Atmospheric rivers in CMIP5 climate ensembles downscaled with a high-resolution regional climate model

Atmospheric rivers (ARs) are important drivers of hazardous precipitation levels and are often associated with intense floods. So far, the response of ARs to climate change in Europe has been investigated using global climate models within the CMIP5 framework. However, the spatial resolution of those models (1–3∘) is too coarse for an adequate assessment of local to regional precipitation patterns. Using a regional climate model with 0.22∘ resolution, we downscaled an ensemble consisting of 1 ERA-Interim (ERAI) reanalysis data hindcast simulation, 9 global historical, and 24 climate scenario simulations following greenhouse gas emission scenarios RCP2.6, RCP4.5, and RCP8.5. The performance of the climate model to simulate AR frequencies and AR-induced precipitation was tested against ERAI. Overall, we find a good agreement between the downscaled CMIP5 historical simulations and ERAI. However, the downscaled simulations better represented small-scale spatial characteristics. This was most evident over the terrain of the Iberian Peninsula, where the AR-induced precipitation pattern clearly reflected prominent east–west topographical elements, resulting in zonal bands of high and low AR impact. Over central Europe, the models simulated a smaller propagation distance of ARs toward eastern Europe than obtained using the ERAI data. Our models showed that ARs in a future warmer climate will be more frequent and more intense, especially in the higher-emission scenarios (RCP4.5, RCP8.5). However, assuming low emissions (RCP2.6), the related changes can be mostly mitigated. According to the high-emission scenario RCP8.5, AR-induced precipitation will increase by 20 %–40 % in western central Europe, whereas mean precipitation rates increase by a maximum of only 12 %. Over the Iberian Peninsula, AR-induced precipitation will slightly decrease (∼6 %) but the decrease in the mean rate will be larger (∼15 %). These changes will lead to an overall increased fractional contribution of ARs to heavy precipitation, with the greatest impact over the Iberian Peninsula (15 %–30 %) and western France (∼15 %). Likewise, the fractional share of yearly maximum precipitation attributable to ARs will increase over the Iberian Peninsula, the UK, and western France. Over Norway, average AR precipitation rates will decline by −5 % to −30 %, most likely due to dynamic changes, with ARs originating from latitudes > 60∘ N decreasing by up to 20 % and those originating south of 45∘ N increasing. This suggests that ARs over Norway will follow longer routes over the continent, such that additional moisture uptake will be impeded. By contrast, ARs from >60∘ N will take up moisture from the North Atlantic before making landfall over Norway. The found changes in the local AR pathway are probably driven by larger-scale circulation changes such as a change in dominating weather regimes and/or changes in the winter storm track over the North Atlantic

South Pacific Convergence Zone dynamics, variability and impacts in a changing climate

The South Pacific Convergence Zone (SPCZ) is a diagonal band of intense rainfall and deep atmospheric convection extending from the equator to the subtropical South Pacific. Displacement of the SPCZ causes variability in rainfall, tropical-cyclone activity and sea level that affects South Pacific island populations and surrounding ecosystems. In this Review, we synthesize recent advances in understanding the physical mechanisms responsible for the SPCZ location and orientation, its interactions with the principal drivers of tropical climate variability, regional and global effects of the SPCZ and its response to anthropogenic climate change. Emerging insight is beginning to provide a coherent description of the character and variability of the SPCZ over synoptic, intraseasonal, interannual and longer timescales. For example, the diagonal orientation of the SPCZ and its natural variability are both the result of a subtle chain of interactions between the tropical and extratropical atmosphere, forced and modulated by the underlying sea surface temperature gradients. However, persistent biases in, and deficiencies of, existing models limit confidence in future projections. Improved climate models and new methods for regional modelling might better constrain future SPCZ projections, aiding climate change adaptation and planning among vulnerable South Pacific communities

Climate change impacts on the South Pacific at different scales : precipitations, tropical cyclones, extremes

Ce travail de thèse traite du changement climatique dans le Pacifique Sud, d'ici à la fin du siècle dans le scénario RCP8.5 (=scénario le plus extrême équivalent à augmentation du forçage radiatif de 8.5W.m-2), à plusieurs échelles spatiales ((1) le Pacifique, (2) le Pacifique sud-ouest, (3) et la Nouvelle-Calédonie) et de ses impacts. Les projections climatiques des modèles CMIP5 comportent de nombreuses biais (e.g. double ITCZ, forte dispersion des patrons de changement de SST) dans cette région que nous nous sommes attachés à réduire. Pour ce faire nous avons utilisé un modèle atmosphérique régional (Weather Research and Forecast). (1) A cette échelle nous nous sommes intéressés au devenir de la zone de convergence du pacifique sud (SPCZ). Les simulations de changement climatique ont montré un possible assèchement (-30%) de la SPCZ piloté par des changements de circulation. (2) Nous nous sommes ici intéressés au devenir de la cyclogenèse du Pacifique Sud-Ouest. Les simulations de changement climatique nous ont permis de montrer une diminution de l'intensité des cyclones, une augmentation des précipitations cyclonique, ainssi qu'un possible effondrement du nombre de cyclone (-50%) du à une augmentation du cisaillement vertical du vent. (3) A cette échelle nous nous sommes focalisés sur l'évolution du climat Néo-Calédonien. Les simulations de changement climatique ont montré une diminution moyenne des précipitations de 20%, avec des contrastes très forts en fonction des régions (côte Est vs côte Ouest), ainsi qu'un doublement du nombre de vagues de chaleur. Enfin nous avons montré l'interet de ces simulations régionales pour des études d'impacts appliquées aux écosystèmes.In this thesis we are interested in the South Pacific climate changes, at the end of the 21st century under the RCP8.5 scenario (i.e. the most extreme scenario equivalent to a radiative forcing increase of 8.5W.m-2), at several spatial scales ((1) Pacific, (2) Southwest Pacific, (3) and New Caledonia) and in its impacts. The climate projections of the CMIP5 models include many biases (e.g. double ITCZ, strong intermodel variability of SST change patterns) in this region that we reduced by using a regional atmospheric model (Weather Research and Forecast). (1) At this scale we are interested in the future of the South Pacific Convergence Zone (SPCZ). Climate change simulations showed a possible drying (-30%) of SPCZ driven by circulation changes. (2) We are interested here in the future of the Southwest Pacific cyclogenesis. Climate change simulations have shown a decrease of cyclone intensity, an increase of cyclonic precipitation, and a possible collapse of the cyclones number (-50%) due to an increase of vertical wind shear. (3) And then we focused on the evolution of the New Caledonian climate. Climate change simulations showed a decrease of rainfall (-20%) in average, with very strong contrasts across regions (East coast vs West coast), as well as a doubling of the heat waves number. Finally, we showed the interest of these regional simulations for impact studies applied to ecosystems

Impacts du changement climatique dans le Pacifique Sud à différentes échelles : précipitations, cyclones, extrêmes

In this thesis we are interested in the South Pacific climate changes, at the end of the 21st century under the RCP8.5 scenario (i.e. the most extreme scenario equivalent to a radiative forcing increase of 8.5W.m-2), at several spatial scales ((1) Pacific, (2) Southwest Pacific, (3) and New Caledonia) and in its impacts. The climate projections of the CMIP5 models include many biases (e.g. double ITCZ, strong intermodel variability of SST change patterns) in this region that we reduced by using a regional atmospheric model (Weather Research and Forecast). (1) At this scale we are interested in the future of the South Pacific Convergence Zone (SPCZ). Climate change simulations showed a possible drying (-30%) of SPCZ driven by circulation changes. (2) We are interested here in the future of the Southwest Pacific cyclogenesis. Climate change simulations have shown a decrease of cyclone intensity, an increase of cyclonic precipitation, and a possible collapse of the cyclones number (-50%) due to an increase of vertical wind shear. (3) And then we focused on the evolution of the New Caledonian climate. Climate change simulations showed a decrease of rainfall (-20%) in average, with very strong contrasts across regions (East coast vs West coast), as well as a doubling of the heat waves number. Finally, we showed the interest of these regional simulations for impact studies applied to ecosystems.Ce travail de thèse traite du changement climatique dans le Pacifique Sud, d'ici à la fin du siècle dans le scénario RCP8.5 (=scénario le plus extrême équivalent à augmentation du forçage radiatif de 8.5W.m-2), à plusieurs échelles spatiales ((1) le Pacifique, (2) le Pacifique sud-ouest, (3) et la Nouvelle-Calédonie) et de ses impacts. Les projections climatiques des modèles CMIP5 comportent de nombreuses biais (e.g. double ITCZ, forte dispersion des patrons de changement de SST) dans cette région que nous nous sommes attachés à réduire. Pour ce faire nous avons utilisé un modèle atmosphérique régional (Weather Research and Forecast). (1) A cette échelle nous nous sommes intéressés au devenir de la zone de convergence du pacifique sud (SPCZ). Les simulations de changement climatique ont montré un possible assèchement (-30%) de la SPCZ piloté par des changements de circulation. (2) Nous nous sommes ici intéressés au devenir de la cyclogenèse du Pacifique Sud-Ouest. Les simulations de changement climatique nous ont permis de montrer une diminution de l'intensité des cyclones, une augmentation des précipitations cyclonique, ainssi qu'un possible effondrement du nombre de cyclone (-50%) du à une augmentation du cisaillement vertical du vent. (3) A cette échelle nous nous sommes focalisés sur l'évolution du climat Néo-Calédonien. Les simulations de changement climatique ont montré une diminution moyenne des précipitations de 20%, avec des contrastes très forts en fonction des régions (côte Est vs côte Ouest), ainsi qu'un doublement du nombre de vagues de chaleur. Enfin nous avons montré l'interet de ces simulations régionales pour des études d'impacts appliquées aux écosystèmes

Le monde du métal symphonique (vers une sociologie de l'oeuvre comme création continuée, l'exemple de Nightwish.)

Le metal symphonique est un genre musical qui mêle la musique classique à la musique metal. Nightwish, un groupe d'origine finlandaise, est parmi les représentants les plus reconnus du genre. Prenant pour point de départ les œuvres musicales de ce dernier, la présente recherche interroge, d'un point de vu sociologique, la dimension combinatoire de son metal symphonique. Des sources d'origines différentes le metal symphonique a tout d'un oxymore sont assemblées, peut-être continuées par Nightwish. De la construction collective d'un groupe qui modèle, par les particularités individuelles de ses membres, les œuvres qu'il réalise, aux pratiques des amateurs de Nightwish, en passant par les influences du groupe et son monde imaginaire, cette thèse suit dans le processus de l'œuvre la trace de la continuation. D'un acteur du monde Nightwish à l'autre, l'œuvre musicale ne serait-elle pas un processus continué, une résurrection, à chaque audition, d'une créature mythique, créée et recréée sans cesse ?Symphonic metal is a musical genre that mixes classical music with metal music. Nightwish, a band from Finland, is one of the most recognized of the genre. Starting with its musical art works, this thesis questions, with a sociological approaches, the combinatorial dimension of its symphonic metal. References sources from different origins symphonic metal has everything of an oxymoron are assembled, maybe continued by Nightwish. From the collective elaboration of a band which models, by the individual peculiarities of its members, the art works it makes, to Nightwish' amateurs practices, by way of the influences of the band and its imaginary world, this thesis follows in the art work process the idea of continuation. From an actor of Nightwish' world to another, would musical art work not be a continued process, a resurrection, at each listening, of a mythic creature, made and remade, again and again?SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Proteome-wide probing of the dual NMT-dependent myristoylation tradeoff unveils potent, mechanism-based suicide inhibitors

ABSTRACT N-myristoyltransferases (NMTs) catalyze protein myristoylation, a major and ubiquitous lipid modification. Originally thought to modify only N-terminal glycine α-amino groups (G-myristoylation), NMTs are now known to modify lysine ε-amino groups (K-myristoylation), the significance of which is uncertain. Here we exploited systematic structural proteomics analyses and a novel pipeline involving the Shigella IpaJ protease to discriminate K- and G-myristoylation with unprecedented accuracy and identify the specific features driving each modification. NMT-dependent K-myristoylation occurs post-translationally and only on lysines 1, 2, or 3 following G-myristoylation or caspase cleavage. Direct interactions between the substrate’s reactive amino group and the NMT catalytic base slow K-myristoylation catalysis. IpaJ unmasked novel K-myristoylation sites in a dozen human proteins. The unique properties of NMT-driven K-myristoylation allowed us to design potent, mechanism-based suicide NMT inhibitors. These analyses unravel the respective paths towards K-myristoylation, G-myristoylation, or NMT inhibition, which rely on a very subtle tradeoff embracing the chemical landscape around the reactive group. SIGNIFICANCE STATEMENT We report the specific and unique elements guiding N-myristoyltransferase to either alpha or epsilon myristoylation, allowing us to establish the post-translational nature of N-myristoyltransferase-dependent lysine myristoylation and design novel, potent N-myristoyltransferase inhibitors

Drivers of marine heatwaves in a stratified marginal sea

Marine heatwaves (MHWs) can cause devastating impacts in coastal marine ecosystems, particularly in shallow marginal seas, thereby making the understanding of the drivers of these events of paramount importance. Here, drivers for summer and winter MHWs are explored for the period 1980–2016 in the Baltic Sea, a mid-latitude marginal sea with a permanent haline water-column stratification located on the northwestern European shelf. It was found that summer MHWs are mainly forced by local meteorological conditions over the open water. They are caused by a dominant blocking over Scandinavia promoting anomalous strong shortwave downflux, calm winds, and low vertical mixing with colder sub-thermocline waters. Wintertime MHWs are linked to the advection of warm and moist air originating from the North Atlantic. These air masses lower the oceanic net heat loss at the sea surface primarily in the form of reduced latent and sensible heat losses. Vertical ocean dynamics are also affected during winter MHWs. This study finds a strengthened coastal up- and downwelling due to anomalous strong westerly winds during the time before MHWs culminate in their maximal surface extension

Understanding past and future sea surface temperature trends in the Baltic Sea

The Baltic Sea is one of the fastest-warming semi-enclosed seas in the world over the last decades, yielding critical consequences on physical and biogeochemical conditions and on marine ecosystems. Although long-term trends in sea surface temperature (SST) have long been attributed to trends in air temperature, there are however, strong seasonal and sub-basin scale heterogeneities of similar magnitude than the average trend which are not fully explained. Here, using reconstructed atmospheric forcing fields for the period 1850–2008, oceanic climate simulations were performed and analyzed to identify areas of homogenous SST trends using spatial clustering. Our results show that the Baltic Sea can be divided into five different areas of homogeneous SST trends: the Bothnian Bay, the Bothnian Sea, the eastern and western Baltic proper, and the southwestern Baltic Sea. A classification tree and sensitivity experiments were carried out to analyze the main drivers behind the trends. While ice cover explains the seasonal north/south warming contrast, the changes in surface winds and air-sea temperature anomalies (along with changes in upwelling frequencies and heat fluxes) explain the SST trends differences between the sub-basins of the southern part of the Baltic Sea. To investigate future warming trends climate simulations were performed for the period 1976–2099 using two RCP scenarios. It was found that the seasonal north/south gradient of SST trends should be reduced in the future due to the vanishing of sea ice, while changes in the frequency of upwelling and heat fluxes explained the lower future east/west gradient of SST trend in fall. Finally, an ensemble of 48 climate change simulations has revealed that for a given RCP scenario the atmospheric forcing is the main source of uncertainty. Our results are useful to better understand the historical and future changes of SST in the Baltic Sea, but also in terms of marine ecosystem and public management, and could thus be used for planning sustainable coastal development