With retreating sea ice and increasing human activities in the Arctic come a growing need for reliable sea ice forecasts up to months ahead. We exploit the subseasonal‐to‐seasonal prediction database ...and provide the first thorough assessment of the skill of operational forecast systems in predicting the location of the Arctic sea ice edge on these time scales. We find large differences in skill between the systems, with some showing a lack of predictive skill even at short weather time scales and the best producing skillful forecasts more than 1.5 months ahead. This highlights that the area of subseasonal prediction in the Arctic is in an early stage but also that the prospects are bright, especially for late summer forecasts. To fully exploit this potential, it is argued that it will be imperative to reduce systematic model errors and develop advanced data assimilation capacity.
Plain Language Summary
The need for reliable forecasts for the sea ice evolution from weeks to months in advance has substantially grown in the last decade. Sea ice forecasts are of critical importance to manage the opportunities and risks that come with increasing socioeconomic activities in the rapidly changing Arctic, which, despite the reduction of the sea ice cover, remains an extreme environment. The position of the sea ice edge is a key parameter for potential forecast users, such as Arctic mariners. However, little is known about the ability of current operational subseasonal forecast systems to predict the evolution of the ice edge. Therefore, we assess for the first time the skill of state‐of‐the‐art forecast systems, using a new verification metric that quantifies the accuracy of the ice edge position in a meaningful way. Our results demonstrate that subseasonal sea ice predictions are in an early stage, although skillful predictions 1.5 months ahead are already possible. We argue that relatively modest investments into reducing initial state and model errors will lead to major returns in predictive skill.
Key Points
The skill in predicting the location of the Arctic sea ice edge differs substantially among subseasonal forecasting systems
The most skillful system beats climatological forecasts more than 1.5 months ahead, with then highest skills in late summer
Major improvements are possible by reducing errors in initial states and model formulation
Background It has frequently been speculated that pruritus and skin lesions develop after topical exposure to aeroallergens in sensitized patients with atopic dermatitis (AD). Objective We sought to ...study cutaneous reactions to grass pollen in adult patients with AD with accompanying clear IgE sensitization to grass allergen in an environmental challenge chamber using a monocenter, double-blind, placebo-controlled study design. Methods Subjects were challenged on 2 consecutive days with either 4000 pollen grains/m3 of Dactylis glomerata pollen or clean air. The severity of AD was assessed at each study visit up to 5 days after challenge by (objective) scoring of AD (SCORAD). Additionally, air-exposed and non–air-exposed skin areas were each scored using local SCORAD scoring and investigator global assessments. Levels of a series of serum cytokines and chemokines were determined by using a Luminex-based immunoassay. The primary end point of the study was the change in objective SCORAD scores between prechallenge and postchallenge values. Results Exposure to grass pollen induced a significant worsening of AD. A pronounced eczema flare-up of air-exposed rather than covered skin areas occurred. In grass pollen–exposed subjects a significantly higher increase in CCL17, CCL22, and IL-4 serum levels was observed. Conclusions This study demonstrates that controlled exposure to airborne allergens of patients with a so-called extrinsic IgE-mediated form of AD induced a worsening of cutaneous symptoms.
Marine oomycetes have recently been shown to be concurrently infected by (-)ssRNA viruses of the order
. In this work, even higher virus variability was found in a single isolate of
, a recently ...described member of
phylogenetic Clade 6a, which was isolated from brackish estuarine waters in southern Portugal. Using total and small RNA-seq the full RdRp of 13 different potential novel bunya-like viruses and two complete toti-like viruses were detected. All these viruses were successfully confirmed by reverse transcription polymerase chain reaction (RT-PCR) using total RNA as template, but complementarily one of the toti-like and five of the bunya-like viruses were confirmed when dsRNA was purified for RT-PCR. In our study, total RNA-seq was by far more efficient for de novo assembling of the virus sequencing but small RNA-seq showed higher read numbers for most viruses. Two main populations of small RNAs (21 nts and 25 nts-long) were identified, which were in accordance with other
species. To the best of our knowledge, this is the first study using small RNA sequencing to identify viruses in
spp.
Van der Waals forces are among the weakest, yet most decisive interactions governing condensation and aggregation processes and the phase behaviour of atomic and molecular matter. Understanding the ...resulting structural motifs and patterns has become increasingly important in studies of the nanoscale regime. Here we measure the paradigmatic van der Waals interactions represented by the noble gas atom pairs Ar-Xe, Kr-Xe and Xe-Xe with a Xe-functionalized tip of an atomic force microscope at low temperature. Individual rare gas atoms were fixed at node sites of a surface-confined two-dimensional metal-organic framework. We found that the magnitude of the measured force increased with the atomic radius, yet detailed simulation by density functional theory revealed that the adsorption induced charge redistribution strengthened the van der Waals forces by a factor of up to two, thus demonstrating the limits of a purely atomic description of the interaction in these representative systems.
Mean and maximum longevity (i.e., age-at-death) in free-ranging American bison (
Bison bison
) subject to natural selection is difficult to estimate in the wild; hence, data on age-at-death for ...free-ranging populations is sparse. I used a 20-year time series of age-at-death data from 1909 bison to estimate mean longevity of hunter-killed bison in a growing population. I tested the following predictions: (a) mean longevity of hunted females was greater than males, (b) mean longevity for hunted animals was less than those dying from natural causes, and (c) longevity did not respond to increasing population size (i.e., density independence). In support of my prediction, mean age-at-death of females (6.3 ± 3.8 (SD) years old) was greater than that for males (5.3 ± 2.7 years old); however, the difference was only 1 year. Most bison (45%) died as mature adults (4–7 years old), and few lived to become dominant or aged adults, which may have important implications for social ecology or population dynamics. Maximum longevity (i.e., oldest age-at-death) was 22 and 25 years old for males and females, respectively. The mean age-at-death of hunted females was 1.4 years younger than a small sample that died of natural causes. Contrary to my prediction, longevity increased slightly for females, but not males, with an increase in abundance. These data may be useful for better understanding bison demography and life history strategies, as well as parameterizing population models, particularly for hunted populations. Similar data from unhunted populations subject to natural selection would be informative to test the generality of these findings.
Limited information exists on mercury concentrations and environmental drivers of mercury bioaccumulation in high latitude terrestrial carnivores. Spatial patterns of mercury concentrations in ...wolverine (Gulo gulo, n = 419) were assessed across a 1,600,000 km2 study area in relation to landscape, climate, diet and biological factors in Arctic and boreal biomes of western Canada. Hydrogen stable isotope ratios were measured in wolverine hair from a subset of 80 animals to assess the spatial scale for characterizing environmental conditions of their habitat. Habitat characteristics were determined using GIS methods and raster datasets at two scales, the collection location point and a 150 km radius buffer, which was selected based on results of a correlation analysis between hydrogen stable isotopes in precipitation and wolverine hair. Total mercury concentrations in wolverine muscle ranged >2 orders of magnitude from 0.01 to 5.72 μg/g dry weight and varied geographically, with the highest concentrations in the Northwest Territories followed by Nunavut and Yukon. Regression models at both spatial scales indicated diet (based on nitrogen stable isotope ratios) was the strongest explanatory variable of mercury concentrations in wolverine, with smaller though statistically significant contributions from landscape variables (soil organic carbon, percent cover of wet area, percent cover of perennial snow-ice) and distance to the Arctic Ocean coast. The carbon and nitrogen stable isotope ratios of wolverine muscle suggested greater mercury bioaccumulation could be associated with feeding on marine biota in coastal habitats. Landscape variables identified in the modelling may reflect habitat conditions which support enhanced methylmercury transfer to terrestrial biota. Spatially-explicit estimates of wet atmospheric deposition were positively correlated with wolverine mercury concentrations but this variable was not selected in the final regression models. These landscape patterns provide a basis for further research on underlying processes enhancing methylmercury uptake in high latitude terrestrial food webs.
Realization of long-range magnetic order in surface-supported two-dimensional systems has been challenging, mainly due to the competition between fundamental magnetic interactions as the short-range ...Kondo effect and spin-stabilizing magnetic exchange interactions. Spin-bearing molecules on conducting substrates represent a rich platform to investigate the interplay of these fundamental magnetic interactions. Here we demonstrate the direct observation of long-range ferrimagnetic order emerging in a two-dimensional supramolecular Kondo lattice. The lattice consists of paramagnetic hexadeca-fluorinated iron phthalocyanine (FeFPc) and manganese phthalocyanine (MnPc) molecules co-assembled into a checkerboard pattern on single-crystalline Au(111) substrates. Remarkably, the remanent magnetic moments are oriented in the out-of-plane direction with significant contribution from orbital moments. First-principles calculations reveal that the FeFPc-MnPc antiferromagnetic nearest-neighbour coupling is mediated by the Ruderman-Kittel-Kasuya-Yosida exchange interaction via the Au substrate electronic states. Our findings suggest the use of molecular frameworks to engineer novel low-dimensional magnetically ordered materials and their application in molecular quantum devices.
The development of chemical systems with switchable molecular spins could lead to the architecture of materials with controllable magnetic or spintronic properties. Here, we present conclusive ...evidence that the spin of an organometallic molecule coupled to a ferromagnetic substrate can be switched between magnetic off and on states by a chemical stimulus. This is achieved by nitric oxide (NO) functioning as an axial ligand of cobalt(II)tetraphenylporphyrin (CoTPP) ferromagnetically coupled to nickel thin-film (Ni(001)). On NO addition, the coordination sphere of Co(2+) is modified and a NO-CoTPP nitrosyl complex is formed, which corresponds to an off state of the Co spin. Thermal dissociation of NO from the nitrosyl complex restores the on state of the Co spin. The NO-induced reversible off-on switching of surface-adsorbed molecular spins observed here is attributed to a spin trans effect.
PDF
