Modeling Forest Emissivity at L-Band and a Comparison With Multitemporal Measurements

This letter describes recent advances in modeling forest emissivity at L-band. The formulation is based on a previously developed discrete model and includes a new representation of forest litter. Comparisons with multitemporal radiometric data collected in the framework of the ldquoBray 2004rdquo experiment, which was carried out within Les Landes forest, are shown and discussed. Input variables are given by using detailed ground measurements. In general, the model reproduces both absolute values and temporal variations of measured brightness temperature. The contribution of the litter to overall emission was found to be important.     

The relation of Holocene fluvial terraces to changes in climate and sediment supply,South Fork Payette River,Idaho

Well-preserved Holocene terraces along the South Fork Payette River in central Idaho provide a record of fluvial system behavior in a steep mountain watershed characterized by weathered and erodible Idaho Batholith granitic rocks. Terrace deposit ages were provided by ¹⁴C dating of charcoal fragments and optically stimulated luminescence (OSL) dating of sandy sediments. Along with pairing of many terrace tread heights, these data indicate episodic downcutting during the Holocene, with a mean incision rate of ～0.9 m/ka from ～7 ka to present. Prior to 7 ka, the river incised to within～3 m of current bankfull, but then aggraded by ～5 m over at least a ～10 km-long reach in an episode centered ～7–6 ka. Aggradation may relate to (1) increased hillslope sediment input from landslides and debris flows in steep tributary basins with abundant grussified granitic bedrock, (2) possible local landslide-damming of the channel, (3) decreased peak discharge, or (4) a combination of these factors. Middle Holocene channel aggradation ca. 7–6 ka corresponds with a period of prolonged and widespread aridity in the northern Rocky Mountains. Between ～5 and 1.3 ka, the river aggraded slightly and then remained stable, forming a prominent terrace tread at ～3 m above current bankfull. Modest aggradation to vertical stability of the South Fork Payette River at the 1.5 m terrace level ～1.0–0.7 ka corresponds with large fire-related debris flows in tributaries during Medieval droughts. Three intervals of incision (～5.5–5 ka, 1.3–1.0 ka and 0.5 ka) correspond with frequent but small fire-related sedimentation events and generally cooler, wetter conditions suggesting increased snowmelt runoff discharges. Other possible drivers of channel incision include an increase in stochastic or climate-modulated large storms and floods and a reduction in delivery of hillslope sediment to the channel. Aggradation is more confidently tied to climate through increases in hillslope sediment delivery and (or) decreased stream power, both likely related to warmer, drier conditions (including high-severity fires) that reduce snowmelt and decrease vegetation cover on steep slopes. Thus, the Holocene terraces of the South Fork Payette River do not reflect simple stepwise incision with periods of vertical stability and lateral migration, but record substantial episodes of aggradation as well. We infer that increases in hillslope erosion and mass movements combined with reduced discharges during prolonged droughts episodically reverse the post-glacial trend of downcutting, in particular during the middle Holocene. The present bedrock-dominated channel implies a strong tendency toward incision in the late Holocene.     

A tilted Bianchi type-V perfect fluid solution for stiff matter

We present a solution to the Einstein field equations for a massless scalar field in a Bianchi type-V spacetime, which can be interpreted as a solution for a perfect fluid with the equation of state of stiff matter. This solution complements a solution previously given by us for an anisotropic fluid.     

Passive revolution: A church‐military partnership in the Philippines

In the Philippines, a Catholic social movement for local development and broad structural transformation, referred to as Basic Ecclesial Communities, offers a counter‐narrative to state development. Predicated on the power of networked local groups, the Diocese of San Carlos has taken the original concept and rescaled it, operating a variety of social‐action programmes at the diocese level. The focus of this paper is a unique partnership between the diocese and the Armed Forces of the Philippines, which has produced a number of measurable positive changes in under‐serviced areas. We remain uncertain, however, about the extent to which the church is cooperating with, or being co‐opted by, the military as it enters into partnership, and many members of the clergy share our scepticism. In this paper we draw upon Gramsci's concept of passive revolution (1971) as a means to conceptualize both the efforts of the church to reform society from within, and the reaffirmation of the hegemonic discourse that seems inevitable.     

Management Strategies to Sequester Carbon in Agricultural Soils and to Mitigate Greenhouse Gas Emissions

Carbon sequestration in agricultural soils is frequently promoted as a practical solution for slowing down the rate of increase of CO₂ in the atmosphere. Consequently, there is a need to improve our understanding of how land management practices may affect the net removal of greenhouse gases (GHG) from the atmosphere. In this paper we examine the role of agriculture in influencing the GHG budget and briefly discuss the potential for carbon mitigation by agriculture. We also examine the opportunities that exist for increasing soil C sequestration using management practices such as reduced tillage, reduced frequency of summer fallowing, introduction of forage crops into crop rotations, conversion of cropland to grassland and nutrient addition via fertilization. In order to provide information on the impact of such management practices on the net GHG budget we ran simulations using CENTURY (a C model) and DNDC (a N model) for five locations across Canada, for a 30-yr time period. These simulations provide information on the potential trade-off between C sequestration and increased N₂O emissions. Our model output suggests that conversion of cropland to grassland will result in the largest reduction in net GHG emissions, while nutrient additions via fertilizers will result in a small increase in GHG emissions. Simulations with the CENTURY model also indicated that favorable growing conditions during the last 15 yr could account for an increase of 6% in the soil C at a site in Lethbridge, Alberta. Presented at the International Workshop on Reducing Vulnerability of Agriculture and Forestry to Climate Variability and Climate Change, Ljubljana, Slovenia, 7–9 October 2002.     

Platelet development in cuboid diamonds: insights from micro-FTIR mapping

Fourier transform infrared mapping of diamonds can reveal detailed information on impurities, with a spatial context. We apply this technique, combined with in situ isotopic analysis of carbon, to the study of cuboid diamond growth in a sample that exhibits some mixed-habit growth. While there has been some uncertainty in the literature regarding sectoral differences in nitrogen aggregation and subsequent platelet development, the data from this study appear far more conclusive. We show that despite nitrogen being concentrated in octahedral sectors, there is no detectable difference in the concentration-adjusted rate of nitrogen aggregation within octahedral and cuboid sectors. However, the resultant platelet development is significantly reduced in cuboid sectors compared to contemporaneously formed octahedral sectors. This finding has significant implications for the classification of diamonds using the relationship between their platelet intensity and the absorption caused by B centres. It means that cuboid diamonds naturally fall below the linear relationship that has been termed regular, which would lead to them being incorrectly interpreted as having experienced heating or deformation. The data also support earlier suggestions that large hydrogen concentrations in the diamond-forming fluid may be required for cuboid growth. We further suggest that high nitrogen and hydrogen concentrations are required for mixed-habit diamond growth, which might be the product of specific fluid chemistries that occur in reducing mantle environments.     

Observations and implications of damage from the magnitude Mw 6.3 Christchurch, New Zealand earthquake of 22 February 2011

This paper describes the observations made by a reconnaissance team following the 22nd February 2011, M_w 6.3, Christchurch, New Zealand earthquake (GNS Science, 2011). The team comprised of members of the UK based Earthquake Engineering Field Investigation Team who spent 5 days collecting observations on damage resulting from the earthquake. Although the magnitude of this earthquake was not particularly high (M_w 6.3), the shallow focus and close proximity resulted in locally very high ground motions, widespread damage and 182 fatalities. The earthquake is also particularly notable for the widespread liquefaction it caused, landslides and rockfalls in the hills south of Christchurch, and the significant damage suffered by unreinforced masonry and historic structures. Over wide areas of central Christchurch, recorded accelerations were in excess of those required by the current New Zealand seismic loadings standard (NZS1170.5:2004: Standards New Zealand 2004) and therefore the earthquake presented a valuable opportunity to assess performance of modern buildings under code-level ground acceleration.     

Local erosion rates versus active tectonics: cosmic ray exposure modelling in Provence (south-east France)

Over the past decade, in situ-produced cosmogenic nuclides have revolutionised the study of landscape evolution. In particular, numerous studies have demonstrated that, in active tectonic settings, cosmic ray exposure dating of deformed or displaced geomorphic features makes it possible to quantify long-term deformation rates. In western European countries, erosion due to climatically driven processes and human activities is probably the factor that most limits the accuracy of exposure ages and landscape modification rates. In this study, we present the results of a depth-profiling technique applied to alluvial terraces located along the Rhône and the Moyenne Durance rivers. The expected decrease with depth of the measured ¹⁰Be concentrations has been modelled using a χ² inversion method in order to constrain the exposure history of the alluvial sediments. The results suggest that: (1) over the Quaternary, the local surface erosion rates including both regional uplift and climatically driven processes acting on landforms are on the order of 30 m/Myr in southeastern France, and (2) providing a fairly good bracketing of the exposure age, the modelled abandonment age of alluvial terraces affected by the Moyenne Durance Fault allows estimating incision rates, comparing the alluvial terrace elevations with topographic river profiles, and a minimum vertical slip rate value of roughly 0.02 mm/yr for the southern segment of the Moyenne Durance Fault.     

Firmgrounds – key surfaces in the recognition of parasequences in the Aptian Lower Greensand Group, Isle of Wight (southern England)

Aptian Lower Greensand Group exposures in the cliffs of the Isle of Wight (southern England) display a consistent coarsening-up cyclicity on the scale of centimetres to tens of metres that reflects the bed, bed-set, parasequence, parasequence set and sequence hierarchy. These coarsening-up cycles are most commonly recognized at the scale of parasequences (20 cm to 10 m thick), genetically related groups of which form parasequence sets. Both parasequences and parasequence sets contain the succession of biofacies that culminate in firmground development. Numerous episodes of erosion, deposition and colonization are recorded, reflecting multiple erosion/bypass events. The increase in mean grain-size through each cycle is reflected by changes in physical sedimentary structures; ichnofauna or bioturbational fabric; fossil fauna and diagenesis. Interbedded mudstones, siltstones and sandstones in the lower beds of each cycle display a variety of structures ranging from low-angle, hummocky, or tabular cross-strata, sandstone-filled erosional gutters and planar lamination. The cleaner sandstones found in the upper parts to each cycle are often completely bioturbated with only rare stratification and pebble/plant debris-filled scours preserved. Bioturbational fabrics change upward through each cycle from small, subhorizontal, mud- or sandstone-filled burrows to large, branching, clay-filled or cemented burrow systems. The top surface of each cycle is marked by a fossil epifauna indicative of firm to hard substrate conditions. Concentrations of bivalves, brachiopods, bryozoa, crinoids and corals are preferentially cemented by iron oxide, carbonate or phosphate. Such cements were early and thus utilized by firm or hard substrate dwellers. This fossiliferous, cemented sandstone is overlain by a flooding surface marked by the mudstone and silt-rich sandstones at the base of the next cycle. Together, the fauna and ichnofauna in each cycle represent the gradual development of firm substrate conditions, culminating in the diverse firmground fauna preserved at the top of each cycle. The fauna and changing substrate conditions reflect the hiatuses developed during successive episodes of marine flooding. High species diversity is matched by complex patterns of taphonomic feedback in the mature firmground faunas that mark major flooding surfaces. Increasing faunal maturity allows recognition of a hierarchy of hiatuses. This hierarchy is analogous to the parasequence–parasequence set division. The stratigraphic condensation of firmgrounds can be used to empirically define the condensed section, the thickness of sediment between firmgrounds being a function of sediment supply and water depth (accommodation space).