The ECMWF Ensemble Prediction System: Looking Back (more than) 25 Years and Projecting Forward 25 Years

This paper has been written to mark 25 years of operational medium-range ensemble forecasting. The origins of the ECMWF Ensemble Prediction System are outlined, including the development of the precursor real-time Met Office monthly ensemble forecast system. In particular, the reasons for the development of singular vectors and stochastic physics - particular features of the ECMWF Ensemble Prediction System - are discussed. The author speculates about the development and use of ensemble prediction in the next 25 years.Comment: Submitted to Special Issue of the Quarterly Journal of the Royal Meteorological Society: 25 years of ensemble predictio

Invariant Set Theory: Violating Measurement Independence without Fine Tuning, Conspiracy, Constraints on Free Will or Retrocausality

Invariant Set (IS) theory is a locally causal ontic theory of physics based on the Cosmological Invariant Set postulate that the universe $U$ can be considered a deterministic dynamical system evolving precisely on a (suitably constructed) fractal dynamically invariant set in $U$'s state space. IS theory violates the Bell inequalities by violating Measurement Independence. Despite this, IS theory is not fine tuned, is not conspiratorial, does not constrain experimenter free will and does not invoke retrocausality. The reasons behind these claims are discussed in this paper. These arise from properties not found in conventional ontic models: the invariant set has zero measure in its Euclidean embedding space, has Cantor Set structure homeomorphic to the p-adic integers ($p \ggg 0$) and is non-computable. In particular, it is shown that the p-adic metric encapulates the physics of the Cosmological Invariant Set postulate, and provides the technical means to demonstrate no fine tuning or conspiracy. Quantum theory can be viewed as the singular limit of IS theory when when $p$ is set equal to infinity. Since it is based around a top-down constraint from cosmology, IS theory suggests that gravitational and quantum physics will be unified by a gravitational theory of the quantum, rather than a quantum theory of gravity. Some implications arising from such a perspective are discussed.Comment: In Proceedings QPL 2015, arXiv:1511.0118

Signal and noise in regime systems: a hypothesis on the predictability of the North Atlantic Oscillation

Studies conducted by the UK Met Office reported significant skill at predicting the winter NAO index with their seasonal prediction system. At the same time, a very low signal-to-noise ratio was observed, as measured using the `ratio of predictable components' (RPC) metric. We analyse both the skill and signal-to-noise ratio using a new statistical toy-model which assumes NAO predictability is driven by regime dynamics. It is shown that if the system is approximately bimodal in nature, with the model consistently underestimating the level of regime persistence each season, then both the high skill and high RPC value of the Met Office hindcasts can easily be reproduced. Underestimation of regime persistence could be attributable to any number of sources of model error, including imperfect regime structure or errors in the propagation of teleconnections. In particular, a high RPC value for a seasonal mean prediction may be expected even if the models internal level of noise is realistic.Comment: Published in the Quarterly Journal of the Royal Meteorological Society (2019

Superdeterminism Without Conspiracy

Superdeterminism -- where the Measurement-Independence assumption in Bell's Theorem is violated -- is typically treated with derision as it appears to imply contrived conspiratorial correlations between properties $\lambda$ of particles being measured, and nominally accurate measurement settings $x$ and $y$. Based on an analysis of Pearlean interventions needed to determine whether $x$ and $y$ are free variables, we show that whilst conspiracy implies superdeterminism, superdeterminism does not imply conspiracy. In conspiratorial superdeterminism these interventions are consistent with physical theory; in non-conspiratorial superdeterminism they are inconsistent. A non-conspiratorial locally-causal superdeterministic model is developed, based in part on the generic properties of chaotic attractors and in part on an arbitrarily fine discretisation of complex Hilbert Space. Here the required interventions are inconsistent with rational-number constraints on exact measurement settings $X$ and $Y$. In this model, hidden variables $\lambda$ are defined as the information, over and above the freely chosen determinants of $x$ and $y$, which determine $X$ and $Y$. These rationality constraints limit the freedom to vary $x$ and $y$ keeping $\lambda$ fixed. These constraints disappear with any coarse-graining of $\lambda$ and hence $X$. We show how quantum mechanics might be `gloriously explained and derived' as the singular continuum limit of a superdeterministic discretisation of Hilbert Space. We argue that the real message behind Bell's Theorem is the need to develop more holistic theories of fundamental physics -- notably gravitational physics -- some ideas for moving in this direction are discussed

Putting a Floor on Energy Savings: Comparing State Energy Efficiency Resource Standards

Energy efficiency resource standards (EERS) refer to policies that require utilities and other covered entities to achieve quantitative goals for reducing energy use by a certain year. EERS policies generally apply to electricity and natural gas sales and electricity peak demand, though they also cover other energy sources in Europe. Our study aggregates information about the requirements of existing EERS policies for electricity sales in the United States. We convert quantitative goals into comparable terms to compare the nominal stringency of EERS programs across states. EERS programs also differ in their nonquantitative requirements, including flexibility measures, measurement and verification programs, and penalties and positive incentives. We compare the U.S. policies to similar policies in the European Union and discuss important policy issues, including exogenous changes in fuel prices and issues with utility management of energy efficiency programs.energy efficiency, electricity, energy efficiency resource standards, state regulation

Warkworth 12-m VLBI Station: WARK12M

This report summarizes the geodetic VLBI activities in New Zealand in 2010. It provides geographical and technical details of WARK12M - the new IVS network station operated by the Institute for Radio Astronomy and Space Research (IRASR) of Auckland University of Technology (AUT). The details of the VLBI system installed in the station are outlined along with those of the collocated GNSS station. We report on the status of broadband connectivity and on the results of testing data transfer protocols; we investigate UDP protocols such as 'tsunami' and UDT and demonstrate that the UDT protocol is more efficient than 'tsunami' and 'ftp'. In general, the WARK12M IVS network station is fully equipped, connected and tested to start participating in regular IVS observational sessions from the beginning of 2011.Comment: 5 pages, 1 figure, Accepeted for the IVS 2010 Annual Repor

On the interaction of stochastic forcing and regime dynamics

Stochastic forcing can, sometimes, stabilise atmospheric regime dynamics, increasing their persistence. This counter-intuitive effect has been observed in geophysical models of varying complexity, and here we investigate the mechanisms underlying stochastic regime dynamics in a conceptual model. We use a six-mode truncation of a barotropic β-plane model, featuring transitions between analogues of zonal and blocked flow conditions, and identify mechanisms similar to those seen previously in work on low-dimensional random maps. Namely, we show that a geometric mechanism, here relating to monotonic instability growth, allows for asymmetric action of symmetric perturbations on regime lifetime and that random scattering can “trap” the flow in more stable regions of phase space. We comment on the implications for understanding more complex atmospheric systems

Historical reconstruction of the Atlantic Meridional Overturning Circulation from the ECMWF operational ocean reanalysis

A reconstruction of the Atlantic Meridional Overturning Circulation (MOC) for the period 1959–2006 has been derived from the ECMWF operational ocean reanalysis. The reconstruction shows a wide range of time-variability, including a downward trend. At 26N, both the MOC intensity and changes in its vertical structure are in good agreement with previous estimates based on trans-Atlantic surveys. At 50N, the MOC and strength of the subpolar gyre are correlated at interannual time scales, but show opposite secular trends. Heat transport variability is highly correlated with the MOC but shows a smaller trend due to the warming of the upper ocean, which partially compensates for the weakening of the circulation. Results from sensitivity experiments show that although the time-varying upper boundary forcing provides useful MOC information, the sequential assimilation of ocean data further improves the MOC estimation by increasing both the mean and the time variability

Prevalence of cervical disease at age 20 after immunisation with bivalent HPV vaccine at age 12-13 in Scotland: retrospective population study

The manuscript was reviewed by Jo’s Trust, which supports the conclusions. It made the following statement: We think (it has) massive implications for the screening programme, vaccine and also impact on diagnoses in the future. It gives weight for activity to increase vaccine uptake, has implications on screening intervals. The clinically relevant herd protection is very interesting too. It also feeds into our policy calls for a new IT infrastructure (for the screening programme in England) to record and enable invitations based on whether someone has at the vaccine if intervals can be extended. Funding: This study has been undertaken as part of the programme of surveillance of immunisation against human papillomavirus in Scotland, included within the routine work of Health Protection Scotland, a part of the Scottish National Health Service. No funding has been received from industry.Peer reviewedPublisher PD