A New Tool for Inundation Modeling: Community Modeling Interface for Tsunamis (ComMIT)

Almost 5 years after the 26 December 2004 Indian Ocean tragedy, the 10 August 2009 Andaman tsunami demonstrated that accurate forecasting is possible using the tsunami community modeling tool Community Model Interface for Tsunamis (ComMIT). ComMIT is designed for ease of use, and allows dissemination of results to the community while addressing concerns associated with proprietary issues of bathymetry and topography. It uses initial conditions from a precomputed propagation database, has an easy-to-interpret graphical interface, and requires only portable hardware. ComMIT was initially developed for Indian Ocean countries with support from the United Nations Educational, Scientific, and Cultural Organization (UNESCO), the United States Agency for International Development (USAID), and the National Oceanic and Atmospheric Administration (NOAA). To date, more than 60 scientists from 17 countries in the Indian Ocean have been trained and are using it in operational inundation mapping.     

The July 15, 2009 Fiordland,New Zealand Tsunami: Real-Time Assessment

On 15 July 2009, a Mw 7.8 earthquake occurred off the New Zealand coast, which by serendipitous coincidence occurred while the International Tsunami Symposium was in session in Novosibirsk, Russia. The earthquake generated a tsunami that propagated across the Tasman Sea and was detected in New Zealand, Australia and as far away as the US West coast. Small boats close to the epicenter were placed in jeopardy, but no significant damage was observed despite a measured run-up height of 2.3 m in one of the Sounds in close proximity to the source (Wilson in GNS Science Report 46:62 2009). Peak-to-trough tsunami heights of 55 cm were measured at Southport, Tasmania and a height of 1 m was measured in Jackson Bay, New Zealand. The International Tsunami Symposium provided an ideal venue for illustration of the value of immediate real-time assessment and provided an opportunity to further validate the real time forecasting capabilities with the scientific community in attendance. A number of agencies with responsibility for tsunami forecast and/or warning, such as the NOAA Center for Tsunami Research, the Pacific Tsunami Warning Center, GNS Science in New Zealand, the Australian Bureau of Meteorology and the European Commission Joint Research Centre were all represented at the meeting and were able to demonstrate the use of state of the art numerical models to assess the tsunami potential and provide warning as appropriate.     

Estimation of the acceleration of the solar-system barycenter relative to a system of reference quasars

It is shown that geodetic VLBI observations can be used to estimate the external acceleration of the barycenter of the solar system. This relies on the fact that, in special relativity, the acceleration of the motion of a coordinate origin relative to reference points leads to a drift in the secular aberration, manifest as systematic proper motions of the reference points in the direction of the acceleration vector. The VLBI time-delay equation is modified such that the acceleration vector appears in explicit form. Formulas for a new form of the fundamental VLBI equation and its partial derivative with respect to the acceleration are presented.     

A new estimator for VLBI baseline length repeatability

The goal of this paper is to introduce a more effective technique to approximate for the “repeatability–baseline length” relationship that is used to evaluate the quality of geodetic VLBI results. Traditionally, this relationship is approximated by a quadratic function of baseline length over all baselines. The new model incorporates the mean number of observed group delays of the reference radio sources (i.e. estimated as global parameters) used in the estimation of each baseline. It is shown that the new method provides a better approximation of the “repeatability–baseline length” relationship than the traditional model. Further development of the new approach comes down to modeling the repeatability as a function of two parameters: baseline length and baseline slewing rate. Within the framework of this new approach the station vertical and horizontal uncertainties can be treated as a function of baseline length. While the previous relationship indicated that the station vertical uncertainties are generally 4–5 times larger than the horizontal uncertainties, the vertical uncertainties as determined by the new method are only larger by a factor of 1.44 over all baseline lengths.     

Three‐body problem periodic orbits with vanishing angular momentum

Periodic solutions of the general three‐body problem are investigated in the shape space. Two different solutions are considered: the first is an extension of the well‐known figure‐eight orbit, and the second one is from the free‐fall problem. Using the shape space, we reduce the dimension of the problem. These orbits are obtained numerically and described on the Euclidean plane and on the shape sphere. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Stars of early types in the region of the Orion Stellar association OB1 from observations of the glazar space telescope

Byurakan Astrophysical Observatory; SKB Granit; Geneva Observatory; Cosmonaut Preparation Center. Translated from Astrofizika, Vol. 32, No. 2, pp. 197–202, March–April, 1990.     

Linear collapse of spatially linear,three-dimensional,potential null points

The collapse of the magnetic field in the vicinity of a null point creates a large electrical current. Non-ideal effects in the surrounding plasma can then allow the onset of magnetic reconnection, which is important in many astrophysical phenomena. An elegant technique is used to show that spatially linear, initially potential, three-dimensional null points have a tendency to collapse with a growth of either the spine current or the fan current or a combination of both. The rate of collapse is determined for an incompressible plasma flow with open boundary conditions. An initial plasma flow affects the rate of collapse by speeding it up.     

Dynamical properties of the Venus mesosphere from the radio-occultation experiment VeRa onboard Venus Express

The dynamics of Venus’ mesosphere (60–100 km altitude) was investigated using data acquired by the radio-occultation experiment VeRa on board Venus Express. VeRa provides vertical profiles of density, temperature and pressure between 40 and 90 km of altitude with a vertical resolution of few hundred meters of both the Northern and Southern hemisphere. Pressure and temperature vertical profiles were used to derive zonal winds by applying an approximation of the Navier–Stokes equation, the cyclostrophic balance, which applies well on slowly rotating planets with fast zonal winds, like Venus and Titan. The main features of the retrieved winds are a midlatitude jet with a maximum speed up to 140 ± 15 m s^?1 which extends between 20°S and 50°S latitude at 70 km altitude and a decrease of wind speed with increasing height above the jet. Cyclostrophic winds show satisfactory agreement with the cloud-tracked winds derived from the Venus Monitoring Camera (VMC/VEx) UV images, although a disagreement is observed at the equator and near the pole due to the breakdown of the cyclostrophic approximation. Knowledge of both temperature and wind fields allowed us to study the stability of the atmosphere with respect to convection and turbulence. The Richardson number Ri was evaluated from zonal field of measured temperatures and thermal winds. The atmosphere is characterised by a low value of Richardson number from ～45 km up to ～60 km altitude at all latitudes that corresponds to the lower and middle cloud layer indicating an almost adiabatic atmosphere. A high value of Richardson number was found in the region of the midlatitude jet indicating a highly stable atmosphere. The necessary condition for barotropic instability was verified: it is satisfied on the poleward side of the midlatitude jet, indicating the possible presence of wave instability.     

Role of the biogenic factor in platinum accumulation by oceanic ferromanganese nodules

A complex study of oceanic ferromanganese nodules (FMN) from the abyssal Clarion-Clipperton Fracture Zone and Lamont Guyot (Pacific Ocean) is performed. The concentrations of noble and trace elements are determined by AAS, INAA, and RFA-SR. Furthermore, SEM, and activation autoradiography are applied. Experiments are carried out using Pt, Au, and Ir radionuclides (radioisotope indicator method).