FN Archimer Export Format
PT J
TI Space-time structure of long ocean swell fields
BT
AF DELPEY, Matthias T.
ARDHUIN, Fabrice
COLLARD, Fabrice
CHAPRON, Bertrand
AS 1:1;2:1;3:3;4:2;
FF 1:;2:;3:;4:PDG-DOP-DCB-OPS-LOS;
C1 Serv Hydrog & Oceanog Marine, F-29200 Brest, France.
IFREMER, ZI Ctr Brest, Lab Oceanog Spatiale, F-29280 Plouzane, France.
Collecte Localisat Satellites, Div Radar, F-29280 Plouzane, France.
C2 SHOM, FRANCE
IFREMER, FRANCE
CLS, FRANCE
SI BREST
SE PDG-DOP-DCB-OPS-LOS
IN WOS Ifremer jusqu'en 2018
copubli-france
IF 3.303
TC 40
UR https://archimer.ifremer.fr/doc/00025/13647/10881.pdf
LA English
DT Article
AB The space-time structure of long-period ocean swell fields is investigated, with particular attention given to features in the direction orthogonal to the propagation direction. This study combines space-borne synthetic aperture radar (SAR) data with numerical model hindcasts and time series recorded by in situ instruments. In each data set the swell field is defined by a common storm source. The correlation of swell height time series is very high along a single great circle path with a time shift given by the deep water dispersion relation of the dominant swells. This correlation is also high for locations situated on different great circles in entire ocean basins. Given the Earth radius R, we define the distance from the source R alpha and the transversal angle beta so that alpha and beta would be equal the colatitude and longitude for a storm centered on the North Pole. Outside of land influence, the swell height field at time t, H-ss(alpha, beta, t) is well approximated by a function H-ss,H-0(t - R alpha/C-g)/root(alpha sin(alpha)) times another function r(2) (beta), where C-g is a representative group speed. Here r(2) (beta) derived from SAR data is very broad, with a width at half the maximum that is larger than 70 degrees, and varies significantly from storm to storm. Land shadows introduce further modifications so that in general r(2) is a function of beta and alpha. This separation of variables and the smoothness of the H-ss field, allows the estimation of the full field of H-ss from sparse measurements, such as wave mode SAR data, combined with one time series, such as that provided by a single buoy. A first crude estimation of a synthetic H-ss field based on this principle already shows that swell hindcasts and forecasts can be improved by assimilating such synthetic observations.
PY 2010
PD DEC
SO Journal Of Geophysical Research-oceans
SN 0148-0227
PU Amer Geophysical Union
VL 115
IS C12037
UT 000285465500002
DI 10.1029/2009JC005885
ID 13647
ER
EF