New Insights Into Cyclone Impacts on Sea Ice in the Atlantic Sector of the Arctic Ocean in Winter

Peer reviewe

Impact of three intense winter cyclones on the sea ice cover in the Barents Sea : A case study with a coupled regional climate model

We utilize a nudged simulation with the coupled regional atmosphere-ocean-sea ice model HIRHAM-NAOSIM over the Arctic to conduct an in-depth analysis of the impact of a sequence of three intense cyclones on the sea ice cover in the Barents and Kara Seas in February 2020. To clarify the underlying mechanisms we decompose changes in sea ice concentration (SIC) and thickness (SIT) into their dynamic and thermodynamic contributions and analyze them in concert with simulated changes in the wind forcing and the surface energy budget. Our findings reveal that changes in SIT during and after the cyclone passages are mostly driven by dynamic processes such as increased ice drift and deformation. With respect to SIC, the relative importance of dynamics and thermodynamics depends on the considered time scale and on the general conditions of the cyclone passages. If cyclones follow on each other in rapid succession, dynamic mechanisms dominate the SIC response for time scales of more than 2 weeks and thermodynamic effects via advection of warm-moist/cold-dry air masses on the cyclone's front/back side only play a secondary role. However, if sufficiently long time elapses until the arrival of the next storm, thermodynamic SIC increase due to refreezing under the influence of cold and dry air at the backside of the cyclone becomes the dominating mechanism during the days following the cyclone passage.Peer reviewe

Why Are Outcomes Different for Registry Patients Enrolled Prospectively and Retrospectively? Insights from the Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF).

Background: Retrospective and prospective observational studies are designed to reflect real-world evidence on clinical practice, but can yield conflicting results. The GARFIELD-AF Registry includes both methods of enrolment and allows analysis of differences in patient characteristics and outcomes that may result. Methods and Results: Patients with atrial fibrillation (AF) and ≥1 risk factor for stroke at diagnosis of AF were recruited either retrospectively (n = 5069) or prospectively (n = 5501) from 19 countries and then followed prospectively. The retrospectively enrolled cohort comprised patients with established AF (for a least 6, and up to 24 months before enrolment), who were identified retrospectively (and baseline and partial follow-up data were collected from the emedical records) and then followed prospectively between 0-18 months (such that the total time of follow-up was 24 months; data collection Dec-2009 and Oct-2010). In the prospectively enrolled cohort, patients with newly diagnosed AF (≤6 weeks after diagnosis) were recruited between Mar-2010 and Oct-2011 and were followed for 24 months after enrolment. Differences between the cohorts were observed in clinical characteristics, including type of AF, stroke prevention strategies, and event rates. More patients in the retrospectively identified cohort received vitamin K antagonists (62.1% vs. 53.2%) and fewer received non-vitamin K oral anticoagulants (1.8% vs . 4.2%). All-cause mortality rates per 100 person-years during the prospective follow-up (starting the first study visit up to 1 year) were significantly lower in the retrospective than prospectively identified cohort (3.04 [95% CI 2.51 to 3.67] vs . 4.05 [95% CI 3.53 to 4.63]; p = 0.016). Conclusions: Interpretations of data from registries that aim to evaluate the characteristics and outcomes of patients with AF must take account of differences in registry design and the impact of recall bias and survivorship bias that is incurred with retrospective enrolment. Clinical Trial Registration: - URL: http://www.clinicaltrials.gov . Unique identifier for GARFIELD-AF (NCT01090362)

Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

Abstracts from the 8th International Conference on cGMP Generators, Effectors and Therapeutic Implications

This work was supported by a restricted research grant of Bayer AG

Cyclone Impacts on Sea Ice Concentration in the Atlantic Arctic Ocean: Annual Cycle and Recent Changes

AbstractWe quantify sea ice concentration (SIC) changes related to synoptic cyclones separately for each month of the year in the Greenland, Barents and Kara Seas for 1979–2018. We find that these SIC changes can be statistically significant throughout the year. However, their strength varies from region to region and month to month, and their sign strongly depends on the considered time scale (before/during vs. after cyclone passages). Our results show that the annual cycle of cyclone impacts on SIC is related to varying cyclone intensity and traversed sea ice conditions. We further show that significant changes in these cyclone impacts have manifested in the last 40 years, with the strongest changes occurring in October and November. For these months, SIC decreases before/during cyclones have more than doubled in magnitude in the Barents and Kara Seas, while SIC increases following cyclones have weakened (intensified) in the Barents Sea (Kara Sea).Plain Language Summary: We study how the sea ice cover in the Arctic Ocean changes due to the passage of low‐pressure systems (cyclones). Our study covers all years between 1979 and 2018 and each individual month of the year. Our results show that the passage of cyclones can affect the sea ice year around, but the strength and the sign (less or more sea ice concentration due to cyclones) of this impact varies strongly. These variations in cyclone impacts throughout the year are related to variations in the strength of the cyclones and changes in the state of the sea ice cover (e.g., thinner vs. thicker ice). We further show that the cyclone impact on the Arctic sea ice has changed during the last 40 years. These changes are strongest in autumn, particularly in October and November. In these months, the strength of the destructive cyclone impacts on sea ice has more than doubled in some regions of the Arctic compared to previous times. In some regions, however, also the strength of ice preserving cyclone impacts (more sea ice due to cyclones) has intensified recently.Key Points: Cyclones can significantly impact the sea ice in the Atlantic Arctic in all months of the year, but with strong spatiotemporal variations Impacts are stronger in the cold season than in summer due to variations in cyclone intensity and traversed sea ice conditions Significant changes emerged throughout the year, recently strongest in the Barents Sea in autumn due to a reduced mean ice concentration Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Horizon 2020 Framework Programme http://dx.doi.org/10.13039/100010661https://doi.org/10.24381/cds.adbb2d47https://www.cen.uni-hamburg.de/icdc/data/ocean/easy-init-ocean/ecmwf-oras5.htm

Cyclone Impacts on Sea Ice Concentration in the Atlantic Arctic Ocean: Annual Cycle and Recent Changes

We quantify sea ice concentration (SIC) changes related to synoptic cyclones separately for each month of the year in the Greenland, Barents and Kara Seas for 1979–2018. We find that these SIC changes can be statistically significant throughout the year. However, their strength varies from region to region and month to month, and their sign strongly depends on the considered time scale (before/during vs. after cyclone passages). Our results show that the annual cycle of cyclone impacts on SIC is related to varying cyclone intensity and traversed sea ice conditions. We further show that significant changes in these cyclone impacts have manifested in the last 40 years, with the strongest changes occurring in October and November. For these months, SIC decreases before/during cyclones have more than doubled in magnitude in the Barents and Kara Seas, while SIC increases following cyclones have weakened (intensified) in the Barents Sea (Kara Sea)