Science directions in a post-COP21-world of transient climate change: enabling regional to local predictions in support of reliable climate information

During recent decades, through theoretical considerations and analyses of observations andmodel simulations, the scientific community has fundamentally advanced our understanding of thecoupled climate system, thereby establishing that humans affect the Earth’s climate. Resulting from thisremarkable accomplishment, the COP21 agreement marks a historic turning point for climate research bycalling for actionable regional climate change information on time scales from seasonal to centuries for thebenefit of humanity, as well as living and nonliving elements of the Earth environment. Out of the underlyingUnited National Framework Convention on climate Change process, improving seamless regional climateforecast capabilities emerges as a key challenge for the international research community. Addressing itrequires a multiscale approach to climate predictions. Here we offer a vision that emphasizes enhancedscientific understanding of regional to local climate processes as the foundation for progress. The scientificchallenge is extreme due to the rich complexity of interactions and feedbacks between regional andglobal processes, each of which affects the global climate trajectory. To gain the necessary scientific insightand to turn it into actionable climate information require technical development, international coordination,and a close interaction between the science and stakeholder communities

Generation of optical Schrödinger cat states in intense laser-matter interactions

The physics of intense laser–matter interactions1,2 is described by treating the light pulses classically, anticipating no need to access optical measurements beyond the classical limit. However, the quantum nature of the electromagnetic fields is always present3. Here we demonstrate that intense laser–atom interactions may lead to the generation of highly non-classical light states. This was achieved by using the process of high-harmonic generation in atoms4,5, in which the photons of a driving laser pulse of infrared frequency are upconverted into photons of higher frequencies in the extreme ultraviolet spectral range. The quantum state of the fundamental mode after the interaction, when conditioned on the high-harmonic generation, is a so-called Schrödinger cat state, which corresponds to a superposition of two distinct coherent states: the initial state of the laser and the coherent state reduced in amplitude that results from the interaction with atoms. The results open the path for investigations towards the control of the non-classical states, exploiting conditioning approaches on physical processes relevant to high-harmonic generation.Peer ReviewedPostprint (author's final draft

Quantum optical analysis of high-order harmonic generation in H2+_2^+ molecular ions

We present a comprehensive theoretical investigation of high-order harmonic generation in H$_2^+$ molecular ions within a quantum optical framework. Our study focuses on characterizing various quantum optical and quantum information measures, highlighting the versatility of HHG in two-center molecules towards quantum technology applications. We demonstrate the emergence of entanglement between electron and light states after the laser-matter interaction. We also identify the possibility of obtaining non-classical states of light in targeted frequency modes by conditioning on specific electronic quantum states, which turn out to be crucial in the generation of highly non-classical entangled states between distinct sets of harmonic modes. Our findings open up avenues for studying strong-laser field-driven interactions in molecular systems, and suggest their applicability to quantum technology applications.Comment: 21 pages (14 main text + 7 appendix), 9 figures (8 main text + 1 appendix

Eddy heat fluxes from direct current measurements of the Antarctic Polar Front in Shag Rocks Passage

Determining meridional heat flux in the Southern Ocean is critical to the accurate understanding and model simulation of the global ocean. Mesoscale eddies provide a significant but poorly-defined contribution to this transport. An eighteen-month deep-water current meter array deployment in Shag Rocks Passage (53°S, 48°W) between May 2003 and November 2004 provides estimates of the eddy flux of heat across the Polar Front. We calculate a statistically nonzero (99% level), vertically coherent local poleward heat flux of 12.0 ± 5.8 kW m-2 within the eddy frequency band at ~2750 m depth. Exceeding previous deep-water estimates by up to an order of magnitude, this highlights the large spatial variation in flux estimates and illustrates that constriction of circumpolar fronts facilitates large eddy transfers of heat southwards

Global ocean modeling and state estimation in support of climate research

During the last decade it has become obvious that the ocean circulation shows vigorous variability on a wide range of time and space scales and that the concept of a "sluggish" and slowly varying circulation is rather elusive. Increasing emphasis has to be put, therefore, on observing the rapidly changing ocean state on time scales ranging from weeks to decades and beyond, and on understanding the ocean's response to changing atmospheric forcing conditions. As outlined in various strategy and implementation documents (e.g., the implementation plans of WOCE, AMS, CLIVAR, and GODAE) a combination of the global ocean data sets with a state-of-the-art numerical circulation model is required to interpret the various diverse data sets and to produce the best possible estimates of the time-varying ocean circulation. The mechanism of ocean state estimates is a powerful tool for such a "synthesis" of observations, obtained on very complex space-time pattern, into one dynamically consistent picture of the global time-evolving ocean circulation. This process has much in common with ongoing analysis and reanalysis activities in the atmospheric community. But because the ocean is, and will remain for the foreseeable future, substantially under-sampled, the burden put on the modeling and estimations components is substantially larger than in the atmosphere. Moreover, the smaller dynamical eddy scales which need to be properly parameterized or resolved in ocean model simulations, put stringent requirements on computational resources for ongoing and participated climate research

Impacts of regional mixing on the temperature structure of the equatorial Pacific Ocean. Part 1: Vertically uniform vertical diffusion

AbstractWe investigate the sensitivity of numerical-model solutions to regional changes in vertical diffusion. Specifically, we vary the background diffusion coefficient, κb, within spatially distinct subregions of the tropical Pacific, assess the impacts of those changes, and diagnose the processes that account for them.Solutions respond to a diffusion anomaly, δκb, in three ways. Initially, there is a fast response (several months), due to the interaction of rapidly-propagating, barotropic and gravity waves with eddies and other mesoscale features. It is followed by a local response (roughly one year), the initial growth and spatial pattern of which can be explained by one-dimensional (vertical) diffusion. At this stage, temperature and salinity anomalies are generated that are either associated with a change in density (“dynamical” anomalies) or without one (“spiciness” anomalies). In a final adjustment stage, the dynamical and spiciness anomalies spread to remote regions by radiation of Rossby and Kelvin waves and by advection, respectively.In near-equilibrium solutions, dynamical anomalies are generally much larger in the latitude band of the forcing, but the impact of off-equatorial forcing by δκb on the equatorial temperature structure is still significant. Spiciness anomalies spread equatorward within the pycnocline, where they are carried to the equator as part of the subsurface branch of the Pacific Subtropical Cells, and spiciness also extends to the equator via western-boundary currents. Forcing near and at the equator generates strong dynamical anomalies, and sometimes additional spiciness anomalies, at pycnocline depths. The total response of the equatorial temperature structure to δκb in various regions depends on the strength and spatial pattern of the generation of each signal within the forcing region as well as on the processes of its spreading to the equator

Induction of apoptosis by overexpression of the DNA-binding and DNA-PK-activating protein C1D

Apoptosis is induced in various tumor cell lines by vector-dependent overexpression of the conserved gene C1D that encodes a DNA-binding and DNA-PK-activating protein. C1D is physiologically expressed in 50 human tissues tested, which points to its basic cellular function. The expression of this gene must be tightly regulated because elevated levels of C1D protein, e.g. those induced by transient vector-dependent expression, result in apoptotic cell death. Cells transfected with C1D-expressing constructs show terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling of DNA ends. Transfections with constructs in which C1D is expressed in fusion with the (enhanced) green fluorescent protein from A. victoria (EGFP) allow the transfected cells to be identified and the morphological changes induced to be traced. Starting from intense nuclear spots, green fluorescence reflecting C1D expression increases dramatically at 12-24 hours post-transfection. Expression of C1D-EGFP protein is accompanied by morphological changes typical of apoptotic cell death, e.g. cytoplasmic vacuolation, membrane blebbing and nuclear disintegration. Cell shrinkage and detachment from extracellular matrix are observed in monolayer cultures while suspension cells become progressively flattened. The facility to differentiate between transfected and non-transfected cells reveals that non-transfected cells co-cultured with transfected cells also show the morphological changes of apoptosis, which points to a bystander effect. C1D-dependent apoptosis is not induced in cells with non-functional p53. Accordingly, C1D-induced apoptosis is discussed in relation to its potential to activate DNA-PK, which has been considered to act as an upstream activator of p53

“Chapter 13: Sea Level Change” in Climate Change 2013: The Physical Science Basis: Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change

This chapter considers changes in global mean sea level, regional sea level, sea level extremes, and waves. Confidence in projections of global mean sea level rise has increased since the Fourth Assessment Report (AR4) because of the improved physical understanding of the components of sea level, the improved agreement of process-based models with observations, and the inclusion of ice-sheet dynamical changes

Testing variational estimation of process parameters and initial conditions of an earth system model

We present a variational assimilation system around a coarse resolution Earth System Model (ESM) and apply it for estimating initial conditions and parameters of the model. The system is based on derivative information that is efficiently provided by the ESM's adjoint, which has been generated through automatic differentiation of the model's source code. In our variational approach, the length of the feasible assimilation window is limited by the size of the domain in control space over which the approximation by the derivative is valid. This validity domain is reduced by non-smooth process representations. We show that in this respect the ocean component is less critical than the atmospheric component. We demonstrate how the feasible assimilation window can be extended to several weeks by modifying the implementation of specific process representations and by switching off processes such as precipitation