FN Archimer Export Format
PT J
TI On the unsteady steepening of short gravity waves near the crests of longer waves in the absence of generation or dissipation
BT 
AF Peureux, Charles
   ARDHUIN, Fabrice
   Guimarães, Pedro Veras
AS 1:1;2:1;3:2;
FF 1:;2:;3:;
C1 Univ. Brest CNRS Ifremer IRD Laboratoire d'Océanographie Physique et Spatiale 29200 Brest, France
   LHEEA lab UMR6598 École Centrale de Nantes 44300 Nantes, France
C2 CNRS, FRANCE
   ECOLE CENT NANTES, FRANCE
UM LOPS
IN WOS Cotutelle UMR
   copubli-france
IF 3.938
TC 3
UR https://archimer.ifremer.fr/doc/00661/77318/78765.pdf
   https://archimer.ifremer.fr/doc/00661/77318/83369.pdf
LA English
DT Article
DE ;instability;modulation;wind waves
AB The wave action equation provides a general framework that has been applied to the conservative hydrodynamic interactions between short and long surface waves. So far, only a limited range of solutions have been investigated. Here we show that the wave action equation predicts that groups of short waves propagating over long monochromatic waves are unstable. We demonstrate theoretically and numerically a new ratchet‐type instability that progressively condenses short wave action around the long wave crests due to the correlation of phase speed and action fluctuations. This instability is of particular interest because it may lead to a higher probability of breaking for short waves propagating in directions within ±35 degrees of the dominant waves direction. This preferred breaking could have a strong impact on cross‐wind and down‐wind slope statistics and thus air‐sea exchanges and remote sensing. Plain Language Summary Short waves riding on long waves tend to focus their energy near the crest of the long waves. This focusing is most pronounced for short waves propagating within 35 degrees of the long wave direction, and may lead to a preferential breaking of short waves. This effect may explain the relatively low energy observed in short waves that propagate near the direction of the long waves. 
PY 2021
PD JAN
SO Journal Of Geophysical Research-oceans
SN 2169-9275
PU American Geophysical Union (AGU)
VL 126
IS 1
UT 000623522000022
DI 10.1029/2020JC016735
ID 77318
ER

EF