Search

Climate hazards associated with compound events (CEs) have lately received increasing attention over South America (SA) due to their potential risks and amplification of impacts. This work addressed the evaluation of different temperature‐ and precipitation‐based CE in SA considering the CORDEX‐CORE ensemble of regional climate models (RCMs) and their driving earth system models (ESMs) in the reference period 1981–2010 and the late 21st century (2070–2099), for the Representative Concentration Pathways (RCPs) 2.6 and 8.5 scenarios. The assessment focused on model performance for the individual events—heatwaves (HWs), Extreme rainfall (ER) days, and dry‐spells (DSs)—and their compound occurrence in terms of climatological frequency and duration. The spatial patterns of individual events were adequately reproduced by the RCMs, evidencing general overestimations in extreme precipitation intensities. In terms of CE, the frequencies of coincident HWs and DSs (sequential DSs and ER) were remarkable over central‐eastern Brazil and southern SA (southeastern SA). The main features of CE were generally well‐simulated by the RCMs, although they presented regional differences such as an underestimation of the maximum frequencies of these two CE in northeastern Brazil and southeastern SA, respectively. The high‐resolution information was generally in line with the larger‐scale driving ESMs. The climate change signal analysis generally showed robust future increases in CE frequency and duration in different areas of SA, as for coincident HWs and DSs (sequential DSs and ER) over northern SA and southern Brazil (southeastern SA). This was mostly consistent among the RCMs ensemble and notably strengthened in the worst‐case scenario (RCP 8.5). Key Points: Coincident heatwaves and dry‐spells (DSs) and sequential DSs and extreme rainfall are remarkable compound events (CEs) over South AmericaRegional climate models can reproduce the frequency and duration of CEs, but with some regional differencesCEs are generally expected to be more frequent in the late 21st century, particularly in the Representative Concentration Pathway 8.5 scenario [ABSTRACT FROM AUTHOR]

The representation of the South American Monsoon System (SAMS) by general circulation models (GCMs) is of key relevance for a better understanding of the physical rationale behind the recent climate changes over South Tropical South America (STSA) and their expected changes in a global warming scenario. During the last four decades, STSA experienced a lengthening of the dry season associated with diverse forcings. In this work, a set of 16 GCMs historical Coupled Model Intercomparison Project Phase 6 coupled simulations were evaluated during 1979–2014 in terms of how well they reproduced the atmospheric circulation over STSA through a circulation‐patterns (CPs) approach. Nine CPs were first identified based on low‐level winds from the ERA5 reanalysis. Focus was put on the representation of CPs during the dry‐to‐wet transition season (July‐October). Model performance depended on the seasonal cycle and spatial structure of the CPs. GCMs adequately reproduced the different CPs, with lower skills in the transition seasons. GCMs tended to go from dry to wet conditions too quickly, evidencing deficiencies in the representation of the SAMS onset, related to a poor representation of the southerly wind intrusions to STSA and the variability of the South American low‐level jet. Some GCMs were able to associate the occurrence of anomalous dry and wet years with specific CPs, suggesting well‐represented physical mechanisms controlling precipitation variability. This study could identify a few GCMs that adequately simulated the CPs in STSA (among them, CESM2, CMCC‐CM2‐HR4 and MPI‐ESM1‐2‐HR), which is relevant for driving high‐resolution models and the analysis of future projections. Key Points: Some general circulation models (GCMs) adequately represented both the seasonal cycle and spatial structure of circulation patternsGCMs often struggled in representing the monsoon initiation and the variability of the South American low‐level jetGCMs tended to go from dry to wet conditions too quickly [ABSTRACT FROM AUTHOR]

A collection of 10 high-impact extreme precipitation events occurring in Southeastern South America during the warm season has been analyzed using statistical (ESD) and dynamical downscaling approaches. Regional Climate Models from the CORDEX database for the South American domain at two horizontal resolutions, 50 km and 25 km, short-term simulations at 20 km and at 4 km convective-permitting resolution and statistical downscaling techniques based on the analogue method and the generalized linear model approach were evaluated. The analysis includes observational datasets based on gridded data, station data and satellite products that allow assessing the observational uncertainty that characterizes extreme events in the region. It is found that the ability of the modelling strategies in capturing the main features of the extreme rainfall varies across the events. The higher the horizontal resolution of the models, the more intense and localized the core of the rainfall event, being the location of the exit region of the low-level jet and the low-level moisture flux convergence during the initial stages of the events the most relevant features that determine models' ability of capturing the location and intensity of the core of the heavy rainfall. ESD models based on the generalized linear approach overestimate the spatial extension of the events and underestimate the intensity of the local maxima. Weather-like convective-permitting simulations depict an overall good performance in reproducing both the rainfall patterns and the triggering mechanisms of the extreme events as expected, given that these simulations are strongly controlled by the initial conditions. [ABSTRACT FROM AUTHOR]

The main features of daily extreme precipitation and circulation types in southern South America (SSA) were evaluated and compared in both multiple observational datasets (rain gauges, CHIRPS, CPC and MSWEP) and simulations from four regional climate models (RCMs) driven by ERA-Interim during 1980–2010. The inter-comparison of extreme events, characterised in terms of their intensity, frequency and spatial coverage, varied across SSA showing large differences among observational datasets and RCMs and reflecting the current observational uncertainty when evaluating precipitation extremes at a daily scale. The spread between observational datasets was smaller than for the RCMs. Most of the RCMs successfully captured the spatial pattern of extreme precipitation across SSA, although RCA4 (REMO) usually underestimated (overestimated) precipitation intensities, particularly the maximum amounts in southeastern South America (SESA), where the extremes are remarkable. The synoptic circulation was described by a classification of circulation types (CTs) using Self-Organizing Maps (SOM). Specific CTs were found to significantly enhance the occurrence of extreme precipitation events in sectorized areas of SESA. The RCMs adequately reproduced the SOM node frequencies, although they tended to simplify the predominant CTs into a more reduced number of configurations. They appropriately represented the extreme precipitation frequencies conditioned by each CT, exhibiting some limitations in the location and intensity of the resulting precipitation systems. These sorts of evaluations contribute to a better understanding of the physical mechanisms responsible for extreme precipitation and of their future projections in a climate change scenario. [ABSTRACT FROM AUTHOR]

Southeastern South America (SESA) stands out as a remarkable region of occurrence of deep convection. This is mainly due to the proximity of the Andes, which eventually determine their magnitude and intensity. In this work, we used a set of convection-permitting (4 km horizontal resolution) regional climate models to explore their ability to reproduce the synoptic forcings that trigger deep convection over La Plata basin. The study considered simulating three extreme convective precipitation events in two different timescales. On one hand, a short-term simulation initiated a few hours before the onset of each event, spanning 3–4 days. On the other hand, as regional climate modelling, a 6-month simulation that includes the three selected events. In contrast to parameterized convection, the convection-permitting resolutions not only intensified the events, but also modified the location of the maximum precipitation by modulating the low-level atmospheric circulation. Vertically integrated moisture flux convergence emerged as a noticeable footprint of deep moist convection, regardless of the model and timescale. The performance of the models in reproducing the observed precipitation was also quantitatively analyzed. The skill depends on the spatial scale. The results were case-dependent in the short-term simulations. However, an analysis over multiple events in the long-term simulations revealed that, in general, convection-permitting resolutions better capture the spatial distribution of the extreme precipitation in SESA. The study comprises the first multi-model ensemble of convection-permitting simulations over the region, a seed for a further analysis with a more complete ensemble to better understand the results presented here. [ABSTRACT FROM AUTHOR]

The aim of this work is to present preliminary results of the statistical and dynamical simulations carried out within the framework of the Flagship Pilot Study in southeastern South America (FPS-SESA) endorsed by the Coordinated Regional Climate Downscaling Experiments (CORDEX) program. The FPS-SESA initiative seeks to promote inter-institutional collaboration and further networking with focus on extreme rainfall events. The main scientific aim is to study multi-scale processes and interactions most conducive to extreme precipitation events through both statistical and dynamical downscaling techniques, including convection-permitting simulations. To this end, a targeted experiment was designed considering the season October 2009 to March 2010, a period with a record number of extreme precipitation events within SESA. Also, three individual extreme events within that season were chosen as case studies for analyzing specific regional processes and sensitivity to resolutions. Four dynamical and four statistical downscaling models (RCM and ESD respectively) from different institutions contributed to the experiment. In this work, an analysis of the capability of the set of the FPS-SESA downscaling methods in simulating daily precipitation during the selected warm season is presented together with an integrated assessment of multiple sources of observations and available CORDEX Regional Climate Model simulations. Comparisons among all simulations reveal that there is no single model that performs best in all aspects evaluated. The ability in reproducing the different features of daily precipitation depends on the model. However, the evaluation of the sequence of precipitation events, their intensity and timing suggests that FPS-SESA simulations based on both RCM and ESD yield promising results. Most models capture the extreme events selected, although with a considerable spread in accumulated values and the location of heavy precipitation. [ABSTRACT FROM AUTHOR]

Intrauterine intestinal obstruction complicated by midgut volvulus is a serious life-threatening diagnosis. Immediate surgical intervention is generally the course of action upon diagnosis to prevent morbidity and mortality. We report a case of intrauterine intestinal obstruction where the neonate then presented with an unusual onset of volvulus within the first 12 hours of life. The patient was born with generalized edema, a distended abdomen, and pallor. Unlike many cases, the patient did not present with typical signs of volvulus. Diagnostic imaging preceding delivery and the stable postnatal clinical course did not offer a justification for immediate laparotomy. Less than 24 hours later, the patient's hemoglobin significantly dropped leading to an emergent laparotomy. Findings included a volvulus of the terminal ileum and large amounts of intraluminal blood. Our case report includes an analysis of clinical observations that should be considered so that patients presenting with similar signs receive earlier surgical intervention. [ABSTRACT FROM AUTHOR]

The article discusses the weather condition in southern South America which include the countries of Chile, Uruguay, Argentina and adjacent areas of Southern Brazil for the years 2014 to 2015. It mentions that temperature in the said areas during the said period is above-normal and that Argentina and Uruguay have the mean temperature. It cites several notable climatic events in the region including the heavy rainfall in Chile and the decline in precipitation in Argentina.

Background Rett syndrome ( RTT) is an intellectual deficit and movement disorder that develops during early childhood in girls. Affected children are normal until 6-18 months of age, after which symptoms begin to appear. Most cases of RTT are due to mutations in the Me CP2 gene leading to disruption of neuronal communication in the central nervous system. In addition, RTT patients show peripheral ailments such as gastrointestinal ( GI), respiratory, and cardiac dysfunction. The etiology of intestinal dysfunction in RTT is not well-understood. Reports on the presence of Me CP2 in the peripheral nervous system are scant. As such we examined the levels of Me CP2 in human and murine GI tissue and assessed Me CP2 expression at various developmental stages. Methods Immunohistochemistry for Me CP2, HuC/D, juvenile beta tubulin, and GFAP was performed on human and murine intestine. Western blots of these same tissues were probed with Me CP2, vAChT, nNOS, and beta-actin antibodies. Key Results Me CP2 is expressed throughout the GI tract. Me CP2 is expressed specifically in the enteric nervous system of the GI tract. Me CP2 is expressed in the GI tract throughout development with appearance beginning at or before E11.5 in the murine intestine. Conclusions & Inferences The proof of Me CP2 expression in enteric neurons suggests that the GI dysmotility in Rett may arise from enteric network dysfunction secondary to Me CP2 mutation. [ABSTRACT FROM AUTHOR]

Lymphatic malformations in the neck can present as large fetal neck masses causing airway obstructions with potential perinatal demise and can pose a therapeutic challenge. We present a rare case of prenatally diagnosed large fetal neck mass with features of lymphatic malformation with intralesional hemorrhage of uncertain origin. Postnatal evaluation showed a complex cystic-solid lesion eroding through the skin with an open wound that made it clinically hard to differentiate from a teratoma. Given that malignancy could not be completely ruled out, surgery was favored. Final pathology showed a complex lymphatic malformation with intralesional hemorrhage, despite having no associated capillary, venous or arterial malformations. [ABSTRACT FROM AUTHOR]