Seasonal and elevational contrasts in temperature trends in Central Chile between 1979 and 2015

We analyze trends in temperature from 18 temperature stations and one upper air sounding site at 30°–35° S in central Chile between 1979–2015, to explore geographical and season temperature trends and their controls, using regional ocean-atmosphere indices. Significant warming trends are widespread at inland stations, while trends are non-significant or negative at coastal sites, as found in previous studies. However, ubiquitous warming across the region in the past 8 years, suggests the recent period of coastal cooling has ended. Significant warming trends are largely restricted to austral spring, summer and autumn seasons, with very few significant positive or negative trends in winter identified. Autumn warming is notably strong in the Andes, which, together with significant warming in spring, could help to explain the negative mass balance of snow and glaciers in the region. A strong Pacific maritime influence on regional temperature trends is inferred through correlation with the Interdecadal Pacific Oscillation (IPO) index and coastal sea surface temperature, but the strength of this influence rapidly diminishes inland, and the majority of valley, and all Andes, sites are independent of the IPO index. Instead, valley and Andes sites, and mid-troposphere temperature in the coastal radiosonde profile, show correlation with the autumn Antarctic Oscillation which, in its current positive phase, promotes subsidence and warming at the latitude of central Chile

A fifty year record of winter glacier melt events in southern Chile, 38°–42°S

Little is known about the frequency and potential mass balance impact of winter glacier melt events. In this study, daily atmospheric temperature soundings from the Puerto Montt radiosonde (41.43°S) are used to reconstruct winter melting events at the glacier equilibrium line altitude in the 38°–42°S region of southern Chile, between 1960 and 2010. The representativeness of the radiosonde temperatures to near-surface glacier temperatures is demonstrated using meteorological records from close to the equilibrium line on two glaciers in the region over five winters. Using a degree-day model we estimate an average of 0.28 m of melt and 21 melt days in the 15 June–15 September period each year, with high inter-annual variability. The majority of melt events are associated with midlatitude migratory high pressure systems crossing Chile and northwesterly flows, that force adiabatic compression and warm advection, respectively. There are no trends in the frequency or magnitude of melt events over the period of record, but the annual frequency of winter melt days shows a significant, although rather weak and probably non-linear, relationship to late winter and early spring values of a multivariate El Niño Southern Oscillation Index (MEI)

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Análisis de la estabilidad de la relación entre la Oscilación del Sur y la precipitación en América del Sur

Stability analysis of the relationship between the Southern Oscillation and rainfall in South America Abstract The Southern Oscillation (SO) is a significant factor of the interannual rainfall variability in South America, particularly in the northern portion of the continent; the coastal sector of northern Peru; Northeast Brazil; the southern part of the Paraná basin; and central Chile. Using sea level pressure at Darwin as an index for the SO, it is determined that its relationship with rainfall in those regions has varied significantly during the past hundred years. The possibility that these fluctuations reflect changes in the functioning of the SO is not excluded. This situation limits considerably the potential of this SO index in statistical models of climate forecasting in South America, and makes uncertain the extrapolation to the past of relationships between the SO and the interannual climate variability, observed during the present.Analyse de la stabilité de la relation entre l'Oscillation du Sud et la précipitation en Amérique du Sud Résumé L' Oscillation du Sud (OS) est un facteur important forçant la variabilité interannuelle de la precipitation en Amérique du Sud, notamment dans le secteur nord du continent, dans la région côtière du nord du Pérou, dans le nord-est brésilien, dans le bassin du fleuve Parana, et dans le Chili central. En utilisant la pression à Darwin comme un indice de 1' OS, un changement de la relation entre celle-ci et la précipitation est observé au cours du dernier siècle. Il est possible que ces fluctuations mettent en évidence des changements dans le fonctionnement de 1' OS. D'une part, cette situation limite considérablement l'utilisation de cet indice de 1' OS dans des modèles statistiques de prévision climatique. D' autre part, ce fait introduit un certain degré d'incertitude dans les études basées sur l'extrapolation de relations actuelles OS-variabilité climatique pour l' interprétation du passé lointain.Resumen La Oscilación del Sur (OS) es un factor significativo de la variabilidad interanual de la precipitación en América del Sur, particularmente en el sector norte del continente; en la región costera del norte de Perú; en el nordeste brasileño; en la cuenca del río Paraná; y en Chile central. Utilizando la presión en Darwin como un índice de la OS, se determina que su relación con la precipitación en esas regiones ha cambiado significativamente a lo largo de los últimos cien años. No se excluye la posibilidad que tales fluctuaciones reflejen cambios en el funcionamiento de la OS. Esta situación limita considerablemente la utilización de este índice de la OS en modelos estadísticos de pronóstico climático y añade un grado adicional de incertidumbre a las extrapolaciones hacia el pasado remoto de las relaciones regionales actuales entre la OS y la variabilidad climática interanual.Aceituno Patricio, Montecinos Aldo. Análisis de la estabilidad de la relación entre la Oscilación del Sur y la precipitación en América del Sur. In: Bulletin de l'Institut Français d’Études Andines, tome 22, N°1, 1993. Enregistrements du phénomène El Niño et d’événements ENSO en Amérique du Sud. pp. 53-64

Seasonal Diagnostic and Predictability of Rainfall in Subtropical South America Based on Tropical Pacific SST

Artículo de publicación ISIThe seasonality of the simultaneous relationship between tropical Pacific SST and rainfall, as well as rainfall predictability one season in advance in subtropical South America (258–408S), is studied using different multivariate techniques. This study shows that ENSO-related rainfall anomalies in subtropical South America are restricted mostly to regions on the eastern and western sides of the continent and mainly during the second half of the year. The relationship is almost exclusively of the warm–wet/cold–dry type, but a more widespread impact is found when anomalously warm conditions prevail in the equatorial Pacific. A spatially coherent region with a significant warm–wet/cold–dry signal is detected in southeastern South America during austral spring (October– November), including southern Brazil, southern Paraguay, Uruguay, and eastern Argentina. This signal moves inland toward the west from spring to early summer. During late winter (July–August), a similar SST–rainfall relationship is found in subtropical Chile and southern Brazil. In Chile, a southward propagation of the signal is observed from winter to spring. Most significant ENSO-related rainfall anomalies seem to occur after the maximum in the precipitation annual cycle. The combined analysis of seasonal diagnostics and predictability of rainfall show that the seasonal rainfall predictability in subtropical South America based on tropical Pacific SST to a greater extent is restricted to a specific time of the year and regions that broadly coincide with those where the simultaneous SST–rainfall relationship is significant. This fact suggests that persistence of tropical Pacific SST anomaly is the major source of seasonal rainfall predictability in this region, when SST is used as a predictor

Climatological characterization of puelche winds down the western slope of the extratropical andes mountains using the NCEP climate forecast system reanalysis

The existence of strong easterly winds down the western slope of the south-central Andes in Chile, locallyknown as Puelche winds, has been known by the meteorological community since at least the mid-twentiethcentury. However, this is the first time that a climatological characterization of them is presented. The analysisis based on 36 yr of daily CFSR–NCEP reanalyzed data, validated by surface weather observations. Puelchewinds are present all year round. The main synoptic-scale forcing of Puelche winds in south-central Chile isthe passage of cold anticyclonic systems across the Andes Mountains. As these systems progress into theSouth American continent, a zonal surface circulation crossing from Argentina (upslope) to Chile (down-slope) develops. Unlike terral and raco, other foehnlike winds at subtropical latitudes in Chile, the Puelchewinds are forced by both meridional and zonal pressure gradients. Presumably, the smaller altitude of theAndes Mountains south of 358S allows the air crossing from east to west in response to the presence of themigratory high pressure system over Argentina. As in other places where foehnlike winds develop,the warming extends far from places where the Puelche is actually observed, that is, to the west of the Andesinto the surface at the coastal and the central depression areas. This ‘‘foehn clearance’’ is the result ofcloudless sky and drier atmosphere that would allow an increase in the solar radiation reaching the surfaceand a subsequent warming of the near-surface air. The foehn clearance also drives an enhanced nighttimecooling, especially on the days after the onset of the Puelche event