High-Frequency Response of the Atmospheric Electric Potential Gradient Under Strong and Dry Boundary-Layer Convection

The spectral response of atmospheric electric potential gradient gives important information about phenomena affecting this gradient at characteristic time scales ranging from years (e.g., solar modulation) to fractions of a second (e.g., turbulence). While long-term time scales have been exhaustively explored, short-term scales have received less attention. At such frequencies, space-charge transport inside the planetary boundary layer becomes a sizeable contribution to the potential gradient variability. For the first time, co-located (Évora, Portugal) measurements of boundary-layer backscatter profiles and the 100-Hz potential gradient are reported. Five campaign days are analyzed, providing evidence for a relation between high-frequency response of the potential gradient and strong dry convection.     

Determining the drivers of long‐term aridity variability: a southern African case study

This paper highlights the importance of differentiating between precipitation amount and moisture availability (‘humidity’/‘aridity’) when considering proxy records of climate change. While the terms are sometimes used interchangeably, moisture availability is determined by both (i) precipitation amount and (ii) temperature, through its influence on potential evapotranspiration. As many palaeoenvironmental proxies reflect changes in this water balance rather than purely precipitation amount, it is important to distinguish between the potential relative influences of precipitation and temperature if those records are to be interpreted in terms of climate mechanisms and/or compared with model outputs. As a case study, we explore how precipitation and temperature have determined moisture availability in South Africa's summer rainfall zone over the last 45 000 years. Using quantitative reconstructions of mean annual temperature, summer rainfall amount and an aridity index, our analysis reveals strong spatiotemporal variability in the relative influences of precipitation and temperature on aridity. Temperature is shown to have exerted a considerable and even dominant influence on moisture availability, resulting in elevated humidity during the last glacial period, despite significant reductions in precipitation amount.     

Effectiveness of the structural fisheries policy in the European Union

This paper presents an analysis of the effectiveness of the community structural policy in the fisheries sector by comparing the relative level of compliance with objectives (reduction of fleets and economic viability) with the mechanisms that have been implemented (structural funds and allocation of quotas). On the one hand, this analysis shows that there is a positive correlation between the level of structural funds and the attainment of goals. On the other hand, it was found that the greater the relative availability of quotas, the poorer the countries performed in complying with the objective of reducing the fishing capacity, and the higher the expectations of achieving acceptable yields. These correlations, however, were not very strong.     

Marine protected areas in Puerto Rico: Historical and current perspectives

In Puerto Rico, the environmental legislation for establishing marine protected areas (MPAs) is complex due to its current political position with the United States (US) as not only local but also federal US laws affect designations. Historically, during the Spanish rule, mangrove forests were protected for extractive reasons (i.e., charcoal) and the first protected area was established by 1918 as an Insular Forest. Currently, of the 37 MPAs recognized and investigated in this work, the vast majority (73%) are Natural Reserves, followed by Commonwealth Forests (13.5%). Most MPAs in Puerto Rico were implemented using a top-down approach (i.e., government) which follows US federal guidelines for protecting endangered species, critical habitats, and natural and cultural resources. The development of management plans for MPAs on the island is increasingly adopting a public participatory process. However, this latter process is new for the government of Puerto Rico that has not incorporated a policy based on an Integrated Coastal Management.     

Microstructure measurements in natural waters: Methodology and applications

Modern approaches to microstructure data processing, including wavelet denoising, are discussed. The wavelet procedure is applied to small-scale shear signals before estimating the dissipation rate ε and to the temperature/density profiles used to calculate Thorpe scales. Microstructure data obtained on the Mediterranean shelf of Catalonia are used to illustrate various approaches to the Thorpe displacement calculations. It is suggested that the Weibull probability function is an appropriate model for the Thorpe scale distribution. Microstructure measurements from the upper layer of the Boadella reservoir (Catalonia, Spain) support this finding.A new analytical approximation for the 1D Panchev–Kesich spectrum is deduced and the results of ε computation are compared with spectral fitting by the widely used Nasmyth spectrum. Applying the Kraichnan spectral model to compute ε from temperature spectra in the convective-viscous sub-range is examined as an alternative to the Batchelor spectrum. Microstructure measurements taken in Lake Banyoles (Catalonia, Spain) and in the North Atlantic were used for spectral calculations.Statistical analysis of eddy K_b and thermal K_θ diffusivities measured on a shallow shelf of the Black Sea shows the importance of process-orientated domain averaging of the diffusivities in obtaining good correspondence between K_b and K_θ in active turbulent regions. In weakly turbulent, stratified interior layers, the averaged K_b and K_θ differ significantly, which may point to the inapplicability of isotropic formulae used for ε and temperature dissipation χ_θ estimates, as well as to a dependence of the mixing efficiency γ on the Richardson number or in some cases on regions of fossil turbulence.     

Paleontology,sedimentology and paleoenvironment of a new fossiliferous locality of the Jurassic Cañadón Asfalto Formation,Chubut Province,Argentina

A new Late Jurassic assemblage of “conchostracans”, ostracods, bivalves and caddisfly cases from the locality “Estancia La Sin Rumbo”, Chubut Province (Patagonia, Argentina) is recorded. The fossils occur in the upper part of an outcropping 45 m thick volcaniclastic lacustrine sequence of yellowish tuffs and tuffites of the Puesto Almada Member, which is the upper member of the Cañadón Asfalto Formation with U/Pb age of 161 ± 3 Ma. The sequence represents one sedimentary cycle composed of a (lower) hemicycle of expansion and a (higher) hemicycle of contraction of the water body. The invertebrates lived in small freshwater bodies during the periods of expansion of the lake. The occurrence of a great number of small spinicaudatans, associated with mud-cracks, is evidence of dry climatic conditions and suggests several local mortality events. The spinicaudatan record of the fushunograptid–orthestheriid (component of the Eosestheriopsis dianzhongensis fauna) and the presence of Congestheriella rauhuti Gallego and Shen, suggest a Late Jurassic (Oxfordian to Tithonian) age. Caddisfly cases are recorded for the first time in the Cañadón Asfalto Basin.