207 research outputs found
The influence of the NE winter monsoon on productivity changes in the Gulf of Aden, NW Arabian Sea, during the last 530ka as recorded by foraminifera
No full textBenthic and selected planktic foraminifera and stable isotope records were determined in a piston core from the Gulf of Aden, NW Arabian Sea that spans the last 530 ka. The benthic foraminifera were grouped into four principal assemblages using Q-mode Principal Component Analyses. Comparison of each of these assemblages with the fauna of the nearby regions enabled us to identify their specific environmental requirements as a function of variability in food supply and strength of the oxygen minimum zone and by that to use them as indicators of surface water productivity. The benthic foraminiferal productivity indicators coupled with the record of Globigerina bulloides, a planktic foraminifer known to be sensitive to productivity changes in the region, all indicate higher productivity during glacial intervals and productivity similar to present or even reduced during interglacial stages. This trend is opposite to the productivity pattern related to the SW summer monsoon of the Arabian Sea and indicates the role of the NE winter monsoon on the productivity of the Gulf of Aden. A period of exceptionally enhanced productivity is recognized in the Gulf of Aden region between similar to 60 and 13 kyr indicating the intensification of the NE winter monsoon to its maximal activity. Contemporaneous indication of increased productivity in other parts of the Arabian Sea, unexplained so far by the SW summer monsoon variability, might be related to the intensification of the NE winter monsoon. Another prominent event of high productivity, second in its extent to the last glacial productivity event is recognized between 430 and 460 kyr. These two events seem to correspond to periods of similar orbital positioning of rather low precession land eccentricity) amplitude for a relatively long period. Glacial boundary conditions seem to control to a large extent the NE winter monsoon variability as also indicated by the dominance of the 100 ka cycle in the investigated time series. Secondary in their importance are the 23 and 41 ka cycles which seem also to contribute to the NE monsoonal variability. Following the identification of productivity events related to the NE winter monsoon in the Gulf of Aden, it is possible now to extend this observation to other parts of the Arabian Sea and consider the contribution of this monsoonal system to the productivity fluctuations preserved in the sedimentary records. (C) 2000 Elsevier Science B.V. All rights reserved
EnMAP - The future hyperspectral Satellite Mission Product Generation
No full textThe basic components of the future German satellite mission EnMAP (Environmental Mapping and Analysis Program) are the project management led by the Space Agency of the German Aerospace Centre (DLR) located in Bonn-Oberkassel, the space segment consisting of the satellite bus and the hyperspectral instrument established by Kayser Threde in Munich and OHB-Systems in Bremen, the science advisory group headed by GFZ (Deutsches GeoForschungsZentrum) and the ground segment led by DLR. The ground segment is responsible for the establishment of missions operations (e.g. satellite and instrument control), provision of the payload ground segment services (e.g. data reception, operational processing, archiving, user interfacing, product handling) and development of the processor/calibration/validation (PCV) system. This paper describes briefly the EnMAP mission, the mission objectives, the instrument and satellite bus characteristics, the ground segment structure and mainly addresses the concept and activities within the PCV sub-system, which is responsible for the generation of high quality hyperspectral data product
Report and preliminary results of Poseidon Cruise 304 (POS304) Galway - Lisbon; 5. - 22. Oct. 2003
No full textReport and preliminary results of Meteor-Cruise M29/1, Buenos-Aires - Montevideo, 17.6.-13.7.1994
No full textThe manganese nodules of the Kane Gap (East Atlantic). Indicators of sedimentation - erosion changes
No full textRecent activities in the hyperspectral imaging network (Hyper-I-Net): A European consortium fostering imaging spectroscopy research
No full text10Be-dating of a manganese crust from Central North Pacific and implications for ocean palaeocirculation
No full textOne of the most promising applications of the new 10Be detection technique using accelerator mass spectrometry is the determination of growth rates of Mn-nodules and crusts1–5. Because the half life of cosmogenic 10Be (1.5 Myr) is of the same order as the time needed for a few millimetres of nodule material to grow, 10Be is a useful tool for unravelling such evolution during the late Tertiary, when most nodules are assumed to have started their growth6. Mass spectrometric measurement of a 10Be profile across the manganese crust VA 13-2 from the Central Pacific, using a tandem van de Gr£ a ff accelerator, yields growth rates of 2.7 and 4.8 mm Myr−1 for the layers of the crust accumulated between Recent and 6 Myr BP and between 6 and 11 Myr, respectively. Using these measurements as well as 230Th dating, we have been able to distinguish boundaries between zones in the crust with different structures and chemical compositions and to assign ages to them. These ages are 0.12, 2.9–3.4, 5.7–6.7, 7–9, 10–12 and 13–16 Myr BP. All of these boundaries apparently coincide with the times reported for Quaternary and late Tertiary palaeoclimatic events, suggesting that the crust growth has been strongly influenced by palaeoclimate
Mapping Ni-Cu (PGE) bearing ultramafic rocks and associated gossans with airborne and simulated EnMAP satellite hyperspectral imagery, Nunavik, CANADA
No full textThis study investigates the use of AISA optical airborne hyperspectral (2 m spatial resolution) and simulated satellite EnMAP (30 m) to produce detailed lithologic maps in a subarctic region (Nunavik, Canada) where ultramafic rock units associated with Ni-Cu-(PGE) mineralization are exposed in the presence of lichen coatings. Spectral mixture analysis methods were used to first derive image endmembers and subsequently unmix the image pixels to generate abundance maps that can be used to map the geological materials of interest, specifcally mafic, ultramafic and gossan units. Results demonstrates the feasibility of both AISA and EnMAP to provide large scale reconnaissance mapping capability of geologic materials over vast subarctic and arctic regions where field access is limited
Coupled retrieval of the three phases of water from spaceborne imaging spectroscopy measurements
No full text[EN] Measurements of reflected solar radiation by imaging spectrometers can quantify water in different states (solid, liquid, gas) thanks to the discriminative absorption shapes. We developed a retrieval method to quantify the amount of water in each of the three states from spaceborne imaging spectroscopy data, such as those from the German EnMAP mission. The retrieval couples atmospheric radiative transfer simulations from the MODTRAN5 radiative transfer code to a surface reflectance model based on the Beer-Lambert law. The model is inverted on a per-pixel basis using a maximum likelihood estimation formalism. Based on a unique coupling of the canopy reflectance model HySimCaR and the EnMAP end-to-end simulation tool EeteS, we performed a sensitivity analysis by comparing the retrieved values with the simulation input leading to an R-2 of 0.991 for water vapor and 0.965 for liquid water. Furthermore, we applied the algorithm to airborne AVIRIS-C data to demonstrate the ability to map snow/ice extent as well as to a CHRIS-PROBA dataset for which concurrent field measurements of canopy water content were available. The comparison between the retrievals and the ground measurements showed an overall R-2 of 0.80 for multiple crop types and a remarkable clustering in the regression analysis indicating a dependency of the retrieved water content from the physical structure of the vegetation. In addition, the algorithm is able to produce smoother and more physically-plausible water vapor maps than the ones from the band ratio approaches used for multispectral data, since biases due to background reflectance are reduced. The demonstrated potential of imaging spectroscopy to provide accurate quantitative measures of water from space will be further exploited using upcoming spaceborne imaging spectroscopy missions like PRISMA or EnMAP.This study is funded within the EnMAP scientific preparation program under the DLR Space Administration with resources from the German Federal Ministry for Economic Affairs and Energy, Berlin, Germany (grant ID 59EE1923) and the Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences.Bohn, N.; Guanter-Palomar, LM.; Kuester, T.; Preusker, R.; Segl, K. (2020). Coupled retrieval of the three phases of water from spaceborne imaging spectroscopy measurements. Remote Sensing of Environment. 242:1-16. https://doi.org/10.1016/j.rse.2020.111708S11624
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