Project Abstract

Mitigation plans to counteract overheating in urban areas need to be based on a thorough knowledge of the state of the thermal environment, most importantly on the presence of areas which consistently demonstrate higher or lower urban land surface temperatures (hereinafter referred to as “hot spots” or “cold spots”, respectively). 

This is because Land Surface Temperature (LST) is a controlling factor of energy exchange between the surface and the atmosphere, and thus a cause of meteorological and climatic variation. Such exchange is through latent and sensible heat as well as the emission of radiation at the thermal infrared part of the spectrum.

As a matter of fact, as urban areas are covered with buildings and pavements; as a result moist soil and vegetation are being replaced with cement and asphalt. These materials have high thermal mass and tend to absorb more solar radiation than the surfaces found in rural areas, with the result being higher land surface temperatures. Additionally these surfaces are impermeable and tend to dry more quickly after precipitation, reducing evaporation, which has a cooling effect in green areas.

Project Description & Overview

The main objective of the project is to develop and apply a methodological approach for the recognition of thermal “hot spots” and “cold spots” in New York City and Athens, during the warm months of the year. Results will be analyzed separately for each city as well as in a combined manner in view of recognizing potential similarities which may be rolled out as urban typologies.

Specific objectives are:

• (a) the classification of land cover in each city (current state and retrospectively for a period of 20 years),
• (b) the estimation of LST from Landsat-8 at 30 m x 30 m and Sentinel-3 and MODIS at 1 km x 1 km spatial resolution,
• (c) the estimation of the downscaled LST at 30 m x 30 m on a, roughly, daily basis – and diurnally to the extent possible – with the use of the results of b),
• (d) the analysis of the extracted land surface temperatures so as to recognize and cluster “hot spots” and “cold spots”,
• (e) the correlation of the “hot spots” and “cold spots” to such independent variables as: (e1) the urban form—the two and three-dimensional urban structure (e2) the urban fabric – the surface materials and (e3) the urban green – presence, extent and distribution,
• (f) the estimation of the Surface Park Cooling Intensity, both in areas with extended parks as well as in areas with pocket parks.

Datasets

Satellite data (free) from: Landsat 8 (visible and TIR), Sentinel-2 (visible) and Sentinel-3 (TIR) and MODIS from Aqua and Terra (vIS and TIR).

Competencies

Provisionally image processing and/or GIS.

Learning Outcomes & Deliverables

• Students will understand the thermal/climate dynamics of urban areas
• Students will exploit the potential of earth observation satellites and remote sensing for urban applications
• Deliverables
  • City maps depicting thermal hot spots, the cooling intensity of parks, land use/land cover as well as changes over space and time

Students

Yushan Luo, Xavier Neo, and Bing Yang