Area-Averaged Sensible Heat Flux and a New Method to Determine Zero-Plane Displacement Length over an Urban Surface using Scintillometry

Field observations of area-averagedturbulence characteristics were conducted in a densely built-up residential neighbourhood in Tokyo, Japan. In addition to eddy-correlation (EC) sensors a scintillometer was used for the first time in a city. Significant results include: (1) Scintillometer-derived sensible heat fluxes, Q_H, obtained at a height 3.5 times the building height agree well with those using the EC technique; (2) source areas for the scintillometer fluxes are larger than for the EC sensors, so that at low heights over inhomogeneous terrain scintillometry offers advantages; (3) new similarity relationships for dissipation rates are proposed for urban areas; (4) a new technique that uses simultaneous scintillation measurements at two heights to directly estimate area-averaged zero-plane displacement height, z_d, is proposed. z_d estimated in this way depends slightly on atmospheric stability (lower z_d under more unstable conditions).     

Snow disappearance timing is dominated by forest effects on snow accumulation in warm winter climates of the Pacific Northwest,United States

Forests modify snow processes and affect snow water storage as well as snow disappearance timing. However, forest influences on snow accumulation and ablation vary with climate and topography and are therefore subject to temporal and spatial variability. We utilize multiple years of snow observations from across the Pacific Northwest, United States, to assess forest–snow interactions in the relatively warm winter conditions characteristic of maritime and transitional maritime–continental climates. We (a) quantify the difference in snow magnitude and disappearance timing between forests and open areas and (b) assess how forest modifications of snow accumulation and ablation combine to determine whether snow disappears later in the forest or in the open. We find that snow disappearance timing at 12 (out of 14) sites ranges from synchronous in the forest and open to snow persisting up to 13 weeks longer in the open relative to a forested area. By analyzing accumulation and ablation rates up to the day when snow first disappears from the forest, we find that the difference between accumulation rates in the open and forest is larger than the difference between ablation rates. Thus, canopy snow interception and subsequent loss, rather than ablation, set up longer snow duration in the open. However, at two relatively windy sites (hourly average wind speeds up to 8 and 17 m/s), differential snow disappearance timing is reversed: Snow persists 2–5 weeks longer in the forest. At the windiest sites, accumulation rates in the forest and open are similar. Ablation rates are higher in the open, but the difference between ablation rates in the forest and open at these sites is approximately equivalent to the difference at less windy sites. Thus, longer snow retention in the forest at the windiest sites is controlled by depositional differences rather than by reduced ablation rates. These findings suggest that improved quantification of forest effects on snow accumulation processes is needed to accurately predict the effect of forest management or natural disturbance on snow water resources.     

Holocene palaeoenvironments at the timberline in the French Alps—a multidisciplinary approach

An attempt is made to reconstruct the palaeoenvironmental Holocene history at the timberline on the basis of the analysis of various palaeoecological proxy indicators available on a marshy area and its surroundings in the Taillefer Massif (Isère. France). The multidisciplinary approach involves analyses of pollen assemblages. plant macrofossils, coleoptera remains. subfossil trunks extracted from lakes or peat-bogs. and charcoals derived from the surrounding soils. This enables definition of the respective roles of five forest taxa ( Pinus uncinata Mill., Pinus cembra L., Larix decidua Mill., Abies alba Mill, and Picea abies L. Karsten) in the evolution of high altitude forests during the Holocene. Pinus uncinata was present on the plateau throughout the Holocene. Larix and Pinus cembra were present only during two periods: 7500-5000 BP and 3500-2000 BP. All trees disappeared from the plateau at about 2000 BP, while, at lower altitude. Abies was replaced by Picea. The action of both climate and early human impact can explain these changes.     

Multivariate discriminant analysis of bioclastic turbidites

A piston core from the southern Blake Basin penetrated nine distinct bioclastic carbonate turbidites separated by pelagic terrigenous clay units. X-ray diffraction analysis of the carbonate mineralogy of the graded, laminated, and homogenous units of the individual turbidite units indicated a general loss of unstable carbonates in the homogenous unit beyond that contained in the lower two units. Univariate and multivariate statistical tests were employed to determine the significance of the changes and to determine if different units of a turbidite sequence could be consistently grouped by statistical methods. Principal components, discriminant function, and cluster analysis were used in the multivariate tests. The graded and laminated units were closely related in mineralogy with little significant differences. The mineralogy of the homogenous units was significantly different than that of the other two units except in one example. Cluster analysis generated five groupings of the samples with the end members consisting of graded and laminated units at one end and homogenous units at the other.     

Radar altimetry of South Tharsis,Mars

Martian altitudes were measured by radar during the oppositions of 1971 and 1963 using the 64-m antenna at Goldstone (California). The resultant topographic profiles substantiate a zonal classification of the volcanic flows blanketing the south flanks of Arsia Mons, and they confirm the existence of a secondary, parasitic shield attached from the SSW to the main Arsia shield. The secondary shield is about 400 km in diameter at its base and at least 4 km high at its center. South of Valles Marineris, the Tharsis plateau is bounded by the approximate longitudes of 80° in the east and 140° in the west. In the Sinai Planum, closely adjacent to Coprates Chasma, another rise has been detected, bounded by longitudes of 55° in the east and 80° in the west. A volcanic shield of diameter 80 km, capped with a 22 km caldera has been identified near the crest of the rise. Topographic highs of about 1 km are associated with heavily faulted tracts such as Claritas Fossae. The distribution and orientation of the lunar-mare-like ridges in Sinai Planum appear to be independent of the regional gradients. Segments of the chaotic terrain at the eastern terminus of Valles Marineris are located as much as 6 km below the level of the surrounding plains.     

On the stroboscopic method of second order

It is assumed that the dynamical system can be represented by equations of the form $$\begin{gathered} \dot x = \varepsilon _i f_i (x,y) \hfill \\ \dot y = u(x,y) + \varepsilon _i g_i (x,y) \hfill \\ \end{gathered} $$ as this is the case for the Lagrange equations in celestial mechanics. The perturbation functionsf _i andg _i may also depend on the timet. The fast angular variabley is now taken as independent variable. Using perturbation theory and expanding in Taylor series the differential equations for the zeroth, first, second, ... order approximations are obtained. In the stroboscopic method in particular the integration is performed analytically over one revolution, say from perigee to perigee. By the rectification step applied tox andt, the initial values for the next revolution are obtained. It is shown how the second order terms can be determined for the various perturbations occurring in satellite theory. The solution constructed in this way remains valid for thousands of revolutions. An important feature of the method is the small amount of computing time needed compared with numerical integration.     

Domestic water supply impacts by underground coal mining in Virginia, USA

 Underground coal mining can affect wells and springs used as water supplies. In Virginia, concerns over such impacts are felt by both surface owners and coal-mining firms. Virginia's geologic history has caused faults and fractures to be common in its coalfield region, relative to other Appalachian coal-mining areas. The results of 73 investigations of alleged domestic water supply impacts by underground mining were analyzed; the investigations were conducted by the Virginia Division of Mined Land Reclamation (VDMLR). This analysis was conducted with reference to guidelines that define a primary zone of underground mining influence where dewatering of aquifers is to be expected. The VDMLR data set included 27 investigations of alleged water supply impacts by partial-extraction room-and-pillar mines, 41 investigations of high-extraction room-and-pillar mines, and 4 investigations of longwall mines. VDMLR investigators found that 14 of 16 water supplies within the primary zone of influence were likely to have been affected by pillar-retreat mining, but no water supplies within the primary zone of influence for longwall and room-and-pillar mines were represented in the data base. VDMLR investigators found 42 of 56 water supplies outside of the primary zones were likely to have been affected by mining; these cases represented room-and-pillar, pillar-retreat, and longwall mining. Geologic circumstances not directly related to subsidence were found to be responsible for 31 of these 42 impacts. These geologic circumstances included subsurface fractures and other geologic features acting as aquifers that were drained by underground mining operations. VDMLR investigators also found some of the investigated water losses to have been caused by factors other than mining. These results demonstrate the inherent difficulties of any attempt to rigidly define a "zone of underground mining impact" based solely on mine subsidence effects, especially in regions where geologic faults and fractures are common such as the southwest Virginia coalfield. Received: 4 August 1995 · Accepted: 23 October 1995     

Market-oriented conservation governance: The particularities of place

Conservation policy and practice is increasingly turning towards market-based interventions to reconcile the growing conflicts between environmental conservation and rural livelihood needs. This short introductory paper to the special issue on “market-oriented conservation governance” critically investigates the growing commitment to markets as a means of meeting conservation objectives and livelihood security. We distinguish market oriented conservation from neoliberal conservation and argue for a grounded, empirically rich investigation into the passive and active promotion of markets in conservation landscapes – analysis which pays attention to how and why certain markets are promoted by ENGOs, governments and private sector, as well as how rural people negotiate livelihoods and markets when adjusting to conservation pressures. Such an approach takes seriously how the particularities of place, from local harvests to trans-local trade, shape market-oriented conservation in practice and expose the messiness of such ventures. The range of papers in this special issue show how neither neoliberal nor market-based interventions in conservation are uniform in character, impact and outcome, and that while identifying the patterns and logic behind these processes remains crucial, the basis for understanding how markets inform conservation, must be done by drawing on empirical data that speaks clearly to how actors variously engage the logic of market-driven conservation in terms of their histories and contemporary realities. We argue that doing so makes it possible to understand not only what is ‘new’ about contemporary market-oriented conservation but also its continuities with earlier forms of command and control conservation.