Differences between two ensembles of Goddard Earth Observing System Chemistry‐Climate Model simulations isolate the impact of North Pacific sea surface temperatures (SSTs) on the Arctic winter ...climate. One ensemble of extended winter season forecasts is forced by unusually high SSTs in the North Pacific, while in the second ensemble SSTs in the North Pacific are unusually low. High – Low differences are consistent with a strengthened Western Pacific atmospheric teleconnection pattern, and in particular, a weakening of the Aleutian low. This relative change in tropospheric circulation inhibits planetary wave propagation into the stratosphere, in turn reducing polar stratospheric temperature in mid‐ and late winter. The number of winters with sudden stratospheric warmings is approximately tripled in the Low ensemble as compared with the High ensemble. Enhanced North Pacific SSTs, and thus a more stable and persistent Arctic vortex, lead to a relative decrease in lower stratospheric ozone in spring, affecting the April clear‐sky UV index at Northern Hemisphere midlatitudes.
Key Points
Enhanced North Pacific SSTs inhibit tropospheric planetary wave driving
Enhanced North Pacific SSTs lead to a cooler polar stratosphere in late winter
North Pacific SSTs affect Arctic total ozone and clear‐sky UV flux in spring
Nitrogen oxides (NOxNO+NO2) are produced during combustion processes and, thus may serve as a proxy for fossil fuel-based energy usage and committed greenhouse gases and other pollutants. We use ...high-resolution nitrogen dioxide (NO2) data from the Ozone Monitoring Instrument (OMI) to analyze changes in urban NO2 levels around the world from 2005 to 2014, finding complex heterogeneity in the changes. We discuss several potential factors that seem to determine these NOx changes. First, environmental regulations resulted in large decreases. The only large increases in the United States may be associated with three areas of intensive energy activity. Second, elevated NO2 levels were observed over many Asian, tropical, and subtropical cities that experienced rapid economic growth. Two of the largest increases occurred over recently expanded petrochemical complexes in Jamnagar (India) and Daesan (Korea). Third, pollution transport from China possibly influenced the Republic of Korea and Japan, diminishing the impact of local pollution controls. However, in China, there were large decreases over Beijing, Shanghai, and the Pearl River Delta, which were likely associated with local emission control efforts. Fourth, civil unrest and its effect on energy usage may have resulted in lower NO2 levels in Libya, Iraq, and Syria. Fifth, spatial heterogeneity within several megacities may reflect mixed efforts to cope with air quality degradation. We also show the potential of high-resolution data for identifying NOx emission sources in regions with a complex mix of sources. Intensive monitoring of the world's tropical subtropical megacities will remain a priority, as their populations and emissions of pollutants and greenhouse gases are expected to increase significantly.
We modeled the differentiation of the South Pole–Aitken (SPA) impact melt sheet to determine whether noritic lithologies observed within SPA formed as a result of the impact. Results indicate ...differentiation of SPA impact melt can produce noritic layers that may accommodate observed surface compositions but only in specific scenarios. One of nine modeled impact melt compositions yielded layers of noritic materials that account for observations of noritic lithologies at depths of ~6 km. In this scenario, impact occurred before a hypothesized lunar magma ocean cumulate overturn. The 50 km deep melt sheet would have formed an insulating quenched layer at the surface before differentiating. The uppermost differentiated layers in this scenario have FeO and TiO2 contents consistent with orbital observations if they were subsequently mixed with the uppermost quenched melt layer and with less FeO‐ and TiO2‐enriched materials such as ejecta emplaced during younger impacts. These results verify that noritic lithologies observed within SPA could have formed as a direct result of the impact. Therefore, locations within SPA that contain noritic materials represent potential destinations for collecting samples that can be analyzed to determine the age of the SPA impact. Potential destinations include central peaks of Bhabha, Bose, Finsen, and Antoniadi craters, as well as walls of Leibnitz and Schrödinger basins. Additionally, potential remnants of the uppermost quenched melt may be preserved in gabbroic material exposed in “Mafic Mound.” Exploring and sampling these locations can constrain the absolute age of SPA, a task that ranks among the highest priorities in lunar science.
Key Points
SPA impact melt differentiation accommodates observed noritic surface materials
SPA formed before LMO overturn to produce noritic material at the lunar surface
Norite‐bearing materials represent key samples for dating the age of SPA
OBJECTIVESThe 1-year data from the international ADVANCE (Assessing Diagnostic Value of Non-invasive FFRCT in Coronary Care) Registry of patients undergoing coronary computed tomography angiography ...(CTA) was used to evaluate the relationship of fractional flow reserve derived from coronary CTA (FFRCT) with downstream care and clinical outcomes. BACKGROUNDGuidelines for management of chest pain using noninvasive imaging pathways are based on short- to intermediate-term outcomes. METHODSPatients (N = 5,083) evaluated for clinically suspected coronary artery disease and in whom atherosclerosis was identified by coronary CTA were prospectively enrolled at 38 international sites from July 15, 2015, to October 20, 2017. Demographics, symptom status, coronary CTA and FFRCT findings and resultant site-based treatment plans, and clinical outcomes through 1 year were recorded and adjudicated by a blinded core laboratory. Major adverse cardiac events (MACE), death, myocardial infarction (MI), and acute coronary syndrome leading to urgent revascularization were captured. RESULTSAt 1 year, 449 patients did not have follow-up data. Revascularization occurred in 1,208 (38.40%) patients with an FFRCT ≤0.80 and in 89 (5.60%) with an FFRCT >0.80 (relative risk RR: 6.87; 95% confidence interval CI: 5.59 to 8.45; p < 0.001). MACE occurred in 55 patients, 43 events occurred in patients with an FFRCT ≤0.80 and 12 occurred in those with an FFRCT >0.80 (RR: 1.81; 95% CI: 0.96 to 3.43; p = 0.06). Time to first event (all-cause death or MI) occurred in 38 (1.20%) patients with an FFRCT ≤0.80 compared with 10 (0.60%) patients with an FFRCT >0.80 (RR: 1.92; 95% CI: 0.96 to 3.85; p = 0.06). Time to first event (cardiovascular death or MI) occurred cardiovascular death or MI occurred more in patients with an FFRCT ≤0.80 compared with patients with an FFRCT >0.80 (25 0.80% vs. 3 0.20%; RR: 4.22; 95% CI: 1.28 to 13.95; p = 0.01). CONCLUSIONSThe 1-year outcomes from the ADVANCE FFRCT Registry show low rates of events in all patients, with less revascularization and a trend toward lower MACE and significantly lower cardiovascular death or MI in patients with a negative FFRCT compared with patients with abnormal FFRCT values. (Assessing Diagnostic Value of Non-invasive FFRCT in Coronary Wave ADVANCE; NCT02499679).
Incorporating the ROCA into ovarian cancer screening has been shown to double the number of screen-detected ovarian cancers compared with single-threshold rules.5 In the UKCTOCS, 202 638 ...postmenopausal women aged 50–74 years were randomly assigned in a 1:1:2 ratio to receive either annual multimodal screening (MMS), which included CA125 testing with the ROCA followed by repeat CA125 and TVS as a second line test, TVS alone (ultrasound screening USS), or no screening.6 Consistent with PLCO, results published after a median of 11·1 years of follow-up reported no significant mortality reduction in either screening group (MMS 15% reduction 95% CI –3 to 30 and USS 11% reduction –7 to 27).6 However, the difference in mortality between the screened and unscreened groups appeared to widen with time, and the authors postulated that a delayed mortality benefit might emerge with additional follow-up. There was a shift in the distribution of disease stage at diagnosis with MMS; women in the MMS group had a 24·5% lower incidence of stage IV ovarian cancers and a 47·2% higher incidence of stage I ovarian cancers than women randomly assigned to no screening, but this difference was accompanied by a higher case fatality rate for stage I cancers (14·8% in the MMS group vs 9·4% in the no screening group). ...although some ovarian cancers might have been detected earlier with MMS, the earlier diagnosis was not enough to alter the prognosis of these cancers and did not translate into lives saved. ...alternative approaches to screening that target women at higher risk as opposed to the general population might prove more effective at reducing ovarian cancer deaths and could lessen the harm from false positive screens, as has been exemplified by lung cancer screening.8 Consequently, screening for ovarian cancer remains elusive but is not a lost cause; there is simply much more work to be done.
A meteorological reanalysis dataset and experiments of the Goddard Earth Observing System Chemistry-Climate Model, Version 2 (GEOS V2 CCM) are used to study the boreal winter season teleconnections ...in the Pacific-North America region and in the stratosphere generated by Central Pacific and Eastern Pacific El Niño. In the reanalysis data, the sign of the North Pacific and stratospheric response to Central Pacific El Niño is sensitive to the composite size, the specific Central Pacific El Niño index used, and the month or seasonal average that is examined, highlighting the limitations of the short observational record. Long model integrations suggest that the response to the two types of El Niño are similar in both the extratropical troposphere and stratosphere. Namely, both Central Pacific and Eastern Pacific El Niño lead to a deepened North Pacific low and a weakened polar vortex, and the effects are stronger in late winter than in early winter. However, the long experiments do indicate some differences between the two types of El Niño events regarding the latitude of the North Pacific trough, the early winter polar stratospheric response, surface temperature and precipitation over North America, and globally averaged surface temperature. These differences are generally consistent with, though smaller than, those noted in previous studies.
Abstract
Aims
Non-invasive assessment of stable chest pain patients is a critical determinant of resource utilization and clinical outcomes. Increasingly coronary computed tomography angiography ...(CCTA) with selective CCTA-derived fractional flow reserve (FFRCT) is being used. The ADVANCE Registry, is a large prospective examination of using a CCTA and FFRCT diagnostic pathway in real-world settings, with the aim of determining the impact of this pathway on decision-making, downstream invasive coronary angiography (ICA), revascularization, and major adverse cardiovascular events (MACE).
Methods and results
A total of 5083 patients with symptoms concerning for coronary artery disease (CAD) and atherosclerosis on CCTA were enrolled at 38 international sites from 15 July 2015 to 20 October 2017. Demographics, symptom status, CCTA and FFRCT findings, treatment plans, and 90 days outcomes were recorded. The primary endpoint of reclassification between core lab CCTA alone and CCTA plus FFRCT-based management plans occurred in 66.9% confidence interval (CI): 64.8–67.6 of patients. Non-obstructive coronary disease was significantly lower in ICA patients with FFRCT ≤0.80 (14.4%) compared to patients with FFRCT >0.80 (43.8%, odds ratio 0.19, CI: 0.15–0.25, P < 0.001). In total, 72.3% of subjects undergoing ICA with FFRCT ≤0.80 were revascularized. No death/myocardial infarction (MI) occurred within 90 days in patients with FFRCT >0.80 (n = 1529), whereas 19 (0.6%) MACE hazard ratio (HR) 19.75, CI: 1.19–326, P = 0.0008 and 14 (0.3%) death/MI (HR 14.68, CI 0.88–246, P = 0.039) occurred in subjects with an FFRCT ≤0.80.
Conclusions
In a large international multicentre population, FFRCT modified treatment recommendation in two-thirds of subjects as compared to CCTA alone, was associated with less negative ICA, predicted revascularization, and identified subjects at low risk of adverse events through 90 days.
Comprehensive chemistry‐climate model experiments and observational data are used to show that up to half of the satellite era early springtime cooling trend in the Arctic lower stratosphere was ...caused by changing sea surface temperatures (SSTs). An ensemble of experiments forced only by changing SSTs is compared to an ensemble of experiments in which both the observed SSTs and chemically and radiatively active trace species are changing. By comparing the two ensembles, it is shown that warming of Indian Ocean, North Pacific, and North Atlantic SSTs and cooling of the tropical Pacific have strongly contributed to recent polar stratospheric cooling in late winter and early spring. When concentrations of ozone‐depleting substances and greenhouse gases are fixed, polar ozone concentrations show a small but robust decline due to changing SSTs. Ozone loss is larger in the presence of changing concentrations of ozone‐depleting substances and greenhouse gases. The stratospheric changes can be understood by examining the tropospheric height and heat flux anomalies generated by the anomalous SSTs. Finally, recent SST changes have contributed to a decrease in the frequency of late winter stratospheric sudden warmings.
Key Points
SSTs have driven ∼1/2 of observed spring cooling trend in Arctic stratosphere
Recent SST trends have driven polar ozone depletion
SST anomalies generate anomalous wave driving of the vortex
The effect of El Niño‐Southern Oscillation (ENSO) on the frequency and character of Northern Hemisphere major mid‐winter stratospheric sudden warmings (SSWs) is evaluated using a meteorological ...reanalysis data set and comprehensive chemistry‐climate models. There is an apparent inconsistency between the impact of opposite phases of ENSO on the seasonal mean vortex and on SSWs: El Niño leads to an anomalously warm, and La Niña leads to an anomalously cool, seasonal mean polar stratospheric state, but both phases of ENSO lead to an increased SSW frequency. A resolution to this apparent paradox is here proposed: the region in the North Pacific most strongly associated with precursors of SSWs is not strongly influenced by El Niño and La Niña teleconnections. In the observational record, both La Niña and El Niño lead to similar anomalies in the region associated with precursors of SSWs and, consistent with this, there is a similar SSW frequency in La Niña and El Niño winters. A similar correspondence between the penetration of ENSO teleconnections into the SSW precursor region and SSW frequency is found in the comprehensive chemistry‐climate models. The inability of some of the models to capture the observed relationship between La Niña and SSW frequency appears related to whether the modeled ENSO teleconnections result in extreme anomalies in the region most closely associated with SSWs. Finally, it is confirmed that the seasonal mean polar vortex response to ENSO is only weakly related to the relative frequency of SSWs during El Niño and La Niña.
Key Points
EN and LN cause more frequent SSW despite having opposite effects in winter‐mean
ENSO teleconnections are consistent with this seeming paradox
Model differences in ENSO‐SSW frequency are related to modeled teleconnections
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