Atmospheric Oscillations Research Articles

Dynamics and connectivity of an extended arch filament system

Aims.In this study, we analyzed a filament system, which expanded between moving magnetic features (MMFs) of a decaying sunspot and opposite flux outside of the active region from the nearby quiet-Sun network. This configuration deviated from a classical arch filament system (AFS), which typically connects two pores in an emerging flux region. Thus, we called this system an extended AFS. We contrasted classical and extended AFSs with an emphasis on the complex magnetic structure of the latter. Furthermore, we examined the physical properties of the extended AFS and described its dynamics and connectivity.Methods.The extended AFS was observed with two instruments at the Dunn Solar Telescope (DST). The Rapid Oscillations in the Solar Atmosphere (ROSA) imager provided images in three different wavelength regions, which covered the dynamics of the extended AFS at different atmospheric heights. The Interferometric Bidimensional Spectropolarimeter (IBIS) provided spectroscopic Hαdata and spectropolarimetric data that was obtained in the near-infrared (NIR) Ca IIλ8542 Å line. We derived the corresponding line-of-sight (LOS) velocities and used He IIλ304 Å extreme ultraviolet (EUV) images of the Atmospheric Imaging Assembly (AIA) and LOS magnetograms of the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) as context data.Results.The NIR Ca IIStokes-Vmaps are not suitable to definitively define a clear polarity inversion line and to classify this chromospheric structure. Nevertheless, this unusual AFS connects the MMFs of a decaying sunspot with the network field. At the southern footpoint, we measured that the flux decreases over time. We find strong downflow velocities at the footpoints of the extended AFS, which increase in a time period of 30 min. The velocities are asymmetric at both footpoints with higher velocities at the southern footpoint. An EUV brigthening appears in one of the arch filaments, which migrates from the northern footpoint toward the southern one. This activation likely influences the increasing redshift at the southern footpoint.Conclusions.The extended AFS exhibits a similar morphology as classical AFSs, for example, threaded filaments of comparable length and width. Major differences concern the connection from MMFs around the sunspot with the flux of the neighboring quiet-Sun network, converging footpoint motions, and longer lifetimes of individual arch filaments of about one hour, while the extended AFS is still very dynamic.

Warm Events Induce Loss of Resilience in Organic Carbon Production in the Northeast Pacific Ocean

AbstractBetween 2013 and 2016, a series of warm events induced by ocean atmosphere oscillations negatively impacted productivity in the northeast Pacific Ocean. For two consecutive winters (2013–2014 and 2014–2015), suppressed wind stress and warm near‐surface ocean temperature anomalies restricted vertical mixing between the surface and underlying nutrient‐enriched waters. Here we assess historical data of sea surface temperature and sea level pressure, along with nearly a decade of biogeochemical float data to evaluate the impact of these warm events on organic carbon production. The first stratified winter experienced little apparent impact on the magnitude of net organic carbon production in the growing season relative to prior years, suggesting an immediate resilience from reduced new nutrients, apparently depending on recycled iron. However, the subsequent winter experienced virtually zero net production; a loss of resilience, perhaps due to net iron removal with export, was evident. We find that consistently enhanced winter stratification decreased carbon production much more so than a single warm winter. This study highlights the sensitivity of marine productivity to ocean atmosphere oscillations, reducing deep ocean carbon sequestration with prolonged ocean warming and stratification.

Relevance of wind stress and wave-dependent ocean surface roughness on the generation of winter meteotsunamis in the Northern Gulf of Mexico

Meteotsunamis associated with passing squall lines are often observed ahead of cold fronts during the winter in the Northern Gulf of Mexico. Winter meteotsunamis occur simultaneously with wind speed variations (~5–20 m/s) and sea-level atmospheric pressure oscillations (~1–6 hPa) with periods between several minutes to 2 h. In order to enhance understanding of meteotsunami generation and propagation, the Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system is applied to one of the most intense winter meteotsunamis measured in the Northern Gulf of Mexico during the decade 2009–2018. The model, verified with sea level and atmospheric observations, is able to reproduce the timing and intensity of the wind at 10 m elevation and sea level atmospheric pressure fluctuations. The mean bias between observed and measured wind speeds and atmospheric pressure are 1.73 m/s and 0.63 hPa, respectively. The maximum meteotsunami elevation and its timing are successfully captured with a 7% underestimation of the maximum elevation. The relative effect of atmospheric pressure and wind stress on meteotsunami generation is assessed with different numerical simulations. Results indicate that both wind stress and atmospheric pressure changes contributed to the generation of the meteotsunami. Wind stress was the dominant force in shallow waters (<15 m in this application), while the effects of atmospheric pressure disturbances dominated over areas with Froude number close to one (~40 m in this application). During the passage of the squall line, the sea surface became rougher in a sea state characterized by young and steep local ocean waves. Compared to a purely wind-speed-dependent roughness scheme, the application of a wave-dependent roughness parameterization improved the modeled meteotsunami maximum elevation by 37%.

Global analysis for periodic variations in gravity wave squared amplitudes and momentum fluxes in the middle atmosphere

Abstract. Atmospheric gravity waves (GWs) are an important coupling mechanism in the middle atmosphere. For instance, they provide a large part of the driving of long-period atmospheric oscillations such as the Quasi-Biennial Oscillation (QBO) and the semiannual oscillation (SAO) and are in turn modulated. They also induce the wind reversal in the mesosphere–lower thermosphere region (MLT) and the residual mean circulation at these altitudes. In this study, the variations in monthly zonal mean gravity wave square temperature amplitudes (GWSTAs) and, for the first time, absolute gravity wave momentum flux (GWMF) on different timescales such as the annual, semiannual, terannual and quasi-biennial variations are investigated by spectrally analyzing SABER observations from 2002 to 2015. Latitude–altitude cross sections of spectral amplitudes and phases of GWSTA and absolute GWMF in the stratosphere and mesosphere are presented and physically interpreted. It is shown that the time series of GWSTA and GWMF at a certain altitude and latitude results from the complex interplay of GW sources, propagation through and filtering in lower altitudes, oblique propagation superposing GWs from different source locations, and, finally, the modulation of the GW spectrum by the winds at a considered altitude and latitude. The strongest component is the annual variation, dominated in the summer hemisphere by subtropical convective sources and in the winter hemisphere by polar vortex dynamics. At heights of the wind reversal, a 180∘ phase shift also occurs, which is at different altitudes for GWSTA and GWMF. In the intermediate latitudes a semiannual variation (SAV) is found. Dedicated GW modeling is used to investigate the nature of this SAV, which is a different phenomenon from the tropical SAO also seen in the data. In the tropics a stratospheric and a mesospheric QBO are found, which are, as expected, in antiphase. Indication for a QBO influence is also found at higher latitudes. In previous studies a terannual variation (TAV) was identified. In the current study we explain its origin. In particular the observed patterns for the shorter periods, SAV and TAV, can only be explained by poleward propagation of GWs from the lower-stratosphere subtropics into the midlatitude and high-latitude mesosphere. In this way, critical wind filtering in the lowermost stratosphere is avoided and this oblique propagation is hence likely an important factor for MLT dynamics.

A study of gravity wave activities based on intensive radiosonde observations at Bengkulu during YMC-Sumatra 2017

Gravity waves are generated from local regions such as convection, topography, jet stream and fronts. It is important to understand their activities because the quasi-biennial oscillation and general circulation in middle atmosphere are affected by their activities. However, the scale of gravity waves is too broad to understand their characters and activities in detail. The purpose of this study is to clarify three-dimensional dynamical circulation driven by gravity waves around the equatorial region. The Campaign of Years of Maritime Continent-Sumatra (YMC-Sumatra) has been operated since 2017 to expedite the progress of improving understanding and prediction of local multi-scale variability of the maritime continent weather-climate system and its global impact. We use intensified radiosonde observation data at Bengkulu during December 2017 and examine the relation between gravity wave activities and background state. The results showed that the heat flux of the gravity waves is proportional to the vertical shear of the background zonal wind. From the relation between gravity wave energy and Richardson number, it is suggested that the gravity waves having large amplitude modify the background state around 15 km.

Multi-wavelength observations of the 2014 June 11 M3.9 flare: temporal and spatial characteristics

We present multi-wavelength observations of an M-class flare (M3.9) that occurred on 2014 June 11. Our observations were conducted with the Dunn Solar Telescope (DST), employing adaptive optics, the multi-camera system Rapid Oscillations in Solar Atmosphere (ROSA), the new Hydrogen-Alpha Rapid Dynamics camera (HARDcam) in various wavelengths, such as Ca II K, Mg I b2 (at 5172.7 Å), and Hα narrow band and G-band continuum filters. Images were re-constructed using the Kiepenheuer-Institut Speckle Interferometry Package (KISIP) code, to improve our image resolution. We observed intensity increases of ≈120%–150% in the Mg, Ca K and Hα narrow band filters during the flare. Intensity increases for the flare observed in the SDO EUV channels were several times larger, and the X-rays, as recorded by GOES, increased over a factor of 30 for the harder band. Only a modest delay was found between the onset of flare ribbons of a nearby sympathetic flare and the main flare ribbons observed in these narrow band filters. The peak flare emission occurred within a few seconds for the Ca K, Mg and Hα bands. Time-distance techniques indicate propagation velocities of ≈60 km s−1 for the main flare ribbon and as high as 300 km s−1 for smaller regions, which we attribute to filament eruptions. This result and delays and velocities observed with SDO (≈100 km s−1) for different coronal heights agree well with the simple model of energy propagation versus height, although a more detailed model for the flaring solar atmosphere is needed. Finally, we detected marginal quasi-periodic pulsations (QPPs) in the 40–60 s range for the Ca K, Mg and Hα bands, and such measurements are important for disentangling the detailed flare-physics.

ОБЩАЯ ОЦЕНКА СТАТИСТИЧЕСКОЙ ЗНАЧИМОСТИ И КЛИМАТИЧЕСКОЙ РОЛИ ГЛОБАЛЬНЫХ АТМОСФЕРНЫХ И ОКЕАНИЧЕСКИХ ОСЦИЛЛЯЦИЙ

Discovery of the global atmospheric and oceanic oscillations was regarded as an essential addition to the wide range of multi-scale processes characterizing the variability of the global climate system short-term dynamics. Interannual global atmospheric oscillation (GAO) was found during the study of a physical mechanism and indices of the well-known events of El Niño (Byshev et al., 2012.). The first report on the multi-decadal oscillation of the of the ocean upper active layer heat content (MOHO) was published in 2016 (Byshev et al., 2016 ). Subsequent heat content evolution studies of these intra-century processes in the atmosphere and in the ocean allowed to propose a new realistic approach to improvement a theory and methods of the modern climate variability evaluating (Byshev et al., 2017; Byshev et al., 2018; Serykh et al., 2019). The article provides a brief annotated review of the main publications devoted to the substantiation and analytical description of the basic concepts of short-period variability of the modern climate associated with the global effects of inter-annual atmospheric oscillation (GAO) and multi-decadal oscillation of the ocean upper active layer heat content of the world ocean (MOHO).

TREND-RUN model application of surface temperature and its implications for South African forestry and reforestation using local weather services data

Temperature can directly and indirectly impact the livelihood of inhabitants of a country and the natural environment as a whole. The surface temperature trend approximations for South Africa (SA) were calculated using a linear-regression fitting model. The model was adapted at The University of Reunion Island and was referred to as the Trend-Run model. The geophysical signal of the model was split into a sum of oscillations, which was used to clarify most of its variability. The trend values were calculated from the residual terms as a linear function. The model used atmospheric oscillations, which included Annual (AO), Semi-Annual (SAO), Quasi-Biennial Oscillations (QBO), El Niño-Southern Oscillation (ENSO), the 11-years solar cycle-Sun Spot Number (SSN) and Indian Ocean Dipole (IOD). The South African Weather Service (SAWS) data were used for the study. Data sets over a 31-year period, from March 1980 to December 2011, were used to measure the validity of the Trend-Run model, to determine the contribution and effect of this particular oscillation, and the validity of the model. The Trend-Run model showed very high applicability to the surface temperatures in all provinces across the SA region under investigation. High coefficient of determination values between (0.70-0.91) were recorded for surface temperatures across all provinces in the country with minor variations. The AO, ENSO and SAO were the highest contributing forcings in the model, thereby showing their high relevance to the success of this model in the study area. The temperature increases are expected to negatively impact on the biomes of SA, including the forest biome. Selected tree species of Acacia, Eucalyptus and Pinus could be impacted negatively with rising temperatures, which would negatively impact on the forestry industry in SA. As expected, the model did obtain a high success rate that ranged from 70% to 91% in the areas under study, however, there was still room for improvement by the possible inclusion of additional atmospheric forcings to the model that maybe be applicable to the weather and forestry distribution in SA.

Observations of middle atmospheric seasonal variations and study of atmospheric oscillations at equatorial regions

The equatorial atmospheric regions are unique and one of the most important parts of the Earth's atmosphere. These regions receive the maximum energy from the Sun, and are highly turbulent and influenced by the processes of the Northern Hemisphere as well as by the Southern Hemisphere. Atmospheric temperature is one the most sensitive parameters and having imprints of dynamical, radiative and chemical processes. Thermal structure, seasonal variability and atmospheric oscillations occurring in the equatorial middle atmosphere have been studied here using temperature profiles retrieved from the Sounding of the Atmosphere using the Broadband Emission Radiometry (SABER) instrument on-board Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite during January 2002 to December 2015 (14 years). In the present work, three geographical locations over the Equatorial latitudes and ±120° longitude have been chosen, considering 5° × 15° latitude-longitude grid between the altitudes ranging from 20 to 100 km. A detailed time series and climatology analyses have been performed over these regions and significant longitudinal differences have been observed. Characteristics of Semi Annual oscillation (SAO), Annual Oscillation (AO) and Quasi Biennial Oscillation (QBO) have been investigated using Lomb Scargle Periodogram and wavelet transform analysis techniques. It has been noted the longitudinal differences in the spectral amplitudes of equatorial oscillations relative to the zonal mean spectrum. The longitudinal asymmetry might be due to the vertically propagating planetary waves. From the analysis, it is also observed that SAO is showing the highest amplitude at 45 km and 75–85 km, and QBO is showing significant amplitude in the lower stratosphere. At higher altitudes, amplitudes of different oscillations (viz. SAO, AO, and QBO) are very weak, and temperatures variations are not revealing any significant pattern. Moreover, from the climatology and time series of the temperature measurements, high temperature (∼260 K) has been noticed at 55–65 km height range. In addition to that, seasonal variations over equatorial regions have been studied and the strength of seasonal differences are found to be about 9 K (summer-winter) at higher altitudes.

Propagation to the upper atmosphere of acoustic-gravity waves from atmospheric fronts in the Moscow region

Abstract. The paper uses experimental data of pressure variations on the Earth's surface during the passage of an atmospheric front recorded by a network of four microbarographs in the Moscow region. Applying these experimental data, empirical approximations of atmospheric pressure field oscillations are suggested. The obtained approximating surface pressure functions are used as the lower boundary condition for simulating the vertical propagation of acoustic-gravity waves from a source in the lower troposphere. Estimates of the amplitude of temperature disturbances in the upper atmosphere caused by acoustic-gravity waves from a propagating atmospheric front are obtained. For the amplitude of wave temperature disturbances, values of about 200 K are obtained. The amplitude of temperature disturbances in the upper atmosphere caused by background pressure fluctuations on the Earth's surface is estimated at 4–5 K.

Atmospheric oscillations provide simultaneous measurement of neutron star mass and radius

ABSTRACT Neutron stars with near-Eddington observable luminosities were shown to harbour levitating atmospheres, suspended above their surfaces. We report a new method to simultaneously measure the mass and radius of a neutron star based on oscillations of such atmospheres. In this paper, we present an analytic derivation of a family of relativistic, oscillatory, spherically symmetric eigenmodes of the optically and geometrically thin levitating atmospheres, including the damping effects induced by the radiation drag. We discover characteristic maxima in the frequencies of the damped oscillations and show that from a measurement of the frequency maximum and of the luminosity one can determine the mass and radius of the neutron star. In addition to the stellar parameters, observation of the variation of the oscillation frequencies with flux would allow us to estimate the stellar luminosity and therefore the distance to the source with an accuracy of a few per cent. We also show that the ratio of any two undamped eigenfrequencies depends only on the adiabatic index of the atmosphere, while for the damped eigenfrequencies, this ratio varies with the luminosity. The damping coefficient is independent of the mode number of the oscillations. Signatures of the dynamics of such atmospheres will be reflected in the source’s X-ray light curves.

Scalar Nonstandard Interactions in Neutrino Oscillation.

The scalar nonstandard interactions (NSI) can also introduce matter effect for neutrino oscillation in a medium. Especially the recent Borexino data prefer nonzero scalar NSI, η_{ee}=-0.16. In contrast to the conventional vector NSI, the scalar type contributes as a correction to the neutrino mass matrix rather than the matter potential. Consequently, the scalar matter effect is energy independent while the vector one scales linearly with neutrino energy. This leads to significantly different phenomenological consequences in reactor, solar, atmospheric, and accelerator neutrino oscillations. A synergy of different types of experiments, especially those with matter density variation, is necessary to identify the scalar NSI and guarantee the measurement of CP violation at accelerator experiments.

A New 200‐Year Spatial Reconstruction of West Antarctic Surface Mass Balance

AbstractHigh‐spatial resolution surface mass balance (SMB) over the West Antarctic Ice Sheet (WAIS) spanning 1800–2010 is reconstructed by means of ice core records combined with the outputs of the European Centre for Medium‐Range Weather Forecasts “Interim” reanalysis (ERA‐Interim) and the latest polar version of the Regional Atmospheric Climate Model (RACMO2.3p2). The reconstruction reveals a significant negative trend (−1.9 ± 2.2 Gt/year·per decade) in the SMB over the entire WAIS during the nineteenth century, but a statistically significant positive trend of 5.4 ± 2.9 Gt/year·per decade between 1900 and 2010, in contrast to insignificant WAIS SMB changes during the twentieth century reported earlier. At regional scales, the Antarctic Peninsula and western WAIS show opposite SMB trends, with different signs in the nineteenth and twentieth centuries. The annual resolution reconstruction allows us to examine the relationships between SMB and large‐scale atmospheric oscillations. Although SMB over the Antarctic Peninsula and western WAIS correlates significantly with the Southern Annular Mode due to the influence of the Amundsen Sea Low, and El Niño/Southern Oscillation during 1800–2010, the significant correlations are temporally unstable, associated with the phase of Southern Annular Mode, El Niño/Southern Oscillation and the Pacific decadal oscillation. In addition, the two climate modes seem to contribute little to variability in SMB over the whole WAIS on decadal‐centennial time scales. This new reconstruction also serves to identify unreliable precipitation trends in ERA‐Interim and thus has potential for assessing the skill of other reanalyses or climate models to capture precipitation trends and variability.

Intraseasonal responses of sea surface and deep oceanic temperature anomalies in the northern Indian Ocean–western Pacific to the 30–60-day boreal summer atmospheric intraseasonal oscillation

The 30–60-day boreal summer atmospheric intraseasonal oscillation (BSISO) is the predominant intraseasonal variability of the Asian summer monsoon, and has a strong dynamical and thermodynamical impact on the underlying oceans in the northern Indian Ocean–western Pacific. This study uses composite analysis of satellite-observed sea surface temperature (SST) data, as well as atmospheric and oceanic reanalysis datasets for the period 1998–2013, to identify the intraseasonal behavior of SST and deep ocean temperatures during the life cycle of the BSISO. With the BSISO as an organized entity evolving both eastward and northward from the equatorial Indian Ocean, the BSISO-induced SST anomalies propagate coherently into several basins, including the Arabian Sea, Bay of Bengal, South China Sea, and western Pacific, characterized by the alternate occurrence of basin-wide positive and negative SST anomalies, which primarily respond to the active and suppressed convection phases of the BSISO due to anomalous southwesterlies and northeasterlies together with the resultant surface heating anomalies. Significant BSISO-induced oceanic temperature anomalies occur in the equatorial Indian Ocean and western Pacific, with the largest-amplitude anomalous signals arising around the thermocline and extending downward into the deep ocean to below 1000 m or more, which are associated with the equatorial eastward-propagating oceanic Kelvin waves forced by anomalous surface wind stress. However, the local and remote effects of such equatorial oceanic Kelvin waves on the SST and deep oceanic temperature anomalies, especially north of the equator, differ from different basins through the consequential coastal Kelvin waves and reflected Rossby waves.

Atmospheric neutrino oscillation analysis with improved event reconstruction in Super-Kamiokande IV

A new event reconstruction algorithm based on a maximum likelihood method has been developed for Super-Kamiokande. Its improved kinematic and particle identification capabilities enable the analysis of atmospheric neutrino data in a detector volume 32% larger than previous analyses and increases sensitivity to the neutrino mass hierarchy. Analysis of a 253.9 kton-year exposure of the Super-Kamiokande IV atmospheric neutrino data has yielded a weak preference for the normal hierarchy, disfavoring the inverted hierarchy at 74% assuming oscillations at the best fit of the analysis.

Analytical solution for the vertical structure eigenfunction in diagnosis of the low frequency wave-type perturbations in primitive dynamics equation

This study presents an analytical solution to the problem of determining the vertical modal structure of low-frequency atmospheric oscillations. This analytical solution is critically compared with the numerical solution of this problem known in the literature, and good agreement for vertical normal modes with the wave number less than 9 is found. Applicability of the analytical solution for diagnosing the atmospheric climate variability and the quality of its simulation by contemporary GCM is briefly discussed.

Neutrino mass matrix in a gauge group SU(2)L × U(1)e × U(1)μ × U(1)τ

The electroweak unification group [Formula: see text] in which each fermion multiplet has its own [Formula: see text] factor was proposed in 1986 to get the neutrino mass matrix. In this paper, the gauge group [Formula: see text] is restricted to lepton section only, leaving quark multiplets as in the Standard Model. In addition to lepton multiplets [Formula: see text], [Formula: see text] and [Formula: see text], there are three [Formula: see text] singlet right-handed neutrinos [Formula: see text]’s. With the breaking of [Formula: see text] to [Formula: see text], the right-handed neutrinos acquire heavy Majorana masses. Three heavy right-handed neutrinos [Formula: see text]’s are available to generate a [Formula: see text] nondiagonal neutrino mass matrix in terms of three Yukawa couplings [Formula: see text], [Formula: see text], [Formula: see text] of the Higgs scalar doublet to [Formula: see text], [Formula: see text], [Formula: see text] with [Formula: see text], [Formula: see text] and [Formula: see text], respectively. Three Yukawa couplings can be arranged and expressed in terms of masses [Formula: see text], [Formula: see text], [Formula: see text] in three different ways to obtain the results of interest for Case 1: [Formula: see text]; Case 2: [Formula: see text]; Case 3: [Formula: see text]. The results obtained for the three cases are compared with the experimental data from neutrino oscillations. Cases 1 and 2 are relevant for solar neutrino oscillations whereas Case 3 is relevant for atmospheric neutrino oscillations.

Global Atmospheric Oscillation: An Integrity of ENSO and Extratropical Teleconnections

Many researchers have recognized the long distance teleconnections between El Nino–Southern Oscillation (ENSO) events and some other processes in the global climate system happening in areas often very far from the equatorial zone of the Pacific Ocean. In this paper we investigate similar links between ENSO and extratropical processes taken in their whole set. For this goal we compute differences between the sea-level pressure and the near-surface air (sea surface) temperature global fields which correspond to either El Nino or La Nina events observed since the end of the XIX century and up to the beginning of the XXI century. As a result, we establish that an integrity exists of ENSO and the extratropical teleconnections such as North Atlantic Oscillation (NAO), Arctic Oscillation (AO), the Northern Hemisphere annular (NHA) mode as well as the Pacific–North American (PNA) pattern, and their analogs in the Southern Hemisphere in the interannual timescale. Named this integrity the Global Atmospheric Oscillation (GAO), we define two representative indices of GAO, and investigate the temporal dynamics of these indices. This investigation reveals that GAO’s extratropical components may be real irrespective of ENSO while the latter accompanies GAO in all cases. Moreover, in view of a general eastward propagation of the GAO as a spatial structure, some its extratropical components show changes of their features prior the El Nino (La Nina) begins to form. Using these features as fingerprints of the forthcoming evolution of ENSO, we define another GAO index for the El Nino prediction with the lead-time of about 1 year. At last, we establish that some of the CMIP5-models reproduce GAO reasonably well.

Teleconnections and Extreme Ocean States in the Northeast Atlantic Ocean

Abstract. The Northeast Atlantic possesses an energetic and variable wind and wave climate which has a large potential for renewable energy extraction; for example along the western seaboards off Ireland. The role of surface winds in the generation of ocean waves means that global atmospheric circulation patterns and wave climate characteristics are inherently connected. In quantifying how the wave and wind climate of this region may change towards the end of the century due to climate change, it is useful to investigate the influence of large scale atmospheric oscillations using indices such as the North Atlantic Oscillation (NAO), the East Atlantic pattern (EA) and the Scandinavian pattern (SCAND). In this study a statistical analysis of these teleconnections was carried out using an ensemble of EC-Earth global climate simulations run under the RCP4.5 and RCP8.5 forcing scenarios, where EC-Earth is a European-developed atmosphere ocean sea-ice coupled climate model. In addition, EC-Earth model fields were used to drive the WAVEWATCH III wave model over the North Atlantic basin to create the highest resolution wave projection dataset currently available for Ireland. Using this dataset we analysed the correlations between teleconnections and significant wave heights (Hs) with a particular focus on extreme ocean states using a range of statistical methods. The strongest, statistically significant correlations exist between the 95th percentile of significant wave height and the NAO. Correlations between extreme Hs and the EA and SCAND are weaker and not statistically significant over parts of the North Atlantic. When the NAO is in its positive phase (NAO+) and the EA and SCAND are in a negative phase (EA−, SCAND−) the strongest effects are seen on 20-year return levels of extreme ocean waves. Under RCP8.5 there are large areas around Ireland where the 20-year return level of Hs increases by the end of the century, despite an overall decreasing trend in mean wind speeds and hence mean Hs.

Dynamical generation of neutrino mass scales

In this letter we present a simple scenario where the mass scales associated to atmospheric and solar neutrino oscillations are obtained through the dynamical generation of neutrino masses. The main idea is that the two different scales are the result of two independent mechanisms, namely a type-I seesaw generating the atmospheric scale and a radiative 1-loop process providing the solar one. A relation of the two scales, reminiscent of the so-called sequential dominance, is thus obtained.