Sky luminance distribution in the North of Iberian Peninsula during winter

This work is based on the study of outdoor daylight conditions during the winter period in Pamplona (the Iberian Peninsula). The 15 standard sky types proposed by the Commission Internationale de l’Eclairage (CIE) are used. The selected sky type in each moment is the one exhibiting the lowest root mean standard deviation (RMSD) when the theoretical and experimental luminance distributions in the sky hemisphere are compared. The selection was derived from luminance distribution data from 145 patches of the sky hemisphere and registered every 10 min from October to March from 2007 and 2008.The most frequent sky type observed in winter in Pamplona is V.5 (cloudless polluted with a broad solar corona), with a frequency of occurrence of 21%. Notwithstanding, the group of overcast skies exhibits a slightly higher frequency (40%) than the clear skies (37%). Seven out of the 15 standard sky types, i.e.V.5, I.1, III.4, II.1, IV.4, II.2 and III.3, are practically 80% of those under study. In order to provide a possible application in daylight climates studies, the frequency of occurrence of the 15 sky types is included in eleven intervals of solar elevation on the threshold corresponding to the time period and the location considered.     

Rare earth element geochemistry in cold-seep pore waters of Hydrate Ridge, northeast Pacific Ocean

The concentrations of rare earth elements (REEs), sulphate, hydrogen sulphide, total alkalinity, calcium, magnesium and phosphate were measured in shallow (<12 cm below seafloor) pore waters from cold-seep sediments on the northern and southern summits of Hydrate Ridge, offshore Oregon. Downward-decreasing sulphate and coevally increasing sulphide concentrations reveal sulphate reduction as dominant early diagenetic process from ~2 cm depth downwards. A strong increase of total dissolved REE (∑REE) concentrations is evident immediately below the sediment–water interface, which can be related to early diagenetic release of REEs into pore water resulting from the re-mineralization of particulate organic matter. The highest pore water ∑REE concentrations were measured close to the sediment–water interface at ~2 cm depth. Distinct shale-normalized REE patterns point to particulate organic matter and iron oxides as main REE sources in the upper ~2-cm depth interval. In general, the pore waters have shale-normalized patterns reflecting heavy REE (HREE) enrichment, which suggests preferential complexation of HREEs with carbonate ions. Below ~2 cm depth, a downward decrease in ∑REE correlates with a decrease in pore water calcium concentrations. At this depth, the anaerobic oxidation of methane (AOM) coupled to sulphate reduction increases carbonate alkalinity through the production of bicarbonate, which results in the precipitation of carbonate minerals. It seems therefore likely that the REEs and calcium are consumed during vast AOM-induced precipitation of carbonate in shallow Hydrate Ridge sediments. The analysis of pore waters from Hydrate Ridge shed new light on early diagenetic processes at cold seeps, corroborating the great potential of REEs to identify geochemical processes and to constrain environmental conditions.     

Polycyclic aromatic hydrocarbons in surface sediments of Binacional Itaipu Lake,Brazil: characteristics,sources and toxicity evaluation

Itaipu Lake, which includes the Itaipu hydroelectric power plant, is one of the largest dams in the world and has a strong relationship with its surroundings. The flooded area has multiple uses such as navigation, recreation, water abstraction for industrial, urban and agricultural irrigation. The lake is located at the frontier between Brazil, Argentina and Paraguay. In this study, superficial sediments collected from nine sampling sites were analysed for grain size, organic matter and 16 priority polycyclic aromatic hydrocarbons (PAHs) using high-performance liquid chromatography (HPLC) with fluorescence detector. The total concentration of PAHs in the dry sediment ranged from 35.21 to 685.37 µg kg^?1. Diagnostic ratios showed that the possible source of PAHs in the Itaipu Lake could be pyrolitic and petrogenic. The potential toxicity of sediment of PAHs varied from not detected to 127.70 µg g^?1, suggesting that some adverse ecological effects would arise due to PAHs in these sediments.     

Lessons from co-impacts assessment under the Mitigation Action Plans and Scenarios (MAPS) Programme

The MAPS Programme has been active in Brazil, Chile, Colombia and Peru in supporting the development of an evidence base to inform the processes involved in climate mitigation policy-making. The programme combines detailed quantitative analysis with an extensive stakeholder engagement process to provide policy and decision makers with the information required for long-term climate mitigation planning.

In recognition of the critical need to consider the developmental context and agenda in climate policy-making, the projects undertaken in these countries have experimented with various types of assessments of developmental impacts at both the macro and micro levels. These impacts have been collectively termed co-impacts to reflect the fact that these may be either positive or negative. In this article the value and challenges associated with co-impacts work for climate mitigation policy are considered. The value of including co-impacts analysis in the MAPS processes included increased stakeholder buy-in, making the case for mitigation action, informing INDCs and the prioritization of particular mitigation actions. Challenges include those associated with obtaining locally relevant data, the selection and operation of appropriate macro-economic models and analytical approaches and working with multidisciplinary teams.

The article concludes by making some suggestions to optimize co-impacts work, through reference to other bodies of literature. The authors highlight that this article is situated within a dominant approach to climate mitigation policy work in developing countries, which implicitly places the non-climate benefits of any action as secondary to the primary benefit of climate change mitigation and constructs an artificial separation of policy formulation and implementation. Practitioners are encouraged to reflect on the implications of these considerations in future efforts.

Policy relevance

One of the primary challenges to advancing climate mitigation policy in developing countries is that of perceived relevance: near-term development priorities are overwhelming. Identifying, understanding and engaging with the co-impacts of mitigation actions has emerged as one way of addressing this challenge. Although still at an experimental phase, experience with co-impacts analysis in the MAPS countries provides some useful lessons in how to develop this area of work.     

Improvement in PWV estimation from GPS due to the absolute calibration of antenna phase center variations

Climatology of column-integrated atmospheric water vapor over Spain has been carried out by means of three techniques: soundings, sun photometers and GPS receivers. Comparing data from stations equipped with more than one of these instruments, we found that a large discontinuity occurred on November 6, 2006, in the differences between the data series from GPS receivers and those from the other two techniques. Prior to that date, the GPS data indicate a wet bias of 2–3 mm for all stations when compared with sounding or photometer data, whereas after that date this bias practically reduces to zero. The root mean square error also decreases about half of its value. On November 6, 2006, the International GNSS Service adopted an absolute calibration model for the antennas of the GPS satellites and receivers instead of the relative one. This change is expected to be an improvement, increasing the accuracy of station position determination and consequently benefiting post-processing products such as zenith total delay from which the atmospheric water vapor content is calculated.     

Synoptic conditions and potential causes of the extreme heavy rainfall event of January 2009 over Mindanao Island,Philippines

Natural Hazards - This study investigates the synoptic conditions that led to the heavy rainfall/flood (HRF) event in Mindanao Island, Philippines (122??127°E;...     

Interaction of Tidal and Fluvial Processes in the Transition Zone of the Santee River, SC, USA

This study was conducted in the freshwater reach of the Santee River approximately 55?±?4?km from the mouth, a transition zone from a fluvial to an estuarine tidal regime. The dataset comprises bathymetric surveys, current profile and bottom pressure measurements at two locations, and time series of discharge. Our data indicate that the transition zone is characterized by strong tidal dissipation and distinctive channel geometry. Tidal dissipation is evident in the rapid decrease of the M₂ amplitude to the mean along-channel velocity ratio from 2.1 to 0.9 over a ??6-km distance. Channel cross-sectional area in the transition zone converges at a higher rate than both upstream and downstream while channel depth reveals threefold variations in the form of adjacent shoals and deeps. We hypothesize that the enhanced tidal dissipation is at the same time a cause and a result of strongly convergent bathymetry in the transition zone.     

Using the DPFT approach to improve flash flood forecasting models

DPFT is a lumped approach for operational flash flood forecasting, based on the unit hydrograph. Using a multi-event alternating iterative algorithm, it identifies a robust and stable average transfer function and a consistent set of effective rainfall series associated with each event at the same time. This key ingredient allows an objective calibration of different loss functions, relating gauged precipitation and effective rainfall. A case study based on an operational French basin (545 km²) is presented. Three lumped production functions have been calibrated and compared. The results show that more elaborate models of loss functions must be proposed, and some possible directions for this are pointed out.Presently at the Institut de Ciences de la Terra Jaume Almera, Apartat 30102, 08080 Barcelona, Spain.Presently at EDF-DTG. Service de Ressources en Eau, BP 4348, 31029 Toulouse Cedex, France.