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Scientific Data Products

Mapping global urban boundaries from the global artificial impervious area (GAIA) data

We generated a 30m resolution global urban boundary dataset in seven representative years (i.e., 1990, 1995, 2000, 2005, 2010, 2015, and 2018). 

Spatial Resolution: 30m;

Temporal Resolution: Every 5 years;

Temporal Coverage: 1990-2015, 2018

GAIA

A harmonized global nighttime light dataset 1992–2018

  1. Li, X., Y. Zhou*, M. Zhao & X. Zhao (2020) A harmonized global nighttime light dataset 1992–2018. Scientific Data, 7, 168.

We generated an integrated and consistent NTL dataset at the global scale by harmonizing the inter-calibrated NTL observations from the DMSP data and the simulated DMSP-like NTL observations from the VIIRS data. The generated global DMSP NTL time-series data (1992–2018) show consistent temporal trends. This temporally extended DMSP NTL dataset provides valuable support for various studies related to human activities such as electricity consumption and urban extent dynamics.

 

Spatial Resolution: 1km;

Temporal Resolution: Annual;

Temporal Coverage: 1992-2018

Nighttime lights

A national dataset of annual urban extent (1985-2015) in the conterminous United States using

  1. Li, X., Y. Zhou*, Z. Zhu & W. Cao (2020) A national dataset of 30m annual urban extent dynamics (1985–2015) in the conterminous United States. Earth Syst. Sci. Data, 12, 357-371.
  2. Li, X., Y. Zhou*, Z. Zhu, L. Liang, B. Yu, and W. Cao (2018), Mapping annual urban dynamics (1985–2015) using time series of Landsat data. Remote Sensing of Environment 216: 674-683.

We mapped urban dynamics from Landsat time series data using the Google Earth Engine (GEE) platform and developed a national dataset of annual urban extent (1985–2015) at a fine spatial resolution (30 m) in the conterminous United States (US). 

Spatial Resolution: 30m;

Temporal Resolution: Annual;

Temporal Coverage: 1985-2015

A dataset of 30 m annual vegetation phenology indicators (1985–2015) in urban areas of the conterminous United States

  1. Li, X., Y. Zhou*, L. Meng, G. R. Asrar, C. Lu & Q. Wu (2019). A dataset of 30-meter annual vegetation phenology indicators (1985-2015) in urban areas of the conterminous United States. Earth Syst. Sci. Data, 2019. 11(2): 881-894.
  2. Li, X., Y. Zhou*, G. R. Asrar and L. Meng (2017). Characterizing spatiotemporal dynamics in phenology of urban ecosystems based on Landsat data. Science of the Total Environment 605-606: 721-734.

In this study, we produced an annual vegetation phenology dataset (phenology indicators of the start of season (SOS) and the end of season (EOS)) in urban ecosystems for the conterminous United States (US), using all available Landsat images on the Google Earth Engine (GEE) platform. 

Spatial Resolution: 30m;

Temporal Resolution: Annual;

Temporal Coverage: 1985-2015

Global Calibrated Nighttime light 1992-2013 at a 1km spatial resolution

  1. Li, X.; Zhou, Y. A Stepwise Calibration of Global DMSP/OLS Stable Nighttime Light Data (1992–2013). Remote Sens. 2017, 9, 637.

We developed a temporally consistent NTL dataset using a stepwise approach to calibrate the NTL time series. Each step was designed to calibrate particular satellites (or years) with systematic over- or under-estimation. Our calibrated NTL observations show a temporally more consistent pattern of NTL time series, as well as a good agreement with socioeconomic data, such as GDP and electricity consumption.

Spatial Resolution: 1km; Temporal Resolution: Annual; Temporal Coverage: 1992-2013

global_ntl

 

Global Urban Extent from 1992 to 2013 at a 1km spatial resolution

  1. Zhou, Y., X. Li, G. R. Asrar, S. J. Smith & M. Imhoff , 2018. A global record of annual urban dynamics (1992–2013) from nighttime lights. Remote Sensing of Environment, 219, 206-220.
  2. Zhou, Y., SJ Smith, CD Elvidge, K Zhao, A Thomson, M Imhoff, 2014. A Cluster-based Method to Map Urban Area from DMSP/OLS Nightlights. Remote Sensing of Environment. 147, 173-185
  3. Zhou, Y., et al., A global map of urban extent from nightlights. Environmental Research Letters, 2015. 10(5): p. 054011.

We developed a new approach to develop spatially and temporally consistent global urban maps from 1992 to 2013, using the DMSP/OLS NTL observations. First, potential urban clusters were delineated using the NTL data and a segmentation method. Then, a quantile-based approach was used to remove rural and suburban areas sequentially in the potential urban clusters. Finally, the derived urban series of the entire study period (1992-2013) were improved for temporal consistency. 

Spatial Resolution: 1km;

Temporal resolution: Annual;

Temporal Coverage: 1992-2013

globalUrban_new

 


Global Wind Energy Potential (Technical, Economic, and Exploitable)

  1. Zhou, Y., et al., Evaluation of Global Onshore Wind Energy Potential and Generation Costs. Environmental Science and Technology, 2012. 46(14): p. 7857–7864.
  2. Zhou, Y. and S. Smith, Spatial and temporal patterns of global onshore wind speed distribution. Environmental Research Letters, 2013. 8(3): p. 034029.

We develop a global map of onshore wind energy potentials (technical, economical, and exploitable) using reanalysis wind speed data (from 1980 to 2009), along with updated wind turbine technology performance, land suitability factors, cost assumptions, and explicit consideration of transmission distance in the calculation of transmission costs.

Spatial Resolution: 0.325 degree; Temporal resolution: 30-year Average; Temporal Coverage: 1980-2009

wind

 


Global Hydropower Potential (Gross, Techinical, Economic, and Exploitable)

  1. Zhou, Y., et al., A Comprehensive View of Global Potential for Hydro-generated Electricity. Energy & Environmental Science, 2015. 8(DOI: 10.1039/C5EE00888C): p. 2622-2633.

We developed a map of global hydropower potential (gross, technical, economic, and exploitable) using runoff and stream flow data, along with turbine technology performance, cost assumptions, and consideration of protected areas.

Spatial Resolution: 0.5 degree; Temporal resolution: 30-year Average; Temporal Coverage: 1971-2000

hydro