Seismic Source Characteristics of Soviet Peaceful Nuclear Explosions

—?During the period 1965 to 1988, the former Soviet Union (FSU) conducted over 120 peaceful nuclear explosions (PNE) at locations widely dispersed throughout the territories of the FSU. These explosions sample a much wider range of source conditions than do the historical explosions at the known nuclear test sites and, therefore, seismic data recorded from these PNE tests provide a unique resource for use in deriving improved quantitative bounds on the ranges of seismic signal characteristics which may require consideration in global monitoring of the Comprehensive Test-Ban Treaty (CTBT). In this paper we summarize the results of a detailed statistical analysis of broadband seismic data recorded at the Borovoye Geophysical Observatory from 21 of these PNE tests at regional distances extending from about 7 to 19 degrees, as well as the results of theoretical waveform simulation analyses of near-regional (Δ?相似文献   

The relationship between freezing and desiccation tolerance in the marine snail Ilyanassa obsoleta (Stimpson)

Temperature acclimation influenced the desiccation tolerance of the marine snail Ilyanassa obsoleta (Nassarius obsoletus). I. obsoleta acclimated to 35‰ seawater at 18°C could survive for 116 hours, and tolerate a 57% loss of body water when desiccated at 15 °C in air with a relative humidity of 35%. In contrast, I. obsoleta acclimated to 3°C seawater survived for only 76 hours, and could not tolerate more than a 37% loss of body water. These results were used to support the proposition that freezing and desiccation tolerance are closely related in I. obsoleta.     

The changes of sensitivity and drift rate of a worden gravimeter with time and temperature

Summary The analysis of the readings taken with aWorden gravimeter during fieldwork over a period of four years when compared with tests in a laboratory shows that its behaviour is not dependent on vibration and that the drift can be separated into two distinct parts; an isothermal drift and a thermal drift. The former is remarkably constant over short and long periods of time and is of the order of 0.01 mgal/hour. The latter is complicated and is dependent on the rate of change of the ambient temperature being different in size and sign, for quick and slow changes of temperature. The sensitivity changes slowly with time, 0.1% per year, and is only slightly affected by temperature. Tares or jumps in the readings are very rare. Modifications to the meter are suggested, consisting of the inclusion of a rheostat in the lighting circuit and the attachment of a thermometer to the outside of the instrument. In order to keep the correction for drift to a small size and to increase the accuracy, returns to a base station should be made according to changes in the ambient temperature rather than at fixed time intervals.

---

Zusammenfassung Die Analyse der Lesungen einesWorden Gravimeters während einer vierjährigen Periode von Feldmessungen und deren Vergleichung mit den Resultaten einer Prüfung im Laboratorium zeigt, dass sein Verhalten nicht von Erschütterungen abhängt und dass sein Drift in zwei deutlich verschiedene Anteile gespalten werden kann, nämlich einen isothermalen und thermalen Drift. Der erstere Anteil ist bemerkenswert konstant über kurze und längere Perioden und seine Grössenordnung ist 0.01 mgal per Stunde. Der letztere ist kompliziert und hängt von der Schnelligkeit der Änderung der Temperatur der Umgebung ab und ist der Grösse und dem Vorzeichen nach verschieden für rasche und langsame Temperaturänderungen. Die Empfindlichkeit ändert sich langsam mit der Zeit, 0.1% per Jahr, und wird nur wenig durch die Temperatur beeinflusst. Sprünge in den Ablesungen sind sehr selten.Es werden zwei Modifikationen des Gravimeters vorgeschlagen, nämlich die Einschaltung eines Widerstandes im Beleuchtungskreis und die Anbringung eines Thermometers am Instrumentengehäuse. Um die Korrektion wegen Drift klein zu halten und die Genauigkeit zu erhöhen, wird empfohlen, dass das Wiederaufsuchen der Basisstation entsprechend der Änderung der Umgebungstemperatur und nicht in bestimmten, festgelegten Zeitintervallen erfolgen soll.

     

Orbital change experiments with a Mars general circulation model

We use a Mars general circulation model to examine the effect of orbital changes on the planet’s general circulation and climate system. Experiments are performed for obliquities ranging from 0° to 60° for two different longitudes of perihelion. Each experiment simulates a full Mars year assuming a fixed atmospheric dust distribution and fixed amount of CO₂ in the atmosphere/cap system. We find that global mean surface temperatures and pressures decline with increasing obliquity due to the increasing extent of the winter polar caps. The seasonal CO₂ cycle and intensity of the solstice circulation amplify considerably with increasing obliquity such that global dust storms are likely at both solstices. The most significant feature of the high obliquity solstice circulations is the development of an intense low-level jet associated with the return branch of the Hadley circulation.Model surface stresses are used to map regions of preferred dust lifting, which are defined in terms of an annual deflation potential. For the present obliquity, the model-predicted regions of high deflation potential are in good agreement with Cantor et al.’s (2001, J. Geophys. Res.106, 23653-23688) observations, which gives us some confidence in the model’s ability to predict where lifting might occur when Mars’ orbit parameters are different than they are today. In general we find that the dust lifting potential increases sharply with obliquity and is greatest at times of high obliquity when perihelion coincides with northern summer solstice. Over an obliquity cycle, the model global annual deflation potential ranges from several tenths of a millimeter at 0° obliquity to almost 15 mm at 60° obliquity. Much higher values are possible when the atmosphere is very dusty.We find a strong correlation between the deflation potential and surface thermal inertia: regions of high deflation potential correspond to regions of high thermal inertia (high rock abundance), and regions of low deflation potential correspond to regions of low thermal inertia (high dust/sand abundance). Furthermore, while the regions of preferred lifting (high deflation potential) expand somewhat with increasing obliquity and dust loading, the central parts of Tharsis, Arabia, and Elysium show no tendency for significant lifting at any obliquity or longitude of perihelion. These regions may therefore be very old and represent net long-term sinks for atmospheric dust. It is the topography of the planet, through its influence on surface pressure and wind systems, which ultimately determines where dust accumulates.Finally, as was found by Fenton and Richardson (2001, J. Geophys. Res.106, 32885-32909), we find no tendency for the development of east-southeasterly winds at the Pathfinder site for any of our orbital change experiments. This suggests that the ancient wind regime discussed by Greeley et al. (2000, J. Geophys. Res.105, 1829-1840) was produced by other factors, such as polar wander.     

To the market and back: Housing policy and state housing in New Zealand

Housing policy in New Zealand has traditionally been characterised by significant market intervention in support of home ownership and a residual state housing rental sector. Within the context of dramatic social welfare reforms in the 1990s, a set of radical housing reforms was introduced that profoundly transformed the role of the state in the housing system. Key elements of the reforms included the creation of a profit-oriented company to manage state rentals, a move to market rents in the state sector and the introduction of an accommodation supplement. This paper examines the underlying rationale and impacts of the reforms focusing on issues of privatisation, tenant turnover, affordability and tenant protest. Having examined the ongoing problems engendered by these reforms the paper reviews more recent political and legislative reforms that were sought to reassert the state's traditional position within the New Zealand housing market. This revised version was published online in July 2006 with corrections to the Cover Date.     

Simulations of the Indian summer monsoon using a nested regional climate model: domain size experiments

Seasonal simulations of the Indian summer monsoon using a 50-km regional climate model (RCM) are described. Results from three versions of the RCM distinguished by different domain sizes are compared against those of the driving global general circulation model (AGCM). Precipitation over land is 20% larger in the RCMs due to stronger vertical motions arising from finer horizontal resolution. The resulting increase in condensational heating helps to intensify the monsoon trough relative to the AGCM. The RCM precipitation distributions show a strong orographically forced mesoscale component (similar in each version). This component is not present in the AGCM. The RCMs produce two qualitatively realistic intraseasonal oscillations (ISOs) associated respectively with monsoon depressions which propagate northwestward from the Bay of Bengal and repeated northward migrations of the regional tropical convergence zone. The RCM simulations are relatively insensitive to domain size in several respects: (1) the mean bias relative to the AGCM is similar for all three domains; (2) the variability simulated by the RCM is strongly correlated with that of the driving AGCM on both daily and seasonal time scales, even for the largest domain; (3) the mesoscale features and ISOs are not damped by the relative proximity of the lateral boundaries in the version with the smallest domain. Results (1) and (2) contrast strongly with a previous study for Europe carried out with the same model, probably due to inherent differences between mid-latitude and tropical dynamics.     

Continental crust under the southern Porcupine Seabight west of Ireland

Two new seismic refraction/wide-angle reflection profiles demonstrate that the crust beneath the southern Porcupine Seabight, out to water depths in excess of 4000 m, is of continental type. They also reveal the rifted margin of the Porcupine basin on its eastern side. Crustal thickness under the Seabight, inclusive of sediments which are up to 6 km thick, decreases from 23 km in the east to about 10 km at a sharp continent-ocean transition in the west.