanization, but also a major indicator of environmental quality. What are the impacts of the magnitude, location, geometry and spatial pattern of impervious surfaces, and the pervious - impervious ratio on regional climates and ecosystems? How does the expansion of impervious surfaces impact the conservation of land and water resources as well as the sustainability and productivity of natural and human ecosystems in a region / watershed?
  • A systematic approach towards long-term monitoring of urbanization and mapping of human settlements at the global and continental scale is urgently needed. However, challenges exist in the consistent definition of urban areas, scale-dependency of urban features, establishment of remote sensing algorithms and methods to access, process, share and link different types of datasets, as well as the ability to validate generated data products. How can consistent impervious surface maps be generated from temporally irregularly-distributed satellite images? What does it take to develop essential urban variables and indicators for sustainable cities for serving the UN Sustainable Development Goals from existing remote sensing data archives such as Landsat?

Research Themes

Urban Remote Sensing:

  • Invention of new algorithms and techniques: urban landscape continuum model; sub-pixel analysis; fractals and scaling; data mining; and time series image analysis.

  • Areas of application: urban heat island modelling; estimation and mapping of urban impervious surfaces; urban sprawl mapping; land surface temperature analysis; urban classification and land characterization; population estimation; public health; and urban sustainability.

  • Theory: Linkage between geography and landscape ecology; and understanding of geographical issues through remote sensing data and methods.

  • GEO Global Urban Observation and Information Initiative: This international initiative involves collaborators from all major countries. Dr. Weng has led to develop a global urban supersite initiative, among others, and the GEO team, under his leadership, has conducted global megacities analyses; defined requirements for global urban monitoring; improved global coverage of urban observation; and developed innovative techniques and indicators to support sustainable cities. His recent works have provided fresh insights into human-environment interactions in the urban areas and in the urbanization process. He has pioneered global urban remote sensing researches by suggesting new research directions, and synthesizing advances across multiple sub-fields.

  • Panelist of U.S. DOE’s Cool Roofs Roadmap and Strategy Review Committee in 2010: help to define roadmap to mitigate urban heat islands in the USA and worldwide.

Urban Climatology and Ecology:

  • Urban heat island (UHI) modeling using remote sensing data and field measurements (Fractal analysis of UHI patterns; estimating UHI parameters using kernel convolution; data mining of UHIs; sub-pixel vegetation fraction-LST relationship in UHI; scaling effect of LST-vegetation abundance relationship; relationship among air pollution, land use density and UHI) 

  • Land surface temperature (LST) estimation, generation, and analysis (LST scaling; development of data fusion algorithms; time-series analysis; spatio-temporal patterns; annual and diurnal temperature cycles modeling; generation of consistent LST data sets; use of LST data for urban, environment, and public health studies)

  • Estimation and mapping of urban extents and impervious surfaces (Systematic analysis of different algorithms for estimation but focusing on sub-pixel, ANN, fuzzy set, and object based;  effects of spectral and spatial resolutions;  seasonality;  relationship of impervious surface pattern with socioeconomic and demographic data; time series night-light analysis)

  • Urban sprawl mapping and environmental impact analysis (urban growth detection and monitoring; dynamic relationship between urban growth and environmental change; urbanization effects; integration of remote sensing and GIS; land use change analysis; time series image analysis)

  • Cities at night (settlements; population; energy use; lighting sources; light emission heterogeneity)

Environmental Sustainability:
  • Population estimation (first use of impervious surface, LST, and vegetation fraction images in population estimation; land use based model; spectral based model)

  • Urban energy consumption (high-resolution building energy data; GIS based building energy modeling; climate change impacts; anthropogenic heat discharge estimation; nighttime urban energy consumption; light pollution)

  • Environmental quality, quality of life, human and environmental health (developing new indicators for urban physical environmental quality; scale effect of census-based urban environmental quality; environmental public health using remote sensing and GIS; West Nile Virus spread in urban settings; effects of landscape pattern on disease spread)

  • Human ecosystems sustainability analysis (use of fuzzy set in assessing urban ecosystem sustainability and temporal change)

  • Human-environment interactions in coastal regions (agricultural land use and sustainability in the Pearl River Delta, southern China; relationship between land use and environmental conservation; water conservancy techniques; effects of changes in physical environment and land use on the sustainability and productivity of natural and human ecosystems; Mangrove-inundation dynamics; carbon dynamics in mangrove ecosystem; Spartina alterniflora invasion)

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