Etienne Bartholomé

A New, Global, Multi-annual (2000-2007) Burnt Area Product at 1 Km Resolution

This paper reports on the development and validation of a new, global, burnt area product. Burnt areas are reported at a resolution of 1 km for seven fire years (2000 to 2007). A modified version of a Global Burnt Area (GBA) 2000 algorithm is used to compute global burnt area. The total area burnt each year (2000-2007) is estimated to be between 3.5 million km 2 and 4.5 million km(2). The total amount of vegetation burnt by cover type according to the Global Land Cover (GLC) 2000 product is reported. Validation was undertaken using 72 Landsat TM scenes was undertaken. Correlation statistics between estimated burnt areas are reported for major vegetation types. The accuracy of this new global data set depends on vegetation type.

Coupling of Vegetation Growing Season Anomalies and Fire Activity with Hemispheric and Regional-Scale Climate Patterns in Central and East Siberia

An 18-yr time series of the fraction of absorbed photosynthetically active radiation (fAPAR) taken in by the green parts of vegetation data from the NOAA Advanced Very High Resolution Radiometer (AVHRR) instrument series was analyzed for interannual variations in the start, peak, end, and length of the season of vegetation photosynthetic activity in central and east Siberia. Variations in these indicators of seasonality can give important information on interactions between the biosphere and atmosphere. A second-order local moving window regression model called the “camelback method” was developed to determine the dates of phenological events at subcontinental scale. The algorithm was validated by comparing the estimated dates to phenological field observations. Using spatial correlations with temperature and precipitation data and climatic oscillation indices, two geographically distinct mechanisms in the system of climatic controls of the biosphere in Siberia are postulated: central Siberia is controlled by an “Arctic Oscillation–temperature mechanism,” while east Siberia is controlled by an “El Nino–precipitation mechanism.” While the analysis of data from 1982 to 1991 indicates a slight increase in the length of the growing season for some land-cover types due to an earlier beginning of the growing season, the overall trend from 1982 to 1999 is toward a slightly shorter season for some land-cover types caused by an earlier end of season. The Arctic Oscillation tended toward a more positive phase in the 1980s leading to enhanced high pressure system prevalence but toward a less positive phase in the 1990s. The results suggest that the two mechanisms also control the fire regimes in central and east Siberia. Several extreme fire years in central Siberia were associated with a highly positive Arctic Oscillation phase, while several years with high fire damage in east Siberia occurred in El Nino years. An analysis of remote sensing data of forest fire partially supports this hypothesis.

The eStation, an Earth Observation processing service in support to ecological monitoring

Abstract The eStation is a collecting and processing system designed to automatically deal with the reception, processing, analysis and dissemination of key environmental parameters derived from remotely sensed data. Developed mainly at the Joint Research Centre of the European Commission, the eStation has been distributed to 47 sub-Saharan countries in the frame of the AMESD (Africa n Monitoring of Environment for Sustainable Development) project to provide local institutions with the capacity to easily access a large range of remote sensing products on vegetation, precipitation, fires and oceans. These products, derived from the processing of images coming from various instruments including SPOT-Vegetation, MSG-SEVIRI and MODIS are developed to allow end-users to make local and regional assessments of the state of marine and terrestrial ecosystems. The products, dispatched to the users through the EUMETSAT data broadcasting system (EUMETCast) or provided by other Earth Observation (EO) data agencies (e.g. NASA), are further processed by the eStation to allow end-users to generate their own environmental, whether terrestrial or marine, assessments and reports. Initially designed as a stand-alone system using an open source development framework, the eStation has recently been further developed as a web processing service to allow a broader range of end-users to access the data and services over the Internet. It is the purpose of this paper to introduce the readers to the eStation and its products, to share the lessons learnt in deploying these services as well as to discuss its more recent use in chained environmental web based modeling services.

Analysis of vegetation pasture climate response on Sahel region through 10 years of remotely sensed data

Studies of impact of human activity on the vegetation dynamics in the Sahel belt of Africa are recently re-invigorated due to a new scientific findings that highlighted the primary role of climate in the drought crises of the 70s-80s. Time series of satellite observations allowed identifying re-greening of the Sahel belt that indicates no sensible human effect on vegetation dynamics at sub continental scale from 80s to late 90s. However, several regional/local crises related to natural resources occurred in the last decades underling that more detailed studies are needed. This study contribute to the understanding of climate/human impact on pasture vegetation status in the Sahel region in the last decade (1999- 2008). The use of a time-series of SPOT-VGT NDVI and FEWS-RFE rainfall estimates allowed to analyze vegetation and rainfall trends and identify local anomalous situation in the region. Trend analysis has been conducted to map a) areas where vegetation has been significantly decreased or increased due to rainfall pattern and b) anomalous zones where vegetation dynamics could not be fully explained by rainfall pattern by. The identified hot-spots areas have been compared with spatial information on the reported humanitarian-food crisis events in order to understand chronic situation where ecosystems carrying capacity is endangered. The results of this study show that even if a general positive re-greening situation is evident for the entire Sahel, some serious hot spots exist in areas where cropping system and pasture activity are conflicting.

Evaluation of remotely sensed DMP product using multi-year field measurements of biomass in West Africa

The Sahelian belt of West Africa is a region characterized by wide climate variations, which can in turn affect the survival of local populations especially in rangeland, as happened during the dramatic food crisis in the 70-80s caused by severe drought. This work has been carried out in the framework of the EU FP7 Geoland2 project as a contribution to the ECOWAS component (Economic Community Of West African States) of the AMESD (African Monitoring of the Environment for Sustainable Development) programme with the purpose of establishing the reliability of Dry Matter Productivity (DMP) developed by Flemish Institute for Technological Research (VITO), a spatial estimation of dry matter (DM) obtained from remotely sensed data. DMP can be of great help in monitoring savanna pasturelands in a region characterized by food insecurity and a significant variability of biomass production, linked to climate variations, which can in turn affect the survival of local populations. The evaluation of DMP was carried out thanks to the Centre de Suivi Ecologique (CSE) and Action Contre la Fame (ACF), the partners who provided the field biomass measurements. The paper shows the correlation of DMP with field measurements of herbaceous biomass, and discusses the differences among the different sites where ground data were collected. The analysis of other environmental variables (land cover, rainfall), which can be influential on rangeland biomass production, is presented in order to better explain the variance of field measurements among the different years.

Changes in vegetation and rainfall patterns in sub-Saharan Africa over the last decade observed by satellites - a national and sub-national synthesis

The African Monitoring of the Environment for Sustainable Development (AMESD) programme, a common initiative of the European Commission (EC) and the African Union Commission, is intended to extend the operational use of Earth Observation technologies and data to environmental and climate monitoring applications. The Natural Resource Monitoring in Africa (NARMA) core information service of the EU project Geoland-2 (http://www.gmesgeoland.info/) provides technical support to AMESD in developing an environmental monitoring capacity over African countries for the needs of the EC services and for regional and continental EC partners in African countries. Recently, there is an increased need in environmental information for the implementation of environmental issues in international cooperation policy. To date, however, decision makers tend to use non-spatial indicators of environmental condition and human impact. Thus, there is a demand to develop new environmental indicators based on Earth Observation derived data and gain user acceptance for them.

Contribution of earth observation data to Congo River basin hydrology understanding

Natural Resource Monitoring in Africa (NARMA) is one of the Core Information Services of EU-FP7 project Geoland2 addressing important sectoral policies that concern with the development of an environmental monitoring capacity over African countries for the needs of the European Commission (EC) services and for regional and continental EC partners in African countries. Congo basin is one of the target area where NARMA has to contribute to the development of AMESD/CICOS services in support to management of water resources focusing on environmental aspects of watersheds. In this contest and to better understand dynamics that occur in the watershed, an analysis has been conducted on the relation between precipitation, river discharge and vegetation dynamics by exploiting available time series of Earth Observation data. Rainfall dynamics has been described using FEWS-NET RFE estimations, river discharge has been monitored using ENVISAT radar altimeter data provided by LEGOS laboratory and vegetation dynamics have been examined through vegetation indices available from long term series of SPOT-VGT data. The comparison between river discharge measured at Bangui (Central African Republic), gauging station and radar altimeter virtual station data demonstrated that these data can be used to estimate river discharge. This result allowed to focus a preliminary analysis on the Uele watershed, Ubangi sub basin, using radar data as a proxy of river discharge, comparing these trends to seasonal rainfall estimates and trying to disentangling the effect of vegetation on discharge-rain relation. Results showed that a strong positive correlation is obtained between rain data and river discharge only at the end of the vegetation season when plants have reduced water demand for evapotranspiration and less intercept rain. Trend analysis on the considered time windows are provided and the contribution of these finding for river water alert monitoring system is discussed.