Somewhere In France Is The Lily

[Verse 1] One day as morning shed its glow Across the eastern sky A boy and girl in accents low In a garden said “Goodbye!” She said “Remember as you stray, When each must do his share, The flowers blooming here today Are emblems over there!” [Refrain] Somewhere in France is the Lily, Close by the English Rose; Somewhere in France is a sweetheart, Facing the battle’s chance, For the flow’r of our youth fights for freedom and truth Somewhere in France [Verse 2] Each morning in that garden fair, Where sweetest perfumes dwell, The lassie whispers low a pray’r For the flowr’s she loves so well. And over there as night draws near, Amid the shot and flame, Unto the flag he holds so dear, A soldier breathes her name. [Refrain

Atlantic Equatorial Undercurrent and associated cold tongue variability

The Atlantic Equatorial Undercurrent (EUC) is studied using a simulation for the period 1990–2002 with a high-resolution ocean general circulation model. Simulated transports of the EUC that supplies the annual mean upwelling in the central and eastern equatorial Atlantic are in good agreement with new transport estimates derived from ship observations, i.e., 19.9 and 14.0 Sv at 35°W and 23°W, respectively. Although the observations are not conclusive concerning the seasonal cycle of EUC transports, the simulated seasonal cycles fit largely in the observed range. The analysis of the EUC variability associated with interannual boreal summer variability of the equatorial cold tongue showed that cold tongue indices, defined either by near-surface temperature or steric height anomalies, are anticorrelated with thermocline EUC transport anomalies: A strong EUC corresponds to low near-surface temperatures and steric heights. The importance of equatorial waves for the cold tongue region is shown: Surface layer transport anomalies at 23°W and 10°W are significantly correlated with both near-surface temperature and steric height anomalies in the equatorial and coastal upwelling regions, indicating an associated eastward phase propagation along the equator toward the African coast where the signal bifurcates into two poleward branches along the coast and is reflected into a westward propagating wave

Detection of linear trends in multi-sensor time series in the presence of autocorrelated noise: Application to the chlorophyll-a SeaWiFS and MERIS datasets and extrapolation to the incoming Sentinel 3-OLCI mission

The detection of long-term trends in geophysical time series is a key issue in climate change studies. This detection is affected by many factors: the size of the trend to be detected, the length of the available data sets, and the noise properties. Although the noise autocorrelation observed in geophysical time series does not bias the trend estimate, it affects the estimation of its uncertainty and consequently the ability to detect, or not, a significant trend. Ignoring the noise autocorrelation level typically leads to an overdetection of significant trends. Due to satellite lifetime, usually between 5 and 10 years, sea surface time series do not cover the same period and are acquired by different sensors with different characteristics. These differences lead to unknown level shifts (biases) between the datasets, which affect the trend detection. In this work, we develop a generic framework to detect and evaluate linear trends and level shifts in multisensor time series of satellite chlorophyll-a concentrations, as provided by the Medium Resolution Imaging Spectrometer instrument (MERIS) and sea-viewing wide field-of-view sensor (SeaWiFS) ocean-color missions. We also discuss the optimization of the observation networks, in terms of needed time overlap between successive time series to reduce the uncertainty on the detection of long-term trends. For the incoming Sentinel 3-Ocean and Land Color Instrument (3-OLCI)mission that should be launched at the end of 2014, we propose a global map of the number of months of observations to enhance the trend detection performed with the joint SeaWiFS-MERIS analysis

Pathways and variability of the off-equatorial undercurrents in the Atlantic Ocean

The cold upwelling waters of the eastern tropical oceans not only interact with the atmospheric circulation via changing the sea surface temperatures but also influence the biological activity via affecting the nutrient and oxygen contents of the upwelling waters. While the sources of the equatorial upwelling associated with the Equatorial Undercurrent (EUC) have been studied extensively, the relevance of the northern and southern off-equatorial undercurrents (NEUC, SEUC) for the off-equatorial upwelling regions has remained unclear. In this study we use output from a high-resolution, 1/12° model (FLAME) to investigate the mean pathways and variability of the off-equatorial undercurrents (OEUCs) in the Atlantic. In particular, a calculation of Lagrangian trajectories helps to gain insight into the source waters of the OEUCs and their connection to the upwelling regions in the eastern tropical Atlantic. In the model solution the sources of both OEUCs belong almost exclusively to the Southern Hemisphere. The pathways of the source waters are found to be governed by strong recirculations between the different eastward and westward zonal currents because of intense eddy motions associated with the tropical instability wave activity. Whereas the SEUC is predominantly fed through the recirculation in the ocean interior, the NEUC is also fed by a weak inflow from the western boundary current. Investigation of the fate of the NEUC shows only a weak direct supply to the upwelling in the Guinea Dome and along the African coast but a significant contribution to the equatorial upwelling

Accounting for Centennial Scale Variability when Detecting Changes in ENSO: a study of the Pliocene

The El Niño Southern Oscillation (ENSO) is the dominant mode of interannual climate variability. However, climate models are inconsistent in future predictions of ENSO, and long term variations in ENSO cannot be quantified from the short instrumental records available. Here we analyse ENSO behaviour in millennial-scale climate simulations of a warm climate of the past, the mid-Pliocene Warm Period (mPWP; ∼3.3 − 3.0Ma). We consider centennial-scale variability in ENSO for both the mPWP and the preindustrial, and consider which changes between the two climates are detectable above this variability. We find that El Niño typically occurred 12% less frequently in the mPWP but with a 20% longer duration, and with stronger amplitude in precipitation and temperature. However low frequency variability in ENSO meant that Pliocene-preindustrial changes in El Niño temperature amplitude in the NINO3.4 region (5° N-5° S, 170° W-120° W) were not always detectable. The Pliocene-preindustrial El Niño temperature signal in the NINO4 region (5° N-5° S, 160° E-150° W) and the El Niño precipitation signal are usually larger than centennial scale variations of El Niño amplitude, and provide consistent indications of ENSO amplitude change. The enhanced mPWP temperature signal in the NINO4 region is associated with an increase in Central Pacific El Niño events similar to those observed in recent decades and predicted for the future. This study highlights the importance of considering centennial scale variability when comparing ENSO changes between two climate states. If centennial scale variability in ENSO has not first been established, results suggesting changes in ENSO behaviour may not be robust

Mechanisms of decadal variability in the shallow subtropical-tropical circulation of the Atlantic Ocean: a model study

A suite of basin-scale models of the thermohaline and wind-driven circulation in the Atlantic Ocean is used to study the mechanisms of decadal variability in the shallow subtropical-tropical cells (STCs). The emphasis is on the spatial patterns of the transport anomalies in the tropical thermocline, particularly their manifestation in the equatorial current system and on the relative role of changes in the deep meridional overturning cell (MOC) associated with variations in the formation of Labrador Sea Water (LSW) in the subpolar North Atlantic. Using wind stress and heat flux variations based on NCEP/NCAR-reanalysis products, the variability of the zonally integrated STC transports is similar to that obtained in a recent regional model study, corroborating the role of both the southern and northern STC in supporting wind-driven transport anomalies of O(2 Sv) near the equator. Sensitivity experiments indicate that changes in subarctic MOC transports associated with the strong variability in LSW formation during the last decades contributed a signal of O(0.3 Sv) to the upper-layer equatorial transports. Whereas the local wind-driven variability clearly dominates on interannual-decadal timescales and is confined to depths down to 150 m, the weak MOC-related signal is primarily reflected in an interdecadal modulation of the STC transports. While a strong part in the STC's transport anomalies is associated with the western boundary current (NBC), there is an important contribution also by weaker, interior ocean flow anomalies which tend to counteract the variability of the NBC

Eddy formation behind the tropical island of Aldabra

Oceanic eddy formation behind the tropical island of Aldabra is examined with a one-layer reduced gravity model. Thresholds for flow separation, eddy formation, eddy shedding, and wake instabilities are determined and compared with theory, observations and results of laboratory experiments for both rotating and non-rotating flows. It is shown that non-rotating fluid theory and the Reynolds number are appropriate for describing the occurrence of eddy shedding. For islands at higher lalitudes, thresholds move nearer those found in rotating laboratory experiments Strouhal numbers calculated from the model results agree with those predicted theoretically, confirming that the frequency of eddy shedding does not increase indefinitely with Reynolds number. Both the model results and data from the CZCS archive suggest that eddy shedding and the associated enhanced biological activity (and thus CO2 uptake) are common phenomena for Aldabra and by implication, other oceanic islands

Climate fluctuations of tropical coupled system: The role of ocean dynamics

The tropical oceans have long been recognized as the most important region for large-scale ocean–atmosphere interactions, giving rise to coupled climate variations on several time scales. During the Tropical Ocean Global Atmosphere (TOGA) decade, the focus of much tropical ocean research was on understanding El Niño–related processes and on development of tropical ocean models capable of simulating and predicting El Niño. These studies led to an appreciation of the vital role the ocean plays in providing the memory for predicting El Niño and thus making seasonal climate prediction feasible. With the end of TOGA and the beginning of Climate Variability and Prediction (CLIVAR), the scope of climate variability and predictability studies has expanded from the tropical Pacific and ENSO-centric basis to the global domain. In this paper the progress that has been made in tropical ocean climate studies during the early years of CLIVAR is discussed. The discussion is divided geographically into three tropical ocean basins with an emphasis on the dynamical processes that are most relevant to the coupling between the atmosphere and oceans. For the tropical Pacific, the continuing effort to improve understanding of large- and small-scale dynamics for the purpose of extending the skill of ENSO prediction is assessed. This paper then goes beyond the time and space scales of El Niño and discusses recent research activities on the fundamental issue of the processes maintaining the tropical thermocline. This includes the study of subtropical cells (STCs) and ventilated thermocline processes, which are potentially important to the understanding of the low-frequency modulation of El Niño. For the tropical Atlantic, the dominant oceanic processes that interact with regional atmospheric feedbacks are examined as well as the remote influence from both the Pacific El Niño and extratropical climate fluctuations giving rise to multiple patterns of variability distinguished by season and location. The potential impact of Atlantic thermohaline circulation on tropical Atlantic variability (TAV) is also discussed. For the tropical Indian Ocean, local and remote mechanisms governing low-frequency sea surface temperature variations are examined. After reviewing the recent rapid progress in the understanding of coupled dynamics in the region, this study focuses on the active role of ocean dynamics in a seasonally locked east–west internal mode of variability, known as the Indian Ocean dipole (IOD). Influences of the IOD on climatic conditions in Asia, Australia, East Africa, and Europe are discussed. While the attempt throughout is to give a comprehensive overview of what is known about the role of the tropical oceans in climate, the fact of the matter is that much remains to be understood and explained. The complex nature of the tropical coupled phenomena and the interaction among them argue strongly for coordinated and sustained observations, as well as additional careful modeling investigations in order to further advance the current understanding of the role of tropical oceans in climate

Net primary productivity estimates and environmental variables in the Arctic Ocean: An assessment of coupled physical-biogeochemical models

The relative skill of 21 regional and global biogeochemical models was assessed in terms of how well the models reproduced observed net primary productivity (NPP) and environmental variables such as nitrate concentration (NO3), mixed layer depth (MLD), euphotic layer depth (Zeu), and sea ice concentration, by comparing results against a newly updated, quality-controlled in situ NPP database for the Arctic Ocean (1959-2011). The models broadly captured the spatial features of integrated NPP (iNPP) on a pan-Arctic scale. Most models underestimated iNPP by varying degrees in spite of overestimating surface NO3, MLD, and Zeu throughout the regions. Among the models, iNPP exhibited little difference over sea ice condition (ice-free vs. ice-influenced) and bottom depth (shelf vs. deep ocean). The models performed relatively well for the most recent decade and towards the end of Arctic summer. In the Barents and Greenland Seas, regional model skill of surface NO3 was best associated with how well MLD was reproduced. . Regionally, iNPP was relatively well simulated in the Beaufort Sea and the central Arctic Basin, where in situ NPP is low and nutrients are mostly depleted. Models performed less well at simulating iNPP in the Greenland and Chukchi Seas, despite the higher model skill in MLD and sea ice concentration, respectively. iNPP model skill was constrained by different factors in different Arctic Ocean regions. Our study suggests that better parameterization of biological and ecological microbial rates (phytoplankton growth and zooplankton grazing) are needed for improved Arctic Ocean biogeochemical modeling