Multisource Data Integration for Fire Risk Management: The Local Test of a Global Approach

In this letter, we propose an algorithm to detect the presence of forest fires using data from both geostationary and polar-orbiting satellites. The very frequent acquisitions of the Spinning Enhanced Visible and Infrared Imager radiometer placed onboard the Meteosat Second Generation-9 satellite are used as main source for the algorithm, while the MEdium Resolution Imaging Spectrometer global vegetation index and the Advanced Along-Track Scanning Radiometer measurements are used to enhance the reliability of the detection. The problem is approached in a “global” way, providing the basis for an automated system that is not dependent on the local area properties. In cooperation with the Centre de Suivi Écologique (Dakar, Senegal), the proposed algorithm was implemented in a “Multisource Fire Risk Management System” for the Senegal area, as briefly described in this letter. A field campaign of one week was carried out in order to perform a validation of the system's detections, showing a good agreement with the fire coordinates measured on the ground. Furthermore, a consistency check was performed using data from the Moderate Resolution Imaging Spectroradiometer (MODIS) Rapid Response System, showing that more than 76% of high-confidence MODIS events are detected by the algorithm.      

One century sedimentary record of Hg and Pb pollution in the Sagua estuary (Cuba) derived from Pb and Cs chronology

The vertical distribution of Hg and Pb were determined in a sediment core collected from the Sagua estuary (North Cuba) that receives input from the Sagua river, one of the most polluted rivers discharging into the Cuban coastal environment. Depth profiles of metal concentrations were converted to time-based profiles using the ²¹⁰Pb dating method and confirmed with the ¹³⁷Cs fallout peak. The mean mass accumulation rate was estimated to be 0.17 ± 0.04 g cm⁻² y⁻¹ (mean sediment accumulation rate 0.52 ± 0.13 cm y⁻¹) and the core bottom was estimated to date back about 130 years. The historical sedimentary record showed a strong enrichment of mercury concentrations in the past decades, caused by the incomplete treatment of industrial wastes from a chlor-alkali plant with mercury-cell technology in the Sagua river basin. Lead fluxes to sediments showed a gradual increase from the 1920s to present, which agrees with a population increase in Sagua la Grande City. Fluxes of both metals have increased the past 25 years, with values reaching a maximum of 0.5 and 3.9 μg cm⁻² y⁻¹ for Hg and Pb, respectively.     

Validation of a kinematic and parametric approach to calculating intensity scenarios

We employ our semi-empirical kinematic model for shear body waves (KF) [Sirovich L. A simple algorithm for tracing out synthetic isoseismals. Bull Seism Soc Am 1996;86(4):1019–27; Sirovich L. Synthetic isoseismals of three earthquakes in California-Nevada. Soil Dyn Earthquake Eng 1997;16:353–62] to back-predict and then validate the regional intensity scenario of a destructive earthquake (Loma Prieta, California, M_s 7.1, October 17, 1989). Only the pre-1988 geological and seismotectonic knowledge was used to set the 11 source parameters of KF (in this sense, our procedure was deterministic). Then, the ranges of the pre-1988 uncertainties were explored by grid search and the parametric combination produced 59,049 sources. The quality of our prediction was measured using the field intensities of 1989 by the US Geological Survey (in the MMI scale). The squared scenario residuals are: 73 for the mean KF scenario and 123 for the best available empirical attenuation of MMI intensity. We stress that, before using KF in the forward mode, its automatic inverse application has already been validated by refinding a series of earthquake sources [Gentile F, Pettenati F, Sirovich L. Validation of the automatic nonlinear source inversion of the US geological survey intensities of the Whittier Narrows, 1987 Earthquake. Bull Seism Soc Am 2004;94(5):1737–47; Pettenati F, Sirovich L. Intensity-based source inversion of three destructive California earthquakes. Bull Seism Soc Am 2007;97(5):1587–606; Sirovich L, Pettenati F. Source inversion of intensity patterns of earthquakes: a destructive shock in 1936 in northeast Italy. J Geophys Res 2004;109:B10309, doi:10.1029/2003JB002919:1–16]. If our technique had been available at the time, the 1989 pattern of damage south of San Francisco would have been conservatively foreseen even from 1983 on.     

The changing Patagonian landscape: Erosion and westward sediment transfer paths in northern Patagonia during the Middle and Late Pleistocene

Pleistocene glaciations have promoted important landscape transformations as a result of high rates of erosion and rapid sediment evacuation to adjacent marine basins. In the Patagonian Andes the role of the Patagonian Ice Sheet on landscape evolution, in particular the spatial patterns of glacial erosion and its influence on sediment fluxes, is poorly documented. Here, we investigate the Middle and Late Pleistocene sedimentary record of the continental slope from Ocean Drilling Program (ODP) Site 861, offshore Patagonia (46°S), to evaluate the link between glaciations, mountain range erosion and continental margin strata formation. Petrographic analysis of the sand-size fraction (0.063–2 mm) and ɛNd and ⁸⁷Sr/⁸⁶Sr measurements in the silt-size fraction (10–63 µm) indicate that glacial erosion over the last 350,000 years has focused within the Patagonian Batholith, with a minor influence of a proximal source to the drilling site, the Chonos Metamorphic Complex. This shows that erosion has focused in the core of the northern Patagonian Andes, coinciding roughly with the location of the Liquiñe-Ofqui Fault Zone and the zone of concentrated precipitation during glaciations, suggesting a combined climatic and structural control on glacial erosion. Temporal variation in the provenance signal is contemporaneous with a marked change in the stratigraphy of ODP Site 861 that occurred after the glaciation of MIS 8 (~240 kyr ago). Before MIS 8, a restricted provenance signal and coarse lithofacies accumulated on the continental slope indicates spatially restricted erosion and efficient transfer of sediment towards the ocean. In contrast, very high provenance variability and finer continental slope lithofacies accumulation after MIS 8 suggest a disorganized expansion of the areas under erosion and a more distal influence of ice sediment discharge to this site. We argue that this change may have been related to a re-organization of the drainage patterns of the Patagonian Ice Sheet and flow of outlet glaciers to the continental margin during the last two glaciations.     

The accretion of brown dwarfs and planets by giant stars – II. Solar-mass stars on the red giant branch

This paper extends our previous study of planet/brown dwarf accretion by giant stars to solar-mass stars located on the red giant branch. The model assumes that the planet is dissipated at the bottom of the convective envelope of the giant star. The evolution of the giant is then followed in detail. We analyse the effects of different accretion rates and different initial conditions. The computations indicate that the accretion process is accompanied by a substantial expansion of the star, and, in the case of high accretion rates, hot bottom burning can be activated. The possible observational signatures that accompany the engulfing of a planet are also extensively investigated. They include the ejection of a shell and a subsequent phase of IR emission, an increase in the ⁷Li surface abundance and a potential stellar metallicity enrichment, spin-up of the star because of the deposition of orbital angular momentum, the possible generation of magnetic fields and the related X-ray activity caused by the development of shear at the base of the convective envelope, and the effects on the morphology of the horizontal branch in globular clusters. We propose that the IR excess and high Li abundance observed in 4–8 per cent of the G and K giants originate from the accretion of a giant planet, a brown dwarf or a very low-mass star.     

The influence of topography on the cloud-to-ground lightning density in South Brazil

A comparative analysis between cloud-to-ground (CG) lightning density and terrain parameters (altitude and terrain slope) in South Brazil is presented. This region is characterized by a contrasting topography, where a mountain chain separates lower (depression) and higher (plateau) landscapes. The altitude and terrain slope data were obtained from the Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM). Two years of CG lightning data (from June 2005 to May 2007) obtained by the Brazilian Lightning Detection Network (BrasilDAT) were used in the study. To avoid intracloud contamination, positive CG flashes with peak currents less than 20 kA were removed from the data set. A relative detection efficiency model was used to correct the lightning data. The results indicate that, for localized areas (following the mountain shape) within this region of Brazil, the CG lightning density is correlated with the terrain slope and not the altitude. This suggests that terrain slope has more influence than altitude on the thunderstorm occurrence and lightning activity. In addition, a temporal analysis shows that over high altitude regions the diurnal variation (amplitude) of lightning activity is stronger and the peak occurs 1 h earlier than over low altitude regions.     

Extended time weather forecasts contributes to agricultural productivity estimates

Weather conditions in critical periods of the vegetative crop development influence crop productivity, thus being a basic parameter for crop forecast. Reliable extended period weather forecasts may contribute to improve the estimation of agricultural productivity. The production of soybean plays an important role in the Brazilian economy, because this country is ranked among the largest producers of soybeans in the world. This culture can be significantly affected by water conditions, depending on the intensity of water deficit. This work explores the role of extended period weather forecasts for estimating soybean productivity in the southern part of Brazil, Passo Fundo, and Londrina (State of Rio Grande do Sul and Paraná, respectively) in the 2005/2006 harvest. The goal was to investigate the possible contribution of precipitation forecasts as a substitute for the use of climatological data on crop forecasts. The results suggest that the use of meteorological forecasts generate more reliable productivity estimates during the growth period than those generated only through climatological information.     

Continuing current in multiple channel cloud-to-ground lightning

In this study we analyze the effects of continuing current initiated by strokes following a new channel to ground in multiple stroke flashes using high-speed video records, electric field measurements from a fast antenna and lightning detection network data. We observed that the long continuing current initiated by a stroke that follows a new channel also obeys the pattern in the initiation of long continuing current suggested by Rakov and Uman [Rakov, V.A., Uman, M.A., 2003. Lightning: Physics and Effects, 687pp., Cambridge Univ. Press, New York.]. We also verify that the statement of Rakov and Uman [Rakov, V.A. and Uman, M.A., 1990. Some properties of negative cloud-to-ground lightning flashes versus stroke order, Journal of Geophysical Research. 95, 5447–5453.] reporting that: “...strokes initiating long continuing currents tend to have lower initial electric field peak than regular strokes” is valid for strokes that create a new channel to ground and are followed by long continuing current (CC). Apparently the reduction of peak current value (I_p) when the stroke is followed by a long CC is stronger than the I_p increase that is commonly observed when strokes follow a new channel. We also find that the “exclusion zone” proposed by Saba et al. [Saba, M.M.F., Pinto, O. Jr., Ballarotti, M.G., 2006a. Relation between lightning return stroke peak current and following continuing current, Geophysical Research Letters 33, L23807, doi:10.1029/2006GL027455.] is valid for new channels initiating CC, and finally we verify that a number of strokes in the same channel larger than four or the existence of a long CC current do not always consolidate the channel in a multiple stroke flash.