Analysis of one-dimensional models for exchange flows under strong stratification     

Kaptein  Steven J.  van de Wal  Koen J.  Kamp  Leon P. J.  Armenio  Vincenzo  Clercx  Herman J. H.  Duran-Matute  Matias 《Ocean Dynamics》2020,70(1):41-56

Ocean Dynamics - One-dimensional models of exchange flows driven by horizontal density gradients are well known for performing poorly in situations with weak turbulent mixing. The main issue with...  相似文献   

Conditional effects of tides and waves on short‐term marsh sedimentation dynamics          下载免费PDF全文

Zhigang Ma  Tom Ysebaert  Daphne van der Wal  Peter M.J. Herman 《地球表面变化过程与地形》2018,43(10):2243-2255

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A framework for testing dynamic classification of vulnerable scenarios in ensemble water supply projections     

Robinson  Bethany  Herman  Jonathan D. 《Climatic change》2019,152(3-4):431-448

Climatic Change - Recent water resources planning studies have proposed climate adaptation strategies in which infrastructure and policy actions are triggered by observed thresholds or...  相似文献   

Effects of local meteorology and aerosols on ozone and nitrogen dioxide retrievals from OMI and pandora spectrometers in Maryland,USA during DISCOVER-AQ 2011     

Andra J. Reed  Anne M. Thompson  Debra E. Kollonige  Douglas K. Martins  Maria A. Tzortziou  Jay R. Herman  Timothy A. Berkoff  Nader K. Abuhassan  Alexander Cede 《Journal of Atmospheric Chemistry》2015,72(3-4):455-482

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JONSMOD 2010     

Herman Gerritsen  Phil Dyke 《Ocean Dynamics》2011,61(11):1809-1809

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Efficient collection of training data for sub-pixel land cover classification using neural networks     

Stien Heremans  Bert Bossyns  Herman Eerens  Jos Van Orshoven 《International Journal of Applied Earth Observation and Geoinformation》2011

Artificial neural networks (ANNs) are a popular class of techniques for performing soft classifications of satellite images. They have successfully been applied for estimating crop areas through sub-pixel classification of medium to low resolution images. Before a network can be used for classification and estimation, however, it has to be trained. The collection of the reference area fractions needed to train an ANN is often both time-consuming and expensive. This study focuses on strategies for decreasing the efforts needed to collect the necessary reference data, without compromising the accuracy of the resulting area estimates. Two aspects were studied: the spatial sampling scheme (i) and the possibility for reusing trained networks in multiple consecutive seasons (ii). Belgium was chosen as the study area because of the vast amount of reference data available. Time series of monthly NDVI composites for both SPOT-VGT and MODIS were used as the network inputs. The results showed that accurate regional crop area estimation (R² > 80%) is possible using only 1% of the entire area for network training, provided that the training samples used are representative for the land use variability present in the study area. Limiting the training samples to a specific subset of the population, either geographically or thematically, significantly decreased the accuracy of the estimates. The results also indicate that the use of ANNs trained with data from one season to estimate area fractions in another season is not to be recommended. The interannual variability observed in the endmembers’ spectral signatures underlines the importance of using up-to-date training samples. It can thus be concluded that the representativeness of the training samples, both regarding the spatial and the temporal aspects, is an important issue in crop area estimation using ANNs that should not easily be ignored.  相似文献   

Precise ionosphere-free single-frequency GNSS positioning     

Torben Schüler  Herman Diessongo  Yaw Poku-Gyamfi 《GPS Solutions》2011,15(2):139-147

Ionospheric delays can be efficiently eliminated from single-frequency data using a combination of carrier phases and code ranges. Unfortunately, GPS and GLONASS ranges are relatively noisy which can limit the use of the positioning method. Nevertheless, position standard deviations are in the range of 6–8 cm (horizontal) and 7–9 cm (3d) obtained from diurnal data batches from selected IGS reference stations can be further reduced to 2–3 cm (3d) for weekly smoothed averages. GPS data sets collected in Ghana (Africa) reveal a typical level of 10 cm of deviation that must be anticipated under average conditions. Looking at the future of GNSS, the European Galileo system will, in contrast to GPS, provide the broadband signal E5 that is by far less affected by multipath thus providing rather precise range measurements. Simulated processing runs featuring both high ionospheric and tropospheric delay variations show a 3d position precision of 4 cm even for a data batch as short as just 1 h, whereas GPS L1/Galileo E1 performance is close to 13 cm for the same data set.  相似文献   

Comment on Garg et al., . ‘Up‐scaling potential impacts on water flows from agricultural water interventions: opportunities and trade‐offs in the Osman Sagar catchment,Musi sub‐basin,India’. Hydrological Processes 27: 3905–3921          下载免费PDF全文

Jetske A. Bouma  Trent W. Biggs  Laurens M. Bouwer 《水文研究》2014,28(8):3350-3351

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The Dynamics of Small Postglacial Lake Basins and the Nature of Their Archaeological Record: A Case Study of the Middle Palaeolithic Site Neumark‐Nord 2, Germany     

Eduard Pop  Corrie Bakels  Wim Kuijper  Herman Mücher  Madeleine van Dijk 《Geoarchaeology》2015,30(5):393-413

Due to favorable conditions of preservation, sedimentary basins provide rich records of human behavior and its environmental context. The conditions for the preservation of archaeological material however vary between basin types (large, river‐fed or small, closed basins), while conditions also differ within a particular basin environment. The goal of this paper is to understand how the dynamics of a small postglacial basin such as Neumark‐Nord 2, a context that dominates the Eemian archaeological record, affected the archaeology situated at its basin margin. The approach used here is to correlate the archaeological record with reconstructions of patterns of deposition and the water conditions within the basin, using lithology, micromorphology, pollen, and macroremains from a transect running from the basin center to the margin. The results show that (1) find levels were exposed to overland flow‐induced winnowing, which vertically concentrated finds but did not cause significant transport, (2) find levels correspond to phases of increased water presence in the basin, and (3) lateral shifts in hominin activity areas may reflect adjustments in the water level. The research shows the importance of large‐scale archaeological excavations and a multidisciplinary sampling strategy that covers both the basin center and the margins, when studying postglacial basin localities like Neumark‐Nord 2.  相似文献   

A multi-hazard regional level impact assessment for Europe combining indicators of climatic and non-climatic change     

Tobias Lung  Carlo Lavalle  Roland Hiederer  Alessandro Dosio  Laurens M. Bouwer 《Global Environmental Change》2013,23(2):522-536

To better prioritise adaptation strategies to a changing climate that are currently being developed, there is a need for quantitative regional level assessments that are systematic and comparable across multiple weather hazards. This study presents an indicator-based impact assessment framework at NUTS-2 level for the European Union that quantifies potential regional changes in weather-related hazards: heat stress in relation to human health, river flood risk, and forest fire risk. This is done by comparing the current (baseline) situation with two future time periods, 2011–2040 and 2041–2070. The indicator values for the baseline period are validated against observed impact data. For each hazard, the method integrates outcomes of a set of coherent high-resolution regional climate models from the ENSEMBLES project based on the SRES A1B emission scenario, with current and projected non-climatic drivers of risk, such as land use and socio-economic change. An index of regional adaptive capacity has been developed and compared with overall hazard impact in order to identify the potentially most vulnerable regions in Europe. The results show strongest increases in impacts for heat stress, followed by forest fire risk, while for flood risk the sign and magnitude of change vary across regions. A major difference with previous studies is that heat stress risk could increase most in central Europe, which is due to the ageing population there. An overall assessment combining the three hazards shows a clear trend towards increasing impact from climaterelated natural hazards for most parts of Europe, but hotspot regions are found in eastern and southern Europe due to their low adaptive capacities. This spatially explicit assessment can serve as a basis for discussing climate adaptation mainstreaming, and priorities for regional development in the EU.  相似文献