Ab initio oscillator strengths for transitions between J=1 odd and J=1,2 even excited states of Ne I

Ab initio theory is developed for radiative transitions between excited states of neon. Calculations of energies for even excited states J=1, J=2 supplement our previous calculations for J=1 odd excited states. Line strengths for transitions between J=1 odd and J=1,2 even states of Ne I are evaluated. A comparison with experiments and semiempirical calculations is given.Comment: 5 page

Mixed configuration-interaction and many-body perturbation theory calculations of energies and oscillator strengths of J=1 odd states of neon

Ab-initio theory is developed for energies of J=1 particle-hole states of neutral neon and for oscillator strengths of transitions from such states to the J=0 ground state. Hole energies of low-Z neonlike ions are evaluated.Comment: 5 pages, 1 figure, 4 table

The ability of a barotropic model to simulate sea level extremes of meteorological origin in the Mediterranean Sea, including those caused by explosive cyclones

Storm surges are responsible for great damage to coastal property and loss of life every year. Coastal management and adaptation practices are essential to reduce such damage. Numerical models provide a useful tool for informing these practices as they simulate sea level with high spatial resolution. Here we investigate the ability of a barotropic version of the HAMSOM model to simulate sea level extremes of meteorological origin in the Mediterranean Sea, including those caused by explosive cyclones. For this purpose, the output of the model is compared to hourly sea level observations from six tide gauge records (Valencia, Barcelona, Marseille, Civitavecchia, Trieste, and Antalya). It is found that the model underestimates the positive extremes significantly at all stations, in some cases by up to 65%. At Trieste, the model can also sometimes overestimate the extremes significantly. The differences between the model and the residuals are not constant for extremes of a given height, which limits the applicability of the numerical model for storm surge forecasting because calibration is difficult. The 50 and 10 year return levels are reasonably well captured by the model at all stations except Barcelona and Marseille, where they are underestimated by over 30%. The number of exceedances of the 99.9th and 99.95% percentiles over a period of 25 years is severely underestimated by the model at all stations. The skill of the model for predicting the timing and value of the storm surges seems to be higher for the events associated with explosive cyclones at all stations

Numerical modeling analysis of the mesoscale environment conducive to two tornado events using the COSMO.Gr model over Greece

The COnsortium for Small-scale MOdeling (COSMO) was formed in October 1998, and its general goal is to develop, improve and maintain a non-hydrostatic limited-area atmospheric model. The COSMO model has been designed both for operational numerical weather prediction (NWP) as well as various scientific applications on the meso-β and meso-γ scale. Two tornado case studies were selected to investigate the ability of COSMO model to depict the characteristics of severe convective weather, which favoured the development of the associated storms. The first tornado (TR01) occurred, close to Ag. Ilias village, 8 Km north-western of Aitoliko city over western Greece on February 7, 2013, while the second tornado (TR02) was developed close to Palio Katramio village, 8 Km southern from Xanthi city over northern Greece on November 25, 2015. Although both tornadoes had a short lifetime, they caused significant damages. The COSMO.GR atmospheric model was initialized with analysis from the European Centre for Medium-Range Weather Forecasts (ECMWF). The resulting numerical products with spatial resolution of 0.02° (∼ 2 km) over the geographical domain of Greece depicted very well the severe convective conditions close to tornadoes formation. The Energy Helicity Index (EHI) diagnostic variable in both numerical simulations showed a gradual increase of values closing to the location and time of the tornadogenesis. Similar to EHI, the storm relative helicity (SRH) spatio-temporal analysis followed a gradual increase prior to the tornadogenesis events and was reduced after them. © 2017 Elsevier B.V

Numerical Modeling Analysis of Tornadoes Using the COSMO.GR Model Over Greece

The COnsortium for Small-scale MOdeling (COSMO) was formed in October 1998, and its general goal is to develop, improve and maintain a non-hydrostatic limited-area atmospheric model, while the Hellenic National Meteorological Service joined the consortium in 1999. The COSMO model has been designed both for operational numerical weather prediction (NWP) as well as various scientific applications on the meso-beta and meso-c scale. Two tornado case studies were selected to investigate the ability of COSMO model to depict the characteristics of severe convective weather, which favored the development of the associated storms. The first tornado occurred, close to Ag. Ilias village, 8 km northwestern from Aitoliko city over western Greece on February 7, 2013, while the second tornado developed close to Palio Katramio village, 8 km southern from Xanthi city over northern Greece on November 25, 2015. Although both tornadoes had a short lifetime, they caused significant impacts. The COSMO. GR atmospheric model was initialized with analysis boundary conditions obtained from the European Centre for Medium-Range Weather Forecasts (ECMWF). The resulting numerical products with spatial resolution of 0.020 degrees (similar to 2 km) over the geographical domain of Greece depicted very well the severe convective conditions close to tornadoes formation

Assessing the Sensitivity of COSMO/GR Atmospheric Model to Effectively Simulate the Influence of Diabatic Heating on Eastern Mediterranean Explosive Cyclogenesis Under Different Parameterizations of the Model Physics

Mediterranean explosive cyclogenesis is the result of the interaction between upper level baroclinic and low level diabatic processes. This interaction presents significant differences in specific Mediterranean sub-areas and in different cases of rapid deepening, especially regarding the evolution of the diabatic processes. In this study, the regional atmospheric model COSMO-GR is used for the evaluation of the spatial and temporal variations of low level diabatic heating in a case of explosive cyclogenesis in the north Aegean Sea. Model runs were performed for a series of different values of the model parameter sea roughness, which has proved to significantly affect the simulation of the diabatic processes. It was found that smaller values of the above parameter compared to the default parameterization, lead to significant enhancement of the model calculated surface turbulent fluxes and the respective surface deepening rates during the explosive deepening period and thus to lower minimum pressures, which are closer to ERA-Interim reanalysis values. Moreover, the intrusion of the diabatic heating in the middle troposphere due to latent heat release was also examined, demonstrating the necessity for the determination of the most suitable parameterization of the model physics

Assessment of offshore wind power potential in the Aegean and Ionian Seas based on high-resolution hindcast model results

In this study long-term wind data obtained from high-resolution hindcast simulations is used to analytically assess offshore wind power potential in the Aegean and Ionian Seas and provide wind climate and wind power potential characteristics at selected locations, where offshore wind farms are at the concept/planning phase. After ensuring the good model performance through detailed validation against buoy measurements, offshore wind speed and wind direction at 10 m above sea level are statistically analyzed on the annual and seasonal time scale. The spatial distribution of the mean wind speed and wind direction are provided in the appropriate time scales, along with the mean annual and the inter-annual variability; these statistical quantities are useful in the offshore wind energy sector as regards the preliminary identification of favorable sites for exploitation of offshore wind energy. Moreover, the offshore wind power potential and its variability are also estimated at 80 m height above sea level. The obtained results reveal that there are specific areas in the central and the eastern Aegean Sea that combine intense annual winds with low variability; the annual offshore wind power potential in these areas reach values close to 900 W/m2, suggesting that a detailed assessment of offshore wind energy would be worth noticing and could lead in attractive investments. Furthermore, as a rough estimate of the availability factor, the equiprobable contours of the event [4 m/s ≤ wind speed ≤ 25 m/s] are also estimated and presented. The selected lower and upper bounds of wind speed correspond to typical cut-in and cut-out wind speed thresholds, respectively, for commercial offshore wind turbines. Finally, for seven offshore wind farms that are at the concept/planning phase the main wind climate and wind power density characteristics are also provided. © 2017 Takvor Soukissian, et al