Influence of El Niño and La Niña on coffee yield in the main coffee-producing regions of Brazil

Theoretical and Applied Climatology - Coffee is the most consumed beverage and one of the most valuable commodities worldwide. The crop is very sensitive to meteorological elements, mainly at the...     

Constraints on the origin and evolution of the layered mound in Gale Crater, Mars using Mars Reconnaissance Orbiter data

Gale Crater contains a 5.2 km-high central mound of layered material that is largely sedimentary in origin and has been considered as a potential landing site for both the MER (Mars Exploration Rover) and MSL (Mars Science Laboratory) missions. We have analyzed recent data from Mars Reconnaissance Orbiter to help unravel the complex geologic history evidenced by these layered deposits and other landforms in the crater. Results from imaging data from the High Resolution Imaging Science Experiment (HiRISE) and Context Camera (CTX) confirm geomorphic evidence for fluvial activity and may indicate an early lacustrine phase. Analysis of spectral data from the CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) instrument shows clay-bearing units interstratified with sulfate-bearing strata in the lower member of the layered mound, again indicative of aqueous activity. The formation age of the layered mound, derived from crater counts and superposition relationships, is ∼3.6-3.8 Ga and straddles the Noachian-Hesperian time-stratigraphic boundary. Thus Gale provides a unique opportunity to investigate global environmental change on Mars during a period of transition from an environment that favored phyllosilicate deposition to a later one that was dominated by sulfate formation.     

Performance evaluation of AR5-CMIP5 models for the representation of seasonal and multi-annual variability of precipitation in Brazilian hydropower sector basins under RCP8.5 scenario

ABSTRACT

Representations of precipitation from CMIP5 models over the 1950–1999 period in hydrographic basins that are relevant to the Brazilian electricity sector are evaluated in this study. The majority of ensemble members adequately represented seasonal variability, although they differed about the patterns of high-frequency interannual variation. The models did not adequately represent seasonal-scale precipitation in the southern region of Brazil. Relative to other models, the CNRM_CM5 and HadGEM2-ES models demonstrated good seasonal and interannual representation over most basins, while the global CanESM2, GFDL-ESM2M and IPSL_CM5A-LR models demonstrated relatively poor performance. The models concur on the impact of the RCP8.5 scenario in the Southeast/Midwest and South sectors over the period 2015–2044, suggesting that precipitation will decrease up to 15% in the basin supplying the Furnas hydropower plant and by 12% in the basin supplying the Itaipú plant, which represents 25% of the hydroelectric production in Brazil.     

Environmental changes affecting light climate in oligotrophic mountain lakes: the deep chlorophyll maxima as a sensitive variable

The North-Patagonian Andean lakes of Argentina are high light, low nutrient environments that exhibit development of deep chlorophyll maxima (DCM) at the metalimnetic layer during summer stratification, at approximately 1 % of surface PAR irradiance. We examined whether the position of DCM changes as a consequence of long-time (global warming: glacial clay input) and short-time (eruption: volcanic ashes) events. We performed different field studies: (1) an interlacustrine analysis of six lakes from different basins, including data of the 2011 volcanic eruption, which caused an unexpected variation in water transparency; and (2) an intralacustrine analysis in which we compared different stations along a transparency gradient in Lake Mascardi caused by glacial clay input at one end of the gradient. In these analyses, we documented changes in DCM depth and its relationship with different parameters. DCM development was not related with thermocline depth or nutrient distribution. In all cases, the only significant variables were Kd 320 nm and Kd PAR. Our study showed that suspended particles (glacial clay and volcanic ashes) can play a crucial role in transparent lakes, affecting lake features such as the phototrophic biomass distribution along the water column. Suspended solid inputs from either glacial clay or volcanic ashes produce a comparable effect, provoking a decrease in light and, consequently, an upper location of the DCM. Thus, the DCM position is highly sensitive to global changes, such as increased temperatures causing glacier recession or to regional changes caused by volcanic eruptions.     

On retrieving patterns in environmental sensor data

As many sensor networks are currently being deployed for environmental monitoring, there is a growing need to develop systems and applications for managing, processing and retrieving massive amounts of data generated from those networks. In this research, a query answering system with pattern mining techniques is investigated specifically for marine sensor data. We consider three applications of pattern mining: similar pattern search, predictive query and query by clustering. In pattern mining for query answering, we adopt the dynamic time warping (DTW) method for similarity measurement. We also propose the use of a query relaxation approach that recommends users change parameters of a given query to get an answer. Finally, we show implementation results of pattern query answering in a marine sensor network deployed in the South East of Tasmania, Australia. Pattern query answering system benefits in accessing and discovering knowledge from sensor data for decision making purposes.     

Vertical Profiles of Major Organic Geochemical Constituents and Extracellular Enzymatic Activities in Sandy Sediments of Aransas and Copano Bays, TX

Vertical distribution patterns of organic geochemical constituents and the enzymes aminopeptidase and β-glucosidase provide insights about the nature and reactivity of sediment organic matter in the sandy sediments of two shallow “South Texas” estuaries. Sediment total organic carbon (TOC) δ¹³C values indicated that the organic matter (OM) was derived more from a mixture of seagrass and phytoplankton than from terrigenous OM. Down-core amounts of TOC and total nitrogen (TN) were <0.2% of dry weight, respectively. Enzyme activities were highest near surface and ranged from 25 to 1 μM/h for aminopeptidase as compared to 5 to 0.2 μM/h for glucosidase. In Aransas Bay, aminopeptidase activity correlated with sediment TN content (r _s = 0.30) and β-glucosidase with TOC content (r _s = 0.27). In Copano Bay, aminopeptidase correlated with TOC, TN, and carbohydrate content (r _s = 0.89, 0.90, and 0.83, respectively). Variations of glucosidase activity also related positively to TOC, TN, and total carbohydrate content (r _s = 0.68, 0.77, and 0.48, respectively). Overall, enzyme activities in these low OM, sandy sediments resembled those for other benthic marine environments.     

Geology, geochemistry, and U–Pb geochronology of the Archean (2.74 Ga) Serra do Rabo granite stocks, Carajás Metallogenetic Province, northern Brazil

The Carajás region, located in the southeastern part of the Amazon Craton, has been considered one of the most important mineral provinces in the world. The Serra do Rabo Granite (SRG) crops out near the eastern termination of the Carajás fault as two granite stocks, elongated approximately in an E–W direction, concordant with the regional structures. Leucomicrocline granite, hornblende–microcline granite, biotite–hornblende–microcline granite, hornblende syenogranite, and subordinate aplite are identified. The granites are grayish pink and coarse to medium grained and have mainly hypidiomorphic granular texture. Granophyric textures are common. The accessory minerals are ilmenite, apatite, zircon, allanite, and rare pyroxene.The SRG rocks are either massive or foliated, with a slightly anastomosed continuous S₁ foliation (E–W/subvertical) outlined by the preferred orientation of quartz, feldspars, and mafic minerals. Locally, decimeter- to meter-wide mylonite/ultramylonite bands (S_1m) occur along the E–W foliation. The S₁ foliation was developed under higher temperatures than those of the S_1m mylonite foliation. The SRG structural evolution was controlled by progressive deformation under decreasing temperature, indicative of syntectonic emplacement. The SRG also has relatively high SiO₂, K₂O, and Na₂O contents; high FeO*/(FeO*+MgO) ratios; high Zr, Ba, Nb, and Ga; and very high rare-earth element contents. The chemical signature is moderately alkaline and metaluminous, comparable to that of the A-type, A2, and ALK-3 granites. The origin of the SRG magmas may be related to the partial melting of crustal sources, such as previously metamorphosed calc-alkaline granites.The SRG crosscuts supracrustal rocks, promoting low-pressure/high-temperature metamorphism. The interaction between regional compressive stresses and the ballooning effect of the granite stocks promoted slight aureole flattening and rheological changes in the supracrustal rocks. The U–Pb zircon age of 2743±1.6 Ma is interpreted as the age of zircon crystallization, granite stock emplacement, and regional horizontal shortening. Other 2.7 Ga syntectonic alkaline granites (e.g. Estrela, Plaquê, Planalto) have been reported in the region.     

Baurusuchus salgadoensis, a New Crocodylomorpha from the Bauru Basin (Cretaceous), Brazil

Baurusuchus salgadoensis is a new baurusuchid crocodylomorph from Bauru Basin (Cretaceous), Brazil, partially preserved through a complete skull. The fossil comes from a fine sandstone sequence of Adamantina Formation, General Salgado County, São Paulo State. The sedimentary sequence where it was found, located in Fazenda Buriti, is considered Turonian-Santonian in age. The described species _Baurusuchus salgadoensis sp. nov. _ is a baurusuchid with an antorbital fenestra, double external nares with a bony septum, two well-fused supraorbitals, the supratemporal fenestrae larger than the orbits and a quadrangular-shaped laterotemporal fenestra. The position of the external nares, located on anterior and terminal portion of the rostrum together with the theropod-like lateral compression of the snout and teeth are indicators that Baurusuchus salgadoensis was a terrestrial crocodyliform. This was a carnivorous species and the lateral compression of the rostrum could be interpreted as a mechanism to increase the skull resistance forces during biting. The pointed, conical teeth, some with crenulated borders, could be used to perforate and to carve the prey. The geological context of Baurusuchus salgadoensis indicates that it probably lived in a hot and arid climate.     

Agrometeorological models for forecasting the qualitative attributes of “Valência” oranges

Forecasting is the act of predicting unknown future events using available data. Estimating, in contrast, uses data to simulate an actual condition. Brazil is the world’s largest producer of oranges, and the state of São Paulo is the largest producer in Brazil. The “Valência” orange is among the most common cultivars in the state. We analyzed the influence of monthly meteorological variables during the growth cycle of Valência oranges grafted onto “Rangpur” lime rootstocks (VACR) for São Paulo, and developed monthly agrometeorological models for forecasting the qualitative attributes of VACR in mature orchard. For fruits per box for all months, the best accuracy was of 0.84 % and the minimum forecast range of 4 months. For the relation between °brix and juice acidity (RATIO) the best accuracy was of 0.69 % and the minimum forecast range of 5 months. Minimum, mean and maximum air temperatures, and relative evapotranspiration were the most important variables in the models.