Marc Paganini

Environmental science: Agree on biodiversity metrics to track from space

Ecologists and space agencies must forge a global monitoring strategy, say Andrew K. Skidmore, Nathalie Pettorelli and colleagues.

Evaluation of the surface urban heat island effect in the city of Madrid by thermal remote sensing

The surface urban heat island (SUHI) effect is defined as the increased surface temperatures in urban areas in contrast to cooler surrounding rural areas. In this article, the evaluation of the SUHI effect in the city of Madrid (Spain) from thermal infrared (TIR) remote-sensing data is presented. The data were obtained from the framework of the Dual-use European Security IR Experiment (DESIREX) campaign that was carried out during June and July 2008 in Madrid. The campaign combined the collection of airborne hyperspectral and in situ measurements. Thirty spectral and spatial high-resolution images were acquired with the Airborne Hyperspectral Scanner (AHS) sensor in a 11, 21, and 4 h UTC scheme. The imagery was used to retrieve the SUHI effect by applying the temperature and emissivity separation (TES) algorithm. The results show a nocturnal SUHI effect with a highest value of 5 K. This maximum value agrees within 1 K with the highest value of the urban heat island (UHI) observed using air temperature data (AT). During the daytime, this situation is reversed and the city becomes a negative heat island.

Heat wave hazard classification and risk assessment using artificial intelligence fuzzy logic

The average summer temperatures as well as the frequency and intensity of hot days and heat waves are expected to increase due to climate change. Motivated by this consequence, we propose a methodology to evaluate the monthly heat wave hazard and risk and its spatial distribution within large cities. A simple urban climate model with assimilated satellite-derived land surface temperature images was used to generate a historic database of urban air temperature fields. Heat wave hazard was then estimated from the analysis of these hourly air temperatures distributed at a 1-km grid over Athens, Greece, by identifying the areas that are more likely to suffer higher temperatures in the case of a heat wave event. Innovation lies in the artificial intelligence fuzzy logic model that was used to classify the heat waves from mild to extreme by taking into consideration their duration, intensity and time of occurrence. The monthly hazard was subsequently estimated as the cumulative effect from the individual heat waves that occurred at each grid cell during a month. Finally, monthly heat wave risk maps were produced integrating geospatial information on the population vulnerability to heat waves calculated from socio-economic variables.

Evaluation of satellite-derived products for the characterization of the urban thermal environment

Abstract. Knowledge of the air and land surface temperature and their temporal and spatial variations within a city environment is of prime importance to the study of urban climate and human–environment interactions and to monitoring environmental changes due to urbanization. We present a number of air and land surface temperature products that have been produced, archived, evaluated, and analyzed for 10 European cities within the framework of the European Space Agency–funded “Urban Heat Islands and Urban Thermography” project. We evaluate in what way these products are suited to explore the urban thermal dynamics and how products with different temporal and spatial resolution can provide a complementary view, both for thermal patterns as well as heat waves. Level of confidence was evaluated through quantitative, qualitative, and user-based analyses.

Spatially detailed retrievals of spring phenology from single-season high-resolution image time series

Vegetation indices derived from satellite image time series have been extensively used to estimate the timing of phenological events like season onset. Medium spatial resolution (≥250 m) satellite sensors with daily revisit capability are typically employed for this purpose. In recent years, phenology is being retrieved at higher resolution (≤30 m) in response to increasing availability of high-resolution satellite data. To overcome the reduced acquisition frequency of such data, previous attempts involved fusion between high- and medium-resolution data, or combinations of multi-year acquisitions in a single phenological reconstruction. The objectives of this study are to demonstrate that phenological parameters can now be retrieved from single-season high-resolution time series, and to compare these retrievals against those derived from multi-year high-resolution and single-season medium-resolution satellite data. The study focuses on the island of Schiermonnikoog, the Netherlands, which comprises a highly-dynamic saltmarsh, dune vegetation, and agricultural land. Combining NDVI series derived from atmospherically-corrected images from RapidEye (5 m-resolution) and the SPOT5 Take5 experiment (10m-resolution) acquired between March and August 2015, phenological parameters were estimated using a function fitting approach. We then compared results with phenology retrieved from four years of 30 m Landsat 8 OLI data, and single-year 100 m Proba-V and 250 m MODIS temporal composites of the same period. Retrieved phenological parameters from combined RapidEye/SPOT5 displayed spatially consistent results and a large spatial variability, providing complementary information to existing vegetation community maps. Retrievals that combined four years of Landsat observations into a single synthetic year were affected by the inclusion of years with warmer spring temperatures, whereas adjustment of the average phenology to 2015 observations was only feasible for a few pixels due to cloud cover around phenological transition dates. The Proba-V and MODIS phenology retrievals scaled poorly relative to their high-resolution equivalents, indicating that medium-resolution phenology retrievals need to be interpreted with care, particularly in landscapes with fine-scale land cover variability.

ESA activities related to forest fires: ATSR World Fire Atlas (WFA), GlobCarbon, and RISK-EOS

During the past few years, the European Space Agency has launched several projects related to forest fires from global to local scales. The ATSR World Fire Atlas (WFA) project started in late 1995 and is still running today. It provides the longest time series ever produced on the global distribution of active fires. The WFA consists of 12 years of coherent and consistent data sets. The night time fire occurrences are derived from the 3.7 micron channel on-board the ATSR instrument series hosted by the ERS-2 and ENVISAT satellites. The ATSR WFA products were validated first in 1998 with the support of IGBP and more recently by extensive comparisons with existing data sets on forest fires events. A smooth transition from the ERS-2 ATSR-2 to the ENVISAT AATSR has been performed in January 2003 and the quality of the WFA products continuity verified. The ATSR WFA products are available in near real time since May 2006. The distribution of the ATSR WFA products will be thoroughly analyzed in this paper and a synthesis of the work performed by more than 900 registered users will be presented. The GlobCarbon project started in early 2003 with the objective to develop a service for the production of multi-year / multi-sensors global level 3 Land products to be used as input to carbon assimilation models. Understanding the spatial and temporal variation in carbon fluxes is essential to constrain models that predict climate change. However our current knowledge of these spatial and temporal patterns is uncertain, particularly over land. One of the bio-geophysical parameters that the GlobCarbon project aims to measure is the fully calibrated estimate of the burned areas quasi-independent of the original satellite sensor. These burned areas estimates are used in dynamic global vegetation models, a central component of the IGBP-IHDP-WCRP Global Carbon Cycle Joint Project. The service will feature global estimates of burned areas amongst other variables from 1998 to 2007, derived from Earth Observation sensors (ERS-2 ATSR-2, ENVISAT AATSR and SPOT VEGETATION). Finally the RISK-EOS project started in 2003 under the framework of the Global Monitoring for Environment and Security (GMES) initiative, with the objective to establish a network of European service providers for the provision of geoinformation services in support to the risk management of meteorological hazards (floods and fires). The Fire component of RISK-EOS feature two main services: the Burn Scar Mapping (BSM) service that provides some seasonal mapping of forests and semi-natural burned areas at high spatial resolution (minimum mapping unit of 3 to 5 ha); and the Regional Fire Monitoring (RFM) service that provides near real time observation of active fires, based on middle resolution satellite data (AQUA/TERRA MODIS and MSG SEVIRI). The RISK-EOS BSM service builds on the achievements of ITALSCAR, a demonstration project for the yearly mapping of burned areas in Italy, using the LANDSAT Thematic Mapper sensor. The paper will provide a synthesis of the RISK-EOS products validation and utility reports collected during the 2006 summer season.

Earth observation supporting multilateral environmental agreements: the initiatives of the european space agency

The European Space Agency (ESA) is carrying out a number of initiatives aimed at exploring and demonstrating the capabilities of EO technology to support the implementation of key environmental conventions (e.g., UNFCCC, UNCCD, UNCBD, Ramsar Convention). This paper provides an overview of the main projects that the European Space Agency is carrying out within the context of this important topic as well as the

Monitoring desertification using EO technologies: Experience of the ESA DUE DesertWatch project

The DesertWatch ESA DUE project, recently successfully completed, aimed at developing an integrated information system tailored on the specific user needs, built on the technological transfer of the most significant results of the related research projects. The resulting DesertWatch Information System, a user-friendly integrated Software remote sensing tool for monitoring desertification, have being installed and is now used in Italy, Turkey and Portugal.