A cold wave of winter 2021 in central South America: characteristics and impacts.

During the austral winter (June-August) of 2021, the meteorological services of Brazil, Argentina, Peru, Paraguay, Bolivia, and Chile all issued forecasts for unusually cold conditions. Record-low minimum temperatures and cold spells were documented, including one strong cold wave episode that affected 5 countries. In this study, we define a cold wave as a period in which daily maximum and minimum air temperatures are below the corresponding climatological 10th percentile for three or more consecutive days. The intense cold wave event in the last week of June, 2021, resulted in record-breaking minimum daily temperatures in several places in central South America and Chile. Several locations had temperatures about 10 °C below average, central South America had freezing conditions, and southern Brazil even saw snow. The cold air surge was characterized by an intense upper-air trough located close to 35° S and 70° W. The southerly flow to the west of this trough brought very cold air northward into subtropical and tropical South America. A northward flow between the lower-level cyclonic and anticyclonic perturbations caused the intense southerly flow between the upper-level ridge and trough. This condition facilitated the inflow of near-surface cold air from southern Argentina into southeastern Brazil and tropical South America east of the Andes. In the city of São Paulo, the cold wave caused the death of 13 homeless people from hypothermia. Frost and snow across southern and southeastern Brazil caused significant damage to coffee, sugarcane, oranges, grapes, and other fruit and vegetable crops. Wine and coffee production fell, the latter by 30%, and prices of food and commodities in the region rose. Supplementary Information: The online version contains supplementary material available at 10.1007/s00382-023-06701-1.

Sources of contamination and modelled pollutant trajectories in a Mediterranean harbour (Tarragona, Spain).

The proximity of commercial harbours to residential areas and the growing environmental awareness of society have led most port authorities to include environmental management within their administration plan. Regarding water quality, it is necessary to have the capacity and tools to deal with contamination episodes that may damage marine ecosystems and human health, but also affect the normal functioning of harbours. This paper presents a description of the main pollutant sources in Tarragona Harbour (Spain), and a numerical analysis of several pollution episodes based on the Port Authority's actual environmental concerns. The results show that pollution generated inside the harbour tends to remain confined within the port, whereas it is very likely that oil spills from a nearby monobuoy may affect the neighbouring beaches. The present combination of numerical models proves itself a useful tool to assess the environmental risk associated to harbour activities and potential pollution spills.

Slow ventricular tachycardia complicating acute myocardial infarction.

Among 200 consecutive cases of acute myocardial infarction (AMI) treated in a CCU, 117 episodes of slow ventricular tachycardia were observed in 72 patients. This figure represents a 36% rate of incidence. It is a relatively high figure because of the close monitoring to which the patient is submitted and because of the early admission to the unit. There were no significant differences of age, sex, or localization of the myocardial necrosis between patients with SVT and those without it. The different mechanisms of production described support an active origin in most of the patients for the following reasons: (1) coexistence of SVT and PVT in 51.3% of the patients; (2) identical QRS morphology in both rhythms; (3) onset of the SVT after a nonprolonged diastole in 70% of the tracings; (4) inhibition of the SVT after increase of the sinus discharge in only 14 occasions; and (5) irregular SVT rhythm in 76.9% of the recordings and ectopic mechanisms with different degrees of exit block. Because of the potential hazard of the SVT, especially if it is assumed to be of an active origin, we recommend lidocaine for patients with a sinus rate faster than 60 per minute or coexisting PVT. Atropine should be used when the sinus rate is slower than 60 per minute assuming a possible escape or passive origin.