| 1. |
- Chrysoulakis, Nektarios, et al.
(author)
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A novel approach for anthropogenic heat flux estimation from space
- 2016
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In: IGARSS 2016 - IEEE International Geoscience and Remote Sensing Symposium. 10-15 July 2016. Beijing; China. - : IEEE. - 2153-7003. - 9781509033324
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Conference paper (peer-reviewed)abstract
- The recently launched H2020 project URBANFLUXES (URBan ANthrpogenic heat FLUX from Earth observation Satellites) investigates the potential of EO to retrieve anthropogenic heat flux, as a key component in the Urban Energy Budget (UEB). URBANFLUXES advances existing Earth Observation (EO) based methods for estimating spatial patterns of turbulent sensible and latent heat fluxes, as well as urban heat storage flux at city scale and local scale. Independent methods and models are engaged to evaluate the derived products and statistical analyses provide uncertainty measures. Optical, thermal and SAR data are exploited to improve the accuracy of the UEB components spatial distribution calculation. Synergistic use of different types and of various resolution EO data allows estimates in local and city scale. Ultimate goal of the URBANFLUXES is to develop a highly automated method for estimating UEB components to use with Copernicus Sentinel data, enabling its integration into applications and operational services.
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| 2. |
- Chrysoulakis, Nektarios, et al.
(author)
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A novel approach for anthropogenic heat flux estimation from space
- 2015
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In: ICUC9 – 9 th International Conference on Urban Climate jointly with 12th Symposium on the Urban Environment. 20-24 July 2015, Toulouse, France.
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Conference paper (other academic/artistic)abstract
- How people live, work, move from place to place, what they consume and the technology they use, all affect the fabric, morphology and emissions in a city and in turn its climate. To understand the relations between urban form, energy use and carbon emissions an important challenge is to disaggregate urban areas into different spatial units and evaluate their impacts on energy fluxes and greenhouse gas emissions. There is a need in Earth system science communities for spatially disaggregated anthropogenic heat data, at local and city scales. The anthropogenic heat flux is the heat flux resulting from vehicular emissions, space heating and cooling of buildings, industrial processing and the metabolic heat release by people. Such information is practically impossible to derive by point in-situ flux measurements, while satellite remote sensing has proven a valuable tool for estimating energy budget parameters exploiting Earth Observation (EO) data. While EO data are widely used for urban studies, their main application area is limited to land cover mapping and similar applications. Nevertheless, currently available EO data and forthcoming satellite systems can considerably contribute to the study of urban climate. To this aim the recently launched H2020 project URBANFLUXES (URBan ANthrpogenic heat FLUX from Earth observation Satellites) investigates the potential of EO to retrieve anthropogenic heat flux, as a key component in the urban energy budget. The urban energy budget is considered in the context of a volume because of the three dimensional nature of the city, and includes the fluxes into, or out of, or the storage change within the control volume. URBANFLUXES advances existing EO-based methods for estimating spatial patterns of turbulent sensible and latent heat fluxes, as well as urban heat storage flux at city scale and local scale. Independent methods and models are engaged to evaluate the derived products and statistical analyses provide uncertainty measures. Optical, thermal and SAR data from existing satellite sensors are exploited to improve the accuracy of the energy budget components spatial distribution calculation. Synergistic use of different types and of various resolution EO data allows estimates in local and city scale. In-situ reflectance measurements of urban materials for calibration. The URBANFLUXES project prepares the ground for further innovative exploitation of EO data in scientific activities involving Earth system modelling and climate change studies in cities. The URBANFLUXES products will support system models to provide more robust climate simulations. Ultimate goal of the URBANFLUXES is to develop a highly automated method for estimating urban energy budget components to use with Copernicus Sentinel data, enabling its integration into applications and operational services. The improved data quality, spatial coverage and revisit times of the Copernicus data will allow support of future emerging applications regarding sustainable urban planning, with the objective of improving the quality of life in cities.
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| 3. |
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| 4. |
- Chrysoulakis, Nektarios, et al.
(author)
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Anthropogenic Heat Flux Estimation from Space: The URBANFLUXES Project
- 2016
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In: AMS 22nd Symposium on Boundary Layers and Turbulence, 20 – 24 June, 2016, Salt Lake City, USA..
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Conference paper (other academic/artistic)abstract
- The H2020 project URBANFLUXES (URBan ANthrpogenic heat FLUX from Earth observation Satellites) investigates the potential of Copernicus Sentinels to retrieve anthropogenic heat flux, as a key component of the Urban Energy Budget (UEB). Temperatures in cities are predicted to rise even more in the future, resulting in increased energy demand for cooling systems in low and mid-latitude cities, modifying UEB. A positive feedback cycle occurs in many urban areas, where higher temperatures result in more energy being used for cooling, which in turn adds to heat emissions and increases temperatures further during periods with increased heat wave risk. It is expected that without mitigation measures, energy demand will continue to increase during the warmest months. URBANFLUXES advances the current knowledge of the impacts of UEB fluxes on urban heat island and consequently on energy consumption in cities. This will lead to the development of tools and strategies to mitigate these effects, improving thermal comfort and energy efficiency. In URBANFLUXES, the anthropogenic heat flux is estimated as a residual of UEB. Therefore, the rest UEB components, namely, the net all-wave radiation, the net change in heat storage and the turbulent sensible and latent heat fluxes are independently estimated from Earth Observation (EO), whereas the advection term is included in the error of the anthropogenic heat flux estimation from the UEB closure. A dense network of conventional meteorological stations is used in each case study city: London, Basel and Heraklion. EO data is initially analyzed to map urban surface morphology and cover, whilst a new approach has been developed to define appropriate zones for energy partitioning. Using these zones as a framework, advanced EO-based methods are used to estimate UEB fluxes: a sophisticated radiative transfer model (Discrete Anisotropic Radiative Transfer) was employed to simulate the net all-wave radiation; the computation of the storage term was based on the Element Surface Temperature Method, supported by the auxiliary datasets; and the estimation of the turbulent heat fluxes was based on the Aerodynamic Resistance Method, supported by standard meteorological measurements. In-situ flux measurements (Eddy Covariance, scintillometry) and bottom-up approaches (inventories, building energy models) were used to evaluate URBANFLUXES outcomes, whereas uncertainties were specified and analyzed. The project exploits Sentinels observations, which provide improved data quality, coverage and revisit times and increase the value of EO data for scientific work and future emerging applications. These observations can reveal novel scientific insights for the detection and monitoring of the spatial distribution of the urban energy budget fluxes in cities, thereby generating new EO opportunities. URBANFLUXES thus exploits the European capacity for space-borne observations to enable the development of operational services in the field of urban environmental monitoring and energy efficiency in cities. It is therefore expected to prepare the ground for further innovative exploitation of European space data in scientific activities (climate variability studies at local and regional scales) and future and emerging applications (sustainable urban planning, mitigation technologies) to benefit climate change mitigation/adaptation and civil protection. More information on the project can be found at http://urbanfluxes.eu.
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| 5. |
- Farsari, Ioanna, et al.
(author)
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Combining satellite and socioeconomic data for Land Use Models estimation
- 2004
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Conference paper (peer-reviewed)abstract
- Land use is an important explanatory variable in urban growth models, which explore the way various factors (e.g. geographic, economic, demographic etc.) interact to simulate growth dynamics. A serious and recurring problem for modelling urban systems has been the lack of spatially detailed data. Remote sensing and Geographical Information Systems have the potential to support such models, by providing data and analytical tools for the study of urban environments. High spatial resolution sensors such as the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) allow the estimation of land covers using either supervised or unsupervised classification techniques. Moreover, the accuracy of the classification can be improved by incorporating ancillary data in the classification scheme. In this study, spatial data from various sources are combined to develop statistical models relating land use to population density, distance from the center of the city, a land use mix index and monetary land values. The work emphasizes spatial relationships between various geographic, land-use, and demographic variables characterizing fine zones across and around regions. It derives and combines land use data for the Heraklion (Greece) region from ASTER images, cartographic maps and Greek National Statistical Service census of population data. The statistical techniques applied for explaining the variability of land use are ordinary and logistic regression. Land use mix appears to be a significant predictive factor whereas the explanatory power of population increases as the grid cell categorization with respect to land use becomes finer.
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| 6. |
- Feigenwinter, Christian, et al.
(author)
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Spatial Distribution of Sensible and Latent Heat Flux in the City of Basel (Switzerland)
- 2018
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In: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing. - 1939-1404 .- 2151-1535. ; 11:8 (S1), s. 2717-2723
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Journal article (peer-reviewed)abstract
- IEEE Urban surfaces are a complex mixture of different land covers and surface materials; the relative magnitudes of the surface energy balance components therefore vary widely across a city. Eddy covariance (EC) measurements provide the best estimates of turbulent heat fluxes but are restricted to the source area. Land surface modeling with earth observation (EO) data is beneficial for extrapolation of a larger area since citywide information is possible. Turbulent sensible and latent heat fluxes are calculated by a combination of micrometeorological approaches (the aerodynamic resistance method, ARM), EO data, and GIS techniques. Input data such as land cover fractions and surface temperatures are derived from Landsat 8 OLI and TIRS, urban morphology was calculated from high-resolution digital building models and GIS data layers, and meteorological data were provided by flux tower measurements. Twenty-two Landsat scenes covering all seasons and different meteorological conditions were analyzed. Sensible heat fluxes were highest for industrial areas, railway stations, and areas with high building density, mainly corresponding to the pixels with highest surface-to-air temperature differences. The spatial distribution of latent heat flux is strongly related to the saturation deficit of vapor and the (minimum) stomatal resistance of vegetation types. Seasonal variations are highly dependent on meteorological conditions, i.e., air temperature, water vapor saturation deficit, and wind speed. Comparison of measured fluxes with modeled fluxes in the weighted source area of the flux towers is moderately accurate due to known drawbacks in the modeling approach and uncertainties inherent to EC measurements, particularly in urban areas.
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| 7. |
- Feigenwinter, Christian, et al.
(author)
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Spatial distribution of sensible and latent heat flux in the URBANFLUXES case study city Basel (Switzerland)
- 2017
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In: 2017 Joint Urban Remote Sensing Event (JURSE). Dubai; United Arab Emirates; 6-8 March 2017. - 9781509058099
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Conference paper (peer-reviewed)abstract
- Turbulent sensible and latent heat fluxes are calculated by a combined method using micrometeorological approaches (the Aerodynamic Resistance Method ARM), Earth Observation (EO) data and GIS-Techniques. The spatial distributions of turbulent heat fluxes were analyzed for 22 for the city of Basel (Switzerland), covering all seasons and different meteorological conditions. Seasonal variations in heat fluxes are strongly dependent on meteorological conditions, i.e. air temperature, water vapor saturation deficit and wind speed. The agreement of measured fluxes (by the Eddy Covariance method) with modeled fluxes in the weighted source area of the flux towers is moderate due to known drawbacks in the modelling approach and uncertainties inherent to EC measurements, particularly also in urban areas.
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| 8. |
- Landier, Lucas, et al.
(author)
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3D modeling of radiative transfer and energy balance in urban canopies combined to remote sensing acquisitions
- 2016
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In: IGARSS 2016 - 2016 IEEE International Geoscience and Remote Sensing Symposium. - 2153-7003.
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Conference paper (peer-reviewed)abstract
- In this paper we present a study on the use of remote sensing data combined to the 3D modeling of radiative transfer (RT) and energy balance in urban canopies in the aim to improve our knowledge on anthropogenic heat fluxes in several European cities (London, Basel, Heraklion, and Toulouse). The approach is based on the forcing by the use of LandSAT8 data of a coupled radiative transfer model DART (Direct Anisotropic Radiative Transfer) (www.cesbio.upstlse.fr/dart) with an energy balance module. LandSAT8 visible remote sensing data is used to better parametrize the albedo of the urban canopy and thermal remote sensing data is used to enhance the anthropogenic component in the coupled model. This work is conducted in the frame of the H2020 project URBANFLUXES, which aim is to improve the efficiency of remote-sensing data usage for the determination of the anthropogenic heat fluxes in urban canopies
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| 9. |
- Landier, Lucas, et al.
(author)
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Calibration of DART Radiative Transfer Model with Satellite Images for Simulating Albedo and Thermal Irradiance Images and 3D Radiative Budget of Urban Environment
- 2016
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In: 36th EARSeL Symposium, 20-24 June 2016, Bonn, Germany.
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Conference paper (other academic/artistic)abstract
- Remote sensing is increasingly used for managing urban environment. In this context, the H2020 project URBANFLUXES aims to improve our knowledge on urban anthropogenic heat fluxes, with the specific study of three cities: London, Basel and Heraklion. Usually, one expects to derive directly 2 major urban parameters from remote sensing: the albedo and thermal irradiance. However, the determination of these two parameters is seriously hampered by complexity of urban architecture. For example, urban reflectance and brightness temperature are far from isotropic and are spatially heterogeneous. Hence, radiative transfer models that consider the complexity of urban architecture when simulating remote sensing signals are essential tools. Even for these sophisticated models, there is a major constraint for an operational use of remote sensing: the complex 3D distribution of optical properties and temperatures in urban environments. Here, the work is conducted with the DART (Discrete Anisotropic Radiative Transfer) model. It is a comprehensive physically based 3D radiative transfer model that simulates optical signals at the entrance of imaging spectro-radiometers and LiDAR scanners on board of satellites and airplanes, as well as the 3D radiative budget, of urban and natural landscapes for any experimental (atmosphere, topography,…) and instrumental (sensor altitude, spatial resolution, UV to thermal infrared,…) configuration. Paul Sabatier University distributes free licenses for research activities. This paper presents the calibration of DART model with high spatial resolution satellite images (Landsat 8, Sentinel 2, etc.) that are acquired in the visible (VIS) / near infrared (NIR) domain and in the thermal infrared (TIR) domain. Here, the work is conducted with an atmospherically corrected Landsat 8 image and Bale city, with its urban database. The calibration approach in the VIS/IR domain encompasses 5 steps for computing the 2D distribution (image) of urban albedo at satellite spatial resolution. (1) DART simulation of satellite image at very high spatial resolution (e.g., 50cm) per satellite spectral band. Atmosphere conditions are specific to the satellite image acquisition. (2) Spatial resampling of DART image at the coarser spatial resolution of the available satellite image, per spectral band. (3) Iterative derivation of the urban surfaces (roofs, walls, streets, vegetation,…) optical properties as derived from pixel-wise comparison of DART and satellite images, independently per spectral band. (4) Computation of the band albedo image of the city, per spectral band. (5) Computation of the image of the city albedo and VIS/NIR exitance, as an integral over all satellite spectral bands. In order to get a time series of albedo and VIS/NIR exitance, even in the absence of satellite images, ECMWF information about local irradiance and atmosphere conditions are used. A similar approach is used for calculating the city thermal exitance using satellite images acquired in the thermal infrared domain. Finally, DART simulations that are conducted with the optical properties derived from remote sensing images give also the 3D radiative budget of the city at any date including the date of the satellite image acquisition.
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| 10. |
- Mitraka, Zina, et al.
(author)
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Towards discriminating between zones with different thermal behaviour in cities
- 2017
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In: 2017 Joint Urban Remote Sensing Event, JURSE 2017. Dubai, United Arab Emirates; 6-8 March 2017.. - 9781509058082
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Conference paper (peer-reviewed)abstract
- The advances in satellite sensor technology, the launch of new satellites and the continuous development of remote sensing technology constantly increase the opportunities for monitoring the thermal behaviour of cities from space. Not only the surface temperature, but several other parameters related to the urban climate can be quantified from Earth Observation (EO) data. In this study, remote sensing techniques are applied to derive EO data products and a methodology is proposed that combines this information to discriminate between zones with different thermal behaviour in cities. Information on the building, pervious and paved surface cover, the surface albedo, the mean building/tree height and the sky view factor is quantified in local scale and then used to identify possible zones with homogeneous thermal characteristics.
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