Olivier Arino

The Global Ocean Data Assimilation Experiment High-resolution Sea Surface Temperature Pilot Project

A new generation of integrated sea surface temperature (SST) data products are being provided by the Global Ocean Data Assimilation Experiment (GODAE) High-Resolution SST Pilot Project (GHRSST-PP). These combine in near-real time various SST data products from several different satellite sensors and in situ observations and maintain the fine spatial and temporal resolution needed by SST inputs to operational models. The practical realization of such an approach is complicated by the characteristic differences that exist between measurements of SST obtained from subsurface in-water sensors, and satellite microwave and satellite infrared radiometer systems. Furthermore, diurnal variability of SST within a 24-h period, manifested as both warm-layer and cool-skin deviations, introduces additional uncertainty for direct intercomparison between data sources and the implementation of data-merging strategies. The GHRSST-PP has developed and now operates an internationally distributed system that provides operatio...

GlobCover: ESA service for global land cover from MERIS

The Globcover initiative comprises the development and demonstration of a service that in first instance produces a global land cover map for year 2005/2006. Globcover uses MERIS fine resolution (300 m) mode data acquired between mid 2005 and mid 2006 and, for maximum user benefit, the thematic legend is compatible with the UN land cover classification system (LCCS). This new product updates and complements the other existing comparable global products, such as the global land cover map at 1 km resolution for the year 2000 (GLC2000) produced by JRC. It is expected to improve such previous global product, in particular because of the finer spatial resolution. The Globcover project is an initiative of ESA in cooperation with an international network of partner including EEA, FAO, GOFC-GOLD, IGBP, JRC and UNEP.

Estimating Tropical Deforestation from Earth Observation Data

This article covers the very recent developments undertaken for estimating tropical deforestation from Earth observation data. For the United Nations Framework Convention on Climate Change process it is important to tackle the technical issues surrounding the ability to produce accurate and consistent estimates of GHG emissions from deforestation in developing countries. Remotely-sensed data are crucial to such efforts. Recent developments in regional to global monitoring of tropical forests from Earth observation can contribute to reducing the uncertainties in estimates of carbon emissions from deforestation. Data sources at approximately 30 m × 30 m spatial resolution already exist to determine reference historical rates of change from the early 1990s. Key requirements for implementing future monitoring programs, both at regional and pan-tropical regional scales, include international commitment of resources to ensure regular (at least yearly) pan-tropical coverage by satellite remote sensing imagery at a sufficient level of detail; access to such data at low-cost; and consensus protocols for satellite imagery analysis.

Geolocation Assessment of MERIS GlobCover Orthorectified Products

The GlobCover project has developed a service dedicated to the generation of multiyear global land cover maps at 300-m spatial resolution using as its main source of data the full-resolution full-swath (300 m) data (FRS) acquired by the MERIS sensor on-board the ENVISAT satellite. As multiple single daily orbits have to be combined in one single data set, an accurate relative and absolute geolocation of GlobCover orthorectified products is required and needs to be assessed. We describe in this paper the main steps of the orthorectification pre-processing chain as well as the validation methodology and geometric performance assessments. Final results are very satisfactory with an absolute geolocation error of 77-m rms and a relative geolocation error of 51-m rms.

Initiative to quantify terrestrial carbon sources and sinks

Questions related to the distribution and spatio-temporal dynamics of the terrestrial carbon fluxes are at the core of current scientific and policy debates. In recent years, the primary concern has been the increasing CO2 content in the atmosphere, its effect on climate, and the associated role of terrestrial ecosystems in mitigating the increase and impact of climate change. However, terrestrial carbon dynamics is also closely related to biodiversity land degradation, and other pressing policy and assessment questions. Yet at the global level, no system in place now can provide quantitative information about carbon sources and sinks systematically, reliably, and accurately.

The role of convective processes over the Zaire‐Congo Basin to the southern hemispheric ozone maximum

During October, satellite measurements show that there is a region of elevated tropospheric ozone over the tropical southern Atlantic Ocean. The cause of the high ozone concentrations has been related to biomass burning in South America and Africa. In this paper, we present evidence from satellite sources, European Center for Medium-Range Weather Forecast analyses, and a mesoscale simulation during October, suggesting that afternoon and evening deep convection in central Africa is responsible for some of the abnormally high concentrations of ozone in the Tropical South Atlantic which extend southeast over southern Africa into the Indian Ocean. The mechanisms for enhancing tropospheric O3 includes (1) the removal of ozone, NOx, and hydrocarbon rich air from fires in eastern Africa within the planetary boundary layer to the middle and upper troposphere by deep convection; (2) the production Of NOx from lightning associated with mesoscale convective systems and the subsequent photochemical production of O3, and (3) the entrainment of O3 rich air from the lower stratosphere into the upper troposphere by deep convection. During the next few years an international field campaign in central Africa (the experiment for regional sources and sinks of oxidants-EXPRESSO), global lightning data, and the launch of the Tropical Rainfall Measuring Mission (TRMM) will help to identify the relative importance of each of the processes over central Africa that could be responsible for high O3 concentrations over the tropical south Atlantic.

Global land cover mapping: current status and future trends

The observation of global-scale land cover (LC) is of importance to international initiatives such as the United Nations Framework Convention on Climate Change (UNFCCC) and Kyoto protocol, governments, and scientific communities in their understanding and monitoring of the changes affecting the environment, and the coordination of actions to mitigate and adapt to global change. As such, reliable and consistent global LC (GLC) datasets are being sought. For instance, GLC datasets are used as an input for many Global Circulation Models, Earth Systems Models and Integrated Assessment Models used for global and regional climate simulations, dynamic vegetation modelling, carbon (stock) modelling, ecosystem modelling, land surface modelling, and impact assessments (Hibbard et al., 2010; Herold et al., 2011).

The GLOBCARBON initiative global biophysical products for terrestrial carbon studies

Understanding the spatial and temporal variation in carbon fluxes is essential to constrain models that predict climate change. However, our current knowledge of spatial and temporal patterns is uncertain, particularly over land. The ESA GLOBCARBON project aims to generate estimates of at-land products quasi-independent of the original Earth Observation source for use in Dynamic Global Vegetation Models, a central component of the ESSP Global Carbon Project. The service features global estimates of: burned area, fAPARS, LAI and vegetation growth cycle. The demonstrator focused on six complete years, from 1998 to 2003 when overlap exists between ESA Earth Observation sensors (ATSR-2, AATSR and MERIS) and VEGETATION but has recently been extended to 2007. This paper presents early results of the first re-processing in the GLOBCARBON project, which was undertaken after comments from users involved in beta testing.

New global land cover mapping exercise in the framework of the ESA Climate Change Initiative

The ESA Climate Change Initiative land cover project focuses on the deriving land cover information driven by requirements for observing Essential Climate Variables. Consultation mechanisms were established with the climate modelling community in order to identify its specific needs in terms of satellite-based global land cover products. Key findings were the needs for successive land cover maps stable over time. As response, an innovative global land cover mapping approach, based on multi-year MERIS and SPOT-Vegetation datasets is proposed. Pre-processing and classification chains able to handle huge amount of data have been developed and a first global land cover map associated to the 2008-2010 epoch is being produced.

Note on the quality of the (A)ATSR land surface temperature record from 1991 to 2009

Land-surface temperature (LST) is a key parameter in the physical study of atmosphere–land interactions as well as for global warming and climate change monitoring on a longer timescale. Remote sensing provides an excellent way to measure LST at a global scale with appropriate spatial and temporal resolution. To retrieve LSTs, measured radiances at the sensor have to be corrected for surface emissivity, atmospheric effects and contaminating clouds. This study is based on the LST data provided by the Along-Track Scanning Radiometers (ATSR-1 and ATSR-2) and the Advanced ATSR (AATSR) on board the three European Space Agency (ESA) satellites, European Remote-Sensing Satellite 1 (ERS-1), ERS-2 and Enviromental Satellite (ENVISAT). The analysis covers data from August 1991 up to December 2009 and contains detailed investigations on global as well as on regional scales with a temporal resolution of 1 month, outlining problems and restrictions within the time series mainly due to cloud contamination and effects of calibration drifts on the cloud detection tests. It is demonstrated that the trends observed, for cooling as well as for warming, are likely to be related to the trends in cloud contamination rather than the trends in the actual LST.