Desert isotope hydrology: Water sources of the Sinai Desert

The isotopic composition of groundwater sources of the Sinai Desert was surveyed. The results are characterized by a large spread in the oxygen-18 and deuterium abundances, compared to equivalent systems from less arid climates. The variability reflects differences in the altitude at which precipitation occurred, the evaporation from stagnant surface waters prior to their infiltration into the ground and admixtures of waters which are not of meteoric or recent origin. It is difficult to distinguish between water sources recharged by direct infiltration and others recharged through the intermediary of flood waters, on the basis of their isotope composition. The isotopio composition enables a clearcut distinction, however, between paleowaters and more recently recharged groundwaters. Among the conclusions: paleowaters play a central role in the deep aquifers of desert areas; direct rain recharge to aquifers is widespread; surface waters which have undergone extensive evaporation contribute their water to local perched aquifers which are found along their route.     

Nonparametric Estimates of the Sea State Bias for the Jason-1 Radar Altimeter

The Jason-1 sea state bias (SSB) is analyzed in depth from the first year of GDR products. Compared to previous missions, this work benefits from two aspects of the empirical determination of the SSB from the altimetric data themselves. First, from a methodological point of view, a nonparametric technique (NP) has been developed and largely tested on TOPEX/Poseidon 1, GFO and Envisat data. The NP estimator has proven to be a useful tool in the SSB estimation, and it is now mature enough to be used for a refined analysis. On the other hand, the SSB can be extracted from three different data sets (crossovers, collinear data, and residuals) with different characteristics. It is then possible to cross calibrate various estimations of the SSB models and to determine the most accurate one. A systematic comparison is made between these different estimates for the Jason-1 altimeter. The collinear and crossover data sets yield very similar estimates despite their difference of spatial and temporal distributions. These SSB models assure consistency with the TOPEX mission when comparing Jason-1 and TOPEX residuals during the tandem phase. Thanks to the present work, the impact of the short wavelengths filtering on the SSB estimation is evidenced. More generally, our understanding of potential errors affecting the sea surface height and their impact onto the SSB estimation is also improved.     

Why chromatic imaging matters

During the last two decades, the first generation of beam combiners at the Very Large Telescope Interferometer has proved the importance of optical interferometry for high-angular resolution astrophysical studies in the near- and mid-infrared. With the advent of 4-beam combiners at the VLTI, the u ? v coverage per pointing increases significantly, providing an opportunity to use reconstructed images as powerful scientific tools. Therefore, interferometric imaging is already a key feature of the new generation of VLTI instruments, as well as for other interferometric facilities like CHARA and JWST. It is thus imperative to account for the current image reconstruction capabilities and their expected evolutions in the coming years. Here, we present a general overview of the current situation of optical interferometric image reconstruction with a focus on new wavelength-dependent information, highlighting its main advantages and limitations. As an Appendix we include several cookbooks describing the usage and installation of several state-of-the art image reconstruction packages. To illustrate the current capabilities of the software available to the community, we recovered chromatic images, from simulated MATISSE data, using the MCMC software SQUEEZE. With these images, we aim at showing the importance of selecting good regularization functions and their impact on the reconstruction.     

NATURAL AND ANTHROPOGENIC FACTORS CONTROLLING GULLY EROSION IN THEBASALTIC UPLAND OF SOUTHERN BRAZIL

This paper describes an analysis of natural and anthropogenic factors controlling the evolution of gullies in a rural basin in the basaltic upland in the State of Rio Grande do Sul, Southern Brazil. In this region of deep ferrallitic soils with more than 60% clay, runoff and erosion are of increasing concern. In the TaboAo drainage basin （100 km^2）, gully erosion was studied in a field survey that measured rills and gullies. Eighty-four gullies were identified. They had an average length of 136 m, were 10 m wide, and 3 m deep and had a volume of 15.458 m3. Each gully was characterised in terms of factors that included slope, geological structure, presence of piping, drainage, soil use, and the presence of surface and subsurface flow. On average, the main channels had knickpoints varying from 2 m to 7 m, and their evolution in the vertical plane increased until bed-rock basalt material was reached, after which gullies increase in width and length. Gully development was also monitored from 1991 to 2003. Subsurface flow appears to be the principal agent controlling their development. Results show that both natural （slope, surface curvature, geological structure and rainfall） and anthropogenic （soil use, road construction） factors are important in gully development. The change in cultural practices throughout the drainage basin from conventional to direct seeding has led to increased subsurface flow, which was more important than surface runoff in causing erosion. However, the higher rainfall during E1 Nifio Southern Oscillation （ENSO） events and the consequently higher subsurface flow were the dominant factors. From 1991 to 2003 a total land loss of 1,013 m3 was observed in one gully, with 236 m^3 lost during the 1992 ENSO and 702 m3 during the 1997 ENSO; 95% of the total volume lost occurred during ENSO periods.     

Cost Shifting in Australian Local Government: an analysis of the spatial impact of pensioner rate concession rebates in New South Wales,Australia

The problem of cost shifting from higher tiers of government to local councils in Australia is widely recognised and has been investigated by several official inquiries. However, it has thus far been difficult to gather reliable estimates of the magnitude of the problem. Quite apart from the taxing definitional and data problems associated with the phenomenon, these difficulties have been compounded by the fact that very few attempts have been made to measure the impact of specific instances of cost shifting in Australian local government, especially its spatial impact. In an attempt to remedy this neglect, this paper seeks to measure the spatial effects of pensioner rate concession rebates on local councils in New South Wales.     

Beyond the epsilon band: polygonal modeling of gradation/uncertainty in area-class maps

A spatial modeling technique is proposed to represent boundary uncertainty or gradation on area-class maps using a simple polygon tessellation with designated zones of indeterminacy or transition zones. The transition zone can be conceptualized as a dual of the epsilon band, but is more flexible and allows for a wide range of polygonal configurations, including polygons with sinuous boundaries, spurs, three-way transition zones, and null polygons. The model is specified using the medial axis to capture the general shape characteristics of a transition zone. Graph theoretic representation of an extended version of the medial axis captures key junctions in both shape and classification and is used to identify well-formed transition zones that can be logically and unambiguously handled by the model. A multivariate classification surface is specified by first defining degrees or probabilities of membership at every point on the medial axis and transition zone boundary. Degrees or probabilities of membership at all other points are defined by linear interpolation. The technique is illustrated with an example of a complex transition zone, and a simple isoline representation that can be derived from the model is presented. The proposed modeling technique promises to facilitate expert characterization of soil formations, ecological systems, and other types of areal units where gradation and/or boundary uncertainty are prevalent.     

Effects of nutrients and irradiance on PSII variable fluorescence of lake phytoplankton assemblages

Phytoplankton from Lake Ontario and six small Canadian lakes (Dorset Lakes) were supplemented with nitrogen (N) and phosphorus (P) to determine how nutrients affect Photosystem II (PSII) variable fluorescence and photoinhibition in natural freshwater communities. Susceptibility of PSII to photoinhibition by photosynthetically active radiation (PAR) and ultraviolet radiation (UVR), as well as recovery potential, was quantified using changes in variable fluorescence and compared between N- and P-supplemented (Nu+) and non-supplemented (Nu?) Lake Ontario phytoplankton. Nu+ communities exhibited slightly higher variable fluorescence than Nu? when dark-adapted (F_v:F_m) or under constant illumination (F_q′:F_m′). Rates of relative electron transport (rETR) were greater for Nu+ than Nu? phytoplankton, with higher non-photochemical quenching (NPQ) by Nu? samples. The initial slope of the rETR-irradiance curve (α) did not differ significantly between nutrient treatments, but the saturation irradiance (E_K) was significantly higher for Nu+ samples than for Nu? samples. Nutrient supplementation increased rates of PAR- and UVR-dependent damage but also recovery, so that net PSII photoinhibition was equally severe as in the absence of added N and P. Additions of N, P, and N + P did not significantly alter F_v:F_m of Dorset Lakes phytoplankton. Compared to the range of variable fluorescence observable over the diel cycle of photoinhibition and recovery in Lake Ontario, the effects of supplemental nutrients observed in this study were minor.     

THE EIGHTIETH BIRTHDAY OF AN EMINENT WORLD CARTOGRAPHER

The multifaceted career and contributions of Professor Konstantin A. Salishchev, Chair of the Moscow University Department of Cartography and eminent world cartographer, are celebrated on the occasion of his eightieth birthday. These contributions include but are not restricted to: scholarly and administrative work in upgrading national atlas cartography worldwide, improvement of the quality of maps and cartographic instruction in higher education, publication of numerous excellent cartographic texts, formulation of the concept of the “cartographic method of research,” and promotion of international cooperation among cartographers and geographers through active participation and leadership in numerous world professional organizations. From the Russian original by I. D. Papanin, G. I. Rychagov, and A. F. Treshnikov.     

Application of a Weighted-Averaging Method for Determining Paleosalinity: A Tool for Restoration of South Florida’s Estuaries

A molluscan analogue dataset is presented in conjunction with a weighted-averaging technique as a tool for estimating past salinity patterns in south Florida’s estuaries and developing targets for restoration based on these reconstructions. The method, here referred to as cumulative weighted percent (CWP), was tested using modern surficial samples collected in Florida Bay from sites located near fixed water monitoring stations that record salinity. The results were calibrated using species weighting factors derived from examining species occurrence patterns. A comparison of the resulting calibrated species-weighted CWP (SW-CWP) to the observed salinity at the water monitoring stations averaged over a 3-year time period indicates, on average, the SW-CWP comes within less than two salinity units of estimating the observed salinity. The SW-CWP reconstructions were conducted on a core from near the mouth of Taylor Slough to illustrate the application of the method.