Reports from the Smithsonian’s Global Volcanism Network, February 2010

Information included in this summary is based on more detailed reports published in the Bulletin of the Global Volcanism Network, vol. 35, no. 2, February 2010 (on the Internet at ). Edited by scientists at the Smithsonian, this bulletin includes reports provided by a worldwide network of correspondents. The reports contain the names and contact information for all sources. Please note that these reports are preliminary and subject to change as events are studied in more detail. The Global Volcanism Program welcomes further reports of current volcanism, seismic unrest, monitoring data, and field observations.     

The nutrient cycle through snow and ice, a review

This paper reviews the merging of the nutrient cycle with the water cycle in the seasonal alpine snow cover, emphasizing physical processes at the snowpack and snow grain scale. Nutrients are incorporated into snowflakes growing in the atmosphere, they are part of the dry deposition from the atmosphere to the snowpack and they reach the snow as plant litter. The physical processes of the accumulation of nutrients and their redistribution in and on the snow grains and in the pore space of the snow matrix are described.¶The first flush of meltwater that reaches the soil carries a solution of nutrients and acids in a concentration several times higher than bulk values, an effect that increases with the age of the snow and the number of melt/freeze cycles and is more pronounced for sulfate than for chloride. Species that are attached to insoluble particles will be concentrated near the snow surface and will display peak concentrations in the final fraction of meltwater.     

Low-l 5-min oscillation observations

Medium resolution CCD-spectrograph observations have been obtained that are suitable for studying long spatial wavelength 5-min oscillations. We find evidence that at wavelengths of order one solar radius the oscillation field is not isotropic. It is also not well described by modes of uniform excitation. The velocity power density per spherical harmonic increases with decreasing l to 1.1 × 10³ cm² s^–2 per 3.5 × 10^–4 Hz angular frequency bandwidth at l = 4. These results are inconsistent with the data of Fossat and Ricort (1975) as analyzed by Christensen-Dalsgaard and Gough (1982), who found a substantially constant modal amplitude at intermediate l values. It is interesting that other calculations have seen a similar dependence at small l in the growth rate of p-modes due to the -mechanism.Visiting Astronomer, Sacramento Peak Observatory.     

Paleoamospheric temperature structure

Radiative equilibrium and radiative convective temperature profiles for the Earth's evolving atmosphere been have calculated. If the atmosphere evolved from one rich in carbon on dioxide, and deficient in oxygen, to its present composition, the temperature structure showed considerable change. The models of 3 to 4 billion years ago display steadily decreasing temperatures with altitude, being 185°K at pressures associated with the present-day upper stratosphere. A lapse rate feature similar to the present-day tropopause is not indicated until about 1 billion years ago; but the stratospheric region is approximately 15°K colder than presently found at comparable pressures. Surface temperatures approximately 10°K warmer than at present existed until nearly 1 billion years ago. When the oxygen content exceeded roughly 0.1 times the present level, surface temperatures began to decrease. If biological processes are important to carbon dioxide—ozone variations, such as has been suggested during the Ice Ages, then estimates of surface temperature should include the effects of both gases.     

Heat Wave Hazards: An Overview of Heat Wave Impacts in Canada

Extreme heat events are natural hazards affecting Canada and many other regions of the world. This paper presents an overview of the issues involved in defining heat waves and harmful hot weather events, followed by a spatial and historical overview of heat waves across Canada, and an assessment of heat wave adaptation potential in selected cities. The Prairies, Southern Ontario, and areas in the St. Lawrence River Valley of both Ontario and Quebec demonstrate the highest temperatures and most frequent occurrences of heat waves, with minimal effects in the North, Pacific Coast, and Maritimes. Montreal frequently experiences extreme heat, and based on its low air conditioning rates and older, high-density housing, it demonstrates limited potential for adaptation to heat events. A scientific assessment was done to identify the effects of heat waves on various sectors of Canadian life including agriculture, livestock, fisheries, construction, transportation, utilities, the environment, and human health. Heat stress has been linked to excess human mortality and illness, violent behaviour, drought, forest fires, tornadoes, decreased agricultural and livestock productivity, construction and transportation difficulties, and reduced electrical power supply. Despite limited research on heat waves in Canada, this study demonstrates that the impacts of heat are profound and far-reaching.     

The effect of EGM2008-based normal, normal-orthometric and Helmert orthometric height systems on the Australian levelling network

This paper investigates the normal-orthometric correction used in the definition of the Australian Height Datum, and also computes and evaluates normal and Helmert orthometric corrections for the Australian National Levelling Network (ANLN). Testing these corrections in Australia is important to establish which height system is most appropriate for any new Australian vertical datum. An approximate approach to assigning gravity values to ANLN benchmarks (BMs) is used, where the EGM2008-modelled gravity field is used to ‘re-construct’ observed gravity at the BMs. Network loop closures (for first- and second-order levelling) indicate reduced misclosures for all height corrections considered, particularly in the mountainous regions of south eastern Australia. Differences between Helmert orthometric and normal-orthometric heights reach 44 cm in the Australian Alps, and differences between Helmert orthometric and normal heights are about 26 cm in the same region. Normal-orthometric heights differ from normal heights by up to 18 cm in mountainous regions >2,000 m. This indicates that the quasigeoid is not compatible with normal-orthometric heights in Australia.     

Smithsonian Institution’s Global Volcanism Network

Information included in this summary is based on more detailed reports published in the Bulletin of the Global Volcanism Network, vol. 32, no. 7, July 2007 (on the Internet at ). Edited by scientists at the Smithsonian, this bulletin includes reports provided by a worldwide network of correspondents. The reports contain the names and contact information for all sources. Please note that these reports are preliminary and subject to change as events are studied in more detail. The Global Volcanism Program welcomes further reports of current volcanism, seismic unrest, monitoring data, and field observations.     

Reports from the Smithsonian’s Global Volcanism Network,June 2008

Information included in this summary is based on more detailed reports published in the Bulletin of the Global Volcanism Network, vol. 33, no. 6, June 2008 (on the Internet at ). Edited by scientists at the Smithsonian, this bulletin includes reports provided by a worldwide network of correspondents. The reports contain the names and contact information for all sources. Please note that these reports are preliminary and subject to change as events are studied in more detail. The Global Volcanism Program welcomes further reports of current volcanism, seismic unrest, monitoring data, and field observations.