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A spatially explicit Global Reef Island Database (GRID) that captures distribution, diversity and relative vulnerability of the world's low-lying reef islands

Low-lying coral reef islands harbour a distinct, yet highly threatened biological and cultural diversity that is increasingly exposed to climate change impacts. The combination of low elevation, small size, sensitivity to changes in boundary conditions (sea level, waves and currents, locally generated sediment supply) and at some locations high population densities, is why low-lying reef islands (LRIs) are considered among the most vulnerable environments on Earth to climate change. To date, their global distribution and influence of climatic, oceanographic, and geologic setting are only poorly documented or restricted to smaller scales. Here, I present the first detailed global analysis of LRIs utilising freely available global datasets to produce a global reef island database (GRID) and associated intrinsic and extrinsic characteristics that can be used within a coastal vulnerability index (CVI). All datasets used to create the GRID were released between 30 November 2015 and 3 August 2023, while the current version of the GRID database was completed in November 2024. When developing the GRID, LRIs are defined as landmasses <30 km² located on or within 1 km of coral reef and with an elevation of <16 m. Development of the GRID required: 1) the creation of a global shoreline vector file containing the geographic distribution of LRIs and 2) the development of a comprehensive global database of LRIs including eight intrinsic and ten extrinsic variables extracted from global datasets. Intrinsic variables include: 1) human populations, 2) island area, 3) island perimeter, 4) mean elevation, 5) island circularity/shape, 6) underlying reef type, 7) geographic isolation and 8) distance to the nearest neighbouring reef island. Extrinsic variables include: 1) mean water depth, 2) standard deviation of mean water depth, 3) mean annual significant wave height, 4) mean annual wave period, 5) mean spring tidal range, 6) relative tidal range, 7) wave-tide regime, 8) relative wave exposure, 9) relative tropical storm exposure and 10) year-2100 projected median sea level rise rate. The GRID was initially derived from version 2.1 of the UNEP-WCMC Global Island Database, a global shoreline vector file based on geometry data from Open Street Map® (OSM) and released in November 2015. The initial vector file was projected using the Mollweide projection, an equal-area pseudo cylindrical map projection chosen for its accurate derivation of area, especially in regions close to the equator, where most LRIs are located. The final GRID contains 34,404 individual LRIs distributed throughout tropical regions of the world's oceans, amassing a total land area of nearly 11,000 km² with approximately 60,740 km of shoreline and housing around 2.6 million people. While intrinsic variables are typically spatially homogenous, LRIs are generally highly spatially clustered throughout the GRID with respect to extrinsic variables. The spatial distribution of LRIs within the GRID was validated using: 1) published data and 2) quantitative accuracy assessments using satellite imagery. Spatial distributions of LRIs captured in the GRID are extremely consistent with those published in the literature (r² = 0.96) and those derived from independent analysis of satellite imagery (r² = 0.94). Finally, the GRID was used to develop an island vulnerability index (IVI) for each LRI on a scale of 0-1 with 0 representing no vulnerability and 1 representing maximum vulnerability. The GRID database is provided as a tab-delimited text file as well as ESRI shapefiles (points and polygons in WGS84 and Mollweide projection) and a comma-separated value file.

Sentinel-5P TROPOMI - Aerosol Optical Depth (AOD), Level 3 - Global

Aerosol optical depth (AOD) as derived from TROPOMI observations. AOD describes the attenuation of the transmitted radiant power by the absence of aerosols. Attenuation can be caused by absorption and/or scattering. AOD is the primary parameter to evaluate the impact of aerosols on weather and climate. Daily AOD observations are binned onto a regular latitude-longitude grid. The TROPOMI instrument onboard the Copernicus SENTINEL-5 Precursor satellite is a nadir-viewing, imaging spectrometer that provides global measurements of atmospheric properties and constituents on a daily basis. It is contributing to monitoring air quality and climate, providing critical information to services and decision makers. The instrument uses passive remote sensing techniques by measuring the top of atmosphere solar radiation reflected by and radiated from the earth and its atmosphere. The four spectrometers of TROPOMI cover the ultraviolet (UV), visible (VIS), Near Infra-Red (NIR) and Short Wavelength Infra-Red (SWIR) domains of the electromagnetic spectrum. The operational trace gas products generated at DLR on behave ESA are: Ozone (O3), Nitrogen Dioxide (NO2), Sulfur Dioxide (SO2), Formaldehyde (HCHO), Carbon Monoxide (CO) and Methane (CH4), together with clouds and aerosol properties. This product is created in the scope of the project INPULS. It develops (a) innovative retrieval algorithms and processors for the generation of value-added products from the atmospheric Copernicus missions Sentinel-5 Precursor, Sentinel-4, and Sentinel-5, (b) cloud-based (re)processing systems, (c) improved data discovery and access technologies as well as server-side analytics for the users, and (d) data visualization services.

Sentinel-5P TROPOMI – Aerosol Layer Height (ALH), Level 3 – Global

Aerosols are an indicator for episodic aerosol plumes from dust outbreaks, volcanic ash, and biomass burning. Daily observations are binned onto a regular latitude-longitude grid. The Aerosol layer height is provided in kilometres. The TROPOMI instrument onboard the Copernicus SENTINEL-5 Precursor satellite is a nadir-viewing, imaging spectrometer that provides global measurements of atmospheric properties and constituents on a daily basis. It is contributing to monitoring air quality and climate, providing critical information to services and decision makers. The instrument uses passive remote sensing techniques by measuring the top of atmosphere solar radiation reflected by and radiated from the earth and its atmosphere. The four spectrometers of TROPOMI cover the ultraviolet (UV), visible (VIS), Near Infra-Red (NIR) and Short Wavelength Infra-Red (SWIR) domains of the electromagnetic spectrum. The operational trace gas products generated at DLR on behave ESA are: Ozone (O3), Nitrogen Dioxide (NO2), Sulfur Dioxide (SO2), Formaldehyde (HCHO), Carbon Monoxide (CO) and Methane (CH4), together with clouds and aerosol properties. This product is created in the scope of the project INPULS. It develops (a) innovative retrieval algorithms and processors for the generation of value-added products from the atmospheric Copernicus missions Sentinel-5 Precursor, Sentinel-4, and Sentinel-5, (b) cloud-based (re)processing systems, (c) improved data discovery and access technologies as well as server-side analytics for the users, and (d) data visualization services.

Süßwasserflüsse über dem Ozean I - Verdunstungsflüsse (FreshOcean)

Die Veränderung des globalen Wasserkreislaufs durch den Klimawandel ist eine der größten Herausforderungen für die Gesellschaft, da trockene Regionen trockener und feuchte Regionen feuchter werden. Das Problem besteht darin, dass 85 % der Verdunstung und 77 % der Niederschläge über den Ozeanen stattfinden und der globale Wasserkreislauf aufgrund der schwierigen Beobachtungsbedingungen über den Ozeanen nur unzureichend verstanden wird. Der Austausch von Süßwasser zwischen dem Ozean und der Atmosphäre findet jedoch in einer obersten dünnen Schicht der Meeresoberfläche statt, den so genannten Oberflächenfilm. Die Verdunstung von Wasserdampf aus den Oberflächenfilmen erhöht deren Salzgehalt, während der Niederschlag den Salzgehalt in den Oberflächenfilmen verringert. Das Hauptziel dieses Forschungsprojekts ist ein umfassendes Verständnis der Dynamik und der Veränderungen des Salzgehalts und der damit zusammenhängenden thermischen Felder in den ozeanischen Oberflächenfilmen und der oberflächennahen Schicht (NSL) sowie deren Zusammenhang mit den verdunstenden Süßwasserflüssen zu erzielen. Einer der Hauptpunkte dieser Arbeit ist, dass Süsswasserflüsse (Verdunstung minus Niederschlag) direkt auf die Meeresoberfläche einwirkt und daher vorwiegend den Salzgehalt der Oberflächenfilme quasi-instant beeinflusst, während die derzeitigen Methoden, die den Salzgehalt der gemischten Schicht verwenden, sich auf dekadischen Skalen beziehen. Eine umfassende Reihe von Experimenten wird in einer großmaßstäblichen Mesokosmenanlage an der Universität Oldenburg durchgeführt, in der die treibenden Kräfte für die Verdunstung kontrolliert werden können (Wassertemperatur, Windgeschwindigkeit, turbulente Vermischung, Lufttemperatur und -feuchtigkeit). Im Mittelpunkt steht eine Expedition in den Mittelatlantik mit seinem hohen Oberflächensalzgehalt, d. h. Verdunstungsraten übersteigen die Niederschlagsraten. Während der Expedition kommt ein funkgesteuertes Katamaran zum Einsatz, der in der Lage ist, Oberflächenfilme zu sammeln. Die Beobachtungen werden durch Messungen von Bojen, schiffsbasierten Messungen und Satelliten unterstützt. Die Arbeiten ergänzen die laufenden Aktivitäten zur Untersuchung des Zusammenhangs zwischen dem Salzgehalt der Oberflächenfilme und den Niederschlägen. Diese Arbeit ist ein erster Schritt, um zu verstehen, wie der Salzgehalt der Oberflächenfilme und der oberflächennahe Salzgehalt verwendet werden können, um dynamische Süsswasserflüsse zu integrieren und Parametrisierungen zur Extrapolation von Süsswasserflüssen unter Verwendung von satellitengestützten Salzgehaltsdaten zu entwickeln.

Großräumige Analyse von Verbuschungsflächen mit NOAA-AVHRR-Daten in Namibia

Seit 1979 erfassen Satelliten der NOAA-Serie die Erde und liefern damit eine der längsten kontinuierlichen Bild-Datenreihen von Satelliten überhaupt. Durch ihre großflächige Abdeckung, ihre hohe zeitliche Auflösung und ihren kostengünstigen Empfang eignen sich diese Daten hervorragend zum Monitoring. Bislang werden diese langen Zeitreihen noch kaum herangezogen, um langfristige Veränderungen von Oberflächenphänomenen zu beschreiben, denn der Großteil der Fernerkundungsarbeiten beschäftigt sich mit neueren Sensoren und deren Anwendungen. Gerade vor dem Hintergrund der Landdegradierung durch unangepaßte Landnutzung in den Trockenräumen der Erde sollten die vorhandenen archivierten Datenreihen zur Langzeitanalyse aber genutzt werden und die Ergebnisse in Konzepte des Landmanagements einfließen. In Namibia vollzieht sich in den Nationalparks und dem Weideland die Landdegradierung durch eine massive Verbuschung, v.a. mit Acacia mellifera. Die Verbuschungsdynamik der letzten 20 Jahre soll in Etosha mit NOA-AVHRR-Daten erfasst werden. Die Ergebnisse aus dem Etosha-Nationalpark können dann zum Monitoring der Verbuschung in Namibia von örtlichen Institutionen eingesetzt werden. So ist die Inwertsetzung der Daten gewährleistet und durch die Weiterentwicklung der NOAA-Serie durch das MODIS-System auch für die Zukunft gewährleistet.

Natural Forest Management in Caracarai, Roraima, Brazil

Objectives: Sustainable management of tropical moist forests through private forest owners will become increasingly important. Media report that in Brazil, particularly in Amazonia, approx. 80 percent of the timber harvested is from illegal sources. Private management of forests according to internationally acknowledged standards offers an opportunity to significantly lower the portion of illegally cut timber. Moreover, it contributes significantly to the conservation of the Amazon forest. Private forest owners show a clear long-term commitment towards the implementation of management standards according that is ecologically compatible, socially acceptable and economically viable. The project area, a pristine forest in legal Amazonia in the transition zone between moist tropical forests and savannas (cerrado), is extremely diverse in floristic and faunistic terms. The institute cooperates with the private forest owner. Main tasks are to document the faunistic and floristic diversity, to calculate the Annual Allowable Cut and to elaborate concepts for site-specific silviculture. Results: To date (Oct. 2006) the following activities were started: - a comprehensive inventory system for planning at the FMU-level has been successfully introduced; - the inventory system for the annual coupe area has been designed and data for the first coupe are being processed; - the annual allowable cut is currently calculated based on the results of the above described inventories; - two fauna surveys are completed; one focusing on large mammals and one on the avi-fauna. A long-term monitoring concept to assess the influence of forest management on the faunistic diversity is currently under development; - forest zoning is completed applying terrestrial surveys and interpreting high-resolution satellite images; - a study on the use of Bethollethia excelsa-fruits (Brazil nuts) is currently implemented; - a study on timber properties of lesser known species is currently implemented.

Forschergruppe (FOR) 1740: Ein neuer Ansatz für verbesserte Abschätzungen des atlantischen Frischwasserhaushalts und von Frischwassertransporten als Teil des globalen Wasserkreislaufs, The Atmospheric Side of the Freshwater Budget

The focus of this project is to analyse the observed surface freshwater fluxes through improved estimates of evaporation and precipitation and their individual error characteristics in the HOAPS climatology and its ground validation in climate-related hotspots of the Atlantic Ocean. To enable that in a consistent manner we propose to establish an error characterization of the HOAPS evaporation data by triple collocations with ship and buoy measurements and between individual satellites and to improve the error characterization of the HOAPS precipitation by analysing available shipboard disdrometer data using point to area statistics. After these improvements, an analysis of the spatio-temporal variability of the surface fresh water balance E-P over the Atlantic Ocean is planned, especially with respect to the Hadley circulation and the hotspot regions of interest to related WPs. Also the atmospheric water transport shall be analysed in order to find the source or target region of local fresh water imbalances. And finally, a consistent inter-comparison of the upcoming global ocean surface salinity fields from SMOS with freshwater fluxes from the HOAPS climatology is proposed.

Global Land Cover Map for 2009 (GlobCover 2009)

The GlobCover initiative of ESA developed and demonstrated a service for the generation of global land cover maps, based on Envisat MERIS Fine Resolution (300 m) mode data. ESA and Université catholique de Louvain demonstrated the possibility to use the GlobCover system operationally by delivering GlobCover 2009, the 2009 global land cover map, within a year of the last satellite acquisition. For maximum user benefit the thematic legend of GlobCover is compatible with the UN Land Cover Classification System (LCCS). The system is based on an automatic pre-processing and classification chain. Finally, the global land cover map was validated by an international group of land cover experts and the validation reports are also available to the user community.

METOP GOME-2 - Ozone (O3) - Global

The Global Ozone Monitoring Experiment-2 (GOME-2) instrument continues the long-term monitoring of atmospheric trace gas constituents started with GOME / ERS-2 and SCIAMACHY / Envisat. Currently, there are three GOME-2 instruments operating on board EUMETSAT's Meteorological Operational satellites MetOp-A, -B, and -C, launched in October 2006, September 2012, and November 2018, respectively. GOME-2 can measure a range of atmospheric trace constituents, with the emphasis on global ozone distributions. Furthermore, cloud properties and intensities of ultraviolet radiation are retrieved. These data are crucial for monitoring the atmospheric composition and the detection of pollutants. DLR generates operational GOME-2 / MetOp level 2 products in the framework of EUMETSAT's Satellite Application Facility on Atmospheric Chemistry Monitoring (AC-SAF). GOME-2 near-real-time products are available already two hours after sensing. The operational ozone total column products are generated using the algorithm GDP (GOME Data Processor) version 4.x integrated into the UPAS (Universal Processor for UV / VIS Atmospheric Spectrometers) processor for generating level 2 trace gas and cloud products. The new improved DOAS-style (Differential Optical Absorption Spectroscopy) algorithm called GDOAS, was selected as the basis for GDP version 4.0 in the framework of an ESA ITT. GDP 4.x performs a DOAS fit for ozone slant column and effective temperature followed by an iterative AMF / VCD computation using a single wavelength. For more details please refer to relevant peer-review papers listed on the GOME and GOME-2 documentation pages: https://atmos.eoc.dlr.de/app/docs/

METOP GOME-2 - Cloud Top Pressure (CTP) - Global

The Global Ozone Monitoring Experiment-2 (GOME-2) instrument continues the long-term monitoring of atmospheric trace gas constituents started with GOME / ERS-2 and SCIAMACHY / Envisat. Currently, there are three GOME-2 instruments operating on board EUMETSAT's Meteorological Operational satellites MetOp-A, -B and -C, launched in October 2006, September 2012, and November 2018, respectively. GOME-2 can measure a range of atmospheric trace constituents, with the emphasis on global ozone distributions. Furthermore, cloud properties and intensities of ultraviolet radiation are retrieved. These data are crucial for monitoring the atmospheric composition and the detection of pollutants. DLR generates operational GOME-2 / MetOp level 2 products in the framework of EUMETSAT's Satellite Application Facility on Atmospheric Chemistry Monitoring (AC-SAF). GOME-2 near-real-time products are available already two hours after sensing. OCRA (Optical Cloud Recognition Algorithm) and ROCINN (Retrieval of Cloud Information using Neural Networks) are used for retrieving the following geophysical cloud properties from GOME and GOME-2 data: cloud fraction (cloud cover), cloud-top pressure (cloud-top height), and cloud optical thickness (cloud-top albedo). OCRA is an optical sensor cloud detection algorithm that uses the PMD devices on GOME / GOME-2 to deliver cloud fractions for GOME / GOME-2 scenes. ROCINN takes the OCRA cloud fraction as input and uses a neural network training scheme to invert GOME / GOME-2 reflectivities in and around the O2-A band. VLIDORT [Spurr (2006)] templates of reflectances based on full polarization scattering of light are used to train the neural network. ROCINN retrieves cloud-top pressure and cloud-top albedo. The cloud-top pressure for GOME scenes is derived from the cloud-top height provided by ROCINN and an appropriate pressure profile. For more details please refer to relevant peer-review papers listed on the GOME and GOME-2 documentation pages: https://atmos.eoc.dlr.de/app/docs/

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