Effect of the Grijalva-Usumacinta system on the circulation adjacent to the eastern shelf of Yucatan

Turbidity is a good indicator to determine the quality of the water; it is a measure of the number of particles in suspension in the water. Using ocean color data, we analyzed the seasonal variability of turbidity in front of the Campeche Bank and part of the confluence zone of the coastal currents coming from the Tamaulipas-Veracruz and Campeche platforms [94°W-87.6°W and 18°N-24°N]. The extended platform has several river discharges that are strongly influenced by winds and the loop current coming from the Strait of Yucatan. 2003-2020 was analyzed using satellite images (reflectance, Chlorophyll, sea surface temperature, and altimetry), reanalyzed winds and discharges from the grijalva-usumacinta river system. We used seasonal climatologies, Hovmoller diagrams, and Orthogonal and Complex Empirical Functions to describe the data. In addition, through the “Coastal and Regional Ocean Community model-CROCO) the surface fields of Salinity and velocity were incorporated into the analysis. The results indicated that the seasonal turbidity and its intensification in autumn and winter on the western side of the Campeche platform are due mainly to the contribution of intense flows from the Grijalva-Usumacinta which is further dynamically mix in autumn by the southwest winds, the cyclonic gyres, and the return currents. In spring-summer, the same forcing persists; however, the turbidity decreases due to the ineffectiveness of the intense zonal winds to produce Ekman transport

Satellite-derived variability in chlorophyll, wind stress, sea surface height, and temperature in the northern California Current System

Satellite-derived data provide the temporal means and seasonal and nonseasonal variability of four physical and biological parameters off Oregon and Washington (41°–48.5°N). Eight years of data (1998–2005) are available for surface chlorophyll concentrations, sea surface temperature (SST), and sea surface height, while six years of data (2000–2005) are available for surface wind stress. Strong cross-shelf and alongshore variability is apparent in the temporal mean and seasonal climatology of all four variables. Two latitudinal regions are identified and separated at 44°–46°N, where the coastal ocean experiences a change in the direction of the mean alongshore wind stress, is influenced by topographic features, and has differing exposure to the Columbia River Plume. All these factors may play a part in defining the distinct regimes in the northern and southern regions. Nonseasonal signals account for ∼60–75% of the dynamical variables. An empirical orthogonal function analysis shows stronger intra-annual variability for alongshore wind, coastal SST, and surface chlorophyll, with stronger interannual variability for surface height. Interannual variability can be caused by distant forcing from equatorial and basin-scale changes in circulation, or by more localized changes in regional winds, all of which can be found in the time series. Correlations are mostly as expected for upwelling systems on intra-annual timescales. Correlations of the interannual timescales are complicated by residual quasi-annual signals created by changes in the timing and strength of the seasonal cycles. Examination of the interannual time series, however, provides a convincing picture of the covariability of chlorophyll, surface temperature, and surface height, with some evidence of regional wind forcing

VARIABILIDAD ESPACIO TEMPORAL DE LA DERIVA DE LOS VIENTOS OESTES MEDIANTE VIENTOS SATELITALES (QUIKSCAT) SPATIAL AND TEMPORAL VARIABILITY OF WESTERLY WIND DRIFT BY SATELLITE WINDS (QUIKSCAT)

Mediante el uso de 110 imágenes mensuales (1999-2008) del esfuerzo del viento proveniente del satélite Quikscat se analizó la zona donde divergen los vientos hacia el ecuador y hacia los polos. En las cercanías del borde oriental del Pacífico, tanto para el norte como para el sur, se estudió el desplazamiento de las zonas de divergencia de los vientos (DZD) mediante una serie de tiempo versus posición. Mediante análisis estadístico se encontró que el DZD está influenciado por señales de alta frecuencia (periodo de 3 meses), estacional (periodo de 12 meses) e interanual (periodos superior a dos años) asociado al evento cálido de El Niño. La señal más robusta de la serie es la estacional, mostrando que el DZD de la región norte está fuertemente acoplado a la región sur. Además, el DZD de la región norte muestra un mayor desplazamiento estacional, asociado posiblemente a la forma de la línea de costa ya que la región sur está sometida a forzantes de origen polar.<br>By mean of 110 monthly images (1999-2008) of wind stress from Quikscat satellite, the divergence zone of equatorward and poleward winds was analyzed. At the surrounding area of the Pacific Eastern boundary, for both north and south, the displacement of the wind divergence zone (DDZ) was studied by a time serie versus position. The statistical analysis reveals that DDZ is influenced by high frequency (3 months), seasonal (12 months) and interannual signals (> 2 years), the last associated to warm event of El Niño. The most predominant signal was the seasonal, showing DDZ in the northern zone is highly coupled with the DDZ in the south. Furthermore, the DDZ of the northern zone showed a major seasonal displacement in comparison to the southern area, likely associated to the shape of coastline, since the southern zone is influenced by polar signals

ANALISIS DE PARAMETROS OCEANOGRAFICOS Y ATMOSFERICOS DEL SENO DE RELONCAVI ANALYSIS OF OCEANOGRAPHIC AND ATMOSPHERIC PARAMETERS OF SENO DE RELONCAVI

La recopilación de información histórica, tales como mediciones de corrientes, oleaje y viento no ha sido suficiente para describir la dinámica del seno Reloncaví. Sin embargo, a pesar de la información parcelada, las altas magnitudes de corrientes en las zonas de Chaica, Quillaipe y El Paso Nao nos permiten inducir que las corrientes baroclínicas modulan fuertemente la dinámica de la cuenca. Por otro lado, los vientos mostraron una alta variabilidad estacional y son modulados por la línea de costa, siendo estos en parte responsables de la circulación y el oleaje superficial. Además, la circulación superficial en los primeros 10 m esta fuertemente modulada por el ingreso de aguas dulce del estuario de Reloncaví. Además, la máxima amplitud del nivel del mar es de 7.64 m, con una amplitud promedio de 7.46 m, y donde la mayor parte de la variabilidad del nivel del mar esta asociada a la marea. Finalmente, para describir el comportamiento del oleaje se comparan el método empírico de Massel con el modelo numérico del Mike21. Resultando que el clima de ola estaría siendo modificado por la gran variabilidad espacial y temporal de la magnitud y dirección de las corrientes de la onda de marea.<br>The historical information compilation of currents, waves, and wind measurements has not been enough to appropriately describe the dynamics of Seno de Reloncaví. However, in spite of the low diversity of studies, the high current magnitudes registered at Chaica, Quillaipe and Paso Nao allow us to infer baroclinic currents strongly modulate the basin dynamics. Furthermore, the wind showed a high seasonal variability, and it is modulated by the coastline, thus being somehow responsible of the surface circulation and waves. In addition, the surface circulation (~ 10 m) is strongly modulated by freshwater input coming from Estuario de Reloncaví. Further, the maximum sea level amplitude was 7.64 m, with 7.46 m as an average, where the major sea level variability is linked to tide. Finally, in order to describe the wave behavior, the results of the empiric method of Massel and the numerical model of Mike 21 are compared. As a result, the wave behavior would be modified by the high spatial and temporal variability of magnitude and direction of the tidal wave

Influencia de la península de Mejillones en la variabilidad oceanográfica anual e interanual frente al norte de Chile

La península de Mejillones (23°S) es un bloque estructural que se proyecta más de 40 km desde la costa en la zona norte de Chile dando forma a las bahías de Mejillones y Moreno abiertas hacia el norte y el sur, respectivamente. La variabilidad oceanográfica de mesoescala asociada a esta península fue analizada utilizando información satelital de temperatura superficial del mar, concentración de clorofila-a, transporte de Ekman y corrientes geostróficas. Mediante el uso de diagrama Hovmöller y Funciones Empíricas Ortogonales estacional e interanual se demuestra el rol que juega la península de Mejillones en la variabilidad de los parámetros oceanográficos en el norte de Chile. El decaimiento latitudinal de la temperatura y clorofila es interrumpido abruptamente por la presencia de la península. La forma y orientación de las bahías de Mejillones y Moreno favorecen la retención de aguas de surgencia y la producción biológica reflejada en altas concentraciones de clorofila observadas, esto ocurre independiente de la temperatura y el transporte predominante en la cabeza y al sur de la península. La península interrumpe y desvía hacia el oeste la trayectoria de la corriente de chorro, la que varía estacionalmente de intensidad y puede alejarse más de 100 km desde la costa. Además, los resultados muestran la existencia de una latitud crítica (~22,8°S) o de transición en la que se produce un cambio marcado en la distribución latitudinal del transporte de Ekman.The Mejillones Peninsula (23°S) is a structural zone extending more than 40 km off the north coast of Chile giving shape to the bays of Mejillones and Moreno which are oriented to the north and south of the peninsula, respectively. The mesoscale oceanographic variability associated with the peninsula was analyzed utilizing satellite information on sea surface temperature, chlorophyll-a concentration, geostrophic currents and Ekman transport. The role of the shape of Mejillones Peninsula in the annual and interannual oceanographic variability of the parameters is revealed by means of Hovmöller diagrams and Empirical Orthogonal Functions. The latitudinal decrease of temperature and chlorophyll is abruptly interrupted by the peninsula. The form and orientation of the Mejillones and Moreno bays favor the retention of upwelled waters and the biological production reflected in the high chlorophyll concentration. This occurs independently of the predominant temperature and Ekman transport in the head and south of the peninsula. The peninsula interrupted and deviates to the west the trajectory of the jet stream, which varies seasonally in intensity and could go more than 100 km from the coast. In addition, the results show the existence of critical latitude (~ 22.8°S) or transition in which there is a marked change in the latitudinal distribution of Ekman transport