FN Archimer Export Format
PT J
TI Reconstructing Ocean Surface Current Combining Altimetry and Future Spaceborne Doppler Data
BT 
AF Ubelmann, Clement
   Dibarboure, Gérald
   Gaultier, Lucile
   Ponte, Aurelien
   Ardhuin, Fabrice
   Ballarotta, Maxime
   Faugère, Yannice
AS 1:1;2:2;3:3;4:4;5:4,6;6:5;7:5;
FF 1:;2:;3:;4:PDG-ODE-LOPS-OH;5:;6:;7:;
C1 Ocean Next, La Terrasse, France
   Centre National d'Etudes Spatiales ,Toulouse, France
   Ocean Data Lab, Plouzané, France
   Ifremer, Plouzané ,France
   Collecte Localisation Satellite ,Ramonville Saint Agne, France
C2 OCEAN NEXT, FRANCE
   CNES, FRANCE
   OCEANDATALAB, FRANCE
   IFREMER, FRANCE
   CLS, FRANCE
   CNRS, FRANCE
SI BREST
SE PDG-ODE-LOPS-OH
UM LOPS
IN WOS Ifremer UMR
   WOS Cotutelle UMR
   copubli-france
IF 3.938
TC 13
UR https://archimer.ifremer.fr/doc/00679/79099/81573.pdf
LA English
DT Article
AB Two methods for the mapping of ocean surface currents from satellite measurements of sea level and future current vectors are presented and contrasted. Both methods rely on the linear and Gaussian analysis framework with different levels of covariance definitions. The first method separately maps sea level and currents with single‐scale covariance functions and leads to estimates of the geostrophic and ageostrophic circulations. The second maps both measurements simultaneously and projects the circulation onto 4 contributions: geostrophic, ageostrophic rotary, ageostrophic divergent and inertial. When compared to the first method, the second mapping moderately improves the resolution of geostrophic currents but significantly improves estimates of the ageostrophic circulation, in particular near‐inertial oscillations. This method offers promising perspectives for reconstructions of the ocean surface circulation. Even the hourly dynamics can be reconstructed from measurements made locally every few days because nearby measurements are coherent enough to help fill the gaps. Based on numerical simulation of ocean surface currents, the proposed SKIM mission that combines a nadir altimeter and a Doppler scatterometer with a 300 km wide swath (with a mean revisit time of 3 days) would allow the reconstruction of 50% of the near‐inertial variance around an 18 hour period of oscillation. Plain Language Summary Ocean surface currents are caused by a variety of phenomena that varies at different space and time scales. Here we mainly consider the two dominant contributions. The first is the current resulting from the quasi‐equilibrium between the sloping sea level and the Coriolis force, slowly evolving over a few days. The second is also associated with the Coriolis force, but out of equilibrium: oscillating currents caused by rapid changes of the wind with a narrow range of periods around a natural period of oscillation that increase with latitude from 12 hours at the poles. For many applications it is desirable to separate these two contributions, for example to compute transports associated to the slowly evolving component and to evaluate the amount of kinetic energy pumped by the wind, mostly in the fast oscillations. This separation is easy with hourly sampled in situ measurements, but few are available. Here we show that we can perform this separation using satellite passes with measurements of sea level and a swath of surface current vectors, as can be measured by proposed future satellites. The fast oscillations can be reproduced even if data is available every few days, thanks to their spatial patterns and temporal coherence. 
PY 2021
PD MAR
SO Journal Of Geophysical Research-oceans
SN 2169-9275
PU American Geophysical Union (AGU)
VL 126
IS 3
UT 000636285300024
DI 10.1029/2020JC016560
ID 79099
ER

EF