Ground‐based thermal imagery as a simple,practical tool for mapping saturated area connectivity and dynamics

The hillslope‐riparian‐stream system is a key functional unit of catchments, yet very difficult to measure and monitor due to its tremendous complexity and high spatio‐temporal variability. Here, we present a simple and practical tool for imaging directly these hillslope‐riparian‐area connections. We used a FLIR b50 infrared camera to produce thermal images at the scale of 140 × 140 pixels over the spectral range 7·5–13 µm. Our IR imaging technique is sensitive to the upper 0·1 mm of the water column. Images were obtained from a constant position on the right bank of the Weierbach catchment in Luxembourg, at an incidence angle of approximately 45° over a 5‐week period. The study site measured 5 × 3 m. Our results show that ground‐based IR imagery can discriminate between areas with snow cover, snow melt, soil seepage, and stream water. More importantly, it can detect when and where variably saturated areas are active and when connectivity exists between the hillslope–riparian–stream system. Our proof of concept suggests that this is a simple, inexpensive technology for sequential mapping and characterisation of surface saturated areas and a useful complement to conventional tracer techniques. Copyright © 2010 John Wiley & Sons, Ltd.     

An Improved Parallel Multiple-point Algorithm Using a List Approach

Among the techniques used to simulate categorical variables, multiple-point statistics is becoming very popular because it allows the user to provide an explicit conceptual model via a training image. In classic implementations, the multiple-point statistics are inferred from the training image by storing all the observed patterns of a certain size in a tree structure. This type of algorithm has the advantage of being fast to apply, but it presents some critical limitations. In particular, a tree is extremely RAM demanding. For three-dimensional problems with numerous facies, large templates cannot be used. Complex structures are then difficult to simulate. In this paper, we propose to replace the tree by a list. This structure requires much less RAM. It has three main advantages. First, it allows for the use of larger templates. Second, the list structure being parsimonious, it can be extended to include additional information. Here, we show how this can be used to develop a new approach for dealing with non-stationary training images. Finally, an interesting aspect of the list is that it allows one to parallelize the part of the algorithm in which the conditional probability density function is computed. This is especially important for large problems that can be solved on clusters of PCs with distributed memory or on multicore machines with shared memory.     

Saturn's rings: Infrared brightness variation with solar elevation

The variation in infrared equilibrium brightness temperature of Saturn's A, B, and C rings is modeled as a function of solar elevation B′ with respect to the ring plane. The basic model includes estimates of minimum and maximum interparticle shadowing in a monolayer approximation. Simple laboratory observations of random particle distributions at various illumination angles provide more realistic shadowing functions. Radiation balance calculations yield the physical (kinetic) temperature of particles in equilibrium with radiation from the Sun, Saturn, and neighboring particles. Infrared brightness temperatures as a function of B′ are then computed and compared to the available 20-μm data (Pioneer results are also briefly discussed). The A and B rings are well modeled by an optically thick monolayer, or equivalently, a flat sheet, radiating from one side only. This points to a temperature contrast between the two sides, possibly due to particles with low thermal inertia. Other existing models for the B ring are discussed. The good fit for the monolayer model does not rule out the possibility that the A and B rings are many particles thick. It could well be that a multilayer ring produces an infrared behavior (as a function of tilt angle) similar to that of a monolayer. The C ring brightness increases as B′ decreases. This contrast in behavior can be understood simply in terms of the low C ring optical depth and small amount of interparticle shadowing. High-albedo particles (A?0.5) can fit the C ring infrared data if they radiate mostly from one hemisphere due to slow rotation or low thermal inertia (or both). Alternatively, particles isothermal over their surface (owing to a rapid spin, high inertia, or small size), and significantly darker (A?0.3) than the A and B ring particles, can produce a similar brightness variation with ring inclination. In any case, the C ring particles have significantly hotter physical temperatures than the particles in the A and B rings, whether or not the rings form a monolayer.     

Deep biological communities in the subduction zone of Japan from bottom photographs taken during “nautile” dives in the Kaiko project

Twenty-seven dives of the submersible “Nautile” in the subduction zone around Japan conducted in the French-Japanese Project Kaiko proved that fairly luxuriant benthic communities dominated by deep-sea giant clams of the genusCalyptogena (family Vesicomyidae) were consistently present on the accretionary prism at abyssal depths.Benthic communities characterized by three hitherto undescribed bivalves of the genusCalyptogena were found between depths of about 3800 and 4020 m at the mouth of Tenryu Canyon and at the top of basement swell of the Zenisu Ridge, both situated in the eastern Nankai subduction zone. Sporadic but discrete patches of organisms characterized by one more undescribed bivalve belonging to the genusCalyptogena were observed and collected between depths of 5130 and 5960 m on the landward wall of the Japan and Kouriles Trenches.Photographic inventories were prepared semiquantitatively using each series of bottom photographs taken in these areas with bow cameras of the submersible “Nautile”.Observations on the sporadic but dense distribution of the clams and other characteristic associated organisms match well with the scheme that communities sustained by chemosynthetic energy sources can be present at connate water seepages in subduction zones. These are to date the deepest record of benthic communities supposedly associated with chemosynthetic processes.     

Atmospheric lee waves in the Aegean Sea and their possible influence on the sea surface

Unusual satellite images of the Aegean Sea, in both the visible and infrared ranges, are discussed. Alternating bright and dark features downwind of islands suggest the presence of atmospheric lee waves. However, close examination of these features indicates that the observed signal is likely the signature of the influence of the lee waves on the sea surface rather than the signature of the lee waves themselves through atmospheric effects.     

Conditional Simulation of Multi-Type Non Stationary Markov Object Models Respecting Specified Proportions

Although Boolean model simulation has been widely used during the last two decades to simulate sedimentary bodies (especially in fluvio-deltaic environments), a key issue has subsisted. One of the most important parameter for object model simulation, namely the (non stationary) intensity of the underlying object process, is not a parameter provided by the end user but must instead be computed from other input parameters, such as local proportions of lithofacies, erosion rule between objects of different types and interaction between objects. This paper revisits a birth and death algorithm for simulating conditional, non stationary, multi-type objects models with interaction. It provides workable approximations for computing the local intensity of the underlying point process to respect proportion maps. Simulated examples show that this algorithm is able to reproduce the desired proportions. Important issues for implementing this algorithm are discussed.     

A shallow subsurface controlled release facility in Bozeman, Montana, USA, for testing near surface CO2 detection techniques and transport models

A controlled field pilot has been developed in Bozeman, Montana, USA, to study near surface CO₂ transport and detection technologies. A slotted horizontal well divided into six zones was installed in the shallow subsurface. The scale and CO₂ release rates were chosen to be relevant to developing monitoring strategies for geological carbon storage. The field site was characterized before injection, and CO₂ transport and concentrations in saturated soil and the vadose zone were modeled. Controlled releases of CO₂ from the horizontal well were performed in the summers of 2007 and 2008, and collaborators from six national labs, three universities, and the U.S. Geological Survey investigated movement of CO₂ through the soil, water, plants, and air with a wide range of near surface detection techniques. An overview of these results will be presented.