scholarly journals Review of "Estimation of geostrophic current in the Red Sea based on Sea level anomalies derived from extended satellite altimetry" by Taqi et al.

2018 ◽  
Author(s):  
Anonymous
Keyword(s):  
Sea Level ◽  
Red Sea ◽  
Satellite Altimetry ◽  
Geostrophic Current ◽  
Sea Level Anomalies

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.

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.

Forecasting sea level anomalies from TOPEX/Poseidon and Jason-1 satellite altimetry

2008 ◽  
Vol 83 (5) ◽  
pp. 469-476 ◽  
Author(s):  
Tomasz Niedzielski ◽  
Wiesław Kosek
Keyword(s):  
Sea Level ◽  
Satellite Altimetry ◽  
Sea Level Anomalies

scholarly journals Sea Level Fusion of Satellite Altimetry and Tide Gauge Data by Deep Learning in the Mediterranean Sea

2021 ◽  
Vol 13 (5) ◽  
pp. 908
Author(s):  
Lianjun Yang ◽  
Taoyong Jin ◽  
Xianwen Gao ◽  
Hanjiang Wen ◽  
Tilo Schöne ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Sea Level ◽  
Satellite Altimetry ◽  
Tide Gauge ◽  
The Other ◽  
Tide Gauge Data ◽  
Sea Levels ◽  
Sea Level Anomalies ◽  
Gauge Data ◽  
The Mediterranean

Satellite altimetry and tide gauges are the two main techniques used to measure sea level. Due to the limitations of satellite altimetry, a high-quality unified sea level model from coast to open ocean has traditionally been difficult to achieve. This study proposes a fusion approach of altimetry and tide gauge data based on a deep belief network (DBN) method. Taking the Mediterranean Sea as the case study area, a progressive three-step experiment was designed to compare the fused sea level anomalies from the DBN method with those from the inverse distance weighted (IDW) method, the kriging (KRG) method and the curvature continuous splines in tension (CCS) method for different cases. The results show that the fusion precision varies with the methods and the input measurements. The precision of the DBN method is better than that of the other three methods in most schemes and is reduced by approximately 20% when the limited altimetry along-track data and in-situ tide gauge data are used. In addition, the distribution of satellite altimetry data and tide gauge data has a large effect on the other three methods but less impact on the DBN model. Furthermore, the sea level anomalies in the Mediterranean Sea with a spatial resolution of 0.25° × 0.25° generated by the DBN model contain more spatial distribution information than others, which means the DBN can be applied as a more feasible and robust way to fuse these two kinds of sea levels.

scholarly journals Absolute Baltic Sea Level Trends in the Satellite Altimetry Era: A  Revisit

2021 ◽  
Author(s):  
Julius Oelsmann ◽  
Keyword(s):  
Baltic Sea ◽  
Sea Level ◽  
Satellite Altimetry ◽  
Altimetry Data ◽  
The South ◽  
The Baltic Sea ◽  
The North ◽  
Sea Level Anomalies ◽  
South West ◽  
The Baltic

<p>For sea level studies, coastal adaptation, and planning for future sea level scenarios, regional responses require regionally-tailored sea level information. Global sea level products from satellite altimeter missions are now available through the European Space Agency’s (ESA) Climate Change Initiative Sea Level Project (SL_cci). However, these global datasets are not entirely appropriate for supporting regional actions. Particularly for the Baltic Sea region, complications such as coastal complexity and sea-ice restrain our ability to exploit radar altimetry data.</p><p>This presentation highlights the benefits and opportunities offered by such regionalised advances, through an examination by the ESA-funded Baltic SEAL project (http://balticseal.eu/). We present the challenges faced, and solutions implemented, to develop new dedicated along-track and gridded sea level datasets for Baltic Sea stakeholders, spanning the years 1995-2019. Advances in waveform classification and altimetry echo-fitting, expansion of echo-fitting to a wide range of altimetry missions (including Delay-Doppler altimeters), and Baltic-focused multi-mission cross calibration, enable all altimetry missions’ data to be integrated into a final gridded product.</p><p>This gridded product, and a range of altimetry datasets, offer new insights into the Baltic Sea’s mean sea level and its variability during 1995-2019. Here, we focus on the analysis of sea level trends in the region using both tide gauge and altimetry data. The Baltic SEAL absolute sea level trend at the coast better aligns with information from the in-situ stations, when compared to current global products. The rise in sea level is statistically significant in the region of study and higher in winter than in summer. A gradient of over 3 mm/yr in sea level rise is observed, with sea levels in the north and east of the basin rising more than in the south-west. Part of this gradient (about 1 mm/yr) is directly explained by a regression analysis of the wind contribution on the sea level time series. A sub-basin analysis comparing the northernmost part (Bay of Bothnia) with the south-west reveals that the differences in winter sea level anomalies are related to different phases of the North-Atlantic Oscillation (0.71 correlation coefficient). Sea level anomalies are higher in the Bay of Bothnia when winter wind forcing pushes waters through Ekman transport from the south-west towards east and north.</p><p>The study also demonstrates the maturity of enhanced satellite altimetry products to support local sea level studies in areas characterised by complex coastlines or sea-ice coverage. The processing chain used in this study can be exported to other regions, in particular to test the applicability in regions affected by larger ocean tides. We promote further exploitation and identification of further synergies with other efforts focused on relevant oceanic variables for societal applications.</p>

scholarly journals Sea level trend and variability around the Peninsular Malaysia

2014 ◽  
Vol 11 (3) ◽  
pp. 1519-1541 ◽  
Author(s):  
Q. H. Luu ◽  
P. Tkalich ◽  
T. W. Tay
Keyword(s):  
Indian Ocean ◽  
Sea Level ◽  
Satellite Altimetry ◽  
Tide Gauge ◽  
Peninsular Malaysia ◽  
Sea Level Anomalies ◽  
The Indian Ocean ◽  
Sea Level Trend ◽  
Malacca Strait

Abstract. Peninsular Malaysia is bounded from the west by Malacca Strait and the Andaman Sea both connected to the Indian Ocean, and from the east by South China Sea being largest marginal sea in the Pacific Basin. Resulting sea level along Peninsular Malaysia coast is assumed to be governed by various regional phenomena associated with the adjacent parts of the Indian and Pacific Oceans. At annual scale, sea level anomalies (SLAs) are generated by the Asian monsoon; interannual sea level variability is determined by the El Niño–Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD); while long-term sea level trend is related to global climate change. To quantify the relative impacts of these multi-scale phenomena on sea level trend and variability around the Peninsular Malaysia, long-term tide gauge record and satellite altimetry are used. During 1984–2011, relative sea level rise (SLR) rates in waters of Malacca Strait and eastern Peninsular Malaysia are found to be 2.4 ± 1.6 mm yr−1 and 2.7 ± 1.0 mm yr−1, respectively. Allowing for corresponding vertical land movements (VLM; 0.8 ± 2.6 mm yr−1 and 0.9 ± 2.2 mm yr−1), their absolute SLR rates are 3.2 ± 4.2 mm yr−1 and 3.6 ± 3.2 mm yr−1, respectively. For the common period 1993–2009, absolute SLR rates obtained from both tide gauge and satellite altimetry in Peninsular Malaysia are similar; and they are slightly higher than the global tendency. It further underlines that VLM should be taken into account to get better estimates of SLR observations. At interannual scale, ENSO affects sea level over the Malaysian coast in the range of ±5 cm with a very high correlation. Meanwhile, IOD modulates sea level anomalies mainly in the Malacca Strait in the range of ±2 cm with a high correlation coefficient. Interannual regional sea level drops are associated with El Niño events and positive phases of the IOD index; while the rises are correlated with La Niña episodes and the negative periods of the IOD index. Seasonally, SLAs are mainly monsoon-driven, in the order of 10–25 cm. Geographically, sea level responds differently to the monsoon: two cycles per year are observed in the Malacca Strait, presumably due to South Asian-Indian Monsoon; whereas single annual cycle is noted along east coast of Peninsular Malaysia, mostly due to East Asian-Western Pacific Monsoon. These results imply that a narrow topographic constriction in Singapore Strait may separate different modes of annual and interannual sea level variability along coastline of Peninsular Malaysia.

scholarly journals Coastal sea level anomalies and associated trends from Jason satellite altimetry over 2002–2018

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Keyword(s):  
Sea Level ◽  
Satellite Altimetry ◽  
North Indian Ocean ◽  
Monthly Interval ◽  
Small Scale ◽  
Coastal Zones ◽  
Sea Level Changes ◽  
Western Africa ◽  
Sea Level Anomalies ◽  
Coastal Sea

Abstract Climate-related sea level changes in the world coastal zones result from the superposition of the global mean rise due to ocean warming and land ice melt, regional changes caused by non-uniform ocean thermal expansion and salinity changes, and by the solid Earth response to current water mass redistribution and associated gravity change, plus small-scale coastal processes (e.g., shelf currents, wind & waves changes, fresh water input from rivers, etc.). So far, satellite altimetry has provided global gridded sea level time series up to 10–15 km to the coast only, preventing estimation of sea level changes very close to the coast. Here we present a 16-year-long (June 2002 to May 2018), high-resolution (20-Hz), along-track sea level dataset at monthly interval, together with associated sea level trends, at 429 coastal sites in six regions (Northeast Atlantic, Mediterranean Sea, Western Africa, North Indian Ocean, Southeast Asia and Australia). This new coastal sea level product is based on complete reprocessing of raw radar altimetry waveforms from the Jason-1, Jason-2 and Jason-3 missions.

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