Diagnosing the diurnal surface energy balance over the summer tundra at Princess Marie Bay from simple short-period measurements

Summary Using existing physical parameterizations, a new mathematical model is formulated to diagnose the diurnal variation of the energy fluxes and temperature on the snow-free tundra surface at Princess Marie Bay, Ellesmere Island, Canada. The input to the model consists of three meteorological variables which can be readily measured by an automatic weather station: incoming short-wave radiation, windspeed and screen level temperature. The model is based on the one-dimensional heat conduction equation for unfrozen soil, with surface heat exchange by short- and long-wave radiation and by convection and evaporation. A permafrost surface is used as a lower boundary condition. The model is formulated and tuned using a series of data from the Princess Marie Bay site. It is then tested using a separate data set from the same site and an independent data set from a nearby site.With 10 Figures     

Building a case against economic development

Although development is widely held to be the solution to poverty in the Third World, a case can be made that it is a part of the problem. It is commonly believed that development eradicates poverty through increased production of goods and services, but the past history of that activity also contains an unacknowledged history of socially-constructed scarcity. Poverty is a form of development-induced scarcity caused by the playing out of production relations located within a nexus of interacting technical, social, political, cultural, ecological, and academic relations. In that sense poverty is caused by multiple forces acting within a discursive materialist formation. We have used an analytical framework called the nexus of production relations to elucidate these ideas. This framework also suggests that the opportunities available to the poor for meeting their needs are far more varied and numerous than theories of economic development would have us believe.     

Geology of the Miami Terrace and its paleo-oceanographic implications

The Miami Terrace is a drowned early to middle Tertiary carbonate platform, the outer margin of which has been deeply incised by submarine erosion subsequent to deposition of the limestone terrace. This interpretation is based on the study of high-resolution seismic reflection profiles, rock dredge samples, observations from deep-diving submersibles, and correlation with drill-hole data. The karstic upper terrace (200–375 m) yields limestones and dolostones of early middle Miocene age that have shallow-shelf affinities. Truncated beds of an eastward-dipping deeper-water slope facies are exposed on the upper surface of the erosional lower terrace at 600–700 m. The upper and lower terraces are separated by a discontinuous ridge, probably a drowned Miocene, or post-Miocene bank margin complex. Both terraces and the ridge are capped by dense conglomeratic phosphorites and phosphatic limestones. Phosphorite nodules are more common on the lower terrace whereas the upper terrace yields large phosphorite slabs as well as shark's teeth and bones of marine mammals.

Petrographic study of dredged and submersible-sampled rocks shows that two or more episodes of phosphatization took place intermittent with erosion, grain rounding, reworking and redeposition. Early stages of phosphatization appear to be selective, replacing the more unstable carbonate minerals first, while later stages are nonselective. The origin of most of the phosphorites is the diagenetic replacement of calcium carbonate by francolite.

The karst surface of the upper terrace appears to have been produced by subaerial exposure in the middle to late Miocene as evidenced by shallow-water components in the rocks of the upper terrace plus considerations of local subsidence and eustatic sea-level curves. The erosional lower terrace, 200–300 m deeper than the upper terrace, would have been too deep to have been produced by subaerial or wave erosion. An erosional hiatus of middle Miocene age in JOIDES drill holes on the Blake Plateau indicates that bottom-current velocities in this area increased over this interval. The formation of the lower erosional terrace is related to increased flow of the Gulf Stream system (Florida Current) and bioerosion concurrent with the tectonic uplift and oceanographic closure of the western Caribbean in mid-Miocene time.

The bathymetry, petrology, structure and paleontology of the Miami Terrace, along with correlative data from adjacent areas, argue that a more active Gulf Stream system began as early as the middle Miocene (10.5–16 m.y.B.P.) rather than the early to middle Pliocene (3.5–4.0 m.y.B.P.) as previously suggested.     

Study of the Saldanha Massif (MAR, 36°34′ N): Constrains from rock magnetic and geophysical data

We present a study of the magnetic properties of a group of basalt samples from the Saldanha Massif (Mid-Atlantic Ridge – MAR – 36° 33 54 N, 33° 26 W), and we set out to interpret these properties in the tectono-magmatic framework of this sector of the MAR. Most samples have low magnetic anisotropy and magnetic minerals of single domain grain size, typical of rapid cooling. The thermomagnetic study mostly shows two different susceptibility peaks. The high temperature peak is related to mineralogical alteration due to heating. The low temperature peak shows a distinction between three different stages of low temperature oxidation: the presence of titanomagnetite, titanomagnetite and titanomaghemite, and exclusively of titanomaghemite. Based on established empirical relationships between Curie temperature and degree of oxidation, the latter is tentatively deduced for all samples. Finally, swath bathymetry and sidescan sonar data combined with dive observations show that the Saldanha Massif is located over an exposed section of upper mantle rocks interpreted to be the result of detachment tectonics. Basalt samples inside the detachment zone often have higher than expected oxidation rates; this effect can be explained by the higher permeability caused by the detachment fault activity.     

Some thoughts on the Cold Eddy south of Enshunada

On the basis of the results confirmed in the new volume Kuroshio, a figure is presented on subsurface temperature arranged chronologically for the selected one-degree square to clearly document the bimodal state of the Kuroshio in this area. To extend this analysis of the state further into the non-documented past, a preliminary survey is attempted with the data on air and sea-temperatures at Hachijojima of these 45 years. As may be anticipated, those data are found to bear little in-phase correlation with the Cold Eddy, though they might prove useful after further analysis. Some ideas of analyzing tree-rings on Hachijojima and shallow sea sediments are also discussed in this connection.