http://sedici.unlp.edu.ar:80/handle/10915/86762 2026-07-20T04:45:20Z 2026-07-20T04:45:20Z Suad Corbetta, Federico Richter, Andreas Jorg Marderwald, Eric Rodolfo Mendoza, Luciano Pedro Oscar http://sedici.unlp.edu.ar:80/handle/10915/191192 2026-02-28T04:20:33Z 2023-01-01T00:00:00Z

Objeto de conferencia IV Jornadas de Geociencias para la Ingenieria (Buenos Aires, 1º y 2 de noviembre de 2023) El trabajo presenta el procesamiento de datos de altimetría láser, particularmente los obtenidos por el satélite ICESat-2, y su implementación para el estudio hidrodinámico de la Bahía San Julián. Las observaciones de altimetría permiten estimar la precisión de los modelos de mareas globales en la zona de estudio, al comparar las alturas predichas por los mismos con las observadas. En última instancia, se logra determinar el modelo que mejor se ajusta a los niveles de agua observados por ICESat-2. Los resultados obtenidos prueban la utilidad de la altimetría láser para el estudio de regiones costeras, incentivando nuevas y diversas aplicaciones en casos de difícil monitoreo del nivel de agua. Las recomendaciones expuestas y las dificultades encontradas en el procesamiento de los datos permiten una introducción guiada al método.

2023-01-01T00:00:00Z El trabajo presenta el procesamiento de datos de altimetría láser, particularmente los obtenidos por el satélite ICESat-2, y su implementación para el estudio hidrodinámico de la Bahía San Julián. Las observaciones de altimetría permiten estimar la precisión de los modelos de mareas globales en la zona de estudio, al comparar las alturas predichas por los mismos con las observadas. En última instancia, se logra determinar el modelo que mejor se ajusta a los niveles de agua observados por ICESat-2. Los resultados obtenidos prueban la utilidad de la altimetría láser para el estudio de regiones costeras, incentivando nuevas y diversas aplicaciones en casos de difícil monitoreo del nivel de agua. Las recomendaciones expuestas y las dificultades encontradas en el procesamiento de los datos permiten una introducción guiada al método. Suad Corbetta, Federico Richter, Andreas Jorg Marderwald, Eric Rodolfo Mendoza, Luciano Pedro Oscar http://sedici.unlp.edu.ar:80/handle/10915/184551 2025-09-17T20:13:50Z 2023-01-01T00:00:00Z

Objeto de conferencia 4tas Jornadas de Geociencias para la Ingeniería (Buenos Aires, 1 y 2 de noviembre de 2023) El trabajo presenta el procesamiento de datos de altimetría láser, particularmente los obtenidos por el satélite ICESat-2, y su implementación para el estudio hidrodinámico de la Bahía San Julián. Las observaciones de altimetría permiten estimar la precisión de los modelos de mareas globales en la zona de estudio, al comparar las alturas predichas por los mismos con las observadas. En última instancia, se logra determinar el modelo que mejor se ajusta a los niveles de agua observados por ICESat-2. Los resultados obtenidos prueban la utilidad de la altimetría láser para el estudio de regiones costeras, incentivando nuevas y diversas aplicaciones en casos de difícil monitoreo del nivel de agua. Las recomendaciones expuestas y las dificultades encontradas en el procesamiento de los datos permiten una introducción guiada al método.

2023-01-01T00:00:00Z El trabajo presenta el procesamiento de datos de altimetría láser, particularmente los obtenidos por el satélite ICESat-2, y su implementación para el estudio hidrodinámico de la Bahía San Julián. Las observaciones de altimetría permiten estimar la precisión de los modelos de mareas globales en la zona de estudio, al comparar las alturas predichas por los mismos con las observadas. En última instancia, se logra determinar el modelo que mejor se ajusta a los niveles de agua observados por ICESat-2. Los resultados obtenidos prueban la utilidad de la altimetría láser para el estudio de regiones costeras, incentivando nuevas y diversas aplicaciones en casos de difícil monitoreo del nivel de agua. Las recomendaciones expuestas y las dificultades encontradas en el procesamiento de los datos permiten una introducción guiada al método. Romero, Abelardo Duca, L. Rosa, María Laura Richter, Andreas Jorg Mendoza, Luciano Pedro Oscar Connon, G. C. Juarez, A. Marderwald, Eric Rodolfo http://sedici.unlp.edu.ar:80/handle/10915/184550 2025-09-17T20:13:50Z 2023-01-01T00:00:00Z

Objeto de conferencia 4tas Jornadas de Geociencias para la Ingeniería (Buenos Aires, 1 y 2 de noviembre de 2023) Mediante la determinación de velocidades de propagación de ondas sísmicas superficiales y su análisis de dispersión se pueden estimar espesores corticales y litosféricos representativos para la zona atravesada por la trayectoria de estas ondas. El reciente desarrollo de la sismología GNSS busca utilizar la infraestructura existente de estaciones GNSS para la observación de la propagación de ondas sísmicas, convirtiéndolas en sensores sismológicos. El trabajo aquí presentado muestra los avances de un método de procesamiento y análisis GNSS con el objetivo principal de aportar información observacional al estudio de la propagación de ondas superficiales de sismos fuertes. En él, se consideran estaciones con alta frecuencia de muestreo (1 Hz) pertenecientes a las redes RAMSAC del IGN y la red global del IGS, ambas con libre acceso a los datos. En el procesamiento se aplica la estrategia del Posicionamiento Puntual Preciso (PPP) para el cual se utilizó el software PRIDE PPP-AR, libre y de código abierto. Como resultado del método se obtienen series temporales del movimiento de las estaciones durante el pasaje de las ondas superficiales generadas por los sismos. Para validar las mismas, se comparan con otras técnicas GNSS y datos sismológicos, confirmando la consistencia de los movimientos detectados. También se realizan experimentos con herramientas idénticas a las aplicadas a registros sismológicos, para determinar velocidades de grupo y fase mediante el análisis de su dispersión. Se observa que la infraestructura GNSS no es capaz de reemplazar a las redes sismológicas operativas, no obstante, tiene un enorme potencial para complementar las redes sismológicas y aportar a la validación o mejora regional de modelos de Tierra reológicos.

2023-01-01T00:00:00Z Mediante la determinación de velocidades de propagación de ondas sísmicas superficiales y su análisis de dispersión se pueden estimar espesores corticales y litosféricos representativos para la zona atravesada por la trayectoria de estas ondas. El reciente desarrollo de la sismología GNSS busca utilizar la infraestructura existente de estaciones GNSS para la observación de la propagación de ondas sísmicas, convirtiéndolas en sensores sismológicos. El trabajo aquí presentado muestra los avances de un método de procesamiento y análisis GNSS con el objetivo principal de aportar información observacional al estudio de la propagación de ondas superficiales de sismos fuertes. En él, se consideran estaciones con alta frecuencia de muestreo (1 Hz) pertenecientes a las redes RAMSAC del IGN y la red global del IGS, ambas con libre acceso a los datos. En el procesamiento se aplica la estrategia del Posicionamiento Puntual Preciso (PPP) para el cual se utilizó el software PRIDE PPP-AR, libre y de código abierto. Como resultado del método se obtienen series temporales del movimiento de las estaciones durante el pasaje de las ondas superficiales generadas por los sismos. Para validar las mismas, se comparan con otras técnicas GNSS y datos sismológicos, confirmando la consistencia de los movimientos detectados. También se realizan experimentos con herramientas idénticas a las aplicadas a registros sismológicos, para determinar velocidades de grupo y fase mediante el análisis de su dispersión. Se observa que la infraestructura GNSS no es capaz de reemplazar a las redes sismológicas operativas, no obstante, tiene un enorme potencial para complementar las redes sismológicas y aportar a la validación o mejora regional de modelos de Tierra reológicos. Juárez, Amílcar Richter, Andreas Jorg Romero, Abelardo Marderwald, Eric Rodolfo Mendoza, Luciano Pedro Oscar http://sedici.unlp.edu.ar:80/handle/10915/184464 2025-09-17T04:12:38Z 2003-01-01T00:00:00Z

Objeto de conferencia 4tas Jornadas de Geociencias para la Ingeniería (Buenos Aires, 1 y 2 de noviembre de 2023) El efecto debido a la atracción gravitatoria de la Luna y el Sol y la redistribución de masa por las mareas oceánicas, producto también de estas fuerzas gravitatorias, provocan una deformación de la tierra sólida con períodos semidiurnos y diurnos. Estos fenómenos se denominan marea terrestre y carga oceánica, respectivamente, y sus efectos pueden ser observados mediante el uso de técnicas geodésicas de precisión como sistemas globales de navegación por satélite (Global Navigation Satellite Systems, GNSS). El modelado de efectos de carga oceánica aplica ampliamente el formalismo desarrollado para una respuesta puramente elástica de la tierra sólida a cargas superficiales y utiliza modelos de tierra elásticos procedentes de observaciones sismológicas. En Europa occidental, se detectó una respuesta a la carga oceánica semidiurna ligeramente diferente al modelo puramente elástico debido a efectos de disipación, principalmente en la astenosfera. Resultados previos, que muestran discrepancias entre efectos de carga oceánica observados y modelos de respuesta elástica, motivan la hipótesis que la Patagonia austral (Tierra del Fuego, Santa Cruz y sur de Chubut) comprenda una de las regiones donde la contribución anelástica a los efectos de carga oceánica sea significativa. La región bajo estudio se destaca por una extraordinaria intensidad de las mareas oceánicas y, por consiguiente, de efectos de carga oceánica. En esta región el IGN opera estaciones GNSS permanentes de la red RAMSAC, proveyendo datos de alta calidad y de libre acceso. Los registros de estas estaciones, complementadas por estaciones de las redes IGS (Servicio Internacional GNSS) y CSN (Centro Sismológico Nacional), ofrecen la posibilidad de determinar la señal de deformación debida a la carga oceánica. La comparación de esta señal observada con el modelo elástico permitirá confirmar o descartar nuestra hipótesis. Se presentarán resultados preliminares de un procesamiento GNSS especializado con el fin de extraer parámetros de carga oceánica. Este procesamiento aplica la estratégia del Posicionamiento Puntual Preciso (PPP) en modo cinemático, utilizando el paquete de software PRIDE PPP-AR. Luego de una evaluación automatizada de la calidad y un filtrado de las series temporales de alta resolución de las coordenadas tridimensionales, se determinan parámetros para las principales componentes de mareas mediante el paquete TASK-2000. Se resumirán las primeras experiencias con respecto a las exigencias a los datos GNSS para una determinación exacta del efecto de la carga oceánica y la aptitud de los datos de RAMSAC para este fin.

2003-01-01T00:00:00Z El efecto debido a la atracción gravitatoria de la Luna y el Sol y la redistribución de masa por las mareas oceánicas, producto también de estas fuerzas gravitatorias, provocan una deformación de la tierra sólida con períodos semidiurnos y diurnos. Estos fenómenos se denominan marea terrestre y carga oceánica, respectivamente, y sus efectos pueden ser observados mediante el uso de técnicas geodésicas de precisión como sistemas globales de navegación por satélite (Global Navigation Satellite Systems, GNSS). El modelado de efectos de carga oceánica aplica ampliamente el formalismo desarrollado para una respuesta puramente elástica de la tierra sólida a cargas superficiales y utiliza modelos de tierra elásticos procedentes de observaciones sismológicas. En Europa occidental, se detectó una respuesta a la carga oceánica semidiurna ligeramente diferente al modelo puramente elástico debido a efectos de disipación, principalmente en la astenosfera. Resultados previos, que muestran discrepancias entre efectos de carga oceánica observados y modelos de respuesta elástica, motivan la hipótesis que la Patagonia austral (Tierra del Fuego, Santa Cruz y sur de Chubut) comprenda una de las regiones donde la contribución anelástica a los efectos de carga oceánica sea significativa. La región bajo estudio se destaca por una extraordinaria intensidad de las mareas oceánicas y, por consiguiente, de efectos de carga oceánica. En esta región el IGN opera estaciones GNSS permanentes de la red RAMSAC, proveyendo datos de alta calidad y de libre acceso. Los registros de estas estaciones, complementadas por estaciones de las redes IGS (Servicio Internacional GNSS) y CSN (Centro Sismológico Nacional), ofrecen la posibilidad de determinar la señal de deformación debida a la carga oceánica. La comparación de esta señal observada con el modelo elástico permitirá confirmar o descartar nuestra hipótesis. Se presentarán resultados preliminares de un procesamiento GNSS especializado con el fin de extraer parámetros de carga oceánica. Este procesamiento aplica la estratégia del Posicionamiento Puntual Preciso (PPP) en modo cinemático, utilizando el paquete de software PRIDE PPP-AR. Luego de una evaluación automatizada de la calidad y un filtrado de las series temporales de alta resolución de las coordenadas tridimensionales, se determinan parámetros para las principales componentes de mareas mediante el paquete TASK-2000. Se resumirán las primeras experiencias con respecto a las exigencias a los datos GNSS para una determinación exacta del efecto de la carga oceánica y la aptitud de los datos de RAMSAC para este fin. Pérez Bello, Dinibel Natali, María Paula Meza, Amalia Margarita http://sedici.unlp.edu.ar:80/handle/10915/142868 2022-09-29T04:04:29Z 2019-12-01T00:00:00Z

Articulo Neural Computing and Applications; vol. 31, no. 12 Accurate prediction of total electron content (TEC) is important for monitoring the behavior of the ionosphere and indeed a magnitude of interest to understand the properties and behavior of the Sun–Earth System. The conditions of this medium have a direct impact on a growing variety of critical technological infrastructure. This work presents a comparison between two different artificial neural networks (ANNs): an adaptive neuro-fuzzy inference system and nonlinear autoregressive neural network (NAR-NN) applied to TEC. Both ANNs where tested on four different geomagnetic locations on 4 1-week periods having a variety of geomagnetic disturbance levels. The effect of using different training period lengths and the system response for 60 and 30 min sampling rate TEC time series was investigated. NAR-NN shows a slightly better performance, being the higher difference during the greater perturbations. There is also a better response when sampling rates of 30 min are used.

2019-12-01T00:00:00Z Accurate prediction of total electron content (TEC) is important for monitoring the behavior of the ionosphere and indeed a magnitude of interest to understand the properties and behavior of the Sun–Earth System. The conditions of this medium have a direct impact on a growing variety of critical technological infrastructure. This work presents a comparison between two different artificial neural networks (ANNs): an adaptive neuro-fuzzy inference system and nonlinear autoregressive neural network (NAR-NN) applied to TEC. Both ANNs where tested on four different geomagnetic locations on 4 1-week periods having a variety of geomagnetic disturbance levels. The effect of using different training period lengths and the system response for 60 and 30 min sampling rate TEC time series was investigated. NAR-NN shows a slightly better performance, being the higher difference during the greater perturbations. There is also a better response when sampling rates of 30 min are used. Meza, Amalia Margarita Eylenstein, Bernardo Natali, María Paula Bosch, Guillermo Luis Moirano, Juan Francisco Chalar, Elfriede http://sedici.unlp.edu.ar:80/handle/10915/130018 2021-12-27T20:04:36Z 2021-01-01T00:00:00Z

Articulo Frontiers in Astronomy and Space Sciences; vol. 8 Total solar eclipses are unique opportunities to study how the ionospheric and external geomagnetic field responds to fast changes in the ionizing flux as the moon’s shadow travels through its path over the ionosphere at an average speed of 3,000 km/h. In this contribution, we describe our observing campaign in which we set up GNSS and geomagnetic stations at the city of Valcheta, Río Negro, Argentina (which was located right under the path of totality). We also describe the results obtained from the analysis of the combination of on-site data together with publicly available observations from geodetic and geomagnetic observatories. The large span in latitude of our data allowed us to analyze the different magnitudes of the drop in vertical total electron content (ΔVTEC) with varying occultation percentages. We found an expected reduction in this drop as we move away from totality path but we also detected a new increment in ΔVTEC as we got closer to Earth’s Magnetic Equator. We also compared our observations of the geomagnetic field variations with predictions that were based on the Ashour-Chapman model and we find an overall good agreement, although a ≈20 min delay with the eclipse maximum is evident beyond observing uncertainties. This suggests the presence of processes that delay the response of the lower ionosphere to the loss of the photoionization flux.

2021-01-01T00:00:00Z Total solar eclipses are unique opportunities to study how the ionospheric and external geomagnetic field responds to fast changes in the ionizing flux as the moon’s shadow travels through its path over the ionosphere at an average speed of 3,000 km/h. In this contribution, we describe our observing campaign in which we set up GNSS and geomagnetic stations at the city of Valcheta, Río Negro, Argentina (which was located right under the path of totality). We also describe the results obtained from the analysis of the combination of on-site data together with publicly available observations from geodetic and geomagnetic observatories. The large span in latitude of our data allowed us to analyze the different magnitudes of the drop in vertical total electron content (ΔVTEC) with varying occultation percentages. We found an expected reduction in this drop as we move away from totality path but we also detected a new increment in ΔVTEC as we got closer to Earth’s Magnetic Equator. We also compared our observations of the geomagnetic field variations with predictions that were based on the Ashour-Chapman model and we find an overall good agreement, although a ≈20 min delay with the eclipse maximum is evident beyond observing uncertainties. This suggests the presence of processes that delay the response of the lower ionosphere to the loss of the photoionization flux. Richter, Andreas Groh, Andreas Horwath, Martin Ivins, Erik Marderwald, Eric Rodolfo Hormaechea, José Luis Perdomo, Raúl Aníbal Dietrich, Reinhard http://sedici.unlp.edu.ar:80/handle/10915/125385 2021-09-22T20:07:26Z 2019-01-01T00:00:00Z

Articulo Remote Sensing; vol. 11, no. 8 We use the complete gravity recovery and climate experiment (GRACE) Level-2 monthly time series to derive the ice mass changes of the Patagonian Icefields (Southern Andes). The glacial isostatic adjustment is accounted for by a regional model that is constrained by global navigation satellite systems (GNSS) uplift observations. Further corrections are applied concerning the effect of mass variations in the ocean, in the continental water storage, and of the Antarctic ice sheet. The 161 monthly GRACE gravity field solutions are inverted in the spatial domain through the adjustment of scaling factors applied to a-priori ice mass change patterns based on published remote sensing results for the Southern and Northern Patagonian Icefields, respectively. We infer an ice mass change rate of −24.4 ± 4.7 Gt/a for the Patagonian Icefields between April 2002 and June 2017, which corresponds to a contribution to the eustatic sea level rise of 0.067 ± 0.013 mm/a. Our time series of monthly ice mass changes reveals no indication for an acceleration in ice mass loss. We find indications that the Northern Patagonian Icefield contributes more to the integral ice loss than previously assumed.

2019-01-01T00:00:00Z We use the complete gravity recovery and climate experiment (GRACE) Level-2 monthly time series to derive the ice mass changes of the Patagonian Icefields (Southern Andes). The glacial isostatic adjustment is accounted for by a regional model that is constrained by global navigation satellite systems (GNSS) uplift observations. Further corrections are applied concerning the effect of mass variations in the ocean, in the continental water storage, and of the Antarctic ice sheet. The 161 monthly GRACE gravity field solutions are inverted in the spatial domain through the adjustment of scaling factors applied to a-priori ice mass change patterns based on published remote sensing results for the Southern and Northern Patagonian Icefields, respectively. We infer an ice mass change rate of −24.4 ± 4.7 Gt/a for the Patagonian Icefields between April 2002 and June 2017, which corresponds to a contribution to the eustatic sea level rise of 0.067 ± 0.013 mm/a. Our time series of monthly ice mass changes reveals no indication for an acceleration in ice mass loss. We find indications that the Northern Patagonian Icefield contributes more to the integral ice loss than previously assumed. Natali, María Paula Castaño, Juan Manuel Meza, Amalia Margarita http://sedici.unlp.edu.ar:80/handle/10915/125042 2021-09-17T20:06:56Z 2020-01-01T00:00:00Z

Preprint Advances in Space Research; vol. 65, no. 9 The aim of this work is the analysis of the mid-latitude ionospheric trough (MIT) using the Global Ionospheric Maps from IGS (GIMs) during the solar minimum, year 2008. This study was performed for different local times, 22, 00, 02 and 04 LT on the Northern and Southern hemisphere simultaneously. In the two hemispheres the MIT show asymmetric pattern. The high-latitude troughs are clearly distinguished in autumn and winter. Another feature is the longitudinal development towards the west of the geomagnetic pole covering a wider area in the Northern Hemisphere. Five empirical reference models were tested and compared with the MIT minimum position obtained from GIMs at different local times for both hemisphere. The results show a better agreement with the observations for the Northern Hemisphere specially with the Köehnlein & Raitt model. Fluctuations of 9 days and 27 days of the MIT minimum position are found, which could be related with the solar wind oscillations, especially for 00 and 02 LT in both hemisphere, suggesting a link between them.

2020-01-01T00:00:00Z The aim of this work is the analysis of the mid-latitude ionospheric trough (MIT) using the Global Ionospheric Maps from IGS (GIMs) during the solar minimum, year 2008. This study was performed for different local times, 22, 00, 02 and 04 LT on the Northern and Southern hemisphere simultaneously. In the two hemispheres the MIT show asymmetric pattern. The high-latitude troughs are clearly distinguished in autumn and winter. Another feature is the longitudinal development towards the west of the geomagnetic pole covering a wider area in the Northern Hemisphere. Five empirical reference models were tested and compared with the MIT minimum position obtained from GIMs at different local times for both hemisphere. The results show a better agreement with the observations for the Northern Hemisphere specially with the Köehnlein & Raitt model. Fluctuations of 9 days and 27 days of the MIT minimum position are found, which could be related with the solar wind oscillations, especially for 00 and 02 LT in both hemisphere, suggesting a link between them. Fernández, Laura Isabel Aragón Paz, Juan Manuel Meza, Amalia Margarita Mendoza, Luciano Pedro Oscar http://sedici.unlp.edu.ar:80/handle/10915/124065 2021-09-02T20:06:08Z 2019-01-01T00:00:00Z

Articulo Fire Ecology; vol. 15, no. 1 Background: The objective of this study was to look for a replacement to the radiosonde measurements that are necessary for the construction of an index of potential wildfire severity (i.e., Haines Index, HI) in areas of South America that have had few to no radiosonde launches. To this end, we tested the application of GPT2w, an empirical model originally developed for Global Navigation Satellite System (GNSS) meteorology. By using the GPT2w model, and starting from measured surface meteorological data (air pressure, temperature, and relative humidity), estimators of air temperature and dew-point air temperature at different pressure levels were generated. The selected testing area was a region of South America that included most of the Río de la Plata drainage basin, along with two hazardous areas: Sierras de Córdoba in Argentina and Serra da Canastra in Brazil. This region was chosen due to the availability of the radiosonde launches required for comparison during 2016. Results: To characterize the regional performance of HI, we used data from the European Centre for Medium-Range Weather Forecast’s (ECMWF) reanalysis model (ERA Interim; Dee et al., Quarterly Journal of the Royal Meteorological Society 137: 553–597, 2011) for the period 2000 to 2016. A statistical analysis of the differences between the simulated HI from GPT2w (HI_GPT2w) and the HI values derived from radiosonde measurements (HI_R) was performed. The results showed that HI_GPT2w reproduced HI_R values about 50% of the time, most accurately for lowseverity HI values (2 to 3, on a scale of 2 to 6). In general, HI_GPT2w exhibited an underestimation of HI that increased as the index value increased. We analyzed how this underestimation affected the different HI variants calculated. To this end, we recall that each HI variant results from the sum of the stability and moisture terms. The stability term resulted from the temperature difference at different pressure levels while the moisture term is represented by the dew-point depression. Thus, the pressure level limits in the stability term define the HI variant. In this study, we used the Low-variant HI (950 and 850 hPa) and the Mid-variant HI (850 and 700 hPa). If we analyze this underestimation according to the HI variants, the moisture term is responsible for the Low variant underestimation and the stability term is responsible for the Mid variant. Conclusion: The simple application of GPT2w to extrapolate the vertical values of temperature and its dew-point depression is not enough to reproduce the Haines Index as it was measured from radiosonde measurements. Nevertheless, an improved application of GPT2w and the extrapolated saturation water vapor pressure by using the Integrated Water Vapor from Global Navigation Satellite System (GNSS-IWV) values could improve the results

2019-01-01T00:00:00Z Background: The objective of this study was to look for a replacement to the radiosonde measurements that are necessary for the construction of an index of potential wildfire severity (i.e., Haines Index, HI) in areas of South America that have had few to no radiosonde launches. To this end, we tested the application of GPT2w, an empirical model originally developed for Global Navigation Satellite System (GNSS) meteorology. By using the GPT2w model, and starting from measured surface meteorological data (air pressure, temperature, and relative humidity), estimators of air temperature and dew-point air temperature at different pressure levels were generated. The selected testing area was a region of South America that included most of the Río de la Plata drainage basin, along with two hazardous areas: Sierras de Córdoba in Argentina and Serra da Canastra in Brazil. This region was chosen due to the availability of the radiosonde launches required for comparison during 2016. Results: To characterize the regional performance of HI, we used data from the European Centre for Medium-Range Weather Forecast’s (ECMWF) reanalysis model (ERA Interim; Dee et al., Quarterly Journal of the Royal Meteorological Society 137: 553–597, 2011) for the period 2000 to 2016. A statistical analysis of the differences between the simulated HI from GPT2w (HI_GPT2w) and the HI values derived from radiosonde measurements (HI_R) was performed. The results showed that HI_GPT2w reproduced HI_R values about 50% of the time, most accurately for lowseverity HI values (2 to 3, on a scale of 2 to 6). In general, HI_GPT2w exhibited an underestimation of HI that increased as the index value increased. We analyzed how this underestimation affected the different HI variants calculated. To this end, we recall that each HI variant results from the sum of the stability and moisture terms. The stability term resulted from the temperature difference at different pressure levels while the moisture term is represented by the dew-point depression. Thus, the pressure level limits in the stability term define the HI variant. In this study, we used the Low-variant HI (950 and 850 hPa) and the Mid-variant HI (850 and 700 hPa). If we analyze this underestimation according to the HI variants, the moisture term is responsible for the Low variant underestimation and the stability term is responsible for the Mid variant. Conclusion: The simple application of GPT2w to extrapolate the vertical values of temperature and its dew-point depression is not enough to reproduce the Haines Index as it was measured from radiosonde measurements. Nevertheless, an improved application of GPT2w and the extrapolated saturation water vapor pressure by using the Integrated Water Vapor from Global Navigation Satellite System (GNSS-IWV) values could improve the results Meza, Amalia Margarita Mendoza, Luciano Pedro Oscar Natali, María Paula Bianchi, Clara Eugenia Fernández, Laura Isabel http://sedici.unlp.edu.ar:80/handle/10915/119499 2021-05-31T20:05:33Z 2020-11-01T00:00:00Z

Articulo Geodesy and Geodynamics; vol. 11, no. 6 Annual and seasonal diurnal precipitable water vapor (PWV) variations over Central and South America are analyzed for the period 2007e2013. PWV values were obtained from Global Navigation Satellite Systems (GNSS) observations of sixty-nine GNSS tracking stations. Histograms by climate categories show that PWV values for temperate, polar and cold dry climate have a positive skewed distribution and for tropical climates (except for monsoon subtype) show a negative skewed distribution. The diurnal PWV and surface temperatures (T) anomaly datasets are analyzed by using principal components analysis (PCA). The first two modes represent more than 90% of the PWV variability. The first PCA mode of PWV variability shows a maximum amplitude value in the late afternoon few hours later than the respective values for surface temperature (T), therefore the temperature and the surface conditions (to yield evaporation) could be the main agents producing this variability; PWV variability in inland stations are mainly represented by this mode. The second mode of PWV variability shows a maximum amplitude at midnight, a possible explanation of this behavior is the effect of the sea/valley breeze. The coastal and valley stations are affected by this mode in most cases. Finally, the “undefined” stations, surrounded by several water bodies, are mainly affected by the second mode with negative eigenvectors. In the seasonal analysis, both the undefined and valley stations constitute the main cases that show a sea or valley breeze only during some seasons, while the rest of the year they present a behavior according to their temperature and the surface conditions. As a result, the PCA proves to be a useful numerical tool to represent the main sub-daily PWV variabilities.

2020-11-01T00:00:00Z Annual and seasonal diurnal precipitable water vapor (PWV) variations over Central and South America are analyzed for the period 2007e2013. PWV values were obtained from Global Navigation Satellite Systems (GNSS) observations of sixty-nine GNSS tracking stations. Histograms by climate categories show that PWV values for temperate, polar and cold dry climate have a positive skewed distribution and for tropical climates (except for monsoon subtype) show a negative skewed distribution. The diurnal PWV and surface temperatures (T) anomaly datasets are analyzed by using principal components analysis (PCA). The first two modes represent more than 90% of the PWV variability. The first PCA mode of PWV variability shows a maximum amplitude value in the late afternoon few hours later than the respective values for surface temperature (T), therefore the temperature and the surface conditions (to yield evaporation) could be the main agents producing this variability; PWV variability in inland stations are mainly represented by this mode. The second mode of PWV variability shows a maximum amplitude at midnight, a possible explanation of this behavior is the effect of the sea/valley breeze. The coastal and valley stations are affected by this mode in most cases. Finally, the “undefined” stations, surrounded by several water bodies, are mainly affected by the second mode with negative eigenvectors. In the seasonal analysis, both the undefined and valley stations constitute the main cases that show a sea or valley breeze only during some seasons, while the rest of the year they present a behavior according to their temperature and the surface conditions. As a result, the PCA proves to be a useful numerical tool to represent the main sub-daily PWV variabilities. Mendoza, Luciano Pedro Oscar Meza, Amalia Margarita Aragón Paz, Juan Manuel http://sedici.unlp.edu.ar:80/handle/10915/105123 2020-09-22T20:05:23Z 2020-01-01T00:00:00Z

Preprint Advances in Space Research; vol. 65, no. 9 The development of regional services able to provide ionospheric vertical total electron content (VTEC) maps and ionospheric indexes with a high spatial resolution, and in near-real-time, are of great importance for both civilian applications and the research community. We provide here the methodologies, and an assessment, of such a system. It relies on the public Global Navigational Satellite Systems (GNSS) infrastructure in South America, incorporates data from multiple constellations (currently GPS, GLONASS, Galileo and BeiDou), employs multiple frequencies, and produces continental wide VTEC maps with a latency of just a few minutes. To assess the ability of our system to model the ionospheric behavior we performed a yearround intercomparison between our near-real-time regional VTEC maps, and VTEC maps of veri ed quality produced by several referent analysis centers, resulting in mean biases lower than 1 TEC units (TECU). Also, the evaluation of our products against direct and independent GNSS-based slant TEC measurements shows RMS values better than 1 TECU. In turn, ionospheric weather W-index maps were generated, for calm and disturbed geomagnetic scenarios, solely employing our quality veri ed VTEC maps. The spatial representation of these W-index maps re ects the state of the ionosphere, with a resolution of 0:5 0:5 degrees. Finally, we conclude that our products, computed every 15 minutes, do provide an excellent spatial representation of the regional TEC, and are able to provide the bases for the possible computation of ionospheric W-index maps, also in near-real-time.

2020-01-01T00:00:00Z The development of regional services able to provide ionospheric vertical total electron content (VTEC) maps and ionospheric indexes with a high spatial resolution, and in near-real-time, are of great importance for both civilian applications and the research community. We provide here the methodologies, and an assessment, of such a system. It relies on the public Global Navigational Satellite Systems (GNSS) infrastructure in South America, incorporates data from multiple constellations (currently GPS, GLONASS, Galileo and BeiDou), employs multiple frequencies, and produces continental wide VTEC maps with a latency of just a few minutes. To assess the ability of our system to model the ionospheric behavior we performed a yearround intercomparison between our near-real-time regional VTEC maps, and VTEC maps of veri ed quality produced by several referent analysis centers, resulting in mean biases lower than 1 TEC units (TECU). Also, the evaluation of our products against direct and independent GNSS-based slant TEC measurements shows RMS values better than 1 TECU. In turn, ionospheric weather W-index maps were generated, for calm and disturbed geomagnetic scenarios, solely employing our quality veri ed VTEC maps. The spatial representation of these W-index maps re ects the state of the ionosphere, with a resolution of 0:5 0:5 degrees. Finally, we conclude that our products, computed every 15 minutes, do provide an excellent spatial representation of the regional TEC, and are able to provide the bases for the possible computation of ionospheric W-index maps, also in near-real-time. Bianchi, Clara Eugenia Mendoza, Luciano Pedro Oscar Fernández, Laura Isabel Natali, María Paula Meza, Amalia Margarita Moirano, Juan Francisco http://sedici.unlp.edu.ar:80/handle/10915/86765 2020-02-18T04:04:50Z 2016-01-01T00:00:00Z

Articulo Annales Geophysicae; vol. 34, no. 7 Atmospheric water vapour has been acknowledged as an essential climate variable. Weather prediction and hazard assessment systems benefit from real-time observations, whereas long-term records contribute to climate studies. Nowadays, ground-based global navigation satellite system (GNSS) products have become widely employed, complementing satellite observations over the oceans. Although the past decade has seen a significant development of the GNSS infrastructure in Central and South America, its potential for atmospheric water vapour monitoring has not been fully exploited. With this in mind, we have performed a regional, 7-year-long and homogeneous analysis, comprising 136 GNSS tracking stations, obtaining high-rate and continuous observations of column-integrated water vapour and troposphere zenith total delay. As a preliminary application for this data set, we have estimated local water vapour trends, their significance, and their relation with specific climate regimes. We have found evidence of drying at temperate regions in South America, at a rate of about 2 % per decade, while a slow moistening of the troposphere over tropical regions is also weakly suggested by our results. Furthermore, we have assessed the regional performance of the empirical model GPT2w to blindly estimate troposphere delays. The model reproduces the observed mean delays fairly well, including their annual and semi-annual variations. Nevertheless, a long-term evaluation has shown systematical biases, up to 20 mm, probably inherited from the underlying atmospheric reanalysis. Additionally, the complete data set has been made openly available as supplementary material.

2016-01-01T00:00:00Z Atmospheric water vapour has been acknowledged as an essential climate variable. Weather prediction and hazard assessment systems benefit from real-time observations, whereas long-term records contribute to climate studies. Nowadays, ground-based global navigation satellite system (GNSS) products have become widely employed, complementing satellite observations over the oceans. Although the past decade has seen a significant development of the GNSS infrastructure in Central and South America, its potential for atmospheric water vapour monitoring has not been fully exploited. With this in mind, we have performed a regional, 7-year-long and homogeneous analysis, comprising 136 GNSS tracking stations, obtaining high-rate and continuous observations of column-integrated water vapour and troposphere zenith total delay. As a preliminary application for this data set, we have estimated local water vapour trends, their significance, and their relation with specific climate regimes. We have found evidence of drying at temperate regions in South America, at a rate of about 2 % per decade, while a slow moistening of the troposphere over tropical regions is also weakly suggested by our results. Furthermore, we have assessed the regional performance of the empirical model GPT2w to blindly estimate troposphere delays. The model reproduces the observed mean delays fairly well, including their annual and semi-annual variations. Nevertheless, a long-term evaluation has shown systematical biases, up to 20 mm, probably inherited from the underlying atmospheric reanalysis. Additionally, the complete data set has been made openly available as supplementary material.