Eduardo Agosta | Pontificia Universidad Católica Argentina (original) (raw)
Papers by Eduardo Agosta
Se estudia el ciclo anual de precipitación en la región Pampa Amarilla (RPA). La mayor parte de l... more Se estudia el ciclo anual de precipitación en la región Pampa Amarilla (RPA). La mayor parte de la RPA presenta máximo en marzo, seguido de noviembre y diciembre, y mínimo en invierno. El acumulado octubre-marzo (verano) resulta significativamente distinto al acumulado abril- septiembre (invierno). Se analizan las variaciones, tendencias y cambios de las series temporales en verano e invierno. Las series más largas seleccionadas sobre el centro y norte de La Pampa, muestran cambio positivo y significativo por tendencia lineal, del orden del 44 % de la media regional en verano. Tras una prolongada sequía (1930-1950) el cambio estival irrumpe en la década de los setenta (centro-norte de La Pampa), y en la década de los sesenta (centro-este de La Pampa). Este cambio brusco ha producido una larga fase húmeda extendida hasta comienzos de los dos mil. El cambio de la década del setenta puede estar asociado al cambio de las condiciones medias de la Temperatura superficial del mar (TSM) del...
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Abstract: The summer (Oct-Mar) rainfall in Central-West Argentina (CWA) shows a clear interannual... more Abstract: The summer (Oct-Mar) rainfall in Central-West Argentina (CWA) shows a clear interannual variability modulated by low-frequency oscillations. This determines periods of wet and dry summers that have changed from a quasi-18-year cycle towards lower frequencies in the summer 1976/77 (Compagnucci et al. 2002). The relationship between dry and wet extremes and the atmospheric circulation is analyzed regarding the era pre-1977 and pos-1977. Extreme events were defined using the first and third quartile of the distribution of a summer precipitation index devised for the region. The composite shows differential features between dry and wet extremes and in relation with the change in 1976/777. These results suggest a possible change in the teleconnection between summer rainfall and the atmospheric circulation, from middle to subtropical latitudes by mid-1970s.
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International Journal of Climatology, 2020
Precipitation anomalies over subtropical Argentina in eastern subtropical South America (ESSA) sh... more Precipitation anomalies over subtropical Argentina in eastern subtropical South America (ESSA) show significant signatures of the El Niño Southern Oscillation (ENSO) during the SONDJ (from September to January) season. The correlation maps between seasonal precipitation anomalies and the C‐index show a dipole structure with positive correlation over eastern ESSA and negative over South American convergence zone. Based on principal component analysis, precipitation anomalies within the SONDJ season during ENSO events were discriminated into three categories typical, atypical and nontypical, regarding their precipitation response. Typical (atypical) stands for precipitation anomalies similar (inverse) in comparison to the linear expected anomalies for El Niño or La Niña events. In the period 1979–2016, five (five) typical seasons, two (zero) atypical seasons and six (six) nontypical seasons were recorded under El Niño (La Niña) events. During typical SONDJ seasons under El Niño, precipitation over ESSA is mainly modulated by regional tropospheric circulation anomalies induced by quasi‐stationary Rossby wave propagation from the western South Pacific towards South America. The precipitation anomalies during the two atypical SONDJ seasons in El Niño were overall partly owing to shifts of the sea surface temperature (SST) gradient in the equatorial Pacific, and changes in the Atlantic basin SST anomalies.
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RESUMEN La provincia del Chaco, Argentina, se encuentra en una región de gran gradiente zonal de ... more RESUMEN La provincia del Chaco, Argentina, se encuentra en una región de gran gradiente zonal de precipitación media anual, más húmeda al este y menos al oeste. En el presente trabajo se estudia las variaciones espacio-temporales de la precipitación en escala interanual en el período 1955-2010. Se encuentra que el ciclo anual medio puede describirse mediante una fase seca, de mayo a septiembre, y una húmeda, de octubre a abril, que explica cerca del 80% del acumulado total anual. La clasificación espacial de estaciones, permite definir 4 subregiones distinguibles en la provincia: la subregión I, en el este, la subregión II, en el oeste, la subregión III, en el centronorte, y la subregión IV, en el centro-sur. Se estudió el acumulado en la fase húmeda, que explica el 80% del acumulado total anual, para las subregiones I y II mediante series de precipitación convenientemente diseñadas. La exploración de forzantes del sistema climático indica que la precipitación acumulada en la fase h...
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Atmospheric Research, 2020
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International Journal of Climatology, 2020
The seasonal influence of the phases of El Niño‐Southern Oscillation (ENSO) and of Southern Annul... more The seasonal influence of the phases of El Niño‐Southern Oscillation (ENSO) and of Southern Annular Mode (SAM) on precipitation over eastern Patagonia is examined. Also, their impact in generating persistent daily easterly moisture flux leading to daily precipitation events. The significant signatures of the drivers on precipitation are found in March–April–May (MAM), June–July–August (JJA) for ENSO and November–December–January (NDJ) for SAM. Over the east coast, precipitation is mainly favoured owing to an overall growth of the seasonal mean number of precipitation days (~30%) by central Niño in JJA and by negative SAM phase in NDJ, and growth of the frequency of persistent events of daily westward moisture flux (~90%) by eastern Niña in MAM. A great spatial variability shapes the anomalies. Evidence is shown for weakened seasonal westerlies linked to Eastern Pacific Niño in MAM. Enhanced daily easterlies with net daily westward moisture flux in the region lead to strong daily precipitation. Growth in precipitation intensity in the northeast coast is also associated with Eastern Pacific Niño in MAM. In the interior lands, south of 45°S, westward moisture flux is increased up to ~200% by negative SAM phase in NDJ. The nature of extratropical low‐frequency transient eddies travelling over the South Pacific will influence the frequency and intensity of daily local precipitation as well as the persistent westward flux during ENSO events.
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The SIJ Transactions on Advances in Space Research & Earth Exploration, 2015
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International Journal of Climatology, 2017
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Geoacta, Dec 1, 2012
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Journal of Climate, 2012
The interannual-to-multidecadal variability of central-west Argentina (CWA) summer (October–March... more The interannual-to-multidecadal variability of central-west Argentina (CWA) summer (October–March) precipitation and associated tropospheric circulation are studied in the period 1900–2010. Precipitation shows significant quasi cycles with periods of about 2, 4–5, 6–8, and 16–22 yr. The quasi-bidecadal oscillation is significant from the early 1910s until the mid-1970s and is present in pressure time series over the southwestern South Atlantic. According to the lower-frequency spectral variation, a prolonged wet spell is observed from 1973 to the early 2000s. The precipitation variability shows a reversal trend since then. In that wet epoch, the regionally averaged precipitation has been increased about 24%. The lower-frequency spectral variation is attributed to the climate shift of 1976/77. From the early twentieth century until the mid-1970s, the precipitation variability is associated with barotropic quasi-stationary wave (QSW) propagation from the tropical southern Indian Ocean...
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Journal of Applied Meteorology and Climatology, 2012
Mendoza Province is the major Argentinian vitivinicultural region, and its grape production is fu... more Mendoza Province is the major Argentinian vitivinicultural region, and its grape production is fundamental for the national vintage. The 1979–2009 climate–annual grape yield relationships are analyzed, and total grape yield is shown to depend significantly on regional “summer” (October–March) precipitation. Precipitation negatively affects yields through plant disease and damage/destruction by hail. At interannual scales, summer regional precipitation variability can explains 25% of the yield variance. Summer precipitation modulates yield with a 6–8-yr period: wet (dry) summers can be associated with larger (smaller) grape damage/loss probability during the summer preceding the vintage, as well as lower (higher) grape yields in the subsequent annual campaign because of bud damage. With respect to monthly mean precipitation at Mendoza Observatory, wetter Novembers/Decembers can lead to lower yields. Hail during the summer of the previous harvest and during December could lower yields...
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International Journal of Climatology, 2019
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DESCRIPTION En la página web “NASA Goddard Homepage for Tropospheric Ozone” se reportan datos a n... more DESCRIPTION En la página web “NASA Goddard Homepage for Tropospheric Ozone” se reportan datos a nivel mundial de ozono troposférico obtenidos a partir de las observaciones de los instrumentos OMI y MLS del satélite Aura. A mediados del año 2013, los datos cubrían el período comprendido entre octubre de 2004 y enero de 2013. Posteriormente, a principios de 2014, la serie se extendió hasta diciembre de 2013. Analizando esta nueva serie, se observó que los datos ya publicados hasta enero de 2013 habían sido reemplazados; no solamente se adicionaron los meses faltantes de 2013 sino que todos los valores publicados desde 2004 habían sido recalculados. En este trabajo se reportan las diferencias detectadas en la comparación entre el conjunto de datos común a ambas series (la original, anterior a enero de 2013, y la nueva, actualmente publicada en el sitio web). Estas diferencias son importantes teniendo en cuenta que representan el resultado de una misma observación satelital y deben ser ...
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The present work aims to analyze the tropospheric circulation in the Southern Hemisphere (SH) ass... more The present work aims to analyze the tropospheric circulation in the Southern Hemisphere (SH) associated with anomalously cold summers (ACS, Dec-Feb) in the period 1981-2010 over northernmost Antarctic Peninsula (AP). A quartile criterion is used to identify ACSs, and a wave-activity flux for stationary quasi-geostrophic (QG) eddies on a zonally varying basic flow is used as a diagnostic tool to study wave-train propagation from the Pacific Ocean. It is shown that the summer of 2010 was singularly cold, so this summer is studied separately from the ACS composites previous to 2010. The ACSs prior to 2010 are characterized by a Pacific-South American (PSA)-like quasi-stationary wave (QSW) train that extends barotropically through the troposphere up to the lower stratosphere. It is emanated from a region of anomalous convection in New Zealand and it is directed towards the South Pacific. The wave train leads to an anomalous stationary cyclone that is located to the northwest of the AP....
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Se estudia el ciclo anual de precipitación en la región Pampa Amarilla (RPA). La mayor parte de l... more Se estudia el ciclo anual de precipitación en la región Pampa Amarilla (RPA). La mayor parte de la RPA presenta máximo en marzo, seguido de noviembre y diciembre, y mínimo en invierno. El acumulado octubre-marzo (verano) resulta significativamente distinto al acumulado abril- septiembre (invierno). Se analizan las variaciones, tendencias y cambios de las series temporales en verano e invierno. Las series más largas seleccionadas sobre el centro y norte de La Pampa, muestran cambio positivo y significativo por tendencia lineal, del orden del 44 % de la media regional en verano. Tras una prolongada sequía (1930-1950) el cambio estival irrumpe en la década de los setenta (centro-norte de La Pampa), y en la década de los sesenta (centro-este de La Pampa). Este cambio brusco ha producido una larga fase húmeda extendida hasta comienzos de los dos mil. El cambio de la década del setenta puede estar asociado al cambio de las condiciones medias de la Temperatura superficial del mar (TSM) del...
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Abstract: The summer (Oct-Mar) rainfall in Central-West Argentina (CWA) shows a clear interannual... more Abstract: The summer (Oct-Mar) rainfall in Central-West Argentina (CWA) shows a clear interannual variability modulated by low-frequency oscillations. This determines periods of wet and dry summers that have changed from a quasi-18-year cycle towards lower frequencies in the summer 1976/77 (Compagnucci et al. 2002). The relationship between dry and wet extremes and the atmospheric circulation is analyzed regarding the era pre-1977 and pos-1977. Extreme events were defined using the first and third quartile of the distribution of a summer precipitation index devised for the region. The composite shows differential features between dry and wet extremes and in relation with the change in 1976/777. These results suggest a possible change in the teleconnection between summer rainfall and the atmospheric circulation, from middle to subtropical latitudes by mid-1970s.
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International Journal of Climatology, 2020
Precipitation anomalies over subtropical Argentina in eastern subtropical South America (ESSA) sh... more Precipitation anomalies over subtropical Argentina in eastern subtropical South America (ESSA) show significant signatures of the El Niño Southern Oscillation (ENSO) during the SONDJ (from September to January) season. The correlation maps between seasonal precipitation anomalies and the C‐index show a dipole structure with positive correlation over eastern ESSA and negative over South American convergence zone. Based on principal component analysis, precipitation anomalies within the SONDJ season during ENSO events were discriminated into three categories typical, atypical and nontypical, regarding their precipitation response. Typical (atypical) stands for precipitation anomalies similar (inverse) in comparison to the linear expected anomalies for El Niño or La Niña events. In the period 1979–2016, five (five) typical seasons, two (zero) atypical seasons and six (six) nontypical seasons were recorded under El Niño (La Niña) events. During typical SONDJ seasons under El Niño, precipitation over ESSA is mainly modulated by regional tropospheric circulation anomalies induced by quasi‐stationary Rossby wave propagation from the western South Pacific towards South America. The precipitation anomalies during the two atypical SONDJ seasons in El Niño were overall partly owing to shifts of the sea surface temperature (SST) gradient in the equatorial Pacific, and changes in the Atlantic basin SST anomalies.
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RESUMEN La provincia del Chaco, Argentina, se encuentra en una región de gran gradiente zonal de ... more RESUMEN La provincia del Chaco, Argentina, se encuentra en una región de gran gradiente zonal de precipitación media anual, más húmeda al este y menos al oeste. En el presente trabajo se estudia las variaciones espacio-temporales de la precipitación en escala interanual en el período 1955-2010. Se encuentra que el ciclo anual medio puede describirse mediante una fase seca, de mayo a septiembre, y una húmeda, de octubre a abril, que explica cerca del 80% del acumulado total anual. La clasificación espacial de estaciones, permite definir 4 subregiones distinguibles en la provincia: la subregión I, en el este, la subregión II, en el oeste, la subregión III, en el centronorte, y la subregión IV, en el centro-sur. Se estudió el acumulado en la fase húmeda, que explica el 80% del acumulado total anual, para las subregiones I y II mediante series de precipitación convenientemente diseñadas. La exploración de forzantes del sistema climático indica que la precipitación acumulada en la fase h...
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Atmospheric Research, 2020
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International Journal of Climatology, 2020
The seasonal influence of the phases of El Niño‐Southern Oscillation (ENSO) and of Southern Annul... more The seasonal influence of the phases of El Niño‐Southern Oscillation (ENSO) and of Southern Annular Mode (SAM) on precipitation over eastern Patagonia is examined. Also, their impact in generating persistent daily easterly moisture flux leading to daily precipitation events. The significant signatures of the drivers on precipitation are found in March–April–May (MAM), June–July–August (JJA) for ENSO and November–December–January (NDJ) for SAM. Over the east coast, precipitation is mainly favoured owing to an overall growth of the seasonal mean number of precipitation days (~30%) by central Niño in JJA and by negative SAM phase in NDJ, and growth of the frequency of persistent events of daily westward moisture flux (~90%) by eastern Niña in MAM. A great spatial variability shapes the anomalies. Evidence is shown for weakened seasonal westerlies linked to Eastern Pacific Niño in MAM. Enhanced daily easterlies with net daily westward moisture flux in the region lead to strong daily precipitation. Growth in precipitation intensity in the northeast coast is also associated with Eastern Pacific Niño in MAM. In the interior lands, south of 45°S, westward moisture flux is increased up to ~200% by negative SAM phase in NDJ. The nature of extratropical low‐frequency transient eddies travelling over the South Pacific will influence the frequency and intensity of daily local precipitation as well as the persistent westward flux during ENSO events.
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The SIJ Transactions on Advances in Space Research & Earth Exploration, 2015
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International Journal of Climatology, 2017
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Geoacta, Dec 1, 2012
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Journal of Climate, 2012
The interannual-to-multidecadal variability of central-west Argentina (CWA) summer (October–March... more The interannual-to-multidecadal variability of central-west Argentina (CWA) summer (October–March) precipitation and associated tropospheric circulation are studied in the period 1900–2010. Precipitation shows significant quasi cycles with periods of about 2, 4–5, 6–8, and 16–22 yr. The quasi-bidecadal oscillation is significant from the early 1910s until the mid-1970s and is present in pressure time series over the southwestern South Atlantic. According to the lower-frequency spectral variation, a prolonged wet spell is observed from 1973 to the early 2000s. The precipitation variability shows a reversal trend since then. In that wet epoch, the regionally averaged precipitation has been increased about 24%. The lower-frequency spectral variation is attributed to the climate shift of 1976/77. From the early twentieth century until the mid-1970s, the precipitation variability is associated with barotropic quasi-stationary wave (QSW) propagation from the tropical southern Indian Ocean...
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Journal of Applied Meteorology and Climatology, 2012
Mendoza Province is the major Argentinian vitivinicultural region, and its grape production is fu... more Mendoza Province is the major Argentinian vitivinicultural region, and its grape production is fundamental for the national vintage. The 1979–2009 climate–annual grape yield relationships are analyzed, and total grape yield is shown to depend significantly on regional “summer” (October–March) precipitation. Precipitation negatively affects yields through plant disease and damage/destruction by hail. At interannual scales, summer regional precipitation variability can explains 25% of the yield variance. Summer precipitation modulates yield with a 6–8-yr period: wet (dry) summers can be associated with larger (smaller) grape damage/loss probability during the summer preceding the vintage, as well as lower (higher) grape yields in the subsequent annual campaign because of bud damage. With respect to monthly mean precipitation at Mendoza Observatory, wetter Novembers/Decembers can lead to lower yields. Hail during the summer of the previous harvest and during December could lower yields...
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International Journal of Climatology, 2019
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DESCRIPTION En la página web “NASA Goddard Homepage for Tropospheric Ozone” se reportan datos a n... more DESCRIPTION En la página web “NASA Goddard Homepage for Tropospheric Ozone” se reportan datos a nivel mundial de ozono troposférico obtenidos a partir de las observaciones de los instrumentos OMI y MLS del satélite Aura. A mediados del año 2013, los datos cubrían el período comprendido entre octubre de 2004 y enero de 2013. Posteriormente, a principios de 2014, la serie se extendió hasta diciembre de 2013. Analizando esta nueva serie, se observó que los datos ya publicados hasta enero de 2013 habían sido reemplazados; no solamente se adicionaron los meses faltantes de 2013 sino que todos los valores publicados desde 2004 habían sido recalculados. En este trabajo se reportan las diferencias detectadas en la comparación entre el conjunto de datos común a ambas series (la original, anterior a enero de 2013, y la nueva, actualmente publicada en el sitio web). Estas diferencias son importantes teniendo en cuenta que representan el resultado de una misma observación satelital y deben ser ...
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The present work aims to analyze the tropospheric circulation in the Southern Hemisphere (SH) ass... more The present work aims to analyze the tropospheric circulation in the Southern Hemisphere (SH) associated with anomalously cold summers (ACS, Dec-Feb) in the period 1981-2010 over northernmost Antarctic Peninsula (AP). A quartile criterion is used to identify ACSs, and a wave-activity flux for stationary quasi-geostrophic (QG) eddies on a zonally varying basic flow is used as a diagnostic tool to study wave-train propagation from the Pacific Ocean. It is shown that the summer of 2010 was singularly cold, so this summer is studied separately from the ACS composites previous to 2010. The ACSs prior to 2010 are characterized by a Pacific-South American (PSA)-like quasi-stationary wave (QSW) train that extends barotropically through the troposphere up to the lower stratosphere. It is emanated from a region of anomalous convection in New Zealand and it is directed towards the South Pacific. The wave train leads to an anomalous stationary cyclone that is located to the northwest of the AP....
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