Synoptic-scale variability of surface winds and ocean response to atmospheric forcing in the eastern austral Pacific Ocean
<p>In the Southern Hemisphere, macroscale atmospheric systems such as westerly winds and the southeast Pacific subtropical anti-cyclone (SPSA) influence the wind regime of the eastern austral Pacific Ocean. The average and seasonal behaviors of these systems are well known, although wind varia...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2019-09-01
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| Series: | Ocean Science |
| Online Access: | https://www.ocean-sci.net/15/1247/2019/os-15-1247-2019.pdf |
| _version_ | 1818148839616413696 |
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| author | I. Pérez-Santos I. Pérez-Santos R. Seguel R. Seguel R. Seguel W. Schneider W. Schneider P. Linford D. Donoso D. Donoso E. Navarro E. Navarro C. Amaya-Cárcamo E. Pinilla G. Daneri |
| author_facet | I. Pérez-Santos I. Pérez-Santos R. Seguel R. Seguel R. Seguel W. Schneider W. Schneider P. Linford D. Donoso D. Donoso E. Navarro E. Navarro C. Amaya-Cárcamo E. Pinilla G. Daneri |
| author_sort | I. Pérez-Santos |
| collection | DOAJ |
| description | <p>In the Southern Hemisphere, macroscale atmospheric systems such as
westerly winds and the southeast Pacific subtropical anti-cyclone (SPSA)
influence the wind regime of the eastern austral Pacific Ocean. The average
and seasonal behaviors of these systems are well known, although wind
variability at different time and distance scales remains largely
unexamined. Therefore, the main goal of this study was to determine the
variabilities of surface winds on a spatiotemporal scale from 40 to 56<span class="inline-formula"><sup>∘</sup></span> S,
using QuikSCAT, Advanced Scatterometer (ASCAT), and the fifth major global
European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA5) surface-wind
information complemented with in situ meteorological data. In addition,
interactions between the atmospheric systems, together with the
ocean–atmosphere response, were evaluated for the period 1999–2018. The
empirical orthogonal function detected dominance at the synoptic scale in
mode 1, representing approximately 30 % of the total variance. In this
mode, low and high atmospheric pressure systems characterized wind
variability for a 16.5 d cycle. Initially, mode 2 – which represents
approximately 22 % of the variance – was represented by winds from the
west/east (43–56<span class="inline-formula"><sup>∘</sup></span> S), occurring mostly during spring
and summer/fall and winter at an annual timescale (1999–2008) until they
were replaced by systems cycling at 27.5 d (2008–2015). This reflects
the influence of the baroclinic annular mode in the Southern Hemisphere.
Mode 3, representing approximately 15 % of the variance, involved the
passage of small-scale low and high atmospheric pressure (LAP and HAP)
systems throughout Patagonia. Persistent Ekman suction occurred throughout
the year south of the Gulf of Penas and beyond the Pacific mouth of the
Strait of Magellan. Easterly Ekman transport (ET) piled these upwelled waters
onto the western shore of South America when winds blew southward. These
physical mechanisms were essential in bringing nutrients to the surface and
then transporting planktonic organisms from the oceanic zone to Patagonian
fjords and channels. In the zonal band between 41 and 43<span class="inline-formula"><sup>∘</sup></span> S, the latitude of Chiloé Island, upward Ekman pumping and Ekman transport during spring and summer favored a reduced sea surface temperature and
increased chlorophyll <span class="inline-formula"><i>a</i></span> (Chl <span class="inline-formula"><i>a</i></span>) levels; this is the first time that such Ekman upwelling conditions have been reported so far south in the eastern Pacific Ocean. The influence of the northward-migrating LAP systems on the ocean–atmosphere interphase<span id="page1248"/> allowed us to understand, for the first time, their direct relationship with recorded nighttime air temperature maxima (locally referred to as “nighttime heatwave events”). In the context of global climate change, greater attention should be paid to these processes based on their possible impact on the rate of glacier melting and on the austral climate.</p> |
| first_indexed | 2024-12-11T12:57:31Z |
| format | Article |
| id | doaj.art-c42284f690824d74be29843d0d66af03 |
| institution | Directory Open Access Journal |
| issn | 1812-0784 1812-0792 |
| language | English |
| last_indexed | 2024-12-11T12:57:31Z |
| publishDate | 2019-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Ocean Science |
| spelling | doaj.art-c42284f690824d74be29843d0d66af032022-12-22T01:06:32ZengCopernicus PublicationsOcean Science1812-07841812-07922019-09-01151247126610.5194/os-15-1247-2019Synoptic-scale variability of surface winds and ocean response to atmospheric forcing in the eastern austral Pacific OceanI. Pérez-Santos0I. Pérez-Santos1R. Seguel2R. Seguel3R. Seguel4W. Schneider5W. Schneider6P. Linford7D. Donoso8D. Donoso9E. Navarro10E. Navarro11C. Amaya-Cárcamo12E. Pinilla13G. Daneri14Centro i-mar de la Universidad de los Lagos, Puerto Montt, ChileCentro de Investigación Oceanográfica COPAS Sur-Austral, Universidad de Concepción, Concepción, ChileCentro de Investigación Oceanográfica COPAS Sur-Austral, Universidad de Concepción, Concepción, ChilePrograma de Postgrado en Oceanografía, Departamento de Oceanografía, Universidad de Concepción, Concepción, ChileInstituto de Fomento Pesquero, Putemún, Castro, ChileDepartamento de Oceanografía, Campus Concepción, Universidad de Concepción, Concepción, ChileMillennium Institute of Oceanography (IMO), University of Concepción, Concepción, ChilePrograma de Doctorado en Ciencias mención Conservación y Manejo de Recursos Naturales, Centro i-mar, Universidad de Los Lagos, Puerto Montt, ChileDepartamento de Oceanografía, Campus Concepción, Universidad de Concepción, Concepción, ChilePontificia Universidad Católica de Valparaíso, Valparaíso, ChilePrograma de Postgrado en Oceanografía, Departamento de Oceanografía, Universidad de Concepción, Concepción, ChileMillennium Institute of Oceanography (IMO), University of Concepción, Concepción, ChileDepartamento de Geofísica, Universidad de Concepción, Concepción, ChileInstituto de Fomento Pesquero, Putemún, Castro, ChileCentro de Investigaciones en Ecosistemas de la Patagonia, Coyhaique, Chile<p>In the Southern Hemisphere, macroscale atmospheric systems such as westerly winds and the southeast Pacific subtropical anti-cyclone (SPSA) influence the wind regime of the eastern austral Pacific Ocean. The average and seasonal behaviors of these systems are well known, although wind variability at different time and distance scales remains largely unexamined. Therefore, the main goal of this study was to determine the variabilities of surface winds on a spatiotemporal scale from 40 to 56<span class="inline-formula"><sup>∘</sup></span> S, using QuikSCAT, Advanced Scatterometer (ASCAT), and the fifth major global European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA5) surface-wind information complemented with in situ meteorological data. In addition, interactions between the atmospheric systems, together with the ocean–atmosphere response, were evaluated for the period 1999–2018. The empirical orthogonal function detected dominance at the synoptic scale in mode 1, representing approximately 30 % of the total variance. In this mode, low and high atmospheric pressure systems characterized wind variability for a 16.5 d cycle. Initially, mode 2 – which represents approximately 22 % of the variance – was represented by winds from the west/east (43–56<span class="inline-formula"><sup>∘</sup></span> S), occurring mostly during spring and summer/fall and winter at an annual timescale (1999–2008) until they were replaced by systems cycling at 27.5 d (2008–2015). This reflects the influence of the baroclinic annular mode in the Southern Hemisphere. Mode 3, representing approximately 15 % of the variance, involved the passage of small-scale low and high atmospheric pressure (LAP and HAP) systems throughout Patagonia. Persistent Ekman suction occurred throughout the year south of the Gulf of Penas and beyond the Pacific mouth of the Strait of Magellan. Easterly Ekman transport (ET) piled these upwelled waters onto the western shore of South America when winds blew southward. These physical mechanisms were essential in bringing nutrients to the surface and then transporting planktonic organisms from the oceanic zone to Patagonian fjords and channels. In the zonal band between 41 and 43<span class="inline-formula"><sup>∘</sup></span> S, the latitude of Chiloé Island, upward Ekman pumping and Ekman transport during spring and summer favored a reduced sea surface temperature and increased chlorophyll <span class="inline-formula"><i>a</i></span> (Chl <span class="inline-formula"><i>a</i></span>) levels; this is the first time that such Ekman upwelling conditions have been reported so far south in the eastern Pacific Ocean. The influence of the northward-migrating LAP systems on the ocean–atmosphere interphase<span id="page1248"/> allowed us to understand, for the first time, their direct relationship with recorded nighttime air temperature maxima (locally referred to as “nighttime heatwave events”). In the context of global climate change, greater attention should be paid to these processes based on their possible impact on the rate of glacier melting and on the austral climate.</p>https://www.ocean-sci.net/15/1247/2019/os-15-1247-2019.pdf |
| spellingShingle | I. Pérez-Santos I. Pérez-Santos R. Seguel R. Seguel R. Seguel W. Schneider W. Schneider P. Linford D. Donoso D. Donoso E. Navarro E. Navarro C. Amaya-Cárcamo E. Pinilla G. Daneri Synoptic-scale variability of surface winds and ocean response to atmospheric forcing in the eastern austral Pacific Ocean Ocean Science |
| title | Synoptic-scale variability of surface winds and ocean response to atmospheric forcing in the eastern austral Pacific Ocean |
| title_full | Synoptic-scale variability of surface winds and ocean response to atmospheric forcing in the eastern austral Pacific Ocean |
| title_fullStr | Synoptic-scale variability of surface winds and ocean response to atmospheric forcing in the eastern austral Pacific Ocean |
| title_full_unstemmed | Synoptic-scale variability of surface winds and ocean response to atmospheric forcing in the eastern austral Pacific Ocean |
| title_short | Synoptic-scale variability of surface winds and ocean response to atmospheric forcing in the eastern austral Pacific Ocean |
| title_sort | synoptic scale variability of surface winds and ocean response to atmospheric forcing in the eastern austral pacific ocean |
| url | https://www.ocean-sci.net/15/1247/2019/os-15-1247-2019.pdf |
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