Active channel systems in the West Basin, Andaman Fore Arc: results from high-resolution bathymetry surveys and GIS analysis

2017 ◽  
Vol 10 (10) ◽  
Author(s):  
Saju Varghese ◽  
R.V Manoj
Author(s):  
В. Зинько ◽  
V. Zin'ko ◽  
А. Зверев ◽  
A. Zverev ◽  
М. Федин ◽  
...  

The seismoacoustical investigations was made in the western part of the Kerch strait (Azov sea) near Kamysh-Burun spit. The fracture zone with dislocated sedimentary rocks layers and buried erosional surface was revealed to the west of spit. Three seismofacial units was revealed to the east of spit. The first unit was modern sedimentary cover. The second ones has cross-bedding features and was, probably, the part of early generation of Kamysh-Burun spit, which lied to the east of its modern position. The lower border of the second unit is the erosional surface supposed of phanagorian age. The third unit is screened by acoustic shedows in large part.


2021 ◽  
pp. 1-10
Author(s):  
Adam Weintrit ◽  
Jacek Pietraszkiewicz ◽  
Wiesław Piotrzkowski ◽  
Wojciech Tycholiz

Abstract In recent years the transition of marine navigation to the digital era has been gaining momentum. Implementation of e-Navigation solutions varies from country to country in terms of their priorities, goals, levels and effects. Maritime authorities in Poland have been setting the pace in this transition process, not only in Poland but also in general as a global solution. The most recent example is the planned deployment of a variety of e-Navigation tools in the Vistula Lagoon: from GNSS-RTK Ground-Based Augmentation System, to virtual and synthetic aids to navigation, high-resolution bathymetry and advanced navigational software for piloting. The major objectives of this paper are, first, to summarise recent dynamics in the e-Navigation field, and second, to present a practical implementation of the e-Navigation concept in the Vistula Lagoon area.


Atmosphere ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 37
Author(s):  
Martial Amou ◽  
Amatus Gyilbag ◽  
Tsedale Demelash ◽  
Yinlong Xu

As global temperatures continue to rise unabated, episodes of heat-related catastrophes across the world have intensified. In Kenya, heatwave phenomena and their associated impacts are ignored and neglected due to several reasons, including unreliable and inconsistent weather datasets and heatwave detection metrics. Based on CHIRTS satellite infrared estimates and station blended temperature, this study investigated the spatiotemporal distribution of the heatwave events over Kenya during 1987–2016 using the Heatwave Magnitude Index daily (HWMId). The results showed that contrary to the absence of heatwave records in official national and international disaster database about Kenya, the country experienced heatwaves ranging from less severe (normal) to deadly (super-extreme) between 1987 and 2016. The most affected areas were located in the eastern parts of the country, especially in Garissa and Tana River, and in the west-northern side around the upper side of Turkana county. It was also found that the recent years’ heatwaves were more severe in magnitude, duration, and spatial extent. The highest magnitude of the heatwaves was recorded in 2015 (HWMId = 22.64) while the average over the reference period is around 6. CHIRTS and HWMId were able to reveal and capture most critical heatwave events over the study period. Therefore, they could be used respectively as data source and detection metrics, for heatwaves disaster emergency warning over short period as well as for long-term projection to provide insight for adaptation strategies.


1971 ◽  
Vol 43 ◽  
pp. 413-416 ◽  
Author(s):  
Shinzo Énomé ◽  
Haruo Tanaka

An expansion of the source of a great solar microwave burst was observed a little beyond the west limb on March 30, 1969. This expansion is interpreted in terms of diffusion of energetic electrons in a turbulent magnetic field in the flare region. The height of the source is estimated to have been 104 km.


2012 ◽  
Vol 9 (12) ◽  
pp. 18799-18829
Author(s):  
S. Walter ◽  
A. Kock ◽  
T. Röckmann

Abstract. Oceans are a net source of molecular hydrogen (N2) to the atmosphere, where nitrogen (N2) fixation is assumed to be the main biological production pathway besides photochemical production from organic material. The sources can be distinguished using isotope measurements because of clearly differing isotopic signatures of the produced hydrogen. Here we present the first ship-borne measurements of atmospheric molecular H2 mixing ratio and isotopic composition at the West African coast of Mauritania (16–25° W, 17–24° N). This area is one of the biologically most active regions of the world's oceans with seasonal upwelling events and characterized by strongly differing hydrographical/biological properties and phytoplankton community structures. The aim of this study was to identify areas of H2 production and distinguish H2 sources by isotopic signatures of atmospheric H2. Besides this a diurnal cycle of atmospheric H2 was investigated. For this more than 100 air samples were taken during two cruises in February 2007 and 2008, respectively. During both cruises a transect from the Cape Verde Island towards the Mauritanian Coast was sampled. In 2007 additionally four days were sampled with a high resolution of one sample per hour. Our results clearly indicate the influence of local sources and suggest the Banc d'Arguin as a pool for precursors for photochemical H2 production, whereas N2 fixation could not be identified as a H2 source during these two cruises. With our experimental setup we could demonstrate that variability in diurnal cycles is probably influenced and biased by released precursors for photochemical H2 production and the origin of air masses. This means for further investigations that just measuring the mixing ratio of H2 is insufficient to explain the variability of a diurnal cycle and support is needed, e.g. by isotopic measurements. However, measurements of H2 mixing ratios, which are easy to conduct online during ship cruises could be a helpful tool to easily identify production areas of biological precursors such as VOC's for further investigations.


1987 ◽  
Vol 61 (5) ◽  
pp. 865-889 ◽  
Author(s):  
Thomas W. Bjerstedt

Trace fossils are used in deposystem analysis of Late Devonian–Early Mississippian nearshore facies in the north-central Appalachian Basin. These nearshore facies resulted from separate transgressions during latest Devonian (Cleveland Shale) and earliest Mississippian (Sunbury Shale) time. Emphasis is placed on a well-exposed section at Rowlesburg, West Virginia, where the Oswayo, Cussewago Sandstone, and Riddlesburg Shale Members of the Price Formation are exposed.The Oswayo Member at Rowlesburg preserves an offshore-to-lower shoreface transition in a complex of euryhaline, protected-bay, lagoon, and possible estuarine facies. Cruziana is common and occurs along with Arthrophycus, Bifungites, Chondrites, Planolites, Palaeophycus, Rhizocorallium, Rosselia, Rusophycus, and Skolithos in intensely bioturbated mudstone, siltstone, and sandstone. These lithologies were deposited below fair-weather wave base and grade upsection to upper shoreface facies comprised of thick, horizontally-laminated sandstones with thinner, burrowed mudstone interbeds. Upper shoreface traces consist of Arenicolites, Cruziana, Diplocraterion, Dimorphichnus, Planolites, Thalassinoides, and Skolithos. Skolithos “pipe rock” sandstones occur at the toe of upper shoreface facies. Eastward the Oswayo Member grades into a restricted-bay facies and finally into beach and tidal flat facies near its stratigraphic wedge-out in eastern West Virginia and western Maryland. The Cussewago Sandstone Member at Rowlesburg overlies the Oswayo and is bounded at the top by a disconformity. The Cussewago contains Arenicolites, Isopodichnus, Phycodes, Planolites, and Skolithos in upper shoreface sandstones possibly related to deposition in deltaic or tidal channel systems.Regionally, the Riddlesburg Shale records a range of euryhaline environments in shallow-shelf, open-bay, and probable estuarine facies. The Riddlesburg Shale Member at Rowlesburg is comprised of dark-grey silty shales, siltstones, and hummocky cross-stratified sandstones. Trace fossils include Bergaueria, Bifungites, Fustiglyphus?, Helminthopsis, Planolites, and Skolithos. Lithofacies of the Riddlesburg Shale in West Virginia were markedly influenced by a syndepositionally active basement feature, the West Virginia Dome. Riddlesburg-age shoreface sandstones deposited on the crest of the Dome contain apparent omission surfaces with common Rhizocorallium and Arenicolites, Cruziana?, Planolites, and Skolithos.


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