Ocean surface dynamics derived from TerraSAR-X/TanDEM-X and hydrodynamic modeling

Author(s):  
Andreas Lehmann ◽  
Steffen Suchandt

<p>Dynamical processes at the ocean surface are of high interest because they control the exchange processes between ocean and atmosphere. Furthermore, ocean surface drift determines the dispersion of heat, salt and material such as harmful substances or plastic litter. Still the measurement of ocean surface currents is a challenge because of wave and wave-breaking processes. Here we demonstrate the usefulness of TerraSAR-X/TanDEM-X data to determine ocean surface currents, wave and wind fields. Up to now there are no spatially resolved ocean surface currents measurements available, so that for the validation of surface currents a combined SAR and hydrodynamic modeling methodology is applied. Ocean surface currents are derived from SAR Along-track Interferometry, and the hydrodynamic model is a coupled wave sea ice-ocean model of the Baltic Sea. The model is driven by ERA-Interim atmospheric reanalysis data. Hydrodynamic model data are also used to support the geophysical interpretation of the multiparametrical information of the ocean surface provided by SAR.</p>

2007 ◽  
Vol 30 (4) ◽  
pp. 345-354 ◽  
Author(s):  
Anshu Prakash Mishra ◽  
S. Rai ◽  
A. C. Pandey

2020 ◽  
Author(s):  
Felix L. Müller ◽  
Denise Dettmering ◽  
Claudia Wekerle ◽  
Christian Schwatke ◽  
Marcello Passaro ◽  
...  

<p>Satellite altimetry is an important part of the Global Geodetic Observing System providing precise information on sea level on different spatial and temporal scales. Moreover, satellite altimetry-derived dynamic ocean topography heights enable the computation of ocean surface currents by applying the well-known geostrophic equations. However, in polar regions, altimetry observations are affected by seasonally changing sea-ice cover leading to a fragmentary data sampling.</p><p>In order to overcome this problem, an ocean model is used to fill in data gaps. The aim is to obtain a homogeneous ocean topography representation that enables consistent investigations of ocean surface current changes. For that purpose, the global Finite Element Sea-ice Ocean Model (FESOM) is used. It is based on an unstructured grid and provides daily water elevations with high spatial resolution.</p><p><span>The combination is done based on a Principal Component Analysis (PCA) after reducing both quantities by their constant and seasonal signals. In the main step, the </span><span>most dominant spatial patterns of the modeled water heights </span><span>as provided by the PCA are linked with the </span><span>temporal variability of </span><span>the estimated </span><span>dynamic ocean topography elevations</span><span> from altimetry. At the end, the seasonal signal as well as the absolute reference from altimetry is added back to the data set.</span></p><p><span>T</span><span>his </span><span>contribution</span><span> describes the combination process </span><span>as well as the generated final product: </span><span> a daily, more than 17 years covering dataset of geostrophic ocean currents. The combination is done for the </span><span>marine </span><span>region</span><span>s</span><span> Greenland Sea, Barents Sea and the Fram Strait and includes sea surface height observations of the ESA altimeter satellites ERS-2 and Envisat. In order to evaluate the </span><span>combination </span><span>results, independent </span><span>surface </span><span>drifter </span><span>observations</span><span>, </span><span>corrected for</span> <span>a-geostrophic velocity </span><span>components, are used.</span></p>


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