scholarly journals A New Method for the Collection of Marine Geomagnetic Information: Survey Application in the Colombian Caribbean

2020 ◽  
Vol 9 (1) ◽  
pp. 10
Author(s):  
Karem Oviedo Prada ◽  
Bismarck Jigena Antelo ◽  
Nathalia Otálora Murillo ◽  
Jeanette Romero Cózar ◽  
Francisco Contreras-de-Villar ◽  
...  
Keyword(s):  
Magnetic Data ◽  
Data Repository ◽  
Time Interval ◽  
Side Scan Sonar ◽  
North West ◽  
The North ◽  
Geomagnetic Data ◽  
Long Time ◽  
Advance Research ◽  
Maritime Territory

In recent years, the Oceanographic and Hydrographic Research Center (part of the General Maritime Directorate of Colombia (DIMAR) has made important efforts to advance research in the field of marine geophysics, in particular, the techniques of geomagnetism, sub-bottom profiling, and side-scan sonar, the first being the most developed at the present time. A method is presented for the acquisition of geomagnetic data in marine environments, as used by DIMAR in the Colombian maritime territory. The development of the geomagnetic method not only offers the opportunity to advance basic scientific knowledge, but it is also of great importance in support of national sovereignty issues. Among other applications, the most representative uses of the geomagnetic method are the location of pipelines and metal plates, detection of buried ordnance, identification of sites of archaeological interest, and the identification and characterization of geological structures. As a result of testing the method, a grid of geomagnetic data was surveyed in an area close to the Island of San Andrés in the north-west of the Colombian maritime territory. The survey was prepared with a regional geometric arrangement, the result of which was compared with survey data obtained from the National Oceanic and Atmospheric Administration (NOAA) magnetic data repository and carried out in the same study area. Despite the long time interval between the two surveys, almost 50 years, no significant differences were observed in terms of the analyzed variables. Finally, results show negligible differences between the magnetic data obtained for the years 1970 and 2018 for all the variables measured, such as the inclination, declination, and total magnetic field. These differences may be attributable to a geological component or also to the acquisition and processing methods used in the 1970s.

scholarly journals Bioluminescence and fluorescence of three sea pens in the north-west Mediterranean sea

2020 ◽  
Author(s):  
Warren R Francis ◽  
Anaïs Sire de Vilar
Keyword(s):  
Mediterranean Sea ◽  
Dark Adaptation ◽  
Fluorescence Spectra ◽  
Green Light ◽  
Emission Spectra ◽  
North West ◽  
The North ◽  
Light Production ◽  
Long Time ◽  
Basic Parameters

AbstractBioluminescence of Mediterranean sea pens has been known for a long time, but basic parameters such as the emission spectra are unknown. Here we examined bioluminescence in three species of Pennatulacea, Pennatula rubra, Pteroeides griseum, and Veretillum cynomorium. Following dark adaptation, all three species could easily be stimulated to produce green light. All species were also fluorescent, with bioluminescence being produced at the same sites as the fluorescence. The shape of the fluorescence spectra indicates the presence of a GFP closely associated with light production, as seen in Renilla. Our videos show that light proceeds as waves along the colony from the point of stimulation for all three species, as observed in many other octocorals. Features of their bioluminescence are strongly suggestive of a “burglar alarm” function.

scholarly journals Time-clustering of wave storms in the Mediterranean Sea

2016 ◽  
Author(s):  
Giovanni Besio ◽  
Riccardo Briganti ◽  
Alessandro Romano ◽  
Lorenzo Mentaschi ◽  
Paolo De Girolamo
Keyword(s):  
Spatial Distribution ◽  
Mediterranean Sea ◽  
Time Scales ◽  
Horizontal Resolution ◽  
North West ◽  
Temporal Sampling ◽  
The North ◽  
Allan Factor ◽  
Long Time ◽  
The Mediterranean

Abstract. In this contribution we identify storm time-clustering in the Mediterranean Sea through the analysis of the spatial distribution of the Allan Factor. This parameter is evaluated from long time series of wave height provided by means of oceanographic buoy measurements and hindcast re-analysis spanning in the period 1979–2014 and characterized by a horizontal resolution of about 0.1 degree in longitude and latitude and a temporal sampling of one hour (Mentaschi et a., 2015). Results reveal clustering mainly for two distinct ranges of time scales. The first range of time scales (12 hrs to 50 days) is associated to sequences of storms generated by the persistence of the same meteorological system. The second range, associated to timescales beteween 50 and 100 days, reveals seasonal fluctuations. Transitional regimes are present at some locations in the basin. The spatial distribution of the Allan Factor reveals that the clustering at smaller time scales is present in the North-West of the Mediterranean, while clustering at larger scales is observed in the whole basin. This analysis is believed to be important to assess the local increased flood and coastal erosion risks due to storm clustering.

scholarly journals The Indigenous Peoples of the North in the Mirror of Regional Periodicals in the 1990s – Early 2000s (Based on Materials from the Republic of Sakha (Yakutia))

2020 ◽  
pp. 73-76
Author(s):  
Irina Sergeyevna Astakhova
Keyword(s):  
Content Analysis ◽  
Indigenous Peoples ◽  
Regional Policy ◽  
Historical Research ◽  
Time Interval ◽  
Historical Source ◽  
Thematic Content Analysis ◽  
The North ◽  
Long Time ◽  
The Republic

The paper analyzes the potential of the periodicals as a historical source for the study of state policy in relation to the indigenous peoples of the North. In particular, the experience of the development and application of qualitative thematic content analysis of the republican newspaper “Yakutia” for the peri-od from 1991 to 2000 is shown. Such a study using a continuous sample on such a long time interval has not been performed. Three chronological groups of publications have been identified, which can be cor-related with the stages of regional policy towards indigenous peoples in the 1990s. The main features of each period are revealed. It is emphasized that the use of this method in historical research not only systematizes the sources, but also draws the atten-tion of researchers to some patterns that require further explanation.

scholarly journals New Record of Dust Input and Provenance During Glacial Periods in Western Australia Shelf (IODP Expedition 356, Site U1461) from the Middle to Late Pleistocene

Atmosphere ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1251
Author(s):  
Margot Courtillat ◽  
Maximilian Hallenberger ◽  
Maria-Angela Bassetti ◽  
Dominique Aubert ◽  
Catherine Jeandel ◽  
...  
Keyword(s):  
Major Elements ◽  
Sediment Provenance ◽  
Time Interval ◽  
Geochemical Composition ◽  
North West ◽  
The North ◽  
Murray Darling Basin ◽  
Australian Continent ◽  
International Ocean Discovery Program ◽  
Glacial Periods

International Ocean Discovery Program (IODP) Expedition 356 Site U1461 represents one of the few records from the North West Australian shelf that provides information about aridity fluctuations in Australia during the Quaternary. A combination of chronostratigraphic indicators revealed the (partial) preservation of two major glaciations (Marine Isotope Stage (MIS) 2 and MIS 12) in the sedimentary record. The faunal content (mainly benthic foraminifera, corals and bryozoans) was analyzed to estimate paleo-environments and paleo-depths in order to determine if these sediments have been remobilized by reworking processes. Despite the occurrence of a depositional hiatus (including MIS 5d to MIS 9-time interval), the excellent preservation of faunal content suggests that the preserved sediment is in situ. The geochemical composition of the sediments (Nd and major elements) indicates that during MIS 12 riverine input was likely reduced because of enhanced aridity, and the sediment provenance (mainly atmospheric dust) is likely in the central (Lake Eyre) or eastern (Murray Darling Basin) parts of the Australian continent. MIS 2 is confirmed to be one of the driest periods recorded in Australia but with mixed dust sources from the eastern and western parts of the continent. More humid conditions followed the glacial maximum, which might correspond to the peak of the Indian-Australian Summer Monsoon.

scholarly journals Invisible biodiversity: extinction debts and colonization credits amongst US birds

2021 ◽  
Author(s):  
Davide Dominoni ◽  
Yacob Haddou ◽  
Rebecca Mancy ◽  
Jason Matthiopoulos ◽  
Sofie Spatharis
Keyword(s):  
Land Cover ◽  
Biodiversity Loss ◽  
North West ◽  
The North ◽  
Relative Contribution ◽  
Conservation Actions ◽  
Long Time ◽  
The Usa ◽  
Animal Communities ◽  
Current Species

Abstract Habitat change is a major source of biodiversity loss. However, the response of animal communities to land-cover changes is not instantaneous. In fact, extinctions and colonizations may take up a long time before they fully manifest, leading to extinction debts and colonization credits. Current quantifications of debts and credits do not consider multiple land cover types and their directionality of change. Here we quantify the relative contribution of past and present landscapes to the current species richness of 5500 USA bird communities, explicitly measuring the response of biodiversity to increases and decreases of five land covers. We identified extinctions debts across 12% of the USA whilst colonization credits were instead present in 16% of the land area. Future species loss is predicted in the East following recent urbanization, while new species colonizations are expected mainly in the North-West as a result of forests conversion into grasslands. Furthermore, lags in biodiversity response were dependent not only on the type and amount of land cover change, but also on its directionality. Effective conservation actions rely on reliable predictions of future biodiversity. Our results highlight the essential need of considering past landscape changes when setting policy targets aiming at halting biodiversity loss.

scholarly journals Integrated Interpretation of Magnetic and ERT Data to Characterize a Landfill in the North-West of Cologne, Germany

2021 ◽  
Author(s):  
Ismael M. Ibraheem ◽  
Bülent Tezkan ◽  
Rainer Bergers
Keyword(s):  
Analytical Signal ◽  
Vertical Gradient ◽  
Magnetic Data ◽  
Inversion Method ◽  
Magnetic Survey ◽  
Electrode Arrays ◽  
L1 Norm ◽  
North West ◽  
The North ◽  
Migration Pathways

AbstractElectrical resistivity tomography (ERT) and ground magnetic surveys were applied to characterize an old uncontrolled landfill in a former exploited sand and gravel quarry in an area to the north-west of the city of Cologne, Germany. The total magnetic field and its vertical gradient were recorded using a proton precession magnetometer to cover an area of about 43,250 m2. The magnetic data were transferred to the frequency domain and then reduced to the north magnetic pole. The amplitude of the analytical signal was calculated to define the magnetic materials within and outside the landfill. Eight ERT profiles were constructed based on the results of the magnetic survey using different electrode arrays (Wenner, dipole–dipole, and Schlumberger). In order to increase both data coverage and sensitivity and to decrease uncertainty, a non-conventional mixed array was used. The subsurface resistivity distributions were imaged using the robust (L1-norm) inversion method. The resultant inverted subsurface true resistivity data were presented in the form of 2D cross sections and 3D fence diagram. These non-invasive geophysical tools helped us to portray the covering soil, the spatial limits of the landfill, and the depth of the waste body. We also successfully detected low resistivity zones at deeper depths than expected, which probably be associated with migration pathways of the leachate plumes. The findings of the present study provide valuable information for decision makers with regards to environmental monitoring and assessment.

scholarly journals BILYI KAMIN: SITE STRUCTURE OF THE BIGGEST TRYPILLIA CULTURE SETTLEMENT OF THE SOUTHERN BUH-DNISTER INTERFLUVE

2019 ◽  
Vol 33 (4) ◽  
pp. 362-372
Author(s):  
V. S. Rud ◽  
R. Hofmann ◽  
V. A. Kosakivskyi ◽  
O. V. Zaitseva ◽  
J. Muller
Keyword(s):  
Research Effort ◽  
The South ◽  
Regional Variability ◽  
Total Size ◽  
North West ◽  
The North ◽  
Staggered Arrangement ◽  
Long Time ◽  
Survey System ◽  
North Part

So far research effort regarding Cucuteni—Trypillia mega-sites was to a large extent focussed on the region in the east of the Southern Buh. In contrast, the Southern Buh-Dnister interfluve stands for long time in the shadow of its eastern neighbour. To improve this situation and to gain a better understanding of the macro-regional variability within the Cucuteni—Trypillia cultural complex, in spring 2018 the exploration of the large CTCC site Bilyi Kamin was started by an international team of researchers from Kiel University (Germany) and Institute of Archaeology of the National Academy of Science of Ukraine (Kyiv, Ukraine) which is the largest settlement in this region. Magnetometry in total size of 40.6 ha have been performed using the MAGNETO® MX V3 Survey System of the company SENSYS Sensorik & Systemtechnologie GmbH Bad Saarow (Germany). During our survey large areas in the south, north and near the centre of the site were measured. Based on these data the total extension of the site can be estimated to approximately 97 ha. Different categories of magnetic anomalies can be identified in Bilyi Kamin: 297 rectangular anomalies, which are the ruins of intensively burnt clay houses; 141 rectangular anomalies of houses, burnt with less intensity or eroded; four rectangular anomalies of unique buildings, so-called «megastructures»; 351 anomaly of different-shape objects, most of which can be interpreted as pits; 12 stretched objects, presumably road to the south of the site; linear anomaly of the ditch or natural gully to the north-west from north part of outer circle. The site is built in two circles of houses. The ring corridor between the circles is free from buildings. Some buildings are located outside the circles as well. They are grouped as short lines radial and parallel in respect to the circles. The space inside the circles is built partially. In the north and north-west parts of the site the buildings are grouped mostly in long radial lines. In the south part of the site the number of buildings inside the circles is smaller. This might indicate a heterogeneous character of the population or changes in the development plan. The anomalies of pits from Bilyi Kamin are usually located near the buildings, at side or ending walls. Some groups of pits are not connected to the buildings. It is also possible that some of anomalies of pits, having largest nT values can represent other kind of objects — as for example pottery kilns. In Bilyi Kamin three elongated mega-structures with lengths between 36 and 64 m and widths between 8 and 11.5 m are placed on the 420 Ч (>150) m measuring square (so-called «plaza»). The partly staggered arrangement of these constructions might suggest that they were not built simultaneously but represent a sequence of successively used buildings. Within the concentric ring corridor directly beside of the central plaza, additionally a fourth mega-structure is visible. For the planning of the settlement layout, the placement of a rectangular square on top of the promontory with three large buildings played potentially an important role. These mega-structures and the associated plaza most likely formed the architectural arena of central integrative institutions for decision-making, integrative ritual action, and surplus-consumption at the level of the entire settlement.

scholarly journals Upper layer current variability in the Central Ligurian Sea

Ocean Science ◽  
2010 ◽  
Vol 6 (4) ◽  
pp. 825-836 ◽  
Author(s):  
P. Picco ◽  
A. Cappelletti ◽  
S. Sparnocchia ◽  
M. E. Schiano ◽  
S. Pensieri ◽  
...  
Keyword(s):  
Water Column ◽  
General Circulation ◽  
Minor Role ◽  
Time Interval ◽  
Mean Velocity ◽  
Ligurian Sea ◽  
Near Surface ◽  
North West ◽  
Long Time ◽  
A Minor

Abstract. Long-time series of surface currents and meteorological parameters were analysed to estimate the variability of the upper layer circulation and the response to the local winds. Current meter data were collected by an upward-looking RDI Sentinel 300 kHz ADCP deployed in the Central Ligurian Sea (43°47.77' N; 9°02.85' E) near the meteo-oceanographic buoy ODAS Italia 1 for more than eight months, from 13th of September 2003 to 24th of May 2004. The ADCP sampled the upper 50 m of water column at 8 m vertical resolution and 1 h time interval; surface marine and atmospheric hourly averaged data were provided by the buoy. Currents in the sampled layer were mainly barotropic, directed North-West in accordance with the general circulation of the area, and had a mean velocity of about 18 cm/s and hourly mean peaks up to 80 cm/s. Most of the observed variability in the upper thermocline was determined by inertial currents and mesoscale activity due to the presence of the Ligurian Front. Local wind had a minor role in the near-surface circulation but induced internal waves propagating downward in the water column.

scholarly journals Time clustering of wave storms in the Mediterranean Sea

2017 ◽  
Vol 17 (3) ◽  
pp. 505-514 ◽  
Author(s):  
Giovanni Besio ◽  
Riccardo Briganti ◽  
Alessandro Romano ◽  
Lorenzo Mentaschi ◽  
Paolo De Girolamo
Keyword(s):  
Spatial Distribution ◽  
Mediterranean Sea ◽  
Horizontal Resolution ◽  
Comprehensive Analysis ◽  
North West ◽  
Temporal Sampling ◽  
The North ◽  
Allan Factor ◽  
Long Time ◽  
The Mediterranean

Abstract. In this contribution we identify storm time clustering in the Mediterranean Sea through a comprehensive analysis of the Allan factor. This parameter is evaluated from a long time series of wave height provided by oceanographic buoy measurements and hindcast reanalysis of the whole basin, spanning the period 1979–2014 and characterized by a horizontal resolution of about 0.1° in longitude and latitude and a temporal sampling of 1 h Mentaschi et al. (2015). The nature of the processes highlighted by the AF and the spatial distribution of the parameter are both investigated. Results reveal that the Allan factor follows different curves at two distinct timescales. The range of timescales between 12 h to 50 days is characterized by a departure from the Poisson distribution. For timescales above 50 days, a cyclic Poisson process is identified. The spatial distribution of the Allan factor reveals that the clustering at smaller timescales is present to the north-west of the Mediterranean, while seasonality is observed across the whole basin. This analysis is believed to be important for assessing the local increased flood and coastal erosion risks due to storm clustering.

Assessing the sensitivity of small catchments to an extreme event in the North-west Himalayas

2021 ◽  
Author(s):  
Arkaprabha Sarkar ◽  
Vimal Singh
Keyword(s):  
Surface Runoff ◽  
High Intensity ◽  
Overland Flow ◽  
Extreme Event ◽  
Precipitation Event ◽  
Time Interval ◽  
Initiation Point ◽  
North West ◽  
The North ◽  
Small Catchments

<p>Smaller systems have thresholds lower than those of larger ones. Therefore, the response of a small change can be easily observed in small catchments where a larger system might not respond.</p><p>In this study, we investigated sub-catchments of a small 4<sup>th</sup> order Pranmati River Catchment, located in the North-west Himalayas; it is the part of the Ganga River System. We selected eight sub-catchments of 1<sup>st</sup> to 3<sup>rd</sup> order with area not more than 16 km<sup>2</sup> and analyzed their response to high-intensity rainfall. We calculated drainage density, length of overland flow, infiltration number, and constant of channel maintenance to analyze their behavior in terms of infiltration and surface runoff. The results show that two of the sub-catchments show tendency of low infiltration and higher surface runoff compared to the other sub-catchments. To validate our results, we compared them with the observations and available data of a highly localized high-intensity precipitation event that occurred in July 2018 within the catchment. During this event, there was focused rainfall in one of the sub-catchments that initiated a flash flood. The flood propagated from that sub-catchment along the trunk channel while all other sub-catchments suffered negligible impact. A significant increase in channel width has been observed along the path of the flood. We ran simulations of storm events in HEC-RAS for various rainfall patterns within the given time interval to replicate the event.</p><p>The hydrological simulation of basin-wide uniform rainfall with a Gaussian temporal distribution shows high overland sheet flow in these basins whereas the rest of the basin showed channel flow and low surface runoff. One of these two catchments was the initiation point of the flood event. The results indicate the high sensitivity of the basins and their contrasting responses under similar forces. Minor differences in the values of geomorphic parameters which are inconsequential in the case of large catchments become significant for smaller catchments. It also highlights the degree of spatial heterogeneity of rainfall and the inconsistency of the presently available precipitation datasets.</p>

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