Decrease In Sea Level Research Articles

Feasibility study on use of solar energy in Malaysia’s light rail transit

LRT System is an accessible urban public transportation in Malaysia, especially in Klang Valley. People can commute easily from one place to another. The operations of the LRT System are entirely dependent on the electric power supply, from the movement of trains between stations to the facilities inside the train itself. High consumption of electric grid has contributed to the increase in environmental pollution. In the long-term, the effect can be seen in the decrease in sea level as well as drop-in water supply. Due to that, renewable energy demand is continuously increasing, and current prediction shows that this trend is going to further continues yearly. Usage of electricity from renewable sources such as the solar panel has been proposed in this project paper in order to reduce the negative effect been encountered. The solar PV is a mechanism that can transform the sunlight into direct current electricity by using semiconductors. Hence, with the use of the solar panel, it will reduce energy pollution and climate change impact due to high consumption of electric grid. This research is meant to explore the possibility of using solar panels as an alternative for generating electricity for the Light Rail Transit (LRT) as renewable energy instead of using the power grid. The goal for this project report is to understand the requirements in implementing solar energy on the LRT System in Malaysia.

The main periods and environmental controls of coastal dune development along the west coast of the Korean Peninsula during the mid to late Holocene

This study traces coastal sand dune development processes in East Asia during the Holocene to understand climate and environmental changes. We used optically stimulated luminescence (OSL) dating to examine periods of activation and stabilization of dunes along the western coast of the Korean Peninsula. The results from the Taean Chollipo, Seocheon Dasari, and Gochang Sabanri dunes were then compared with those from previous studies to establish a broad understanding of coastal dune development in this region. Sedimentation rates were calculated for the three dunes, and their development periods were classified through statistical analysis that included data from previous studies. We defined five main periods of late Holocene dune development (<0.1 ka, 0.2–0.5 ka, 1.2–2.0 ka, 2.5–3.2 ka, and 5.5–6.5 ka). These correlated to periods of sea level decrease and global cooling determined by ice rafted debris records. We concluded that the development of coastal dunes in western Korea was influenced by sea level decreases, and global cooling events were enhanced by the East Asian winter monsoon. In addition, human activity increases also contributed to the development of the dunes. This study showed how coastal sand dunes can be evaluated as important indicators of global climate change. These results improved our understanding of how paleoclimate changes affected environmental conditions in East Asia and how coastal dune development periods can be used to reconstruct paleo-environmental conditions.

INDICATORS OF THE IMMUNE SYSTEM OF RESIDENTS OF DIFFERENT REGIONS OF THE ARAL SEA REGION

Environmental pollution against the background of harsh climatic conditions greatly aggravates the situation, creates more difficult conditions for the organism to adapt to environmental factors, while reducing the reserve capacity of the organism. The problems of the Aral Sea, caused by irrational planning of the development of the region's economy, led to a decrease in sea level, a decrease in its volume, an increase in salt content in water, the growth of various diseases. Immunity is a set of protective reactions of the body, which are directed against genetically foreign substances. Antibodies are gammaglobulins, which have the ability to bind to homologous antigens, while causing lysis of microbes and penetrate physiological barriers. Monitoring of immunoglobulins of various classes, these studies are of particular relevance with the current situation. Keywords: immune system, region, Priaralye, immunoglobulins, antibodies

Variability and trend of sea level in southern waters of Java, Indonesia

The coastal area of Java has become a centre of new economic growth. The southern coast of Java, which is directly adjacent to the tropical Indian Ocean, is very vulnerable to sea level rise caused by climate change. Information on variability and trends in sea level are therefore very important for adaptation and disaster mitigation efforts. This research was conducted to determine the variability and trend of sea level in the southern sea of Java. Data used were from satellite altimeter from 1993 to 2018 and tide gauges from 2007 to 2015. The rate of sea level rise was analysed using linear regression. The results showed that the sea level variability in the southern waters of Java was influenced by the Asian–Australian monsoon, eddy currents and the Indian Ocean Dipole (IOD). During June–November, there was a very significant decrease in sea level, especially in the south of East Java and Central Java, which was caused by upwelling and eddy currents. When there was a positive phase of IOD and an El Niño event, sea level decreased; conversely, when the IOD was in a negative phase, sea level increased. For the period 1993–2018, the sea level in the southern waters of Java increased by about 4.7 mm/year.

Estimation of natural reproduction efficiency of semi-anadromous and river fish species in inland water bodies of the Republic of Dagestan, Russia

Aim. Estimation of the natural reproduction efficiency and patterns of formation of fish stocks.Material and Methods. Collection of material was carried out in 2010-2019 in inland water bodies in Dagestan and its shallow Caspian Sea coastal zone. Estimation of the number of juveniles in rivers and canals was carried out using ichthyoplankton cone seines. Fry seines were used to count juveniles of fish in water bodies and in the coastal area. 470 samples of juveniles were collected and 5640 juveniles were analysed. The collection and processing of materials were carried out according to generally accepted methods.Results. The main environmental factors determining the productivity of fish juveniles in the study area in the long-term have been identified. During the observation period, juvenile fish of 15 species were recorded in spawning grounds of inland water bodies. Roach, bream, carp, crucian carp, rudd and vimba bream dominate. In terms of numbers, roach juveniles predominate: their relative proportion being 31.02% with an increase from 27.1% in 2010 to 35.4% in 2018.The second place was occupied by bream juveniles, whose average relative proportion was 12.1%. The third place was occupied by carp juveniles with an average proportion of 9%. Juvenile zander, catfish, pike and kutum are relatively low in abundance from 2 to 4%. The yield of juvenile fish in 2010-2019 decreased 1.7 times compared to 1990-1995.Conclusion. It was established that a decrease in the number of juvenile fishes occurs under the influence of unfavorable environmental factors: decrease in sea level; reduction in spawning areas; the shallowing and silting of migration routes due to the lack of a stable water supply. Measures are proposed to improve the living conditions of aquatic biological resources, aimed at increasing the efficiency of their natural reproduction.

Stratigraphy, palaeoenvironment and mollusks (gastropods and bivalves) of the Toarcian succession of the Central Unit of the South Riffian Ridges (northern Morocco)

In the Central Unit of the South Riffian Ridges, the Toarcian succession is represented by two thick terrigenous detrital formations, Sned and Lmachkha formations, each one is divided into two members. The lower member of the Sned Formation, often rich in belemnite rostra and ammonites of the Tenuicostatum Zone, consists of grey marlstones, with rare marly limestone intercalations. The upper member consists of silty marlstones, with frequent thin limestone beds and contains rare ammonites of the Serpentinus Zone. Its upper part is locally rich in terebratulids. The lower member of the Lmachkha Formation consists of a silty marlstone and silty limestone alternation, and is the richest in benthic macrofauna, composed of rhynchonellids, gastropods, common bivalves, and rare ammonites of the Bifrons Zone. Seven taxa of gastropods and six taxa of bivalves were recorded from this member and described for the first time from the study area. The upper member of the Lmachkha Formation consists of silty marlstone and silty limestone alternation, and contains rare bivalves and rare ammonites of late Toarcian age. The lithofacies and pelagic macrofauna of the lower member of the Sned Formation characterise a relative deep marine environment unfavourable to benthic macrofauna. The second member indicates a gradual decrease in sea-level allowing from its upper part the recurrence of benthic macrofauna, especially terebratulids. The lithofacies and macrofauna of the lower member of the Lmachkha Formation indicate a shallow terrigenous shelf environment. The second member, containing coral reefs in the western and southern peripheries of the Central Unit, characterises a still shallow marine environment. This significant but gradual decrease in sea-level of the Central Unit from the latest early Toarcian to late Toarcian is likely related to the acceleration of sea-floor spreading in the Central Atlantic Ocean.

Subsurface stratigraphy and basin-fill architecture of the late Paleozoic eastern Taos trough, northern New Mexico, U.S.A.

The greater Taos trough located in north-central New Mexico represents one of numerous late Paleozoic basins that formed during the Ancestral Rocky Mountains deformation event. The late Paleozoic stratigraphy and basin geometry of the eastern portion of the greater Taos trough, also called the Rainsville trough, is little known because the strata are all in the subsurface. Numerous wells drilled through the late Paleozoic strata provide a scope for investigating subsurface stratigraphy and basin-fill architecture of the Rainsville trough. Lithologic data obtained predominantly from petrophysical well logs combined with available biostratigraphic data from the greater Taos trough allows construction of a chronostratigraphic framework of the basin fill. Isopach- and structure-maps indicate that the sediment depocenter was just east of the El Oro-Rincon uplift and a westerly thickening wedge-shaped basin-fill geometry existed during the Pennsylvanian. These relationships imply that the thrust system on the east side of the Precambrian-cored El Oro-Rincon uplift was active during the Pennsylvanian and segmented the greater Taos trough into the eastern Rainsville trough and the western Taos trough. During the Permian, sediment depocenter(s) shifted more southerly and easterly and strata onlap Precambrian basement rocks of the Sierra Grande uplift to the east and Cimarron arch to the north of the Rainsville trough. Permian strata appear to demonstrate minimal influence by faults that were active during the Pennsylvanian and sediment accumulation occurred both in the basinal area as well as on previous positive-relief highlands. A general Permian decrease in eustatic sea level and cessation of local-fault-controlled subsidence indicates that regional subsidence must have affected the region in the early Permian.

History and status of sturgeon stock (Acipenseridae) in the Caspian pool

Analysis of materials from long-term studies characterizing the current state of sturgeon stocks in the Volga-Caspian fisheries basin, and the dynamics of commercial catches of beluga, sturgeon and stellate sturgeon in the XX - XXI centuries indicates that the Northern Caspian occupies the leading value in catch volumes, where more than 70 % of sturgeon fish are annually harvested. In the first half of the twentieth century sturgeon stocks were determined by the scale of natural reproduction in rivers and fishing volumes; in the second half, natural and anthropogenic factors began to intensively influence the formation of sturgeon stocks. The development of hydraulic construction on rivers, an increase in the withdrawal of freshwater runoff, a decrease in sea level to -29.0 mBS, pollution by industrial and agricultural runoff have necessitated the development of a set of measures for the reproduction, conservation and rational use of the Caspian’s aquatic biological resources. As a result of the studies, the response of the sturgeons to the changed conditions of reproduction has been determined in order to restore and increase their commercial stocks; high ecological adaptability of sturgeons to various living conditions within their range, their exceptional plasticity and pronounced intraspecific differentiation have been established. These indicators point to the possibility of creating conditions that meet the requirements for water quality for the life of sturgeons during migration and reproduction. In the course of the analysis of the obtained data, the influence of regulation of the Volga River flow on the efficiency of natural reproduction of sturgeons has been evaluated; the role of industrial sturgeon breeding in sturgeon stock formation has been shown; the abundance of juveniles in the North Caspian and adult individuals on feeding pastures of the sea has been estimated; trends in the number of sturgeon producers migrating in the Volga to spawning sites have been identified; the prospects for the restoration and rational use of sturgeons in the Volga-Caspian basin have been determined.

The Links of Climate Change in the Caspian Sea to the Atlantic and Pacific Oceans

The analysis of interannual changes in climatic parameters for the Caspian Sea over the period of 1900–2015 revealed their links to the Atlantic and Pacific oceans. For example, a dramatic Caspian Sea level decrease in the 1930s may be connected with the strengthening of eastern wind in the region caused by the weakening of the North Atlantic influence on the timescales of about eight years. As is known, this led to the precipitation reduction in the Caspian Sea catchment. At the same time, the influence of the Pacific Ocean on the Caspian Sea parameters on the quasi-twenty-year scale has increased since the 1930s. The opposite process occurred from the late 1970s till the middle of the 1990s: the impact of the North Atlantic increased and that of the Pacific Ocean decreased, thus causing the positive anomalies of western wind and in the sea level rise. In the second half of the 1990s, there was a rapid rise in average air temperature in the Caspian Sea region. However, since the late 1990s, the North Atlantic influence on the Caspian region has weakened, that led to the Caspian Sea level drop and to the slowdown of air temperature rise.

Multi-proxy records of Holocene hydroclimatic and environmental changes on the southern coast of South Korea

A well-dated sediment core from the Goheung area of the southern coast of the Korean Peninsula was used to reconstruct the history of environmental and vegetation changes in response to variability in the East Asian summer monsoon (EASM) and the sea-level change during the Holocene. A multi-proxy analysis (palynomorphs, mean grain size, TOC, TS, C/N ratio, and δ13CTOC data) indicated that the study area underwent a change in environment from a fluvio-coastal (a fluvial to intertidal zone) to a subtidal zone due to a sea-level rise at ca. 7500 cal yr BP. Since ca. 6000 cal yr BP, it has gradually returned to a brackish-dominant environment (intertidal zone) due to coastal regression, with a decrease in relative sea-level. Palynological data show that the climate of the southern coast of the Korean Peninsula underwent a gradual cooling trend after ca. 5900 cal yr BP, due to weakening EASM intensity in response to decreasing insolation in the Northern Hemisphere. Therefore, the long-term vegetation dynamics in this study area were controlled primarily by solar insolation–driven temperature changes during the Holocene. They were also associated with sea surface temperature (SST) changes in the western tropical Pacific (WTP). The vegetation dynamics (sharp reduction of broad-leaved trees and freshwater discharge indicators) in our study area indicate cold and dry climatic conditions since ca. 4500 cal BP, which may have been caused by the decreasing SST in the WTP. In addition, the strong link between the Holocene vegetation dynamics in the East Asian coastal area (especially, Quercus-Lepidobalanus and Pinus-Diploxylon) and SST variation in the WTP may suggest that the centennial-timescale recurring variations in EASM activity have been controlled by low-latitude ocean forcing induced by El Niño Southern Oscillation activity.

Strontium stratigraphy of the Oligocene–Early Miocene shellbeds of the Kutch Basin, western India, and its implications

The Kutch Basin is unique among the western Indian sedimentary basins because of its near-complete sequence of post-Palaeozoic rocks. Due to extensive marine influence, the Oligocene–Early Miocene formations of the basin, namely Maniyara Fort, Khari Nadi and Chhasra, contain numerous shellbeds. Although age assignments of these formations exist based on foraminiferal biostratigraphy, detailed numerical age of the lithounits are yet to be established. We have identified a total of eleven distinct shellbeds (oldest SB 01 to youngest SB11) from this interval primarily containing bivalve fossils. Using 87Sr/86Sr of selected oyster and pectinid shells with pristine shell characteristics, we report the age of four shellbeds. The ages of SB 01, SB 04, SB 06 and SB 10 are 24.37, 17.31, 16.85 and 15.38 Ma, respectively. Our dates suggest a Chattian (24.37 Ma) age for SB 01 from the Bermoti Member, validating the previous biostratigraphical estimates from the Maniyara Fort Formation. The Chhasra Formation, however, shows a younger range of ages (17.31–15.38 Ma) characterized by a transition from the Burdigalian (SB 04–SB 06) to the Langhian (SB 10) stages. These dates have important implications in the study of sequence stratigraphy, Palaeobiogeography and tectonic history of the Kutch Basin. A surface with subaerial exposure is found in SB 08 (between 16.85 and 15.38 Ma) that corresponds to a global eustatic sea-level decrease (Mi2). Our new dates will also help evaluate the response of marine fauna to the closure of the Tethyan seaway around 19 Ma due to the formation of ‘Gomphotherium Landbridge’. The dated shellbeds enable us to identify pre- and post-closure fauna and assess the effect of biogeographical separation on these fauna. These dates have important implications in evaluating the regional geological record of western India in the context of various global events.

Distribution of Desalinated Waters of the Amur Estuary in the Okhotsk Sea According to Satellite Observations

The distribution of the desalinated waters of the Amur Estuary in the Northwestern ​​Okhotsk Sea during the summer period was analyzed using satellite data on sea level, salinity, temperature and concentrations of suspended organic carbon. There is good agreement between the spatial distribution of surface water salinity (data from the SMAP satellite) and the sea level (AVISO data) in the study area. The identification of the waters of the Amur Estuary by the surface water temperature and the concentration of suspended organic carbon is limited to the Sakhalin Bay and the coastal waters of Sakhalin Island. An increase (decrease) in the flow of the Amur River during the spring-summer flood leads to an increase (decrease) in sea level in the northern part of the Sakhalin Bay in July. Strengthening of the northwestern (southeastern) winds in September reduces (increases) the inflow of waters with low salinity and elevated sea level to the area north of the Sakhalin Bay.

Selective Recording of Tectonic Forcings in an Oligocene/Miocene Submarine Channel System: Insights From New Age Constraints and Sediment Volumes From the Austrian Northern Alpine Foreland Basin

Detailed characterization of variations in sediment architecture, flux, and transport processes in peri-orogenic basins offers insights into external climatic or tectonic forcings. We tested how four well-known tectonic/erosional events in the Oligocene/Miocene Alpine source area are recorded in the sediment-accumulation rates (SARs) of the deep marine sink in the Northern Alpine Foreland Basin (NAFB): exhumation of the Lepontine Dome (starting at 30 Ma) and the Tauern Window (23-21 Ma), erosion of the Augenstein Formation (~21 Ma), and the visco-elastic relaxation of the European Plate. The Upper Austrian NAFB offers a unique opportunity to investigate external forcings on sedimentary infill due to the large amount of data on the Alpine source and Foreland. Deep-marine sedimentation, forming the Puchkirchen Group and the basal Hall Formation, was controlled by a basin-axial submarine channel (3-5 km wide, >100 km length). Two basin-wide unconformities were recognized in seismic-reflection data: the Northern Slope Unconformity (NSU) and the Base Hall Unconformity (BHU). We combine biostratigraphic and chemostratigraphic analyses of 316 drill-cutting samples from three wells with a large 3D-seismic-reflection data set (3300 km2, >5 km depth) to determine age and duration of the unconformities and to calculate spatially averaged SARs for the submarine channel and its overbanks, separately. Deepening of the basin, recorded by the NSU, occurred between 28.1 and 26.9 Ma. The Puchkirchen Group (26.9–19.6 Ma) is characterized by constant SARs (within standard deviation) in the channel (432–623 (t/m2/Ma)) and on the overbanks (240–340 (t/m2/Ma)). The visco-elastic relaxation of the European Plate results in low SARs on the overbanks (186 (t/m2/Ma)), a decrease in sediment grain size in channel deposits and a decrease in sea level at the BHU (19.6–19.0 Ma). In the upper Hall Formation (19.0–18.1 Ma), clinoforms prograding from the south filled up the basin (1497 (t/m2/Ma)) within 1 Myrs. We conclude that only two of the tectonic signals are recorded in this part of the deep-marine sink, erosion of Augenstein Formation and visco-elastic relaxation of the European Plate; the exhumation of the Tauern Window and Lepontine Dome remain unrecorded.

Gorgan Bay environmental consequences due to the Caspian Sea rapid water level change

The rapid Caspian Sea level fluctuations have caused unstable conditions for coastal areas during the 20st and 21st centuries, and have led to significant losses for economical and social infrastructure. The main objective of this study was to assess the impact of the Caspian Sea level fluctuations on the environment of the Gorgan Bay coasts, which is a large, shallow inlet at the extreme south-east corner of the Caspian Sea. So that, studying required documentations have made it possible to become acquainted with the geographical, geological and environmental conditions of Gorgan Bay. The morphological conditions of coastal lines and diversity of coastal habitats were also assessed in field observations. The geometric structure of coast, their sediment types and the physicochemical properties of soils belonging to coastal habitats were evaluated by determining three transects and nine study sites in the spring and summer 2017. Changes in the coastline of Gorgan Bay were also processed using Land-Sat satellite imagery from 1977, 1995 and 2017. The results exhibited that the environmental vulnerability of the Gorgan Bay coasts depends on the morphological conditions of coastal habitats and alterations in the Caspian Sea level. So that, the plant and animal communities located in the most end of western part of the Gorgan Bay have faced serious challenges during the current century due to the decrease in the Caspian Sea level. Connecting canals between the Bay and Sea will also lose their discharge capacity and the Gorgan Bay will completely be dried up due to this decline. Emergence of large mudflats with sedimentary composition of sandy silt, which has created a very good potential for occurrence of haze, and also replacing the drought ecosystem, instead of the aquatic one, are other environmental events which are expanding vastly in the coastal areas of the Gorgan Bay.

Oceanographic and sedimentological influences on carbonate geochemistry and mineralogy in hypersaline coastal lagoons, Rio de Janeiro state, Brazil

AbstractThe Região dos Lagos situated along the coast east of Rio de Janeiro, Brazil, is dominated by a semiarid microclimate attributed to the occurrence of oceanographic upwelling at nearby Cabo Frio. The upwelling is strongly associated with the dominance of NE winds during austral spring/summer and the directional change of the shoreline orientation. Some coastal hypersaline lagoons from this region have been studied intensively over the last 25 yr because they represent relatively rare sites of modern primary dolomite precipitation. Comparison of environmental signals in three lagoons indicates that during the last ~ 3.0 kyr, changes in oceanographic parameters may have influenced biogeochemical processes associated with the production of carbonate‐bearing sediments. The timing of a decrease in sea level may have influenced a period of more intense upwelling, which coincides with precipitation of stoichiometric dolomite at ~ 2.3 kyr BP in the lagoons located along the coast directly west of Cabo Frio. The dolomite found in the lower sections of cores from Lagoa Vermelha and Brejo do Espinho contains more positive δ18O values, indicating greater evaporation with a period of increased semiarid conditions corresponding to greater terrestrial input. The lower δ13C values indicate re‐equilibration with the input of new carbonate ions derived from the decomposition of organic matter during dolomite formation. In contrast, the sediment core from Lagoa Salgada, located northeast of Cabo Frio, contains no dolomite, and very positive δ13C values recorded in carbonate sediments are attributed to microbially mediated methanogenesis, whereas δ18O values remain relatively constant throughout the core at around zero.

On the Physics of the Warm Water Volume and El Niño/La Niña Predictability

AbstractPrevious work has shown that warm water volume (WWV), usually defined as the volume of equatorial Pacific warm water above the 20°C isotherm between 5°S and 5°N, leads El Niño. In contrast to previous discharge–recharge oscillator theory, here it is shown that anomalous zonal flow acceleration right at the equator and the movement of the equatorial warm pool are crucial to understanding WWV–El Niño dynamics and the ability of WWV to predict ENSO. Specifically, after westerly equatorial wind anomalies in a coupled ocean–atmosphere instability push the warm pool eastward during El Niño, the westerly anomalies follow the warmest water south of the equator in the Southern Hemisphere summer in December–February. With the wind forcing that causes El Niño in the eastern Pacific removed, the eastern equatorial Pacific sea level and thermocline anomalies decrease. Through long Rossby wave dynamics this decrease results in an anomalous westward equatorial flow that tends to push the warm pool westward and often results in the generation of a La Niña during March–June. The anomalously negative eastern equatorial Pacific sea level typically does not change as much during La Niña, the negative feedback is not as strong, and El Niños tend to not follow La Niñas the next year. This El Niño/La Niña asymmetry is seen in the WWV/El Niño phase diagram and decreased predictability during “La Niña–like” decades.

The distribution of the desalinated waters of the amur estuary in the okhotsk sea according to satellite observations

The distribution of the desalinated waters of the Amur Estuary in the Northwestern ​​Okhotsk Sea during the summer period was analyzed using satellite data on sea level, salinity, temperature and concentrations of suspended organic carbon. There is good agreement between the spatial distribution of surface water salinity (data from the SMAP satellite) and the sea level (AVISO data) in the study area. The identification of the waters of the Amur Estuary by the surface water temperature and the concentration of suspended organic carbon is limited to the Sakhalin Bay and the coastal waters of Sakhalin Island. An increase (decrease) in the flow of the Amur River during the spring-summer flood leads to an increase (decrease) in sea level in the northern part of the Sakhalin Bay in July. Strengthening of the northwestern (southeastern) winds in September reduces (increases) the inflow of waters with low salinity and elevated sea level to the area north of the Sakhalin Bay.

The Libycosaurus (Hippopotamoidea, Artiodactyla) intercontinental dispersal event at the early late Miocene revealed by new fossil remains from Kasserine area, Tunisia

ABSTRACT Anthracotheres dispersed from Asia toward Africa at least three times: at the Eocene/Oligocene transition, during the early Miocene and later during the Miocene. Those dispersals are important datum events for African Tertiary biochronology. New fossil remains of early Libycosaurus, the genus implicated in the late Miocene dispersal, are described from a new Tunisian locality of the Kasserine area. The new fossils enhance the hypodigm of Libycosaurus algeriensis and increase the resolution of the phylogenetic position of this species using cladistics analysis. The inclusion of the genus Libycosaurus within the well-described Merycopotamus lineage allows us to constrain its dispersal time. Dispersal of this anthracothere from the Indian sub-continent to Africa was probably facilitated by sea level decrease during the early Tortonian, just preceding the Hipparion dispersal event. This new age estimation refines the resolution of the succession of late Miocene deposits in Maghreb and frames the date of the onset of the Sahara.

Understanding altimetry signals in the Northeastern Ligurian sea using a multi-platform approach

During the Long-Term Glider Mission for Environmental Characterization 2016 sea trial, carried out in the eastern Ligurian Sea (Northwestern Mediterranean Sea), two gliders rated to a maximum depth of 1000 m operated continuously from 3 May 2016–27 June 2016. When possible, glider tracks were synchronized with the contemporaneous footprints of the Jason-2, SARAL/AltiKa and CryoSat-2 altimeters. Temperature and salinity measured by the gliders that were co-localised with the altimeter passages were used to calculate along-track dynamic heights (DH). The latter were then compared with the altimeters’ near real-time absolute dynamic topography (ADT) measurements. ADT and DH values showed very similar, but shifted patterns, suggesting that gliders had sampled the same structures but at different times. Average surface absolute geostrophic velocities at the time of glider transit were used in a novel relocation technique to reposition glider measurements where they would have been at the time of the altimeter passage. The relocation increases the correlation between datasets to a value close to 1 and reduces the RMSE of an order of magnitude, also when the time-difference between measurements was greater than 3 days. The sea level spatial and temporal variability is attributed to the presence of meanders generated by the baroclinic instability of the Liguro- Provençal Current (LPC). These meanders are characterized by a 38 km amplitude and 0.12 m s−1 average propagation speed that are confirmed by the larger scale ocean colour measurements and are in agreement with those previously described in the literature. We found that the presence of LPC meanders in along-track ADT and DH measurements is evidenced by a decrease in sea level when profiles sampled the Modified Atlantic Water, and an increase in sea level when measurements sampled the adjacent waters of Tyrrhenian Sea origin. The relocation technique introduced here is expected to improve future altimetry-glider comparisons, as similar validation experiments were considered possible only when glider and altimetry measurements were near synoptic, and collected up to one day from each other.

The Earliest Asian Duck (Anseriformes: Romainvillia) and the Origin of Anatidae.

A new species of the extinct duck Romainvillia from the Upper Eocene of Kazakhstan is described. This is the earliest duck from Asia, the first record of Romainvillia beyond France and the first reliable evidence of the presence of Romainvilliinae (regarded here as family) in Asia. This occurrence shows a wide range of Romainvillia and suggests a greater similarity of Late Eocene faunas of Western Europe and Asia than it was previously thought. The origin of Romainvilliidae and their presumable descendants Anatidae may be connected with adaptation to a new biotope, the shallowing Late Eocene epicontinental Asian basins (due to a global decrease in sea level).