Theory of geodetic B.V.P.s. applied to the analysis of altimetric data

2008 ◽  
pp. 318-371 ◽  
Author(s):  
Fernando Sansò
Keyword(s):  
Altimetric Data

Blending drifters and altimetric data to estimate surface currents: Application in the Levantine Mediterranean and objective validation with different data types

2021 ◽  
pp. 101850
Author(s):  
Georges Baaklini ◽  
Leila Issa ◽  
Milad Fakhri ◽  
Julien Brajard ◽  
Gina Fifani ◽  
...  
Keyword(s):  
Surface Currents ◽  
Data Types ◽  
Altimetric Data

Seasonal Variation of Surface Circulation Along Peninsular Malaysia' East Coast

2014 ◽  
Vol 71 (4) ◽  
Author(s):  
Muhammad Faiz Pa'suya ◽  
Kamaludin Mohd Omar ◽  
Benny N. Peter ◽  
Ami Hassan Md Din ◽  
Mohd Fadzil Mohd Akhir
Keyword(s):  
Sea Level ◽  
East Coast ◽  
Peninsular Malaysia ◽  
Environmental Data ◽  
Sea Surface ◽  
Northeast Monsoon ◽  
Radar Altimeter ◽  
Sea Level Anomaly ◽  
Surface Circulation ◽  
Altimetric Data

The sea surface circulation pattern over the coast of Peninsula Malaysia's East Coast during Northeast Monsoon (NE) and Southwest Monsoon (SW) are derived using the seasonally averaged sea level anomaly (SLA) data from altimetric data and 1992-2002 Mean Dynamic Ocean Topography. This altimetric data has been derived from multi-mission satellite altimeter TOPEX, ERS-1, ERS-2, JASON-1, and ENVISAT for the period of nineteen years (1993 to 2011) using the Radar Altimeter Database System (RADS). The estimated sea level anomaly (SLA) have shown similarity in the pattern of sea level variations observed by four tide gauges. Overall, the sea surface circulations during the NE and SW monsoons shows opposite patterns, northward and southward respectively. During the SW monsoon, an anti-cyclonic circulation has been detected around the Terengganu coastal area centred at (about 5.5° N 103.5° E) and nearly consistent with previous study using numerical modelling. The estimated geostrophic current field from the altimeter is consistent with the trajectories of Argos-tracked Drifting Buoys provided by the Marine Environmental Data Services (MEDS) in Canada.

scholarly journals Precise altimetric topography in ice-sheet flow studies

1993 ◽  
Vol 17 ◽  
pp. 195-200 ◽  
Author(s):  
F. Remy ◽  
J.F. Minster
Keyword(s):  
Activation Energy ◽  
Flow Direction ◽  
Ice Sheet ◽  
Rheological Parameters ◽  
Least Squares Regression ◽  
Sheet Flow ◽  
Ice Flow ◽  
Flow Models ◽  
Altimetric Data ◽  
Basal Shear

The precision of radar altimetry above an ice sheet can improve glaciological studies such as mass balance surveys or ice-sheet flow models, the first by comparing altimetric data at different times (see this issue), the second by testing or constraining models with data. This paper is a first step towards the latter. From a precise topography deduced by inversion of altimetric data (Remy and others, 1989), we calculate ice-flow direction, balance velocity and basal shear stress. The rheological parameters involved in the relation linking velocity, stress and temperature are then derived by least-squares regression. Ice flow is well represented by setting the Glen parameter,nto 1 ± 0.25 and the activation energy as 70 ± 10 kJ mol−1.

scholarly journals Assessment of an ensemble system that assimilates Jason-1/Envisat altimeter data in a probabilistic model of the North Atlantic ocean circulation

Ocean Science ◽  
2015 ◽  
Vol 11 (3) ◽  
pp. 425-438 ◽  
Author(s):  
G. Candille ◽  
J.-M. Brankart ◽  
P. Brasseur
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Gulf Stream ◽  
North Atlantic Ocean ◽  
Altimeter Data ◽  
Stochastic Perturbations ◽  
The North ◽  
Altimetric Data ◽  
The North Atlantic ◽  
Along Track

Abstract. A realistic circulation model of the North Atlantic ocean at 0.25° resolution (NATL025 NEMO configuration) has been adapted to explicitly simulate model uncertainties. This is achieved by introducing stochastic perturbations in the equation of state to represent the effect of unresolved scales on the model dynamics. The main motivation for this work is to develop ensemble data assimilation methods, assimilating altimetric data from past missions Jason-1 and Envisat. The assimilation experiment is designed to provide a description of the uncertainty associated with the Gulf Stream circulation for years 2005/2006, focusing on frontal regions which are predominantly affected by unresolved dynamical scales. An ensemble based on such stochastic perturbations is first produced and evaluated using along-track altimetry observations. Then each ensemble member is updated by a square root algorithm based on the SEEK (singular evolutive extended Kalman) filter (Brasseur and Verron, 2006). These three elements – stochastic parameterization, ensemble simulation and 4-D observation operator – are then used together to perform a 4-D analysis of along-track altimetry over 10-day windows. Finally, the results of this experiment are objectively evaluated using the standard probabilistic approach developed for meteorological applications (Toth et al., 2003; Candille et al., 2007). The results show that the free ensemble – before starting the assimilation process – correctly reproduces the statistical variability over the Gulf Stream area: the system is then pretty reliable but not informative (null probabilistic resolution). Updating the free ensemble with altimetric data leads to a better reliability with an information gain of around 30% (for 10-day forecasts of the SSH variable). Diagnoses on fully independent data (i.e. data that are not assimilated, like temperature and salinity profiles) provide more contrasted results when the free and updated ensembles are compared.

Ice Surface Elevation of Central Marie Byrd Land

1962 ◽  
Vol 4 (31) ◽  
pp. 121-123 ◽  
Author(s):  
J. C. Behrendt ◽  
R. J. Wold ◽  
F. L. Dowling
Keyword(s):  
Surface Elevation ◽  
Ice Shelf ◽  
Ice Surface ◽  
Altimetric Data ◽  
The Antarctic

An ice surface map of central Marie Byrd Land has been compiled from aero-altimetric data taken on 14,000 km. of flight lines during the Antarctic summer of 1960–61 using standard aircraft equipment. A large depression sloping down towards the Filchner Ice Shelf was determined and earlier known features in the area are shown in greater detail.

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