Actor models have been used for modeling and analyzing distributed and asynchronous systems. Moreover, actors are being increasingly used in industry, and new actor-based languages are designed and used by Google and Microsoft, for example Go, P and Orleans. In the new era of cyber-physical systems, we need methods and techniques for safety and performance assurance of timed models. Floating Ti...

It is not clear whether a worldwide "forest transition" to net reforestation will ever occur, and the need to address the main driver--agriculture--is compelling. We present a mathematical model of land use dynamics based on the world food equation that explains historical trends in global land use on the millennial scale. The model predicts that a global forest transition only occurs under a s...

We demonstrate that any scaling source in the radiation era produces a background of gravitational waves with an exact scale-invariant power spectrum. Cosmic defects, created after a phase transition in the early universe, are such a scaling source. We emphasize that the result is independent of the topology of the cosmic defects, the order of phase transition, and the nature of the symmetry br...

We propose an evolutional scenario of the universe which starts from quantum states with conformal invariance, passing through the inflationary era, and then makes transition to the conventional Einstein spacetime. The space-time dynamics is derived from the renormalizable higherderivative quantum gravity on the basis of a conformal gravity in four dimensions. Based on the linear perturbation t...

By incorporating the wave-induced Coriolis-Stokes forcing into the classical Ekman model, the wind energy input to the Ekman-Stokes layer is investigated, with an emphasis on the surface wave effects when the direction of Stokes drift deviates from that of wind stress. Theoretical analysis of the kinetic energy balance of the EkmanStokes layer shows that the total wind energy input consists of ...

A stand-alone sea ice model is tuned and validated using satellite-derived, basinwide observations of sea ice thickness, extent, and velocity from the years 1993 to 2001. This is the first time that basin-scale measurements of sea ice thickness have been used for this purpose. The model is based on the CICE sea ice model code developed at the Los Alamos National Laboratory, with some minor modi...

We present a “nudged” version of the Met Office general circulation model, the Unified Model. We constrain this global climate model using ERA-40 re-analysis data with the aim of reproducing the observed “weather” over a year from September 1999. Quantitative assessments are made of its performance, focusing on dynamical aspects of nudging and demonstrating that the “weather” is well simulated.

In this article global estimates of 100-yr return values of wind speed and significant wave height are presented. These estimates are based on the ECMWF 40-yr Re-Analysis (ERA-40) data and are linearly corrected using estimates based on buoy data. This correction is supported by global Topographic Ocean Experiment (TOPEX) altimeter data estimates. The calculation of return values is based on th...

A new tropopause definition involving a flow-dependent blending of the traditional thermal tropopause with one based on potential vorticity has been developed and applied to the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalyses (ERA), ERA-40 and ERA-Interim. Global and regional trends in tropopause characteristics for annual and solsticial seasonal means are presented here, ...

The homogeneity of the ECMWF 40-yr Re-Analysis (ERA-40) is assessed. This is done by comparing ERA40 data with results from the NCEP–NCAR reanalysis and also by investigating a known relationship between a modeled (latent heat flux) and an external (SST) quantity. The direct comparison between the two reanalyses reveals a lot of inhomogeneities. They occur mainly in the Southern Hemisphere and ...