Eduardo Agosta - Profile on Academia.edu (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...
2006: Atmospheric conditions during wet and dry summer extremes in central-west Argentina
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.
El Niño Southern Oscillation‐related precipitation anomaly variability over eastern subtropical South America: Atypical precipitation seasons
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.
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...
Atmospheric Research, 2020
Homogeneity is an important characteristic of time series that must be checked before doing any a... more Homogeneity is an important characteristic of time series that must be checked before doing any analysis. Breakpoints in meteorological time series are very common due to climatic jumps caused by natural forcing and/or human activity but also, and mainly, produced by inhomogeneities which are erratic in nature. In this work, five breakpoint tests are analyzed to evaluate their performance in detecting breakpoints for different lengths of time series and intensity of breakpoint, among other features, through the realization of numerical experiments of sensitivity. These tests are: Student's, Mann-Whitney, Buishand-R, Pettit and SNHT. The Student's and Mann-Whitney tests show high probability of false breakpoint detection and problems to reproduce the date when a breakpoint occurs. In addition, the Buishand-R and Pettit are more efficient to reproduce the date of breakpoint when it occurs in the middle of a time series while the SNHT does it for breakpoints in its borders. In this sense, the Pettit, Buishand-R and SNHT tests show better performance than the Mann-Whitney and Student's. Furthermore, an original methodology to detect multi-breakpoints based on the aforementioned tests is applied to precipitation time series from sixty-two rain-gauge stations in subtropical Argentina. A breakpoint around 1976 is detected in the wet season (austral warm season), highly likely linked to the well-documented 1976/77 climate transition, by all the used tests and for most of the stations. To a lesser extent, another breakpoint occurred in the mid-1950's. Other breakpoints are also detected in the early 1980s and the early 2000s, though in few stations and by one or two tests. For the breakpoints found in the mid-1950's and in the early 1980's, a strong relationship with two ENSO's indices is found which suggests that changes in long-term ENSO variability could be the cause of these breakpoints.
“Easterlies”‐induced precipitation in eastern Patagonia: Seasonal influences of ENSO'S FLAVOURS and SAM
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.
The SIJ Transactions on Advances in Space Research & Earth Exploration, 2015
On the website "NASA Goddard Homepage for Tropospheric Ozone", global data of tropospheric ozone ... more On the website "NASA Goddard Homepage for Tropospheric Ozone", global data of tropospheric ozone obtained from observations of OMI and MLS Aura satellite instruments, are reported. In mid-2013, the data was covering the period between October 2004 and January 2013. Subsequently, in early 2014, the time series was extended until December 2013. At present time, the published series has been extended to December 2014. Analysing this new series, we observed that the data already published to January 2013 had been replaced; not only the missing months of 2013 were added but all the values published since 2004 were recalculated. We present the detected differences in the comparison between common data to both time series (the original, before January 2013, and the new one, currently published on the website). These differences are important considering that they represent the result of the same satellite observation and should be considered when comparing results before/after January 2013, especially when adopting a certain confidence level in the spectral analysis of these data to intraseasonal scale. A warn of caution is suggested in the use of these observations and intercomparison with other values of these and other instruments, because of possible recurrent problems of instrumental calibration.
International Journal of Climatology, 2017
This work focuses on the analysis of spatial and temporal variability of precipitation in the cen... more This work focuses on the analysis of spatial and temporal variability of precipitation in the central region of southern Central Argentina (SCA), a climate transition area which has experienced an important agricultural expansion. For this purpose, gauge station precipitation datasets available in the area were extensively used. The annual cycle shows a defined dry season (May-August) and wet season (September-April). Wet season represents over 85% of annual totals. A regionalization analysis of wet-season precipitation suggests five subregions with spatially homogeneous precipitation variability in SCA. Three out the five subregions are located in central SCA. Conveniently devised precipitation indices for the latter subregions show the presence of significant precipitation jumps by the early 1970s, and to a minor extent, the mid-1960s. Precipitation jumps are responsible for the observed long-term trends in central SCA, which explain positive precipitation changes over 30-40% of regional averages in the period 1922-2012. The presence of stationary and non-stationary components in SCA precipitation variability remotely connects the region mainly with variations in equatorial Pacific SSTs. The assessment of greenhouse gases concentration effects on future projections of wet-season precipitation over central SCA is investigated by means of multi-model analysis of historical experiment, and the representative concentration pathways 4.5 (RCP 4.5) and 8.5 (RCP 8.5), provided by the Coupled Model Intercomparison Project Phase 5. Results suggest an overall increased precipitation, roughly 15% respect to present climate, under most severe future scenario.
Geoacta, Dec 1, 2012
El estudio busca definir las condiciones medias de la circulación troposférica y posibles forzant... more El estudio busca definir las condiciones medias de la circulación troposférica y posibles forzantes asociados a la frecuencia de ocurrencia de noches frías (TN10) y noches cálidas (TN90) durante el invierno austral (JJA) sobre Argentina subtropical, al norte de 40°S y adyacencias (ASA) a partir de datos de estaciones meteorológicas y de reanálisis (NCEP/DOE AMIP-II y ECMWF ERA-interim). Se encuentra que la frecuencia de noches cálidas (Tmin superiores al percentil 90, TN90) está modulada interanualmente por la propagación de ondas cuasi-estacionarias (OCE) de Rossby inducidas por anomalías de convección en el Índico y el Pacífico. La alta frecuencia de noches cálidas está asociada a calentamiento anómalo del Pacífico central ecuatorial (fase positiva del El Niño-Oscilación del Sur, ENOS). La baja frecuencia de noches cálidas está relacionada con convección anómala sobre el área monzónica de la India y el Índico sur tropical occidental. Esto favorece la propagación de actividad de OCE de Rossby sobre el Índico, el Pacífico y el sur de Sudamérica. Tal teleconexión a su vez favorece la alta frecuencia de noches frías (Tmin inferiores al percentil 10, TN10). En cambio la baja frecuencia de noches frías está vinculada a variabilidad de baja frecuencia del modo de variabilidad de altas latitudes del hemisferio sur (el MAS). Se encuentra que el fortalecimiento (debilitamiento) del jet subtropical sobre Sudamérica y océanos adyacentes caracteriza los inviernos con alta (baja) frecuencia de noches frías (cálidas) en ASA. Los forzantes remotos encontrados involucran procesos atmosféricos/oceánicos que se interconectan interestacionalmente, lo cual podría permitir desarrollar el pronóstico estadístico-dinámico para invierno de alta o baja frecuencia de noches frías o cálidas en invierno.
AMS Journals Online - Regional Climate Variability Impacts
AMS Journals Online - Central-West Argentina Summer
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...
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...
International Journal of Climatology, 2019
The relationship between daily precipitation and unusually persistent easterly wind recorded at s... more The relationship between daily precipitation and unusually persistent easterly wind recorded at station level along the coast of Eastern Patagonia is examined. Easterly wind events that persist for more than 20 hours (E) are infrequent in Comodoro Rivadavia (CMR); but in about 80% of the times they do occur daily precipitation exceeds 1 mm. Although 2-day persistent easterlies (2E) occur only about 1% of the time in CMR they are associated with 20% of the > 75% percentile rain events. The occurrence of precipitation days (P>= 1mm) during 2E events (P1&2E) is far from randomness for most stations. For daily P1&2E events in CMR, the convergence of westward moisture flux from the Atlantic is key. Its daily frequency shifts toward Niño This article is protected by copyright. All rights reserved. (44%), followed by Neutral 35 (32%), and Niña (25%) conditions. The probability of null precipitation days with westerlies was higher than 95% on average among the stations. The tropospheric circulation anomalous conditions associated with P1&2E events are characterized by a blocking-like flow along 80-90ºW, with anticyclonic anomalies near 60º-70ºS and cyclonic anomalies in the mid-latitudes. The strength of the anomalies is given by the meridional gradient of tropospheric circulation anomalies, stronger during the Niño phase. A P1&2E event at CMR is linked to active slow-moving weather systems linked to tropospheric Rossby waves triggered by upper-level tropospheric mass divergence anomalies in low latitudes. The source and trajectory these Rossby waves are different through ENSO phases. We have found that heavy precipitation over subtropical eastern Argentina during Niño precede CMR P1&2E events by 10 to 8 days. Daily P1&2E events contribute substantially to the mean precipitation total from April to June. The differential influence of the ENSO phases through the seasons of year is evident in such a contribution.
Floods in Eastern Subtropical Argentina: The Contributing Roles of Climate Change and Socioeconomics
Ondas cuasi-estacionarias en el Pacífico sur y veranos fríos anómalos en el extremo norte de la Península Antártica
Condiciones medias de invierno y ondas cuasi-estacionarias de Rossby asociadas a la frecuencia invernal de noches frias y cálidas en Argentina subtropical
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 ...
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....
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...
2006: Atmospheric conditions during wet and dry summer extremes in central-west Argentina
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.
El Niño Southern Oscillation‐related precipitation anomaly variability over eastern subtropical South America: Atypical precipitation seasons
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.
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...
Atmospheric Research, 2020
Homogeneity is an important characteristic of time series that must be checked before doing any a... more Homogeneity is an important characteristic of time series that must be checked before doing any analysis. Breakpoints in meteorological time series are very common due to climatic jumps caused by natural forcing and/or human activity but also, and mainly, produced by inhomogeneities which are erratic in nature. In this work, five breakpoint tests are analyzed to evaluate their performance in detecting breakpoints for different lengths of time series and intensity of breakpoint, among other features, through the realization of numerical experiments of sensitivity. These tests are: Student's, Mann-Whitney, Buishand-R, Pettit and SNHT. The Student's and Mann-Whitney tests show high probability of false breakpoint detection and problems to reproduce the date when a breakpoint occurs. In addition, the Buishand-R and Pettit are more efficient to reproduce the date of breakpoint when it occurs in the middle of a time series while the SNHT does it for breakpoints in its borders. In this sense, the Pettit, Buishand-R and SNHT tests show better performance than the Mann-Whitney and Student's. Furthermore, an original methodology to detect multi-breakpoints based on the aforementioned tests is applied to precipitation time series from sixty-two rain-gauge stations in subtropical Argentina. A breakpoint around 1976 is detected in the wet season (austral warm season), highly likely linked to the well-documented 1976/77 climate transition, by all the used tests and for most of the stations. To a lesser extent, another breakpoint occurred in the mid-1950's. Other breakpoints are also detected in the early 1980s and the early 2000s, though in few stations and by one or two tests. For the breakpoints found in the mid-1950's and in the early 1980's, a strong relationship with two ENSO's indices is found which suggests that changes in long-term ENSO variability could be the cause of these breakpoints.
“Easterlies”‐induced precipitation in eastern Patagonia: Seasonal influences of ENSO'S FLAVOURS and SAM
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.
The SIJ Transactions on Advances in Space Research & Earth Exploration, 2015
On the website "NASA Goddard Homepage for Tropospheric Ozone", global data of tropospheric ozone ... more On the website "NASA Goddard Homepage for Tropospheric Ozone", global data of tropospheric ozone obtained from observations of OMI and MLS Aura satellite instruments, are reported. In mid-2013, the data was covering the period between October 2004 and January 2013. Subsequently, in early 2014, the time series was extended until December 2013. At present time, the published series has been extended to December 2014. Analysing this new series, we observed that the data already published to January 2013 had been replaced; not only the missing months of 2013 were added but all the values published since 2004 were recalculated. We present the detected differences in the comparison between common data to both time series (the original, before January 2013, and the new one, currently published on the website). These differences are important considering that they represent the result of the same satellite observation and should be considered when comparing results before/after January 2013, especially when adopting a certain confidence level in the spectral analysis of these data to intraseasonal scale. A warn of caution is suggested in the use of these observations and intercomparison with other values of these and other instruments, because of possible recurrent problems of instrumental calibration.
International Journal of Climatology, 2017
This work focuses on the analysis of spatial and temporal variability of precipitation in the cen... more This work focuses on the analysis of spatial and temporal variability of precipitation in the central region of southern Central Argentina (SCA), a climate transition area which has experienced an important agricultural expansion. For this purpose, gauge station precipitation datasets available in the area were extensively used. The annual cycle shows a defined dry season (May-August) and wet season (September-April). Wet season represents over 85% of annual totals. A regionalization analysis of wet-season precipitation suggests five subregions with spatially homogeneous precipitation variability in SCA. Three out the five subregions are located in central SCA. Conveniently devised precipitation indices for the latter subregions show the presence of significant precipitation jumps by the early 1970s, and to a minor extent, the mid-1960s. Precipitation jumps are responsible for the observed long-term trends in central SCA, which explain positive precipitation changes over 30-40% of regional averages in the period 1922-2012. The presence of stationary and non-stationary components in SCA precipitation variability remotely connects the region mainly with variations in equatorial Pacific SSTs. The assessment of greenhouse gases concentration effects on future projections of wet-season precipitation over central SCA is investigated by means of multi-model analysis of historical experiment, and the representative concentration pathways 4.5 (RCP 4.5) and 8.5 (RCP 8.5), provided by the Coupled Model Intercomparison Project Phase 5. Results suggest an overall increased precipitation, roughly 15% respect to present climate, under most severe future scenario.
Geoacta, Dec 1, 2012
El estudio busca definir las condiciones medias de la circulación troposférica y posibles forzant... more El estudio busca definir las condiciones medias de la circulación troposférica y posibles forzantes asociados a la frecuencia de ocurrencia de noches frías (TN10) y noches cálidas (TN90) durante el invierno austral (JJA) sobre Argentina subtropical, al norte de 40°S y adyacencias (ASA) a partir de datos de estaciones meteorológicas y de reanálisis (NCEP/DOE AMIP-II y ECMWF ERA-interim). Se encuentra que la frecuencia de noches cálidas (Tmin superiores al percentil 90, TN90) está modulada interanualmente por la propagación de ondas cuasi-estacionarias (OCE) de Rossby inducidas por anomalías de convección en el Índico y el Pacífico. La alta frecuencia de noches cálidas está asociada a calentamiento anómalo del Pacífico central ecuatorial (fase positiva del El Niño-Oscilación del Sur, ENOS). La baja frecuencia de noches cálidas está relacionada con convección anómala sobre el área monzónica de la India y el Índico sur tropical occidental. Esto favorece la propagación de actividad de OCE de Rossby sobre el Índico, el Pacífico y el sur de Sudamérica. Tal teleconexión a su vez favorece la alta frecuencia de noches frías (Tmin inferiores al percentil 10, TN10). En cambio la baja frecuencia de noches frías está vinculada a variabilidad de baja frecuencia del modo de variabilidad de altas latitudes del hemisferio sur (el MAS). Se encuentra que el fortalecimiento (debilitamiento) del jet subtropical sobre Sudamérica y océanos adyacentes caracteriza los inviernos con alta (baja) frecuencia de noches frías (cálidas) en ASA. Los forzantes remotos encontrados involucran procesos atmosféricos/oceánicos que se interconectan interestacionalmente, lo cual podría permitir desarrollar el pronóstico estadístico-dinámico para invierno de alta o baja frecuencia de noches frías o cálidas en invierno.
AMS Journals Online - Regional Climate Variability Impacts
AMS Journals Online - Central-West Argentina Summer
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...
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...
International Journal of Climatology, 2019
The relationship between daily precipitation and unusually persistent easterly wind recorded at s... more The relationship between daily precipitation and unusually persistent easterly wind recorded at station level along the coast of Eastern Patagonia is examined. Easterly wind events that persist for more than 20 hours (E) are infrequent in Comodoro Rivadavia (CMR); but in about 80% of the times they do occur daily precipitation exceeds 1 mm. Although 2-day persistent easterlies (2E) occur only about 1% of the time in CMR they are associated with 20% of the > 75% percentile rain events. The occurrence of precipitation days (P>= 1mm) during 2E events (P1&2E) is far from randomness for most stations. For daily P1&2E events in CMR, the convergence of westward moisture flux from the Atlantic is key. Its daily frequency shifts toward Niño This article is protected by copyright. All rights reserved. (44%), followed by Neutral 35 (32%), and Niña (25%) conditions. The probability of null precipitation days with westerlies was higher than 95% on average among the stations. The tropospheric circulation anomalous conditions associated with P1&2E events are characterized by a blocking-like flow along 80-90ºW, with anticyclonic anomalies near 60º-70ºS and cyclonic anomalies in the mid-latitudes. The strength of the anomalies is given by the meridional gradient of tropospheric circulation anomalies, stronger during the Niño phase. A P1&2E event at CMR is linked to active slow-moving weather systems linked to tropospheric Rossby waves triggered by upper-level tropospheric mass divergence anomalies in low latitudes. The source and trajectory these Rossby waves are different through ENSO phases. We have found that heavy precipitation over subtropical eastern Argentina during Niño precede CMR P1&2E events by 10 to 8 days. Daily P1&2E events contribute substantially to the mean precipitation total from April to June. The differential influence of the ENSO phases through the seasons of year is evident in such a contribution.
Floods in Eastern Subtropical Argentina: The Contributing Roles of Climate Change and Socioeconomics
Ondas cuasi-estacionarias en el Pacífico sur y veranos fríos anómalos en el extremo norte de la Península Antártica
Condiciones medias de invierno y ondas cuasi-estacionarias de Rossby asociadas a la frecuencia invernal de noches frias y cálidas en Argentina subtropical
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 ...
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....