Eberhard Parlow

Urban radiation balance of two coastal cities in a hot and dry environment

Four Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) satellite scenes of Dubai and Abu Dhabi with channels from the visible–near infrared (VNIR) to the thermal infrared (TIR) were analysed to show variations in surface temperature, albedo, emissivity and net radiation in different urban and rural classes. For a better understanding of the spatial coherences of surface properties a land use classification was derived. The different classes were then spatially and temporally compared. The investigations show in the daytime a distinct surface cool island for Dubai and surface cool areas at Abu Dhabi city and its surrounding mangrove areas. Net radiation is mainly controlled by the albedo. The albedo in urban areas is lower than in their surrounding desert environments, therefore the net radiation is higher in the urban areas. The surface temperatures behave contrary to the net radiation and are higher in land use classes, where water is available.

Daytime Turbulence Statistics above a Steep Forested Slope

Six levels of simultaneously sampled ultrasonic data are used to analyse the turbulence structure within a mixed forest of 13 m height on a steep slope (35°) in an alpine valley. The data set is compared to other studies carried out over forests in more ideal, flat terrain. The analysis is carried out for 30-min mean data, joint probability distributions, length scales and spectral characteristics.Thermally induced upslope winds and cold air drainage lead to a wind speed maximum within the trunk space. Slope winds are superimposed on valley winds and the valley-wind component becomes stronger with increasing height. Slope and valley winds are thus interacting on different spatial and time scales leading to a quite complex pattern in momentum transport that differs significantly from surface-layer characteristics. Directional shear causes lateral momentum transports that are in the same order or even larger than the longitudinal ones. In the canopy, however, a sharp attenuation of turbulence is observed. Skewed distributions of velocity components indicate that intermittent turbulent transport plays an important role in the energy distribution.Even though large-scale pressure fields lead to characteristic features in the turbulent structure that are superimposed on the canopy flow, it is found that many statistical properties typical of both mixing layers and canopy flow are observed in the data set.

The available energy over a Scots Pine plantation : What's up for partitioning ?

SummaryErrors influencing the calculation of the available energy above a forest are discussed. The main emphasis is put on the investigation of the problems affecting the measurement of net radiation. This is done by utilizing the data set of a surface energy balance experiment which was conducted in and above a Scots Pine plantation from May 11 to 22, 1992. During that Hartheimer Experiment (HartX) there were redundant measurements of net radiation using five different radiometers of three different designs. The initially fair agreement between the net radiometer readings was considerably improved by introducing different responsivities for the shortand longwave range. The mean deviations to the relative net radiation after correction vary between — 1.4 and 1.2 Wm−2 with standard deviations between ± 5.4 and 6.6 Wm−2. The total error referring to the available energy is estimated to be up to ± 36 Wm−2 (± 6%) around midday decreasing to 10 Wm−2 during nighttime.

A Conceptual List of Indicators for Urban Planning and Management Based on Earth Observation

Sustainable development is a key component in urban studies. Earth Observation (EO) can play a valuable role in sustainable urban development and planning, since it represents a powerful data source with the potential to provide a number of relevant urban sustainability indicators. To this end, in this paper we propose a conceptual list of EO-based indicators capable of supporting urban planning and management. Three cities with different typologies, namely Basel, Switzerland; Tel Aviv, Israel; and Tyumen, Russia were selected as case studies. The EO-based indicators are defined to effectively record the physical properties of the urban environment in a diverse range of environmental sectors such as energy efficiency, air pollution and public health, water, transportation and vulnerability to hazards. The results assess the potential of EO to support the development of a set of urban environmental indicators towards sustainable urban planning and management.

Atmospheric and hydrological boundary conditions for slushflow initiation due to snowmelt

Slush-flows of a large variety of magnitudes were observed during three field campaigns to Liefdefjorden, northwestern Spitsbergen, and one campaign to Karke-vagge, northern Sweden. In the latter campaign, the release and movement of a slush torrent was documented on video and in photographs. Meteorological and snow-hydrological measurements carried out during these campaigns were analysed with respect to slushflow initiation due to snow-melt. Since slushflows are quite common in polar and sub-polar drainage basins (although they are not restricted to these regions), specific atmospheric and hydrological boundary condittons must be fulfilled for slushflow initiation due to snowmelt. Radiative fluxes, air temperatures and wind velocities are the most important atmospheric variables, while snow depth, depth of the water-saturated layer, hydraulic conductivity and snow structure are the primary snow variables of interest. It has been shown that slushflows can be released due to energy input in the snow cover by net radiation and sensible heat within the ordinary range of the high-latitudinal snow melt period. Slush torrent initiation is intensified by a superpositton of both energy fluxes. Infiltration losses were not significant even when permafrost was not present. Crucial for slushflow initiation due to snowmelt is the timing of energy input and meltwater flow through the snowpack.

Towards EO-based sustainable urban planning and management

The increasing availability of Earth Observation (EO) technologies has provided new opportunities for a wide range of urban applications, such as mapping and monitoring of the urban environment, socio-economic estimations, characterization of urban climate, analysis of regional and global impacts and urban security and emergency preparedness. However, a gap exists between the research-focused results offered by the urban EO community and the application of these data and products by urban planners and decision makers. Hence, the main objective of the GEOURBAN (ExploitinG Earth Observation in sUstainable uRBan plAnning & maNagement) project is to bridge this gap by demonstrating the ability of current and future EO systems to depict parameters of urban structure and urban environmental quality at detailed level. This paper introduces the conceptual approach towards the integration of EO-based geo-information into urban and spatial planning and presents and discusses first results of the indicators developed and evaluated by using remote sensing data.

Exploiting earth observation in sustainable urban planning and management — The GEOURBAN project

Sustainable urban planning and management demand innovative concepts and techniques to obtain up-to-date and area-wide information on the characteristics and development of the urban system. The increasing availability of Earth Observation (EO) technologies has provided new opportunities for a wide range of urban applications, such as mapping and monitoring of the urban environment, socio-economic estimations, characterization of urban climate, analysis of regional and global impacts and urban security and emergency preparedness. However, a gap exists between the research-focused results offered by the urban EO community and the application of these data and products by urban planners and decision makers. Hence, the main objective of the GEOURBAN (ExploitinG Earth Observation in sUstainable uRBan plAnning & maNagement) project is to bridge this gap by demonstrating the ability of current and future EO systems to depict parameters of urban structure and urban environmental quality at detailed level. This paper introduces the conceptual approach towards the integration of EO-based geo-information into urban and spatial planning and presents and discusses first results of the indicators developed and evaluated by using remote sensing data.

A novel approach for anthropogenic heat flux estimation from space

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.

Attribution of local climate zones using a multitemporal land use/land cover classification scheme

Abstract. Worldwide, the number of people living in an urban environment exceeds the rural population with increasing tendency. Especially in relation to global climate change, cities play a major role considering the impacts of extreme heat waves on the population. For urban planners, it is important to know which types of urban structures are beneficial for a comfortable urban climate and which actions can be taken to improve urban climate conditions. Therefore, it is essential to differ between not only urban and rural environments, but also between different levels of urban densification. To compare these built-up types within different cities worldwide, Stewart and Oke developed the concept of local climate zones (LCZ) defined by morphological characteristics. The original LCZ scheme often has considerable problems when adapted to European cities with historical city centers, including narrow streets and irregular patterns. In this study, a method to bridge the gap between a classical land use/land cover (LULC) classification and the LCZ scheme is presented. Multitemporal Landsat 8 data are used to create a high accuracy LULC map, which is linked to the LCZ by morphological parameters derived from a high-resolution digital surface model and cadastral data. A bijective combination of the different classification schemes could not be achieved completely due to overlapping threshold values and the spatially homogeneous distribution of morphological parameters, but the attribution of LCZ to the LULC classification was successful.

Evaluation of numerical simulations of CO2 transport in a city block with field measurements

Studying urban air-transport phenomena is highly complex, because of the heterogenous flow patterns that can arise. The main reason for these is the variable topology of urban areas, however, there is a large number of influencing variables such as meteorological conditions (e.g., wind situation, temperature) and anthropogenic factors such as traffic emissions. During a one-year CO2 measurement campaign in the city of Basel, Switzerland, steep CO2 gradients were measured around a large building. The concentration differences showed a strong dependency on the local flow regimes. Analysis of the field data alone did not provide a complete explanation for the mechanisms underlying the observed phenomena. The key numerical parameters were defined and the influence of turbulent kinetic energy dependency on the time interval for the Reynolds decomposition was studied. A Reynolds-Average Navier-Stokes Computational Fluid Dynamics (CFD) approach was applied in the study area and the CO2 concentrations were simulated for six significant meteorological situations and compared to the measured data. Two flow regimes dependent on the wind situation, which either enhanced or suppressed the concentration of CO2 in the street canyon, were identified. The enhancement of CO2 in the street canyon led to a large difference in CO2 concentration between the backyard- and street-sides of a building forming the one wall of the canyon. The specific characteristics of the flow patterns led to the identification of the processes determining the observed differences in CO2 concentrations. The combined analysis of measurement and modeling showed the importance of reliable field measurements and CFD simulations with a high spatial resolution to assess transport mechanisms in urban areas.