Combining the FCM Classifier with Various Kernels to Handle Non-linearity of Class Boundaries

This article presents the use of kernel functions in fuzzy classifiers for an efficient land use/land cover mapping. It focuses on handling mixed pixels obtained from a remote sensing image by considering non-linearity between class boundaries. It uses kernel functions combined with the conventional fuzzy c-means (FCM) classifier. Kernel-based fuzzy c-mean classifiers were applied to classify AWiFS and LISS-III images from Resourcesat-1 and Resourcesat-2 satellites. Optimal kernels were obtained from eight single kernel functions. Fractional images generated from high resolution LISS-IV image were used as reference data. Classification accuracy of the FCM classifier increased with 12.93%. Improvement in overall accuracy shows that non-linearity in the dataset was handled adequately. The inverse multiquadratic kernel and the Gaussian kernel with the Euclidean norm were identified as optimal kernels. The study showed that overall classification accuracy of the FCM classifier improved if kernel functions were included.     

Fish assemblages in coastal lagoons in land-uplift succession: The relative importance of local and regional environmental gradients

The assemblages of young-of-the-year fish were studied in coastal lagoons in an archipelago with post-glacial land-uplift, which affects environmental gradients at local and regional scale, i.e. lagoon habitat isolation and archipelago position, respectively. The categorisation of 40 undisturbed lagoons into nine habitat types based on habitat isolation and archipelago position was supported by clear relationships with spring temperature and total fish abundance. Rutilus rutilus, breams (Abramis/Blicca sp.) and Perca fluviatilis were the most abundant and frequently occurring species. The fish assemblage differed among the nine habitat types. Rutilus rutilus, P. fluviatilis and breams were discriminating species in the majority of habitat types with low physical harshness, whereas Alburnus alburnus and Gasterosteus aculeatus increased their contributions in habitat types with high physical harshness. Rutilus rutilus and breams were thus common in lagoons with high habitat isolation situated in the inner archipelago. These lagoons were characterised by warm water and high vegetation coverage. Gasterosteus aculeatus was restricted to lagoons with low habitat isolation and exposure and low vegetation coverage, situated in the outer archipelago. Perca fluviatilis had the widest distribution of all species. The coverage of two macrophytes, Potamogeton perfoliatus and Zannichellia palustris, and salinity matched best the distance among habitat types. These habitat characteristics, as well as the fish abundances and assemblages differed most across the habitat types in the outer and mid archipelago zones and in the lowest habitat isolation. These patterns suggest that the structuring effect of habitat isolation increases along the archipelago gradient as differences between local and regional conditions increase. In the inner archipelago, overall low physical harshness induces homogeneous conditions and the habitat isolation is less important here than in the other zones. We suggest that this difference in the relative importance of the two gradients depending on the level of respective gradient ultimately forms these heterogeneous coastal habitats in a successional landscape. Rutilus rutilus and P. fluviatilis were responsible for large parts of the assemblage patterns. Although sympatric due to similar habitat requirements, differences in dispersal capability, competitive ability and predation vulnerability may add explanation to detected differences in distribution and abundance in these two species in an open system. Our results also stress the structuring role of vegetation in terms of total coverage and species composition, as these two aspects of macrophyte diversity may act as complementary habitat modifiers across gradients of physical harshness.     

Equatorial Indian Ocean Response during Extreme Indian Summer Monsoon Years Using Reliable CMIP5 Models

Monsoon droughts are characterized by the weakening of surface winds over the equatorial Indian Ocean and increased upper ocean heat storage, thus providin     

Upper Cretaceous bottom current deposits,north-east Greenland

Reported ancient bottom current deposits in deep marine settings are scarce and most of them remain contentious. This study describes sedimentological, ichnological and petrographical characteristics of a drill core that covers ca 10 Myr of Upper Cretaceous stratigraphy at Hold with Hope, north-east Greenland. The core is divided into four facies associations, which are interpreted to reflect deposition from bottom currents, turbidity flows and hemipelagic settling in slope and/or near slope environments. The evidence for bottom current influence is three-fold. Firstly, pervasive indications of winnowing such as marine bioclast-rich lags and outsized clasts on ‘mud on mud’ contacts are suggestive of low-sediment concentration flows capable of transporting up to pebble-sized clasts. Common Mn–Fe–Mg rich carbonate matrix cements and various types of hiatal chemogenic lag deposits showing glauconite, apatite and carbonate clasts also point to condensation, prolonged exposure at the sediment–water interface and recurrent phases of sea-floor erosion. Secondly, such deposits can show indicators for tidal processes such as double mud-drapes, tangential bottom sets in dune-scale cross-bedding and cyclic rhythmites. Thirdly, inverse to normal grading at various scales is common in fully marine, commonly seafloor-derived sediments. Ichnological data indicate considerable taxonomic variability in the bottom current deposits, but recurrent fabrics are characteristically dominated by morphologically simple burrows such as Thalassinoides and Planolites, with secondary Phycosiphon, Nereites, Zoophycos and/or Chondrites. In general, opportunistic taxa are common whereas mature composite ichnofabrics are rare. The omission surfaces are locally burrowed with stiffground to firmground trace fossil suites. The results contribute to establishing sedimentological, ichnological and mineralogical criteria for recognition of bottom current deposits as well as to the understanding of the Late Cretaceous palaeoenvironmental evolution of the Arctic region.     

Stratigraphy,depositional environment,and cultural significance of holocene sediments in patterned wetlands of central Veracruz,Mexico

The coastal wetlands of Veracruz State, Mexico contain many areas of rectilinearly patterned ground. These are the remains of Prehispanic agricultural complexes. Reconnaissance-level stratigraphic studies were carried out in one such wetland area, the “San Juan Basin,” in order to reconstruct the local environmental history. Basal, well-sorted fine sand, which underlies the basin, was likely deposited in the intertidal and beach zones as marine waters gradually left the San Juan Basin. Progradation of the Rio La Antigua delta on the north and the development of coastal dunes on the east closed the embayment by the mid-Holocene. Thereafter, large volumes of silt and clay were deposited in the basin, in large part during the annual floods of the La Antigua River and other streams. Prehispanic inhabitants dug drainage canals and cultivated the seasonally emergent surface leaving behind artifacts, charcoal, and microfossils of maize. The cultivation destroyed original sedimentary structures and converted the naturally deposited sediment to a massive dark gray silty clay. After the fields were abandoned, they were covered by brown silty peat, but the canals and platforms are still detectable on the surface.     

Tectonic Evolution of an Early Precambrian High-Pressure Granulite Belt in the North China Craton

A large-scale high-pressure granulite belt (HPGB), more than 700 km long, is recognized within the metamorphic basement of the North China craton. In the regional tectonic framework, the Hengshan-Chengde HPGB is located in the central collision belt between the western block and eastern block, and represents the deep crustal structural level. The typical high-pressure granulite (HPG) outcrops are distributed in the Hengshan and Chengde areas. HPGs commonly occur as mafic xenoliths within ductile shear zones, and underwent multipile deformations. To the south, the Hengshan-Chengde HPGB is juxtaposed with the Wutai greenstone belt by several strike-slip shear zones. Preliminary isotopic age dating indicates that HPGs from North China were mainly generated at the end of the Neoarchaean, assocaited with tectonic assembly of the western and eastern blocks.     

Burial rates of organic matter along the eastern Canadian margin and stable isotope constraints on its origin and diagenetic evolution

Organic carbon (OC) and nitrogen (N) contents and δ¹³C and δ¹⁵N values in total organic matter (OM) were measured in sub-surface sediments (0–30 cm sub-bottom) from 21 cores raised from the Laurentian Channel of the Gulf of St. Lawrence and the Labrador Sea, to document OM fluxes and storage along the eastern Canadian margin. Storage rates as high as 2.5 g m⁻² yr⁻¹ for OC and 0.2 g m⁻² yr⁻¹ for N are observed in the Laurentian Channel, suggesting that the shelf plays a significant role in terms of OM storage (from 1 to 2% of the primary production). Based on the isotopic composition of the essentially marine OM of the Labrador Sea (δ¹³C/V-PDB=−21.9±0.4‰; δ¹⁵N/AIR=7.6±0.6‰; n=12), there is no isotopic evidence for a significant relative input of terrestrial OM along the Laurentian Channel (δ¹³C/V-PDB=−21.9±0.4‰; δ¹⁵N/AIR=8.0±0.9‰; n=10), either due to high relative fluxes of marine OM and/or to the trapping of continental OM in the estuary and upstream. High storage rates of OM are also observed on the continental rise of the Labrador Sea (as high as 1.1 g C m⁻² yr⁻¹ and 0.09 g N m⁻² yr⁻¹). They contrast with one order of magnitude lower rates on the slope, due to low sedimentation rates (SR) and sediment winnowing by the Western Boundary Undercurrent (WBUC). Reduced early diagenetic alteration of OM is observed, particularly in the Laurentian Channel. It results in discrete (i) losses of OC and N, (ii) shifts in C/N ratios, suggesting preferential removal of N-bearing OM also highlighted by losses in total hydrolysable amino acids (HAA). In the Labrador Sea slope records, due to low SR, OM concentration changes linked to long term temporal variations may superimpose on these diagenetic trends, and some influence of the WBUC is noticeable.     

Prototype detector for ultrahigh energy neutrino detection

Necessary technical experience is being gained from successful construction and deployment of current prototype detectors to search for UHE neutrinos in Antarctica, Lake Baikal in Russia, and the Mediterranean. The prototype detectors have also the important central purpose of determining whether or not UHE neutrinos do in fact exist in nature by observation of at least a few UHE neutrino-induced leptons with properties that are not consistent with expected backgrounds. We discuss here the criteria for a prototype detector to accomplish that purpose in a convincing way even if the UHE neutrino flux is substantially lower than predicted at present.