Differences in Migration Determinants for Linguistic Groups in Canada*

This study utilizes linguistically disaggregated region-to-region migration data between 1981 and 1986 to demonstrate that French and English speaking Canadians react differently to place attributes. A series of log transformed linear regression models suggest that the two populations differ very little in their response to traditional labor market variables but that they diverge dramatically in their response to the linguistic composition of each region. Each group prefers regions with a greater percentage of their own co-linguists, but Francophones are less sensitive than Anglophones to linguistic composition.     

Partition coefficients for trace elements in silicic magmas

Trace element partition coefficients for 29 elements, including the rare earths, have been calculated for augite, hypersthene, sanidine, plagioclase, quartz, biotite, titanomagnetite and ilmenite from rhyodacite and rhyolite at Twin Peaks, Utah. Partition coefficients are intermediate to those reported from dacite and high silica rhyolite. At Twin Peaks, as in less silicic magmas, partitioning between phenocrysts and melt is governed primarily by crystal structure constraints as opposed to very high silica systems where the structure and volatile content of the melt become the dominant control of trace element partitioning.     

The role of damped equatorial waves in the oceanic response to winds

In inviscid shallow water models currents generated by spatially uniform winds are transient and are eliminated by Rossby and equatorial Kelvin waves excited at the eastern and western coasts, respectively. The inclusion of mixing processes can lead to an entirely different steady state in which currents are present. It is shown that the mixing of heat affects the steady state more than does the mixing of momentum because the waves that are important in the oceanic adjustment are divergent.     

The thermodynamic influence of subgrid orography in a global climate model

Assessments of the impacts of climate change typically require information at scales of 10 km or less. Such a resolution in global climate simulations is unlikely for at least two decades. We have developed an alternative to explicit resolution that provides a framework for meeting the needs of climate change impact assessment much sooner. We have applied to a global climate model a physically based subgrid-scale treatment of the influence of orography on temperature, clouds, precipitation, and land surface hydrology. The treatment represents subgrid variations in surface elevation in terms of fractional area distributions of discrete elevation classes. For each class it calculates the height rise/descent of air parcels traveling through the grid cell, and applies the influence of the rise/descent to the temperature and humidity profiles of the elevation class. Cloud, radiative, and surface processes are calculated separately for each elevation class using the same physical parametrizations used by the model without the subgrid orography parametrization. The simulated climate fields for each elevation class can then be distributed in post-processing according to the spatial distribution of surface elevation within each grid cell. Parallel 10-year simulations with and without the subgrid treatment have been performed. The simulated temperature, precipitation and snow water are mapped to 2.5-minute (~5 km) resolution and compared with gridded analyses of station measurements. The simulation with the subgrid scheme produces a much more realistic distribution of snow water and significantly more realistic distributions of temperature and precipitation than the simulation without the subgrid scheme. Moreover, the 250-km grid cell means of most other fields are virtually unchanged by the subgrid scheme. This suggests that the tuning of the climate model without the subgrid scheme is also applicable to the model with the scheme.     

Long-term river discharge and multidecadal climate variability inferred from varved sediments, southwest Alaska

Sedimentological analyses of 289 years (AD 1718-2006) of varved sediment from Shadow Bay, southwest Alaska, were used to investigate hydroclimate variability during and prior to the instrumental period. Varve thicknesses relate most strongly to total annual discharge (r² = 0.75, n = 43, p < 0.0001). Maximum annual grain size depends most strongly on maximum spring daily discharge (r² = 0.63, n = 43, p < 0.0001) and maximum annual daily discharge (r² = 0.61, n = 43, p < 0.0001), while varve thickness is poorly correlated with maximum annual grain size (r² = 0.004, n = 287, p = 0.33). Relations between varve thickness and annual climate variables (temperature, precipitation, North Pacific (NP) and Pacific Decadal Oscillation (PDO) indices) are insignificant. On multidecadal timescales, however, regime shifts in varve thickness and total annual discharge coincide with shifts in NP and PDO indices. Periods with increased varve thickness and total annual discharge were associated with warm PDO phases and a strengthened Aleutian Low. The varve-inferred record of PDO suggests that any periodicity in the PDO varied over time, and that the early 19th century marked a transition to a more frequent or detectable shifts.     

An anomalous thermal water from Hofsstadir western Iceland: Evidence for past CO2 flushing

The geothermal field at Hofsstadir northern Snæfellsnes peninsula, Iceland produces low-temperature geothermal water with about 5.4‰ salinity. The fluid temperature is 87 °C, near the reservoir temperature of 90 °C as assessed from mineral solution/equilibrium conditions. The stable isotopic ratios δ²H and δ¹⁸O show that the water is significantly lighter than present day precipitation anywhere on the Snæfellsnes peninsula. It is offset from the meteoric water line towards isotopically depleted ¹⁸O values, most likely due to CO_2(g) – H₂O exchange at earlier times during evolution of the system. Such a concentration of stable isotopes is unique for Icelandic groundwaters and has not been encountered anywhere else in Iceland. The water may either have its origin far north of the Bay of Breidafjörður in the highland of the western fjordlands or dating back to a Pre-Holocene age when local precipitation was considerably lighter due to the cold climate at that time. The water is highly concentrated in Ca in comparison with seawater and also compared to that of geothermal saline water elsewhere, which indicates intensive and prolonged water–rock interaction. The ¹⁴C concentration is low, about 7.4 pMC (percent modern C), compared to the cold local groundwater of about 74.6 pMC. δ¹³C for the thermal and cold waters is −4.9‰ and −2.3‰, respectively. The geothermal water is used for heating the small town of Stykkishólmur through a central heat exchanger plant due to the high salinity of the water. The outbuilding of a health resort has been planned and the water has been used successfully for the treatment of psoriasis and is claimed to have beneficial effects in bathing therapy for rheumatism as well as for drinking cures.     

Hydrothermal sulfide deposits of the Lucky Strike vent field, Mid-Atlantic Ridge

Several hydrothermal sulfide structures were sampled using Mir manned submersibles in the relatively shallow Lucky Strike vent field, Mid-Atlantic Ridge; the bathymetric position of these structures varies by approximately 100 m. The investigation of the chemical and mineral compositions of hydrothermal ore occurrences led to the conclusion that the initial high-temperature ore-bearing solution ascending toward the surface became unstable and experienced phase separation beneath the ocean floor. The phase separation was responsible for the bathymetric control of hydrothermal ore formation in the ocean.     

Quantitative estimation of groundwater potentiality and rainfall infiltration in a typical crystalline environment

A sophisticated method of measuring water levels is adopted to determine the groundwater potentialities in a typical weathered and fractured environment by storage method. The frequency of the rainfall has shown a direct bearing on recharging the groundwater system compared to the intensity of the rainfall. The Thiessen polygon method is used to determine the weighted average of the rainfall over the basin area to estimate the ground water infiltration rates. The long term average infiltration to the medium is established as 15% of the total rainfall.