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The observed winter Barents-Kara Sea ice concentration (BKS SIC) has shown a close association with the second empirical orthogonal function (EOF) mode of Eurasian winter surface air temperature (SAT) variability, known as Warm Arctic Cold Eurasia (WACE) pattern. However, the potential role of BKS SIC on this WACE pattern of variability and on its long-term trend remains elusive. Here, we show that from 1979 to 2022, the winter BKS SIC and WACE association is most prominent and statistically significant for the variability at the sub-decadal time scale for 5 to 6 years. We also show the critical role of the multi-decadal trend in the principal component of the WACE mode of variability for explaining the overall Eurasian winter temperature trend over the same period. Furthermore, a large multi-model ensemble of atmosphere-only experiments from 1979 to 2014, with and without the observed Arctic SIC forcing, suggests that the BKS SIC variations induce this observed sub-decadal variability and the multi-decadal trend in the WACE. Additionally, we analyse the model simulated first or the leading EOF mode of Eurasian winter SAT variability, which in observations, closely relates to the Arctic Oscillation (AO). We find a weaker association of this mode to AO and a statistically significant positive trend in our ensemble simulation, opposite to that found in observation. This contrasting nature reflects excessive hemispheric warming in the models, partly contributed by the modelled Arctic Sea ice loss.

The lower tropospheric circulation over the eastern Mediterranean during boreal summer is markedly characterized by northerly winds known as the Etesians (Tyrlis et al., 2013). These winds are accompanied by large scale subsidence and clear skies, and can mitigate the emergence of heat waves by bringing colder air from the Eurasian landmass. Here, we employ Causal Effect Networks, obtained by applying the Peter and Clark Momentary Conditional Independence (PCMCI) causal discovery algorithm (Runge, 2018), to identify causal precursors of the Etesians both in mid-latitude circulation fields and tropical convective activity at two different intraseasonal time scales (3 and 7-day average). We identify wave train activity over the North Atlantic and North American region and convective activity over the Arabian Sea and western coast of the Indian peninsula to be causal precursors of Etesians winds defined as 850 hPa meridional wind variations over the eastern Mediterranean at a lag of 3-to-6 days. In general, the influence of tropical drivers, i.e. the Indian summer monsoon (ISM) system, is found to be stronger than that of the mid-latitude wave train, thus corroborating the hypothesis that the ISM affects the circulation over the Mediterranean and Northeast Africa, as suggested by the monsoon-desert mechanisms (Rodwell and Hoskins, 1996). Moreover, at longer time scales (7 to 14-day lag), the main causal influence comes from tropical convective activity over the Indian peninsula, while the effect of the mid-latitude circulation weakens and becomes not significant. We finally employ event coincidence analysis to explore the relationship between Etesians and heat extremes in the eastern Mediterranean and assess the presence of trends in the strength of Etesians outbreaks at intraseasonal variability in the historical period.ReferencesRodwell, M. J. and Hoskins, B.: Monsoons and the dynamics of deserts, Q. J. R. Meteorol. Soc., 122, 1385–1404, 1996.Runge, J.: Causal network reconstruction from time series: From theoretical assumptions to practical estimation, 28, 075310, https://doi.org/10.1063/1.5025050, 2018.Tyrlis, E., Lelieveld, J., and Steil, B.: The summer circulation over the eastern Mediterranean and the Middle East: Influence of the South Asian monsoon, Clim. Dyn., 40, 1103–1123, https://doi.org/10.1007/s00382-012-1528-4, 2013.

Background It has been previously reported during the first COVID outbreak that patients presenting with ST-Segment Elevation Myocardial Infarction (STEMI) and concurrent COVID-19 infection have increased thrombus burden and poorer outcomes [1]. Subsequently, there have been multiple further waves of the pandemic with the emergence of at least two new COVID-19 variants and the emergence of vaccinations. To-date, there have been no reports comparing the outcomes of COVID-19-positive STEMI patients across all waves of the pandemic. Purpose The purpose of this study was to compare the baseline demographic, procedural and angiographic characteristics alongside the clinical outcomes of patients presenting with STEMI and concurrent COVID-19 infection across the COVID-19 pandemic in the UK. Methods This was a single-centre, observational study of 1250 consecutive patients admitted with confirmed STEMI treated with primary percutaneous coronary intervention (PCI) at Barts Heart Centre between 01/03/2020 and 10/03/2022. COVID +ve patients were split into 3 groups based upon the time course of the pandemic (Wave 1: March 2020-June 2020, Wave 2: Sept 2020-March 2021, Wave 3: October 2021-March 2022). Comparison was made between waves and with a control group of COVID-ve patients treated during the same timeframe. Results A total of 135 COVID +ive patients with STEMI (1st Wave: 39 patients, 2nd Wave: 60 patients, 3rd wave 35 pts) were included in the present analysis; and compared with 1115 COVID negative patients. Significant changes in the baseline characteristics, angiographic features and clinical outcomes of COVID +ive patients occurred over time. Early during the pandemic (Wave 1 2020), STEMI patients presenting with concurrent COVID-19 infection had high rates of cardiac arrest, evidence of increased thrombus burden (higher rates of multi-vessel thrombosis, stent thrombosis, higher modified thrombus grade higher use of GP IIb/IIIa inhibitors and thrombus aspiration, coagulability (more heparin for therapeutic ACT), bigger infarcts (lower myocardial blush grade and left ventricular function) and worse outcomes (mortality). However, by wave 3 (late 2021/2022), no differences existed in clinical characteristics, thrombus burden, infarct size or outcomes between COVID +ive patients and those without concurrent COVID-19 infection with significant differences compared to earlier COVID +ve patients. Poor outcomes later in the study period were predominantly in unvaccinated individuals. Conclusions Significant changes have occurred in the clinical characteristics, angiographic features and outcomes of STEMI patients with COVID-19 infection treated by primary PCI during the course of the pandemic. Importantly it appears that angiographic features and outcomes of recent waves are no different to a non-COVID-19 population. Funding Acknowledgement Type of funding sources: None.

A 53-year-old female patient with a history of stent angioplasties in 2014 and coronary artery bypass graft surgery (CABG) to the left anterior descending and obtuse marginal arteries in 2016 underwent coronary angiography in July 2019 due to unstable angina. Both grafts were patent whereas the proximal right coronary artery (RCA) contained an intermediate in-stent stenosis which corresponded to an area of stent deformation with an inward displacement of the struts on both sides of the stent without discontinuity in the stent body (Figures 1 A, B). The stenosis was associated with an instantaneous wave-free ratio of 1.0. Intravascular ultrasound (IVUS) examination (Figures 1, 2) revealed a grossly distorted stent without strut malapposition or neointimal buildup (Figures 1 C and 2 panels 2, 6), which harboured an area with ulcerated atheroma and sparse stent struts indicating stent fracture (SF) (Figures 1 D and 2 panels 3–5). Proximal RCA angulation and hinge motion were observed in February 2014 before the successful implantation of a 3.5 mm × 28 mm biolimus A9-eluting BioMatrix Flex (Biosensor, Morges, Switzerland) stent in order to treat a catheter-induced dissection (Figure 3). Coronary angiography performed before CABG in March 2016 showed a structurally intact proximal RCA stent (Figure 4). Consequently, chronic stent recoil (SR) secondary to loss of radial strength of the stent due to late (> 1 year) SF attributed to mechanical fatigue was diagnosed. Angioplasty with a 3.75 mm non-compliant balloon and then a 3.75 mm paclitaxel-coated balloon was undertaken successfully (Figure 5). The patient was discharged on dual antiplatelet therapy to be taken for at least 12 months. Follow-up angiography at 6 months showed a patent stent without recurrent SR (Figure 6).

We use reanalysis data to substantiate the role of Ural Blocking (UB) in driving the Warm Arctic‐Cold Siberia (WACS) pattern, which represents an anti‐correlation of surface temperature between the Barents‐Kara Seas and Central Asia. We confirm a robust link between UB and the WACS pattern on daily to sub‐seasonal timescales. UB controls the pace of the WACS; warming over the Barents‐Kara Seas and cooling over Central Asia peak 3‐5 days after the UB onset. The observed sea‐ice deficit over the Barents‐Kara Seas in the weeks prior to UB onset is not statistically significant when the long‐term trend in sea‐ice is removed. Thus, the sea‐ice deficit may not have a direct impact on UB occurrence but it develops as a delayed response to UB. The interannual variability of WACS is also strongly linked to UB. We identify an upward trend in wintertime UB in recent decades that accounts for a cooling rate of 1∘C/decade over Central Asia. Over the Barents‐Kara Seas, UB trends explain a small fraction of the warming, which is dominated by Arctic Amplification. Finally, the link between UB and the WACS is statistically robust over the ERA‐Interim period but weaker during the 1990s when the lowest activity of UB Episodes was observed.

During boreal summer, large scale subsidence and a persistent northerly flow, known as the Etesians, characterize the tropospheric circulation over the eastern Mediterranean, respectively bringing clear skies and mitigating the emergence of heat waves. Atmospheric drivers over both South Asia and the North Atlantic have been proposed to influence the intraseasonal variability of subsidence and Etesians over the eastern Mediterranean. Here, we employ Causal Effect Networks, obtained by applying the Peter and Clark Momentary Conditional Independence (PCMCI) causal discovery algorithm, to identify causal precursors of subsidence and Etesians in a set of atmospheric fields. We find that both wave train activity over the North Atlantic/North American region and convective activity over the northern Indian Ocean are causally related to the 3-day average 850 hPa meridional wind variations over the eastern Mediterranean at a lag of 3-to-6 days. For 3-day average 500 hPa vertical wind velocity, causal precursors over the Middle East and Arabian Sea similar to those identified for the Etesian are found. We further explore in detail the different nature of the causal precursors to the Etesians and subsidence over the eastern Mediterranean by applying varying averaging in the variables representing the involved phenomena.

Large historical and future ensemble simulations from the Max-Planck Institute and the Canadian Earth System Models and from CMIP5 have been analysed to investigate the uncertainty due to internal variability in multi-decadal temperature and precipitation trends over Europe. Internal variability dominates the uncertainties in temperature and precipitation trends in all seasons at 30-year time scales. Locally, seasonal 30-year temperature trends deviate up to ±3 °C from the ensemble mean trend. Thus, in the entire of Europe, local seasonal temperature changes until year 2050 from below −1 °C up to more than 4 °C are possible according to the model results. Up to 30 of all ensemble members show negative temperature trends until year 2050 in winter, up to 10 of the members in summer. Uncertainties of 30-year precipitation trends due to internal variability exceed the trends almost everywhere in Europe. Only in few European regions more than 75 of the members agree on the sign of the change until year 2050. In southern Sweden, minimum and maximum winter (summer) temperature trends in the next 30 years differ with up to 7 °C (5 °C) between individual members of the large model ensembles. Large positive temperature trends are linked to positive (negative) precipitation trends in winter (summer) in southern Sweden. This variability is attributed to the variability in large scale atmospheric circulation trends, mainly due to internal atmospheric variability. We find only weak linkages between the variability of temperature trends and the dominant decadal to multi-decadal climate modes. This indicates that there is limited potential to predict the multi-decadal variability in climate trends. The main findings from our study are robust across the large ensembles from the different models used in this study but at the local scale, the results depend also on the choice of the model. © Tellus A: 2020. © 2020 The Author(s). Published by Informa UK Limited, trading as Taylor Francis Group.

An unusual case of nitroglycerin-induced Paracentral Acute Middle Maculopathy (PAMM) is presented. A 50-year-old patient with sudden vision loss and scotoma was followed up with swept-source optical coherence tomography (SS-OCT), optical coherence tomography-angiography (OCT-A), and fluorescein angiography (FA). An anal fissure treated with glyceryl trinitrate (GTN) 0.2% ointment with headache and dizziness after application was reported. Fundoscopy OS revealed mild retinal venous dilatation and tortuosity with scattered blot hemorrhages and subtle, parafoveal, whitish lesions in the outer retina. SS-OCT revealed diffuse, hyperreflective lesions in the inner plexiform (IPL), inner nuclear (INL), and outer plexiform layers (OPL). OCT-A revealed focal dropout in the deep capillary plexus. FA showed masking due to blot hemorrhages and early punctuate leakage in the inner retina. This entity was identified as nitroglycerin-induced PAMM. Over the following 8 months, after discontinuation of the ointment application, the patient was symptom-free with stable visual acuity. OCT revealed INL/OPL thinning and confirmed complete lesion resolution. This first report of retinal vascular abnormalities due to nitrite ointment provides an insight into an unknown side effect of nitroglycerin ointment use. A dose-dependent correlation between GTN application and retinal vascular abnormalities remains to be confirmed.

Blocking is associated with outbreaks of easterlies induced by a continuum of features including anticyclones, cyclones or both. Blocking identification methods disagree on the levels of high-latitude blocking (HLB) activity. We investigate the cause of the disagreement in HLB activity over the Northern Hemisphere obtained by two 2D methods: the PV– (Formula presented.) index and the Absolute Geopotential Height (AGH) reversal method. Although both classify as absolute field methods, the former yields nearly twice the winter HLB activity of the latter method. We show that this discrepancy is caused by the addition of a poleward criterion in the AGH method that requires strong poleward westerlies. The additional criterion in the AGH method shifts the focus on the detection of blocking ridges and thus other blocking circulation patterns are under-represented. Both methods agree on the climatology of midlatitude blocking because the poleward criterion has been tuned to capture the strong midlatitude blocking, but the discrepancy grows in high latitudes. HLBs are different because they occur on the northern flank of the westerlies and are associated with the equatorward displacement of the midlatitude jet. HLB anticyclones are weaker and do not induce strong poleward westerlies compared to their midlatitude counterparts. The implementation of a strict poleward criterion designed to identify midlatitude blocks rejects many HLBs. The use of the less strict cut-off threshold (CT) of 0 m (°lat)−1 in the poleward criterion for latitudes higher than 60°N results in the convergence of climatology, interannual variability and trends of HLB between the two methods, especially during winter. The additional HLBs identified by the modified AGH algorithm develop from cyclonic wave breaking that is typical for oceanic blocking. The modified AGH method can be useful in detecting more robust HLB trends in climate model projections. © 2020 The Authors.

Two long-lasting high-pressure systems in summer 2018 led to persisting heatwaves over Scandinavia and other parts of Europe and an extended summer period with devastating impacts on agriculture, infrastructure, and human life. We use five climate model ensembles and the unique 263-year-long Stockholm temperature time series along with a composite 150-year-long time series for the whole of Sweden to set the latest heatwave in the summer of 2018 into historical perspective. With 263 years of data, we are able to grasp the pre-industrial period well and see a clear upward trend in temperature as well as upward trends in five heatwave indicators. With five climate model ensembles providing 20 580 simulated summers representing the latest 70 years, we analyse the likelihood of such a heat event and how unusual the 2018 Swedish summer actually was. We find that conditions such as those observed in summer 2018 are present in all climate model ensembles. An exception is the monthly mean temperature for May for which 2018 was warmer than any member in one of the five climate model ensembles. However, even if the ensembles generally contain individual years like 2018, the comparison shows that such conditions are rare. For the indices assessed here, anomalies such as those observed in 2018 occur in a maximum of 5 % of the ensemble members, sometimes even in less than 1 %. For all of the indices evaluated, we find that the probability of a summer such as that in 2018 has increased from relatively low values in the pre-industrial era (1861–1890, one ensemble) and the recent past (1951–1980, all five ensembles) to higher values in the most recent decades (1989–2018). An implication of this is that anthropogenic climate change has strongly increased the probability of a warm summer, such as the one observed 2018, occurring in Sweden. Despite this, we still find such summers in the pre-industrial climate in our simulations, albeit with a lower probability.

Background: Recent reports suggest an association between ethnicity and COVID-19 mortality. In the present multi-center study, we aimed to assess the differences underlying this association, and ascertain whether ethnicity also mediates other aspects of COVID-19 like cardiovascular complications. Methods: Data were collected from a mixed-ethnicity UK cohort of 613 patients admitted and diagnosed COVID-19 positive, across six hospitals in London during the second half of March 2020: 292 were White Caucasian ethnicity, 203 were Asian and 118 were of Afro-Caribbean ethnicity. Results: Caucasian patients were older (P