Organic matter: size fraction relationships for recent sediments from the Orinoco Delta,Venezuela

Fifteen recent sediment samples from the offshore Orinoco Delta, Venezuela, were separated by sieving and pipette analysis into seven size fractions ranging from 4ø to 10ø, in 1 ø units. Total organic carbon was determined for each size fraction and the organic matter characterized by pyrolysis and pyrolysis-gas chromatography. The sediments average 0.98% organic matter with somewhat higher values nearshore. Nearshore sediments also had higher organic contents in the coarsest fractions and a decrease in organic matter from coarse to fine sediment fractions. Sediments from further offshore generally show the highest organic contents in the finer fractions. Pyrolysis showed a low bitumen content and confirmed that the kerogen was dominantly terrestrial and gas prone. The observed trends were attributed to sorting of organic matter by its physical characteristics, with the denser, coarse-grained material settling out nearshore and the Finer-grained material being carried further from shore and settling out with finer-grained sediments.     

Quaternary glaciation of the Bale Mountains,Ethiopia

Central Ethiopia comprises a high plateau at 2000–3000 m, formed from Tertiary lava flows and bisected by the Eastern African Rift. Ten volcanic mountains rise to altitudes of just over 4000 m, but on only three has Quaternary glaciation been substantiated by published field observations. On the Bale Mountains (4400 m), a previous report based on limited evidence proposed an ice‐cap extending to 600 km². Based on aerial photographs and ground surveys, this paper reports evidence of a more complex situation. A wide spread of large erratic boulders on the plateau records a central ice cap of 30 km², though ice probably extended for a further 40 km². Further north two groups of deeply incised and clearly glaciated valleys contain moraines and roches moutonnées (60 km²). On interfluves between them and on the open north slopes are moraines from an earlier stage of the same glaciation or from a distinct older event. Altogether about 180 km² may have been glaciated. Cores dated by ¹⁴C from inside and outside the glaciated area suggest that at least the northern valley glaciers may date from the Last Glacial Maximum. Estimated equilibrium line altitudes for these glaciers and the ice‐cap are 3750–4230 m. Copyright © 2005 John Wiley & Sons, Ltd.     

The microscale cooling effects of water sensitive urban design and irrigation in a suburban environment

There is still considerable uncertainty about precipitation at high elevation in mountain terrain due to the relatively few in situ measurements available and to the particular variability of the parameter. In this study, several spatialization techniques were tested, some for climatological time scale and others for daily fields, for precipitation over the western Alps for the period of 1990–2012. The study domain and period were chosen for the quality of available in situ observations and density of the network. First, a weather-type classification was established with a technique based on canonical correlation analysis combining large- and regional-scale data. The spatialization techniques applied for the climatological time scale were adapted from the Aurelhy method which uses elevation and principal components of the topography as predictors. The spatialization techniques applied to daily fields were based on kriging of daily rain gauges and used the climatological fields as predictors. This study aims to validate the advantage of using the climatology of the weather type of the day as predictor for daily fields over a monthly climatology. The climatology of the weather type of the day seems to demonstrate some small improvement.Finally, annual means over the period of 1990–2012 were produced using several methods, including some from accumulation of daily fields and others from the spatialization of in situ station means. Precipitation at high elevations and vertical climatological gradients were particularly scrutinized. Annual means based on sums of daily fields seem to have better performances.This paper only presents results for precipitation but temperature was also analysed.     

Assessment and Assimilation of FY-3 Humidity Sounders and Imager in the UK Met Office Global Model

China's Feng Yun 3(FY-3) polar orbiting satellites are set to become an important source of observational data for numerical weather prediction(NWP),atmospheric reanalyses,and climate monitoring studies over the next two decades.As part of the Climate Science for Service Partnership China(CSSP China) program,FY-3 B Microwave Humidity Sounder 1(MWHS-1) and FY-3 C MWHS-2 observations have been thoroughly assessed and prepared for operational assimilation.This represents the first time observations from China's polar orbiting satellites have been used in the UK's global NWP model.Since 2016,continuous data quality monitoring has shown occasional bias changes found to be correlated to changes in the energy supply scheme regulating the platform heating system and other transient anomalies.Nonetheless,MWHS-1 and MWHS-2 significantly contribute to the 24-h forecast error reduction by 0.3% and 0.6%,respectively,and the combination of both instruments is shown to improve the fit to the model background of independent sounders by up to 1%.The observations from the Microwave Radiation Imager(MWRI) also are a potentially significant source of benefits for NWP models,but a solar-dependent bias observed in the instrument half-orbits has prevented their assimilation.This paper presents the bases of a correction scheme developed at the Met Office for the purpose of a future assimilation of MWRI data.     

Stemflow and throughfall in a tropical dry forest

The rainfall received by a small plot of tropical deciduous forest on sand dunes in Veracruz, Mexico, was partitioned into stemflow and throughfall components to determine whether funnelling by stemflow could reduce soil leaching by transmitting large volumes of water through vertical soil pathways beneath each stem. Although soil infiltration capacities were high, only a very small proportion of incoming rainfall was funnelled by canopy stems. This is attributed to the widely-branched morphology of mature trees. Smaller trees and shrubs were more effective funnellers of rainfall, and a crude estimate of the magnitude of stemflow in the understorey stratum in one rain event suggested a contribution approximately ten times that of canopy stemflow. However, even if augmented by the understorey stratum in this way, total stemflow is unlikely to have exceeded 10 per cent of gross precipitation, implying that it does not represent an important leaching-avoidance mechanism in this forest.     

Interpreting complex fluvial channel and barform architecture: Carboniferous Central Pennine Province,northern England

The Bashkirian Lower Brimham Grit of North Yorkshire, England, is a fluvio‐deltaic sandstone succession that crops out as a complex series of pinnacles, the three‐dimensional arrangement of which allows high‐resolution architectural analysis of genetically‐related lithofacies assemblages. Combined analysis of sedimentary graphic log profiles, architectural panels and palaeocurrent data have enabled three‐dimensional geometrical relationships to be established for a suite of architectural elements so as to develop a comprehensive depositional model. Small‐scale observations of facies have been related to larger‐scale architectural elements to facilitate interpretation of the palaeoenvironment of deposition to a level of detail that has rarely been attempted previously, thereby allowing interpretation of formative processes. Detailed architectural panels form the basis of a semi‐quantitative technique for recording the variety and complexity of the sedimentary lithofacies present, their association within recognizable architectural elements and, thus, the inferred spatio‐temporal relationship of neighbouring elements. Fluvial channel‐fill elements bounded by erosional surfaces are characterized internally by a hierarchy of sets and cosets with subtly varying compositions, textures and structures. Simple, cross‐bedded sets represent in‐channel migration of isolated mesoforms (dunes); cosets of both trough and planar‐tabular cross‐bedded facies represent lateral‐accreting and downstream‐accreting macroforms (bars) characterized by highly variable, yet predictable, patterns of palaeocurrent indicators. Relationships between sandstone‐dominated strata bounded by third‐order and fifth‐order surfaces, which represent in‐channel bar deposits and incised channel bases, respectively, chronicle the origin of the preserved succession in response to autocyclic barform development and abandonment, major episodes of incision probably influenced by episodic tectonic subsidence, differential tilting and fluvial incision associated with slip on the nearby North Craven Fault system. Overall, the succession represents the preserved product of an upper‐delta plain system that was traversed by a migratory fluvial braid‐belt system comprising a poorly‐confined network of fluvial channels developed between major sandy barforms that evolved via combined lateral‐accretion and downstream‐accretion.     

Forbidden Ca ii in the Sun unmasked by way of Venus

Eleven high-dispersion spectra of Venus, taken with blue Doppler shifts have enabled us to unmask the 7323.88 Å forbidden line of Ca ii from terrestrial absorption. We obtain an equivalent width of 7.4±0.4 mÅ for this line in integrated sunlight. Our value of W _λ is smaller than previous values and much more accurate. The HSRA solar model gives a solar calcium abundance of A _Ca = 6.21.     

Semiperiodic variations in CO2 abundance on Venus

Photoelectric spectral scans of the P branch of the 8689 Å CO₂ band on Venus were made using the 107-inch coude scanner during seven observing periods in the past 2 years. The relative CO₂ line strength was determined for each scan, then normalized to remove the spatial variations leaving only temporal variations.The 4-day periodicity in the relative CO₂ line strength noted by Young et al. (1973) is not unique; we do confirm their 4-day periodicity in August 1973. Four other observing periods rule out a 4-day periodicity.A definite North-South asymmetry in the relative CO₂ line strength is noted during 1973, in most cases with the same periodicity present in both hemispheres. When the slit positions are referred to the equator of Venus, particularly near inferior conjunction, the large asymmetrics between the slit positions can be explained by a greater CO₂ line strength over the polar regions and weaker over the equatorial latitudes. The amplitude of variation of each position on the crescent is much greater near inferior conjunction either because we are sampling a smaller area on the planet or because the upper atmospheric abundance is more sensitive to the mechanism causing the variation in the smaller regions sampled at inferior conjunction.Simultaneous H₂O measurementsduring several of the observing runs indicate a lack of correlation in the relative CO₂ line strengths and the H₂O abundance.