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This report shows observed results of cross-shore profiles of the grain size Composition and bottom topography around the observational pier at Ogata Wave Observatory (OWO). The measurements of cross-shore bottom profile have been carried out once a month, and the bottom profile change in recent 10 years is small except before 2000 and after 2005. After 2005, shoreline advance is observed even though Joetsu-Ogata coast have been suffered from severe beach erosion for long time. From the results of grain size analysis, it is found that relative fine sand accumulates around the observational pier after 2005.

International audience; Tree-ring width provides a retrospective record of the amount of growth that has taken place during one year. Carbon isotope composition in tree-rings provides an integrated record of the balance between CO2 assimilation rate and stomatal conductance during the period in which the ring was produced. We compared the influence of climatic variations on tree-ring width and carbon isotope composition in the major tree species of three contrasting ecosystems: a coastal Douglas-fir (Pseudotsuga menziesii) forest in British Columbia, a boreal aspen (Populus tremuloides) forest and a boreal Jack pine (Pinus banksiana) forest, both in Saskatchewan. At least four cores were sampled from five dominant trees in each site. In addition, five trees from the co-dominant red-cedar species (Thuja occidentalis) were also sampled in British Columbia. After measurements of annual radial increment, the α-cellulose was extracted from the rings formed within the 1981-2001 period. A year-by-year analysis of their carbon and oxygen isotope compositions (δ13C and δ18O, respectively) was performed. Over the two decades, the average δ13C values of the four species were in the range –23.2‰ to –24.0‰. Maximum interannual variations of δ13C ranged from 1.2‰ to 2.5‰ for T. occidentalis and P. tremuloides, respectively. In all species, interannual changes in δ13C and δ18O were significantly related to variations in vapor pressure deficit averaged over the growing season period. These covariations were interpreted as reflecting reduction in stomatal conductance in response to atmospheric moisture stress. Whereas a negative correlation between tree-ring width and δ13C was expected under such conditions, no significant relationship was observed between radial growth and δ13C in any site. However, in the Jack Pine site, which is characterized by a very low soil water reserve, 80% of the variation in radial growth was explained by an empirical model that included: (i) early growing season precipitation; (ii) summer mean temperature; and (iii) previous-year ring width. Relationships between tree-ring measurements and climate variables were much less obvious in the Douglas-fir and the aspen sites. These results emphasize the complexity of the environmental controls on carbon isotope discrimination and growth in trees that dominate these northern ecosystems.

International audience; We investigate the tropical Atlantic vertical structure variability (1981-2000) based on the CLIPPER ocean general circulation model (OGCM). We aim at determining to what extent the observed interannual variability can be explained by the low-frequency wave dynamics. The linear vertical modes of the OGCM climatological stratification are estimated along the equator. The baroclinic mode contributions to surface zonal current and sea level anomalies are calculated and analyzed at interannual timescales. The second baroclinic mode is the most energetic. The first (third) mode exhibits a variability peak in the west (east). The summed-up contribution of the high-order baroclinic modes (4-6) is as energetic as the gravest modes and is largest in the east. Wave components are then derived by projection onto the associated meridional structures. The effect of longitudinal boundaries near the equator is taken into consideration. Equatorial Kelvin and Rossby waves propagations, with phases speed close to the theory, are identified for the first three baroclinic modes. The comparison with a multimode linear simulation corroborates the propagating properties of the OGCM waves coefficients. An estimation of the meridional boundary reflection efficiency indicates that wave reflections take place at both boundaries. A 65% reflection efficiency is found at the eastern boundary. Our study suggests that low-frequency wave dynamics is to a large extent at work in the tropical Atlantic. On the basis of what is known on the Pacific El Niño-Southern Oscillation mode this may provide a guidance for investigating ocean-atmosphere mechanisms that can lead to the Atlantic zonal equatorial mode.

The concurrent effects of increasing atmospheric CO2 concentration, climate variability, and cropland establishment and abandonment on terrestrial carbon storage between 1920 and 1992 were assessed using a standard simulation protocol with four process-based terrestrial biosphere models. Over the long-term (1920-1992), the simulations yielded a time history of terrestrial uptake that is consistent (within the uncertainty) with a long-term analysis based on ice core and atmospheric CO2 data. Up to 1958, three of four analyses indicated a net release of carbon from terrestrial ecosystems to the atmosphere caused by cropland establishment. After 1958, all analyses indicate a net uptake of carbon by terrestrial ecosystems, primarily because of the physiological effects of rapidly rising atmospheric CO2. During the 1980s the simulations indicate that terrestrial ecosystems stored between 0.3 and 1.5 Pg C yr(-1), which is within the uncertainty of analysis based on CO2 and O-2 budgets. Three of the four models indicated tin accordance with O-2 evidence) that the tropics were approximately neutral while a net sink existed in ecosystems north of the tropics. Although all of the models agree that the long-term effect of climate on carbon storage has been small relative to the effects of increasing atmospheric CO2 and land use, the models disagree as to whether climate variability and change in the twentieth century has promoted carbon storage or release. Simulated interannual variability from 1958 generally reproduced the El Nino/Southern Oscillation (ENSO)-scale variability in the atmospheric CO2 increase, but there were substantial differences in the magnitude of interannual variability simulated by the models. The analysis of the ability of the models to simulate the changing amplitude of the seasonal cycle of atmospheric CO2 suggested that the observed trend may be a consequence of CO2 effects, climate variability, land use changes, or a combination of these effects. The next steps for improving the process-based simulation of historical terrestrial carbon include (1) the transfer of insight gained from stand-level process studies to improve the sensitivity of simulated carbon storage responses to changes in CO2 and climate, (2) improvements in the data sets used to drive the models so that they incorporate the timing, extent, and types of major disturbances, (3) the enhancement of the models so that they consider major crop types and management schemes, (4) development of data sets that identify the spatial extent of major crop types and management schemes through time, and (5) the consideration of the effects of anthropogenic nitrogen deposition. The evaluation of the performance of the models in the context of a more complete consideration of the factors influencing historical terrestrial carbon dynamics is important for reducing uncertainties in representing the role of terrestrial ecosystems in future projections of the Earth system. [References: 106]

Dans uncontexteclimat iquee t stationnel donne,l’und es facteurs majeurs de laproduction d’u ne cosysteme est son indic ef oliair e( Lea fAre aI ndex pour les anglophones ,a brege par LAI) ,c ’est-a-dire sa s urfac ed ef euilles exprimee par unit ed e s urfac eau sol. La r elation entrecep arametree t laproductivitee st evidente:l’indic ef oliaire representel a s urfacep ar laquelle les flux de carbone (echanges photosynthetiques)e t d’eau (transpiration) transitent. L’accumulation de matiere seche depend ainsid el ’indicef oliaire,du rayonnement incident,et de l’efficienced econversion de ce r ayonnement vi a laphotosynthesee nm atiere seche. Le s agronomes connaissent bien cef onctionnement et sont desormais capables de predirel e rendement d’une cultureapartir de son indicef oliaire. Cetted emarche est d’ailleurs utilisee couramment comme moyen de controle et de taxation des rendements alarge echelle,les indice s foliaires etant estimes par teledetection. Toutefois,pour nos principales especes forestieres, les gammes de fluctuation de cep arametred u couvert et le determinisme de s es variation s sont encorem alconnus, tandis quel es liaisons productivite/ind icef oliaireal’echell e du peuplement commencent seulement aetrep rospectees.

Using satellite measurements from the Total Ozone Mapping Spectrometer (TOMS) and Ozone Monitoring Instrument (OMI) version 8, this work presents the total column ozone (TCO) trends over Mexico and, in particular, over the state of Zacatecas. Interannual variations and their statistical dispersion show a surprisingly systematic behavior. Yearly low values occur during December and January, while high values between April and May. A significant depletion of about 2.5% in TCO between 1978 and 1994 is derived from their statistical analysis, which also shows stabilization from 1996 to 2013. Although the depletion is merely significant, it is a sign that the studied regions, crossed by the Tropic of Cancer, have not escaped to the depletion of the ozone layer. The characterization described herein is important in terms of the correlation of TCO and ultraviolet radiation levels.

Methane (CH4) is a major greenhouse gas whose global warming potential is 23 times more important than carbon dioxide (CO2). CH4 concentrations have steadily increased since the beginning of the industrial era, reaching an unprecedent level (almost 1800 ppb at present times). CH4 is currently considered as a one of the major driver of the climate change and its warming potential has leaded the Kyoto protocol to plan a significative reduction of its emissions. The objective of this thesis is to examine the factors that contribute to the CH4 global budget as well as its year-to-year variations. To that purpose, we have implemented a methane simulation in a global model of chemistry and transport. Conducting a CH4 simulation requires a comprehensive set of interannual varying CH4 emission inventories as well as a year-to-year varying 3-D fields of concentrations of hydroxyl radicals (OH) that is the main sink for CH4. The first part of this thesis examines the OH interannual variation, using results from a "full-chemistry" simulation that accounts for interannual variations in emissions of the main O3 precursors (including carbon monoxide (CO), nitrogen oxides (NOx), and hydrocarbons) as well as the year-to-year variation in meteorology (e.g. atmospheric water vapor content), lightning emissions, and overhead O3 column. We calculated a global OH concentration of 1.22×106 molec cm-3 averaged over the period. We find that global OH concentrations steadily increased during the early 90's by 8% and reached a maximum in 1997. Afterward, concentrations decrease by 5%. We find that changes in water vapor concentrations, anthropogenic emissions of CO and NOx, lightning NOx emissions, and overhead ozone column all play a role in driving the OH year-to-year variations. The relative contributions of these parameters depend on the latitudinal and altitudinal regions of the troposphere. We examine in particular the influence of the 1997-1998 ENSO on the global OH concentrations. We find that the 1997-1998 ENSO resulted in a large increase in OH in the tropical areas and in the extra-tropical areas of the northern hemisphere (largely driven by an increase in water vapor) while it leads to a decrease in OH in the extra-tropical region of the southern hemisphere (that results from changes in the transport pathways that bring CO in the most southern latitudes and deplete OH). Our results (in terms of OH variability) are in contradiction to those found by other methods, especially those using inverse modeling approaches that are based on methyl chloroform (CH3CCl3) observations. This may results from poorly constrained sources. We then seek to implement a comprehensive set of CH4 emissions in our global model. We used anthropogenic CH4 emission data set of anthropogenic emissions from the International Institute of Technology (IIASA) whose emissions vary between 250 and 290 Tg/year between 1990 and 2000. We estimated biomass burning emissions, derived from an inventory of the total annual biomass burned area and emission factors that we constrained with measurements of the isotopic composition of atmospheric methane. This results in a global emissions rate of 60 Tg/year, which is much stronger than most of previous studies. We also developed a wetland scheme that accounts for soil carbon content, wetland fraction areas, soil temperature and humidity (with the three latter parameters varying interannually) and we evaluated the wetland areas with satellite-based estimates. Our global wetland emissions amount to about 150 Tg/year. We find a global CH4 lifetime of 10.6 years, which is in the range of values reported in previous studies. Comparing our results with different set of measurements gives promising results. The model reproduces well the year-to-year variation even if it slightly overestimates concentrations after 2000. By conducting different set of sensitivity simulations, we investigated the role of different parameters on the CH4 variations. We find that the long-term trend in CH4 is driven by a competition between anthropogenic emissions and tropospheric decay. Peaks of growth rate are driven by biomass burning emissions and to a lesser extend, wetland emissions. We find that even if we used increasing anthropogenic emissions during the 90s (that is in contradiction with some previous studies), reconstructing the observed year-to-year variation of CH4 concentrations was possible if one considers an increasing in OH during the 90s.