Multiple exposures and dynamic vulnerability: Evidence from the grape industry in the Okanagan Valley, Canada

This paper assesses the vulnerability of grape growers and winery operators in the Okanagan Valley, British Columbia to climate variability and change, in the context of other sources of risk. Through interviews and focus groups, producers identified the climatic and non-climatic risks relevant to them and the strategies employed to manage these risks. The results show that the presence of multiple exposures affects the way in which producers are vulnerable to climate change. Producers are vulnerable to conditions that not only affect crop yield, but also affect their ability to compete in or sell to the market. Their sensitivity to these conditions is influenced in part by institutional factors such as trade liberalization and a “markup-free delivery” policy. Producers’ ability to adapt or cope with these risks varies depending on such factors as the availability of resources and technology, and access to government programmes. Producers will likely face challenges associated with the supply of water for irrigation due to a combination of climatic changes and changing demographics in the Okanagan Valley, which in turn affect their ability to adapt to climatic conditions. Finally, adaptations made by producers can change the nature of the operation and its vulnerability, demonstrating the dynamic nature of vulnerability.     

Faeroe-Iceland plume: Rare-earth evidence

Rare-earth abundances through the 3000-m thick Faeroes Plateau basalt monitor the Faeroe-Iceland plume activity with time. An abrupt change from light Re-enriched to depleted patterns is observed naer the boundary of the middle and upper series of the Faeroes Plateau basalt. The discontinuity seems to reflect a change of volcanic regime from plume-derived to more akin to oceanic type. The change also coincides with field evidence for beginning of subsidence of the plateau. Using existing spreading rate history for the North Atlantic during the 50–60-m.y. B.P. period, which is one of deceleration, the change of volcanic regime suggests a decline of intensity of the Faeroe-Iceland plume during the late part of the period. Rising blobs, rather than a continuous plume, appears preferable for modeling the temporal plume activity.     

Transition Regimes in Valley Airflows

A three-dimensional, non-hydrostatic model was used to examine the dynamical characteristics of morning and evening transition periods in the atmosphere over four idealised valleys. The simulations provided detailed structure over full diurnal cycles of the valley-wind system. An essentially two-dimensional simulation (Case 1) clearly showed valley-side slope flows, driven by pressure gradients and modulated by vertical diffusion and Coriolis effects. The rotation of the wind was clockwise on both valley sides, contrary to most observations in nature. Three-dimensional simulations (Cases 2–4) rectified this feature and that for Case 4 satisfactorily modelled the valley-plain wind system throughout the diurnal cycle. Three types of transition were identified with the aid of different tools: hodographs; space-time evolution of the wind fields; and the evolution of the forcing terms in the momentum and temperature equations. Whichever type or Case was considered, the evening transition was longer than the morning one and the along-valley transition followed the along-slope one. In Cases 1 and 4 the evening transition started up to 2 h before sunset and the morning transition started up to 2.5 h after sunrise. In the three-dimensional cases the evening transition began at about 1700 and ended at about 2400, starting at the bottom of the valley and propagating up both valley sides, but at different speeds. It also started at the ground and propagated vertically. The morning transition began at about 0900 and ended at about 1100, also starting at the bottom of the valley and propagating both vertically and up the valley sides, albeit with different regimes on the two sides. The along-valley transition lagged that on the slopes by about 1.5 h. In Case 1 the forcing terms were dominated by the pressure gradient and the vertical diffusion, with the Coriolis effects introducing an along-valley component to the slope flows. The three dimensional cases were more complex, with not only the addition of the effects of advection and horizontal diffusion but also more temporal variation of more of the forcings than in Case 1.     

Design and tests of a trawl-resistant package for an acousticDoppler current profiler

A package designed to protect an RD Instrument Ltd. acoustic Doppler current profiler survived several passages of a bottom trawl. The package, in the shape of a truncated pyramid, has a base 4 m by 3.3 m and a height of 53 cm. The authors describe the package, its deployment method, and field test results where a trawl was repeatedly dragged over the unit. The device has been used successfully three times on the continental shelf. Some acoustic measurements were also made to ascertain the effect of the package on the beam pattern. The results show that this design can protect the instrument from bottom trawls and the acoustic beams are minimally affected by the plastic plate in front of the instrument transducers     

Snow accumulation distribution on Spitsbergen, Svalbard, in 1997

A survey of the regional snow accumulation variability on Spitsbergen, Svalbard, was carried out during three field campaigns in May 1997. The survey was carried out along three transects from west-to-east approcimately at the following latitudes: 77°30', 78° and 78°50'degrees north. The altitudes span from sea level to 1000 metres elevation. Snow depth was measured with two different ground-penetrating radar systems, PulsEKKO (450 MHz) and GSSI SIR System-2 (500 MHz), pulled behind snow machines. Snow characteristics such as snow temperature, snow density and stratigraphy were measured in snow pits in nine areas, three along each transect. Our data suggest the following: (1)the accumulation-elevation gradients vary from 3 mm/100 m in the northeast to 237 mm/100 min the central-south with an average value of 104 mm/100m for all measurements: (2)snow accumulation was 38 to 49% higher at the eastern coast than at the western coast; (3) a clear minimum in accumulation (or continental climate) is seen for the central (inland) locations in the middle and northern transects while no such minimum exists along the southern transect; (4) a south-to-north gradient produces 55% and 40% less snow accumulation at the northern locations compared to the southern locations at the western and eastern coasts, respectively. These drops in winter snow accumulation occur over a distance of less than 200 km.