scholarly journals Estimation of geostrophic current in the Red Sea based on sea level anomalies derived from extended satellite altimetry data

Ocean Science ◽  
2019 ◽  
Vol 15 (3) ◽  
pp. 477-488 ◽  
Author(s):  
Ahmed Mohammed Taqi ◽  
Abdullah Mohammed Al-Subhi ◽  
Mohammed Ali Alsaafani ◽  
Cheriyeri Poyil Abdulla
Keyword(s):  
Sea Level ◽  
Red Sea ◽  
Current Data ◽  
Western Coast ◽  
Geostrophic Current ◽  
Geostrophic Currents ◽  
The North ◽  
Sea Level Anomalies ◽  
Western Side ◽  
Anticyclonic Eddies

Abstract. Geostrophic current data near the coast of the Red Sea have large gaps. Hence, the sea level anomaly (SLA) data from Jason-2 have been reprocessed and extended towards the coast of the Red Sea and merged with AVISO data at the offshore region. This processing has been applied to build a gridded dataset to achieve the best results for the SLA and geostrophic current. The results obtained from the new extended data at the coast are more consistent with the observed data (conductivity–temperature–depth, CTD) and hence geostrophic current calculation. The patterns of SLA distribution and geostrophic currents are divided into two seasons: winter (October–May) and summer (June–September). The geostrophic currents in summer are flowing southward over the Red Sea except for narrow northward flow along the east coast. In winter, currents flow to the north for the entire Red Sea except for a small southward flow near the central eastern and western coast. This flow is modified by the presence of cyclonic and anticyclonic eddies, which are more concentrated in the central and northern Red Sea. The results show anticyclonic eddies (AEs) on the eastern side of the Red Sea and cyclonic eddies (CEs) on the western side during winter. In summer, cyclonic eddies are more dominant for the entire Red Sea. The result shows a change in some eddies from anticyclonic during winter to cyclonic during summer in the north between 26.3 and 27.5∘ N. Furthermore, the life span of cyclonic eddies is longer than that of anticyclonic eddies.

scholarly journals Estimation of geostrophic current in the Red Sea based on Sea level anomalies derived from extended satellite altimetry data

2018 ◽  
Author(s):  
Ahmed Mohammed Taqi ◽  
Abdullah Mohammed Al-Subhia ◽  
Mohammed Ali Alsaafani
Keyword(s):  
Sea Level ◽  
Red Sea ◽  
Winter Season ◽  
Geostrophic Current ◽  
Grid Data ◽  
The West ◽  
Geostrophic Currents ◽  
Eastern Side ◽  
Sea Level Anomalies ◽  
Anticyclonic Eddies

Abstract. The geostrophic currents data near the coast of the Red Sea has a large gap. Due to that the sea level anomaly (SLA) data of Jason-2 has been reprocessed and extended towards the coast of the Red Sea and merged with AVISO data at the center of the Red Sea. The processing has been applied to build a grid data to achieve best results for the SLA and geostrophic current. The results obtained from the new extended data at the coast are more consistent with the observed data hence geostrophic current calculation. The estimated geostrophic current match well with that estimated for observed CTD data. The pattern of SLA distribution and geostrophic currents are divided into two seasons; Winter season extends from October to May and Summer from June to September. The geostrophic currents along the eastern Red Sea flow toward north and southward along the west coast. This flow is modified with the presence of the cyclonic and anticyclonic eddies, which are more concentrated at the central and northern side of the Red Sea. The study has shown anticyclonic eddies (AE) on the eastern side of the Red Sea, while cyclonic eddies (CE) on the west side during Winter. During Summer the (CE) are along the eastern side and (AE) along the western side.

Water circulation and shelf waves in the northern Great Barrier Reef lagoon

1981 ◽  
Vol 32 (5) ◽  
pp. 721 ◽  
Author(s):  
E Wolanski ◽  
B Ruddick
Keyword(s):  
Great Barrier Reef ◽  
Sea Level ◽  
Low Frequency ◽  
Current Data ◽  
Barrier Reef ◽  
Sea Levels ◽  
The North ◽  
Level Data ◽  
Shelf Wave ◽  
Salinity Water

Currents and sea levels were measured at a number of locations in the Great Barrier Reef (GBR) lagoon from about 10 to 13� S., during the period October-December 1979. A strong non-tidal, low-frequency modulation of all sea-level and current data was found. The currents nearshore were driven northward by the wind, and then at least partially blocked by the dense network of reefs to the north of 10� s. The water then flowed southward in deeper water adjacent to the reef, driven by a longshore pressure gradient. The low- frequency sea-level data, though not the current records, showed northward phase propagation at speeds characteristic of a first-mode shelf wave trapped in the lagoon between the shore and the reef. Data are presented revealing the intrusion of low-salinity water, through Bligh Entrance, in the GBR lagoon, as a result of river discharges in the Gulf of Papua. It is suggested that low-frequency longshore currents may periodically flush these river plumes from the GBR lagoon and enhance interaction between reefs. In the Coral Sea in front of reef passages, the large horizontal velocities may result in forces upwelling by selective withdrawal and jet entrainment.

Synergistic Use of Satellite and In-Situ Current Data to Improve the Characterisation of Seasonal Trends

2009 ◽  
Author(s):  
Liam Harrington-Missin ◽  
Mark Calverley ◽  
Gus Jeans
Keyword(s):  
Current Data ◽  
Seasonal Trend ◽  
Measured Signal ◽  
Geostrophic Current ◽  
Geostrophic Currents ◽  
Current Regime ◽  
Long Period ◽  
In Situ Data ◽  
One Year

The synergistic use of measured in-situ current data and altimetry derived geostrophic current data provides improved seasonal characterisation of the current regime, West of Shetland. In September 2007, considerable downtime was experienced by an offshore operator, West of Shetland, as a result of unexpectedly high currents persisting for a number of days. This downtime was unanticipated following conclusions derived from one year of in-situ measured data, which suggested a most favourable current regime during the months August to October. Ten years of altimetry derived geostrophic currents were utilised in conjunction with approximately 3 years of in-situ data to assess the validity of the reported seasonal trend. The altimetry derived geostrophic currents correlated well with the dominating long period signal extracted from the in-situ data. Seasonal comparison between the altimetry derived geostrophic currents and the total measured signal showed the previously available measurement year had a relatively benign September. Based on the 10 years of satellite data, the inter-annual variability of the current regime West of Shetland does not show any clear seasonal trend.

scholarly journals North SEAL: a new dataset of sea level changes in the North Sea from satellite altimetry

2021 ◽  
Vol 13 (8) ◽  
pp. 3733-3753
Author(s):  
Denise Dettmering ◽  
Felix L. Müller ◽  
Julius Oelsmann ◽  
Marcello Passaro ◽  
Christian Schwatke ◽  
...  
Keyword(s):  
Sea Level ◽  
North Sea ◽  
Tide Gauge ◽  
Sea Level Changes ◽  
Adaptation Measures ◽  
Isostatic Adjustment ◽  
The North ◽  
Sea Level Anomalies ◽  
Vertical Land Motion ◽  
The North Sea

Abstract. Information on sea level and its temporal and spatial variability is of great importance for various scientific, societal, and economic issues. This article reports about a new sea level dataset for the North Sea (named North SEAL) of monthly sea level anomalies (SLAs), absolute sea level trends, and amplitudes of the mean annual sea level cycle over the period 1995–2019. Uncertainties and quality flags are provided together with the data. The dataset has been created from multi-mission cross-calibrated altimetry data preprocessed with coastal dedicated approaches and gridded with an innovative least-squares procedure including an advanced outlier detection to a 6–8 km wide triangular mesh. The comparison of SLAs and tide gauge time series shows good consistency, with average correlations of 0.85 and maximum correlations of 0.93. The improvement with respect to existing global gridded altimetry solutions amounts to 8 %–10 %, and it is most pronounced in complicated coastal environments such as river mouths or regions sheltered by islands. The differences in trends at tide gauge locations depend on the vertical land motion model used to correct relative sea level trends. The best consistency with a median difference of 0.04±1.15 mm yr−1 is reached by applying a recent glacial isostatic adjustment (GIA) model. With the presented sea level dataset, for the first time, a regionally optimized product for the entire North Sea is made available. It will enable further investigations of ocean processes, sea level projections, and studies on coastal adaptation measures. The North SEAL data are available at https://doi.org/10.17882/79673 (Müller et al., 2021).

scholarly journals NorthSEAL: A new Dataset of Sea Level Changes in the North Sea from Satellite Altimetry

2021 ◽  
Author(s):  
Denise Dettmering ◽  
Felix L. Müller ◽  
Julius Oelsmann ◽  
Marcello Passaro ◽  
Christian Schwatke ◽  
...  
Keyword(s):  
Sea Level ◽  
North Sea ◽  
Tide Gauge ◽  
Sea Level Changes ◽  
Adaptation Measures ◽  
Isostatic Adjustment ◽  
The North ◽  
Sea Level Anomalies ◽  
Vertical Land Motion ◽  
The North Sea

Abstract. Information on sea level and its temporal and spatial variability is of great importance for various scientific, societal and economic issues. This article reports about a new sea level dataset for the North Sea (named NorthSEAL) of monthly sea level anomalies (SLA), absolute sea level trends and sea level mean annual amplitudes over the period 1995–2019. Uncertainties and quality flags are provided together with the data. The dataset has been created from multi-mission cross-calibrated altimetry data, preprocessed 5 with coastal dedicated approaches and gridded with innovative methods to a 6–8 km wide triangular mesh. The comparison of SLA and tide gauge time series shows a good consistency with average correlations of 0.85 and maximum correlations of 0.93. The improvement with respect to existing global gridded altimetry solutions amounts to 8–10 %, and it is most pronounced in complicated coastal environments such as river mouths or regions sheltered by islands. The differences in trends at tide gauge locations depend on the vertical land motion model used to correct relative sea level trends. The best 10 consistency with a median difference of 0.04 ± 1.15 mm/year is reached by applying a recent glacial isostatic adjustment (GIA) model. With the presented sea level dataset, for the first time, a regionally optimized product for the entire North Sea is made available. It will enable further investigations of ocean processes, sea level projections and studies on coastal adaptation measures. The NorthSEAL data is available at https://doi.org/10.17882/79673 (Müller et al., 2021).

scholarly journals I.—The Kishon and Jordan Valleys

1904 ◽  
Vol 1 (12) ◽  
pp. 575-582 ◽  
Author(s):  
T. G. Bonney
Keyword(s):  
Sea Level ◽  
Difficult Problem ◽  
The South ◽  
North West ◽  
The North ◽  
South West ◽  
Western Side ◽  
Physical Geology

That broad trench through the Palestine Highlands, an ancient highway and battlefield of nations—the plain of Esdraelon or the valley of Megiddo, together with the plain of Acre—has for long presented to me a difficult problem in Physical Geology, for it seemed inexplicable by subaerial denudation under existing conditions. Its floor varies roughly from five to eight miles in breadth; running approximately from south-east to north-west, it is bounded on the more western side by the limestone mountains of Samaria and on the more eastern by those of Galilee. The former descend from the ridge of Carmel (1,742 feet at highest) with a fairly steep escarpment, which becomes a little less regular as we follow it to the bastion-mass of Mount Gilboa; the latter correspond in their general outlines with those of the eastern portion of Samaria, but the advance of a lower spur towards the south-west divides the plain of Esdraelon from that of Acre, by a kind of strait in which, so far as I could see, there is but little level ground on either side of the Kishon. This spur, however, of the northern hills, hardly does more than interrupt the floor of the Kishon valley, for above it the great trench is continued between two hill masses, much of these ranging from thirteen to sixteen hundred feet above sea-level. Beyond the strait the upper basin (plain of Esdraelon) quickly broadens out, extending towards the south-east for about fifteen or sixteen miles, where it is divided into two arms by Jebel Duhy (Little Hermon) (1,690 feet), which is thus isolated from Tabor (1,846 feet) on the north, and from Gilboa (1,698 feet) on the south; a broad, rather shallow, grassy valley descending from the last-named mass to lose itself in the plain.

scholarly journals Notes on some animal parasites in British Guiana

1916 ◽  
Vol 7 (2) ◽  
pp. 179-190 ◽  
Author(s):  
G. E. Bodkin ◽  
L. D. Cleare
Keyword(s):  
Sea Level ◽  
Sand Dunes ◽  
Coastal Region ◽  
The South ◽  
British Guiana ◽  
North East ◽  
The North ◽  
South West ◽  
Western Side ◽  
River Valleys

British Guiana lies between the latitudes 0·41′ N. (source of the Essequebo River) and 8° 33′ 22″ N. (Punta Playa), has a depth from north to south of about 500 miles, a seaboard of about 270 miles trending in a south-easterly direction, and occupies in the north-east of South America an area approximately equal in extent to Great Britain. It is bounded on the north by the Atlantic Ocean, on the east by Surinam or Dutch Guiana, on the south and south-west by Brazil, and on the west by Venezuela.The Colony may be divided broadly into three belts. The northern one consists of a low-lying flat and swampy belt of marine alluvium—the coastal region. This rises gradually from the seaboard and extends inland for a distance varying from 5 to 49 miles. It is succeeded by a broader and slightly elevated tract of country of sandy and clayey soils. This belt is generally undulating, and is traversed in places by sand-dunes rising from 50 to 180 ft. above sea-level. The more elevated portion of the Colony lies to the southward of the above-mentioned regions. It rises gradually to the south-west, between the river valleys, which are in many parts swampy, and contains three principal mountain ranges, several irregularly distributed smaller ranges, and in the southern and eastern parts numerous isolated hills and mountains. The eastern portion is almost entirely forest-clad, but on the south-western side there is an extensive area of flat grass-clad savannah land elevated about 300 feet above sea-level.

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