295 research outputs found
The development of a space climatology: 3. Models of the evolution of distributions of space weather variables with timescale
We study how the probability distribution functions of power input to the magnetosphere Pα and of the geomagnetic ap and Dst indices vary with averaging timescale, , between 3 hours and 1 year. From this we develop and present algorithms to empirically model the distributions for a given and a given annual mean value. We show that lognormal distributions work well for ap, but because of the spread of Dst for low activity conditions, the optimum formulation for Dst leads to distributions better described by something like the Weibull formulation. Annual means can be estimated using telescope observations of sunspots and modelling, and so this allows the distributions to be estimated at any given between 3 hour and 1 year for any of the past 400 years, which is another important step towards a useful space weather climatology. The algorithms apply to the core of the distributions and can be used to predict the occurrence rate of “large” events (in the top 5% of activity levels): they may contain some, albeit limited, information relevant to characterizing the much rarer “superstorm” events with extreme value statistics. The algorithm for the Dst index is the more complex one because, unlike ap, Dst can take on either sign and future improvements to it are suggested
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The development of a space climatology: 1. solar-wind magnetosphere coupling as a function of timescale and the effect of data gaps
Different terrestrial space weather indicators (such as geomagnetic indices, transpolar voltage, and ring current particle content) depend on different “coupling functions” (combinations of near-Earth solar wind parameters) and previous studies also reported a dependence on the averaging timescale, {\tau}. We study the relationships of the am and SME geomagnetic indices to the power input into the magnetosphere P_{\alpha}, estimated using the optimum coupling exponent {\alpha} for a range of {\tau} between 1 min and 1 year. The effect of missing data is investigated by introducing synthetic gaps into near-continuous data and the best method for dealing with them when deriving the coupling function, is formally defined. Using P_{\alpha}, we show that gaps in data recorded before 1995 have introduced considerable errors into coupling functions. From the near-continuous solar wind data for 1996-2016, we find {\alpha} = 0.44 plus/minus 0.02 and no significant evidence that {\alpha} depends on {\tau}, yielding P_{\alpha} = B^0.88 Vsw^1.90 (mswNsw)^0.23 sin4({\theta}/2), where B is the Interplanetary Magnetic Field (IMF), Nsw the solar wind number density, msw its mean ion mass, Vsw its velocity and {\theta} is the IMF clock angle in the Geocentric Solar Magnetospheric reference frame. Values of P_{\alpha} that are accurate to within plus/minus 5% for 1996-2016 have an availability of 83.8% and the correlation between P_{\alpha} and am for these data is shown to be 0.990 (between 0.972 and 0.997 at the 2{\sigma} uncertainty level), 0.897 plus/minus 0.004, and 0.790 plus/minus 0.03, for {\tau} of 1 year, 1 day and 3 hours, respectively, and that between P_{alpha} and SME at {\tau} of 1 min. is 0.7046 plus/minus 0.0004
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Particle-in-cell experiments examine electron diffusion by whistler-mode waves: 2. Quasilinear and nonlinear dynamics
Test-particle codes indicate that electron dynamics due to interactions with low amplitude incoherent whistler mode-waves can be adequately described by quasilinear theory. However there is significant evidence indicating that higher amplitude waves cause electron dynamics not adequately described using quasilinear theory. Using the method that was introduced in Allanson et al. (2019, https://dx.doi.org/10.1029/2019JA027088), we track the dynamical response of electrons due to interactions with incoherent whistler-mode waves, across all energy and pitch angle space. We conduct 5 experiments each with different values of the electromagnetic wave amplitude. We find that the electron dynamics agree well with the quasilinear theory diffusion coefficients for low amplitude incoherent waves with , over a timescale of the order of 1000 gyroperiods. However the resonant interactions with higher amplitude waves cause significant non-diffusive dynamics as well as diffusive dynamics. When electron dynamics are extracted and analyzed over timescales shorter than , we are able to isolate both the diffusive and non-diffusive (advective) dynamics. Interestingly, when considered over these appropriately shorter timescales (of the order of hundreds or tens of gyroperiods), the diffusive component of the dynamics agrees well with the predictions of quasilinear theory, even for wave amplitudes up to . Quasilinear theory is based on fundamentally diffusive dynamics, but the evidence presented herein also indicates the existence of a distinct advective component. Therefore, the proper description of electron dynamics in response to wave-particle interactions with higher amplitude whistler-mode waves may require Fokker-Planck equations that incorporate diffusive and advective terms
A genomic rearrangement resulting in a tandem duplication is associated with split hand-split foot malformation 3 (SHFM3) at 10q24
Split hand-split foot malformation (SHFM) is characterized by hypoplasia/aplasia of the central digits with fusion of the remaining digits. SHFM is usually an autosomal dominant condition and at least five loci have been identified in humans. Mutation analysis of the DACTYLIN gene, suspected to be responsible for SHFM3 in chromosome 10q24, was conducted in seven SHFM patients. We screened the coding region of DACTYLIN by single-strand conformation polymorphism and sequencing, and found no point mutations. However, Southern, pulsed field gel electrophoresis and dosage analyses demonstrated a complex rearrangement associated with a ∼0.5 Mb tandem duplication in all the patients. The distal and proximal breakpoints were within an 80 and 130 kb region, respectively. This duplicated region contained a disrupted extra copy of the DACTYLIN gene and the entire LBX1 and β-TRCP genes, known to be involved in limb development. The possible role of these genes in the SHFM3 phenotype is discusse
The development of a space climatology: 2. The distribution of power input into the magnetosphere on a 3‐hourly timescale
Paper 1 in this series (Lockwood et al., 2018a, https://doi.org/10.1029/2018SW001856) showed that the power input into the magnetosphere Pα is an ideal coupling function for predicting geomagnetic “range” indices that are strongly dependent on the substorm current wedge and that the optimum coupling exponent α is 0.44 for all averaging timescales, τ, between 1 min and 1 year. The present paper explores the implications of these results. It is shown that the form of the distribution of Pα at all averaging timescales τ is set by the interplanetary magnetic field orientation factor via the nature of solar wind‐magnetosphere coupling (due to magnetic reconnection in the dayside magnetopause) and that at τ = 3 hr (the timescale of geomagnetic range indices) the normalized Pα (divided by its annual mean, that is, τ=3hr/τ=1yr) follows a Weibull distribution with k of 1.0625 and λ of 1.0240. This applies to all years to a useful degree of accuracy. It is shown that exploiting the constancy of this distribution and using annual means to predict the full distribution gives the probability of space weather events in the largest 10% and 5% to within uncertainties of magnitude 10% and 12%, respectively, at the one sigma level
Linking Human Diseases to Animal Models Using Ontology-Based Phenotype Annotation
A novel method for quantifying the similarity between phenotypes by the use of ontologies can be used to search for candidate genes, pathway members, and human disease models on the basis of phenotypes alone
Supporting genetics in primary care: investigating how theory can inform professional education
Evidence indicates that many barriers exist to the integration of genetic case finding into primary care. We conducted an exploratory study of the determinants of three specific behaviours related to using breast cancer genetics referral guidelines effectively: 'taking a family history', 'making a risk assessment', and 'making a referral decision'. We developed vignettes of primary care consultations with hypothetical patients, representing a wide range of genetic risk for which different referral decisions would be appropriate. We used the Theory of Planned Behavior to develop a survey instrument to capture data on behavioural intention and its predictors (attitude, subjective norm, and perceived behavioural control) for each of the three behaviours and mailed it to a sample of Canadian family physicians. We used correlation and regression analyses to explore the relationships between predictor and dependent variables. The response rate was 96/125 (77%). The predictor variables explained 38-83% of the variance in intention across the three behaviours. Family physicians' intentions were lower for 'making a risk assessment' (perceived as the most difficult) than for the other two behaviours. We illustrate how understanding psychological factors salient to behaviour can be used to tailor professional educational interventions; for example, considering the approach of behavioural rehearsal to improve confidence in skills (perceived behavioural control), or vicarious reinforcement as where participants are sceptical that genetics is consistent with their role (subjective norm)
Temporal variability of quasilinear pitch-angle diffusion
Kinetic wave-particle interactions in Earth's outer radiation belt energize and scatter high-energy electrons, playing an important role in the dynamic variation of the extent and intensity of the outer belt. It is possible to model the effects of wave-particle interactions across long length and time scales using quasilinear theory, leading to a Fokker-Planck equation to describe the effects of the waves on the high energy electrons. This powerful theory renders the efficacy of the wave-particle interaction in a diffusion coefficient that varies with energy or momentum and pitch angle. In this article we determine how the Fokker-Planck equation responds to the temporal variation of the quasilinear diffusion coefficient in the case of pitch-angle diffusion due to plasmaspheric hiss. Guided by in-situ observations of how hiss wave activity and local number density change in time, we use stochastic parameterisation to describe the temporal evolution of hiss diffusion coefficients in ensemble numerical experiments. These experiments are informed by observations from three different example locations in near-Earth space, and a comparison of the results indicates that local differences in the distribution of diffusion coefficients can result in material differences to the ensemble solutions. We demonstrate that ensemble solutions of the Fokker-Planck equation depend both upon the timescale of variability (varied between minutes and hours), and the shape of the distribution of diffusion coefficients. The uncertainty in the ensemble results increases for longer timescales of variability, and when the average diffusion coefficient at that location is high. We discuss time and length scales of wave-particle interactions relative to the drift velocity of high-energy electrons and confirm that arithmetic drift-averaging is can be appropriate in some cases. In other cases, further parameterisation is required to reduce uncertainty in the solution. We demonstrate that in some locations, rare but large values of the diffusion coefficient occur during periods of relatively low number density. Ensemble solutions are sensitive to the presence of these rare values, supporting the need for accurate cold plasma density models in radiation belt descriptions
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