Tide model comparison over the Southwestern Atlantic Shelf

Sea surface height (SSH) as measured by satellites has become a powerful tool for oceanographic and climate related studies. Whereas in the open ocean good accuracy has been achieved, more energetic dynamics and a number of calibration problems have limited applications over continental shelves and near the coast. Tidal ranges in the Southwestern Atlantic (SWA) continental shelf are among the highest in the world ocean, reaching up to 12 m at specific locations. This fact highlights the relevance of the accuracy of the tidal correction that must be applied to the satellite data to be useful in the region. In this work, amplitudes and phases of tidal constituents are extracted from five global tide models and three regional models and compared to the corresponding harmonics estimated from coastal tide gauges (TGs) and satellite altimetry data. The Root Sum Square (RSS) of the misfit of the common set of the five tidal constituents solved by the models (M2, N2, S2, K1 and O1) is higher than 18 cm close to the coast for two of the regional models and higher than 24.5 cm for the rest of the models considered. Both values are too high to provide an accurate estimation of geostrophic non-tidal currents from satellite altimetry in the coastal region. On the other hand, the global model with the highest spatial resolution has a RSS lower than 4.5 cm over the continental shelf even when the non-linear M4 overtide is considered. Comparison with in-situ current measurements suggests that this model can be used to de-tide altimetry data to compute large-scale patterns of SSH and associated geostrophic velocities. It is suggested that a local tide model with very high resolution that assimilates in-situ and satellite data should meet the precision needed to estimate geostrophic velocities at a higher resolution both close to the coast and over the Patagonian shelf.Fil: Saraceno, Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmosfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmosfera; ArgentinaFil: D'onofrio, Enrique Eduardo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fiore, Monica Maria Elisa. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Grismeyer, Walter Hugo. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentin

Influencia de la marea astronómica sobre las variaciones del nivel del río Negro en la zona de Carmen de Patagones

El Río Negro, límite natural entre las provincias de Buenos Aires y Río Negro, es uno de los ríos más importantes de la Patagonia que desemboca en el Océano Atlántico. Es navegable desde su desembocadura hasta Carmen de Patagones por embarcaciones de hasta 2,04 m de calado, dificultándose por irregularidades en la profundidad aguas arriba. La onda de marea proveniente del océano Atlántico ingresa al río haciendo que este adopte un régimen semidiumo hasta Carmen de Patagones. El conocimiento de la onda de marea en este tramo del río es de fundamental importancia para la calibración de modelos numéricos, el perfeccionamiento de los sistemas de alerta de inundaciones y la toma de decisiones relacionadas con el manejo costero. En este trabajo se analizan cuatro series de mediciones de marea, dos obtenidas en el hidrómetro de Carmen de Patagones con una duración de 608 y 731 días, una de 77 días proveniente de un mareómetro instalado en el kilómetro 18 del río y una de 79 días obtenida con un sensor de presión fondeado en proximidades de Punta Redonda (desembocadura del Río Negro). Se calculan y comparan los espectros de potencia de las alturas observadas en los tres sitios para detectar los cambios energéticos producidos en la banda de frecuencias correspondientes a la marea astronómica. De su comparación surge que la energía de las componentes semidiumas y diurnas disminuye un 22% y un 45% respectivamente desde la desembocadura del Río Negro hasta Carmen de Patagones. En contraposición se observa un ligero aumento de la energía correspondiente a las frecuencias de las componentes cuarto diurnas. Esto se debe fundamentalmente a procesos no lineales inducidos por aguas someras y a irregularidades en la morfología del fondo del río. Para obtener las amplitudes y épocas de la marea se realizan análisis armónicos por el método de cuadrados mínimos. Las amplitudes de las componentes diurnas en Carmen de Patagones son en promedio un 49% de las obtenidas en Punta Redonda, mientras que para las amplitudes de las componentes semidiumas le corresponde un 42%. Para estudiar las variaciones del nivel medio debidas a los distintos caudales del río y a las ondas de tormenta en Carmen de Patagones, se realiza la convolución de las alturas observadas con filtros pasabajos diseñados a partir de la ventana de Hamming. Para el período considerado se observa una diferencia máxima de 156 cm en los niveles medios y se detecta la presencia de ondas de tormenta. Finalmente para estudiar la influencia de los distintos caudales en la marea astronómica en Carmen de Patagones, se realizan análisis armónicos para diferentes niveles medios. Se encuentra que a una disminución de nivel medio de 156 cm, le corresponde un aumento de 60 cm en la amplitud de la componente M2.The Río Negro, natural limit between Buenos Aires and Río Negro provinces, is one of the most important rivers of the Patagonia that ends in the Atlantic Ocean. It is navigable in the stretch between the mouth and Carmen de Patagones by vessels up to 2.04 m draft, being more difficult upstream because of irregularities in depth. The Atlantic Ocean tidal wave enters into the river producing a semidiurnal regime up to Carmen de Patagones. Knowledge of the tidal wave on this part of the Rio Negro is fundamental to the calibration of numerical models, the improvement of flood warning systems and decision related to coastal management. In this paper four sets of tide measurements are analyzed, two obtained in the Carmen de Patagones hydrometer for a period of 608 and 731 days, other of 77 days coming from a staff installed in the kilometer 18 of the river and the last one of 79 days obtained with a pressure sensor anchored close to Punta Redonda (mouth of the Rio Negro). Power spectrum of observed levels for the three localities are calculated and compared to detect energy changes produced in the frequency band corresponding to the astronomical tide. The comparison shows that the energy of the semidiurnal and diurnal components decreases 22% and 45% respectively from the mouth of the Rio Negro to Carmen de Patagones. In contrast there is a slight increase in energy corresponding to the frequency components of the fourth diurnal. This can be explained by non-linear processes induced by shallow water and irregularities in the morphology of the bottom of the river. To obtain tidal amplitudes and tidal phases, harmonic analyses by the method of least squares are made. Diurnal amplitudes in Carmen de Patagones are in average 49% of those obtained in Punta Redonda, while for the semidiurnal it is a 42%. To study variations in the mean levels due to the different flows of the river and storm waves in Carmen de Patagones, the convolution of observed levels with a low-pass filter designed from the Hamming window is carried out. For the period considered, there is a maximum difference of 156 cm in mean levels and storm waves are detected. Finally, to study the influence of different river’s caudal in the astronomical tide, harmonic analysis are made for different mean levels achieved by the river in Carmen de Patagones. It is found that a decrease in the mean level of 156 cm, has a 60 cm increase in the amplitude of the M2 component.Asociación Argentina de Geofísicos y Geodesta

Tide gauge observations of the Indian ocean tsunami, December 26, 2004, in Buenos Aires coastal waters, Argentina

Sea level oscillations at the Buenos Aires province coastal waters were detected as a response to the magnitude 9.3 earthquake centered off the west coast of northern Sumatra (3.307°N, 95.947°E) on December 26, 2004 at 00:59 UTC. The aim of the present work is to report the first description on sea level oscillations in the Buenos Aires continental shelf generated by oceanic seismic activity. Sea level records gathered at three tide gauge stations located at Santa Teresita (36° 32′S, 56° 40′W), Mar del Plata (38° 05′S, 57° 30′W) and Puerto Belgrano (38° 54′S, 62° 06′W) were filtered and analyzed. The first arrival was measured at Mar del Plata (December 27, 2004, 00:15 UTC). At Santa Teresita and Puerto Belgrano, the tsunami reached the coast 33 min and 4.5 h later than at Mar del Plata, respectively. Maximum wave heights observed were 0.27, 0.15 and 0.20 m at Santa Teresita, Mar del Plata and Puerto Belgrano stations, respectively, and wave periods were detected in the range from 20 to 120 min. Wave amplitudes presented a remarkable temporal variability in the period immediately following tsunami wave arrival. After the first arrivals, waves lasted during the first 40 and 54 h at Mar del Plata and Santa Teresita, respectively. Even though, atmospherically forced sea level oscillations (in the tsunami frequency band) are frequently observed at different tide stations at locations on the Buenos Aires province coast, the weather patterns between December 24 and 27, 2004 showed no evidences of either frontal passages or atmospheric gravity waves. Thus sea level perturbations recorded at Santa Teresita, Mar del Plata and Puerto Belgrano stations can certainly be linked to the Indian Ocean tsunami.Fil: Dragani, Walter Cesar. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: D'onofrio, Enrique Eduardo. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Grismeyer, Walter Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; ArgentinaFil: Fiore, Monica Maria Elisa. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentin

Simultaneous meteorological tsunamis and storm surges at Buenos Aires Coast, Southeastern South America

Meteorological tsunamis are frequently observed in different tide stations at the southeastern coast of South America. They are associated with the occurrence of atmospheric gravity waves during the passages of cold fronts over the Buenos Aires Province continental shelf. On the other hand, storm surges are also frequent in the region, and they are associated with strong and persistent southerlies, which are also frequent during cold front passages. The impact of meteorological tsunamis in coastal erosion and in the statistics of storm surge trends is discussed in this paper. For this study, fifteen meteorological tsunamis (with maximum wave heights higher than 0.20 m), seven of them simultaneous to the occurrence of storm surge events (with extreme levels higher than |±0.60 m|), are selected from April 2010 to January 2013. The impact of meteorological tsunamis in the storm erosion potential index (SEPI) is evaluated. Not significant differences are obtained between SEPI calculated with and without filtering the meteorological tsunami signal from the storm surge data series. Moreover, several experiments are carried out computing SEPI from synthetic sea level data series, but very low changes (lower than 4 %) are also obtained. It is concluded that the presence of moderate meteorological tsunamis on sea level records would not enhance this index at the Buenos Aires Province coast. On the other hand, taking into account that meteorological tsunamis can reach up the 20–30 % of the storm surge height, it was concluded that the statistics of storm surge trends (and their uncertainties) should be revised for Mar del Plata data series.Fil: Dragani, Walter Cesar. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: D'onofrio, Enrique Eduardo. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería; ArgentinaFil: Oreiro, Fernando Ariel. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alonso, Guadalupe. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fiore, Monica Maria Elisa. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Grismeyer, Walter Hugo. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería; Argentin

Comparison of tide model outputs for the northern region of the Antarctic Peninsula using satellite altimeters and tide gauge data

This study compares the common harmonic constants of the O1, K1, P1, Q1, M2, S2, N2, and K2 tidal constituents from eight global and four regional tide models with harmonic constants from satellite altimeter and tide gauge data for the northern region of the Antarctic Peninsula (58Se66S, 53We66W). To obtain a more representative comparison, the study area was divided into three zones with different physical characteristics but similar maximum tidal amplitude variations: Zone I (north of 62S), Zone II (south of 62S and west of the Antarctic Peninsula), and Zone III (between 62S and 64.3S, and east of 58.5W). Root sum square (RSS) values are less than or equal to 3.0, 4.2, and 8.4 cm for zones I, II, and III, respectively. No single model shows superior performance in all zones. Because there are insufficient satellite altimetry observations in the vicinity of Matienzo Base (64.9761S, 60.0683W), this station was analyzed separately and presents the greatest values of both root mean square misfit and RSS. The maximum, minimum, and average amplitude values of the constituents that follow in importance after the eight common tidal constituents, and which have amplitudes greater than 1 cm, are also analyzed.Fil: Oreiro, Fernando Ariel. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografia Naval; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería; ArgentinaFil: D'onofrio, Enrique Eduardo. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografia Naval; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería; ArgentinaFil: Grismeyer, Walter Hugo. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografia Naval; ArgentinaFil: Fiore, Monica Maria Elisa. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografia Naval; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería; ArgentinaFil: Saraceno, Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Instituto Franco-Argentino de Estudios sobre el Clima y sus Impactos; Argentin