A multi-decade record of high quality fCO2 data in version 3 of the Surface Ocean CO2 Atlas (SOCAT)

The Surface Ocean CO2 Atlas (SOCAT) is a synthesis of quality-controlled fCO2 (fugacity of carbon dioxide) values for the global surface oceans and coastal seas with regular updates. Version 3 of SOCAT has 14.7 million fCO2 values from 3646 data sets covering the years 1957 to 2014. This latest version has an additional 4.6 million fCO2 values relative to version 2 and extends the record from 2011 to 2014. Version 3 also significantly increases the data availability for 2005 to 2013. SOCAT has an average of approximately 1.2 million surface water fCO2 values per year for the years 2006 to 2012. Quality and documentation of the data has improved. A new feature is the data set quality control (QC) flag of E for data from alternative sensors and platforms. The accuracy of surface water fCO2 has been defined for all data set QC flags. Automated range checking has been carried out for all data sets during their upload into SOCAT. The upgrade of the interactive Data Set Viewer (previously known as the Cruise Data Viewer) allows better interrogation of the SOCAT data collection and rapid creation of high-quality figures for scientific presentations. Automated data upload has been launched for version 4 and will enable more frequent SOCAT releases in the future. High-profile scientific applications of SOCAT include quantification of the ocean sink for atmospheric carbon dioxide and its long-term variation, detection of ocean acidification, as well as evaluation of coupled-climate and ocean-only biogeochemical models. Users of SOCAT data products are urged to acknowledge the contribution of data providers, as stated in the SOCAT Fair Data Use Statement. This ESSD (Earth System Science Data) “living data” publication documents the methods and data sets used for the assembly of this new version of the SOCAT data collection and compares these with those used for earlier versions of the data collection (Pfeil et al., 2013; Sabine et al., 2013; Bakker et al., 2014). Individual data set files, included in the synthesis product, can be downloaded here: doi:10.1594/PANGAEA.849770. The gridded products are available here: doi:10.3334/CDIAC/OTG.SOCAT_V3_GRID

Roles of marginal seas in absorbing and storing fossil fuel CO2

We review data on the absorption of anthropogenic CO2 by Northern Hemisphere marginal seas (Arctic Ocean, Mediterranean Sea, Sea of Okhotsk, and East/Japan Sea) and its transport to adjacent major basins, and consider the susceptibility to recent climatic change of key factors that influence CO2 uptake by these marginal seas. Dynamic overturning circulation is a common feature of these seas, and this effectively absorbs anthropogenic CO2 and transports it from the surface to the interior of the basins. Amongst these seas only the East/Japan Sea has no outflow of intermediate and deep water (containing anthropogenic CO2) to an adjacent major basin; the others are known to be significant sources of intermediate and deep water to the open ocean. Consequently, only the East/Japan Sea retains all the anthropogenic CO2 absorbed during the anthropocene. Investigations of the properties of the water column in these seas have revealed a consistent trend of waning water column ventilation over time, probably because of changes in local atmospheric forcing. This weakening ventilation has resulted in a decrease in transport of anthropogenic CO2 from the surface to the interior of the basins, and to the adjacent open ocean. Ongoing measurements of anthropogenic CO2, other gases and hydrographic parameters in these key marginal seas will provide information on changes in global oceanic CO2 uptake associated with the predicted increasing atmospheric CO2 and future global climate change. We also review the roles of other marginal seas with no active overturning circulation systems in absorbing and storing anthropogenic CO2. The absence of overturning circulation enables anthropogenic CO2 to penetrate only into shallow depths, resulting in less accumulation of anthropogenic CO2 in these basins. As a consequence of their proximity to populated continents, these marginal seas are particularly vulnerable to human-induced perturbations. Maintaining observation programs will make it possible to assess the effects of human-induced changes on the capacity of these seas to uptake and store anthropogenic CO2

Cryptanalyse algébrique par canaux auxiliaires

PARIS-BIUSJ-Mathématiques rech (751052111) / SudocSudocFranceF

Algebraic Side Channel Analysis

International audienc

Analysis of the Algebraic Side Channel Attack

At CHES 2009, Renauld, Standaert and Veyrat-Charvillon introduced a new kind of attack called Algebraic Side-Channel Attacks (ASCA). They showed that side-channel information leads to effective algebraic attacks. These results are mostly experiments since strongly based on the use of a SAT solver. This article presents a theoretical study in order to explain and to characterize the algebraic phase of these attacks. We study more general algebraic attacks based on Gröbner methods. We show that the complexity of the Gröbner basis computations in these attacks depends on a new notion of algebraic immunity defined in this paper, and on the distribution of the leakage information of the cryptosystem. We also study two examples of common leakage models: the Hamming weight and the Hamming distance models. For instance the study in the case of the Hamming weight model gives that the probability of obtaining at least 64 (resp. 130) linear relations is about 50 % for the substitution layer of PRESENT (resp. AES). Moreover if the S-boxes are replaced by functions maximizing the new al

Ocean carbon cycling in the Indian Ocean: 1. Spatiotemporal variability of inorganic carbon and air-sea CO2 gas exchange

The spatiotemporal variability of upper ocean inorganic carbon parameters and air-sea CO2 exchange in the Indian Ocean was examined using inorganic carbon data collected as part of the World Ocean Circulation Experiment (WOCE) cruises in 1995. Multiple linear regression methods were used to interpolate and extrapolate the temporally and geographically limited inorganic carbon data set to the entire Indian Ocean basin using other climatological hydrographic and biogeochemical data. The spatiotemporal distributions of total carbon dioxide (TCO2), alkalinity, and seawater pCO2 were evaluated for the Indian Ocean and regions of interest including the Arabian Sea, Bay of Bengal, and 10°N–35°S zones. The Indian Ocean was a net source of CO2 to the atmosphere, and a net sea-to-air CO2 flux of +237 ± 132 Tg C yr?1 (+0.24 Pg C yr?1) was estimated. Regionally, the Arabian Sea, Bay of Bengal, and 10°N–10°S zones were perennial sources of CO2 to the atmosphere. In the 10°S–35°S zone, the CO2 sink or source status of the surface ocean shifts seasonally, although the region is a net oceanic sink of atmospheric CO2

Coulometric total carbon dioxide analysis for marine studies: Assessment of the quality of total inorganic carbon measurements made during the WOCE Indian Ocean CO2 Survey 1994-1996

Two single-operator multiparameter metabolic analyzers (SOMMA)-coulometry systems (I and II) for total carbon dioxide (TCO2) were placed on board the R/V Knorr for the US component of the Indian Ocean CO2 Survey in conjunction with the World Ocean Circulation Experiment-WOCE Hydrographic Program (WHP). The systems were used by six different measurement groups on 10 WHP Cruises beginning in December 1994 and ending in January 1996. A total of 18,828 individual samples were analyzed for TCO2 during the survey. This paper assesses the analytical quality of these data and the effect of several key factors on instrument performance. Data quality is assessed from the accuracy and precision of certified reference material (CRM) analyses from three different CRM batches. The precision of the method was 1.2 μmol/kg. The mean and standard deviation of the differences between the known TCO2 for the CRM (certified value) and the CRM TCO2 determined by SOMMA-coulometry were −0.91±0.58 (n=470) and −1.01±0.44 (n=513) μmol/kg for systems I and II, respectively, representing an accuracy of 0.05% for both systems. Measurements of TCO2 made on 12 crossover stations during the survey agreed to within 3 μmol/kg with an overall mean and standard deviation of the differences of −0.78±1.74 μmol/kg (n=600). The crossover results are therefore consistent with the precision of the CRM analyses. After 14 months of nearly continuous use, the accurate and the virtually identical performance statistics for the two systems indicate that the cooperative survey effort was extraordinarily successful and will yield a high quality data set capable of fulfilling the objectives of the survey

Global relationships of total alkalinity with salinity and temperature in surface waters of the world's oceans

A simple function of sea surface salinity (SSS) and temperature (SST) in the form AT = a + b (SSS − 35) + c (SSS − 35)2 + d (SST − 20) + e (SST − 20)2 fits surface total alkalinity (AT) data for each of five oceanographic regimes within an area‐weighted uncertainty of ±8.1 μmol kg−1 (1σ). Globally coherent surface AT data (n = 5,692) used to derive regional correlations of AT with SSS and SST were collected during the global carbon survey in the 1990s. Such region‐specific AT algorithms presented herein enable the estimation of the global distribution of surface AT when observations of SSS and SST are available

Establishing an early warning alert and response network following the Solomon Islands tsunami in 2013

PROBLEM: On 6 February 2013, an 8.0 magnitude earthquake generated a tsunami that struck the Santa Cruz Islands, Solomon Islands, killing 10 people and displacing over 4700. APPROACH: A post-disaster assessment of the risk of epidemic disease transmission recommended the implementation of an early warning alert and response network (EWARN) to rapidly detect, assess and respond to potential outbreaks in the aftermath of the tsunami. LOCAL SETTING: Almost 40% of the Santa Cruz Islands’ population were displaced by the disaster, and living in cramped temporary camps with poor or absent sanitation facilities and insufficient access to clean water. There was no early warning disease surveillance system. RELEVANT CHANGES: By 25 February, an EWARN was operational in five health facilities that served 90% of the displaced population. Eight priority diseases or syndromes were reported weekly; unexpected health events were reported immediately. Between 25 February and 19 May, 1177 target diseases or syndrome cases were reported. Seven alerts were investigated. No sustained transmission or epidemics were identified. Reporting compliance was 85%. The EWARN was then transitioned to the routine four-syndrome early warning disease surveillance system. LESSON LEARNT: It was necessary to conduct a detailed assessment to evaluate the risk and potential impact of serious infectious disease outbreaks, to assess whether and how enhanced early warning disease surveillance should be implemented. Local capacities and available resources should be considered in planning EWARN implementation. An EWARN can be an opportunity to establish or strengthen early warning disease surveillance capabilities