CIMA   09099
CENTRO DE INVESTIGACIONES DEL MAR Y LA ATMOSFERA
Unidad Ejecutora - UE
artículos
Título:
ARE WIND WAVE HEIGHTS INCREASING IN SOUTH-EASTERN SOUTH AMERICAN CONTINENTAL SHELF BETWEEN 30°S AND 40°S?
Autor/es:
DRAGANI, W. C.; MARTÍN, P.B; SIMIONATO, C. G.; CAMPOS, M.I.
Revista:
CONTINENTAL SHELF RESEARCH
Editorial:
Elsevier Science
Referencias:
Lugar: Amsterdam, The Netherlands; Año: 2009
ISSN:
0278-4343
Resumen:
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In this paper, a possible increase
in wind wave heights in the South-eastern
South American Continental Shelf
between 32°S and 40° is investigated. Both time series of in situ (19962006)
and Topex/Poseidon (19932001) annual mean significant wave heights gathered at
the continental shelf and adjacent ocean present apparent positive trends. Even
though these trends are not statistically different from zero, it must be taken
into account that the available in situ and satellite data have a short
span and, moreover, in situ data present several gaps. Several papers presented
evidences about a possible change in the low atmospheric circulation in this
region of the Southern Hemisphere. Consequently, a weak increase in wave height
might be occurring which would be hard to quantify due to the shortness and the
insufficiency of the available observations. In order to study a possible trend
in mean annual wind wave heights Simulating Waves Nearshore (SWAN) model forced
with NCEP/NCAR surface wind was implemented in a regional domain for the period
1971-2005. The annual root-mean-square heights of the simulated wave show
significant trends at several locations of the inner continental shelf and the adjacent
ocean. The most significant increase is observed between 1991-2000 and 1981-1990
decades. The largest difference (0.20
m, 9%) occurs around 34°S-48°W. The wave height increase
is somewhat lower, 7%, in the continental shelf and in the Río de la Plata estuary. The annual mean
energy density (spatially averaged) also presents a significant positive trend
(0.036 m2/yr) and relatively high
inter-annual variability. The possible link between this inter-annual
variability and El Niño - Southern Oscillation (ENSO) was investigated but no
apparent relationship was found. A possible increase in the annual mean energy
density raises two important issues to be considered. First, if change in the
wind pattern has occurred and it has been able to increase the mean wave height
in the region then it is natural to think that an increase in the mean depth of
the mixed layer of the ocean might have occurred as well. Secondly, an
increment in the wave density energy would be able to produce changes in the
littoral processes and, consequently, in the erosion of the coast. In this
sense, an increase of the erosive processes along the sandy coast of Buenos Aires province
during the last thirty years has been previously reported.