More than 40 model groups worldwide are participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6), providing a new and rich source of information to better understand past, present, ...and future climate change. Here, we use the Earth System Model Evaluation Tool (ESMValTool) to assess the performance of the CMIP6 ensemble compared to the previous generations CMIP3 and CMIP5. While CMIP5 models did not capture the observed pause in the increase in global mean surface temperature between 1998 and 2013, the historical CMIP6 simulations agree well with the observed recent temperature increase, but some models have difficulties in reproducing the observed global mean surface temperature record of the second half of the twentieth century. While systematic biases in annual mean surface temperature and precipitation remain in the CMIP6 multimodel mean, individual models and high‐resolution versions of the models show significant reductions in many long‐standing biases. Some improvements are also found in the vertical temperature, water vapor, and zonal wind speed distributions, and root‐mean‐square errors for selected fields are generally smaller with reduced intermodel spread and higher average skill in the correlation patterns relative to observations. An emerging property of the CMIP6 ensemble is a higher effective climate sensitivity with an increased range between 2.3 and 5.6 K. A possible reason for this increase in some models is improvements in cloud representation resulting in stronger shortwave cloud feedbacks than in their predecessor versions.
Key Points
Temperature, water vapor, and zonal wind speed show improvements in CMIP6 with amplitudes of many long‐standing biases smaller than CMIP3/5
High‐resolution models show significant improvements in their historical CMIP6 simulations for temperature and precipitation mean biases
Spread in effective climate sensitivity in CMIP6 is larger than in previous phases
We outline the scientific motivation behind a search for gravitational waves associated with short gamma ray bursts detected by the InterPlanetary Network (IPN) during LIGO's fifth science run and ...Virgo's first science run. The InterPlanetary Network localisation of short gamma ray bursts is limited to extended error boxes of different shapes and sizes and a search on these error boxes poses a series of challenges for data analysis. We will discuss these challenges and outline the methods to optimise the search over these error boxes.
Experimental and numerical results are presented on the behavior of guided waves in elastic plates in plane strain that include a Gaussian variation of their section, located between two areas of ...constant thickness. The area of varying section is wide compared to the used wavelengths, which allows wave propagation inside this area. The experimental results show that an incident Lamb wave is indeed converted into an adiabatic wave inside the varying section domain. A trapped wave in the Gaussian domain is also observed, depending on the incident mode and on the Gaussian maximum height. Outside the varying section domain, conversion into different Lamb waves is observed. This conversion phenomenon is experimentally quantified by the measurement of the Lamb wave normal displacement and of its carried energy. A numerical study, based on the Finite Elements Method is performed, and successfully compared to the experimental results.
The Earth System Model Evaluation Tool (ESMValTool) is a community
diagnostics and performance metrics tool designed to improve comprehensive
and routine evaluation of Earth system models (ESMs) ...participating in the
Coupled Model Intercomparison Project (CMIP). It has undergone rapid
development since the first release in 2016 and is now a well-tested tool
that provides end-to-end provenance tracking to ensure reproducibility. It
consists of (1) an easy-to-install, well-documented Python package providing the
core functionalities (ESMValCore) that performs common preprocessing
operations and (2) a diagnostic part that includes tailored diagnostics and
performance metrics for specific scientific applications. Here we describe
large-scale diagnostics of the second major release of the tool that
supports the evaluation of ESMs participating in CMIP Phase 6 (CMIP6).
ESMValTool v2.0 includes a large collection of diagnostics and performance
metrics for atmospheric, oceanic, and terrestrial variables for the mean
state, trends, and variability. ESMValTool v2.0 also successfully reproduces
figures from the evaluation and projections chapters of the
Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report
(AR5) and incorporates updates from targeted analysis packages, such as the
NCAR Climate Variability Diagnostics Package for the evaluation of modes of
variability, the Thermodynamic Diagnostic Tool (TheDiaTo) to evaluate the
energetics of the climate system, as well as parts of AutoAssess that
contains a mix of top–down performance metrics. The tool has been fully
integrated into the Earth System Grid Federation (ESGF) infrastructure at
the Deutsches Klimarechenzentrum (DKRZ) to provide evaluation results from
CMIP6 model simulations shortly after the output is published to the CMIP
archive. A result browser has been implemented that enables advanced
monitoring of the evaluation results by a broad user community at much
faster timescales than what was possible in CMIP5.
Guided waves are potential candidates for the nondestructive evaluation of viscoelastic structures due to their relatively long range of propagation. The major drawback is the difficulty in ...interpreting the scattered waves especially at high frequency-thickness values since many modes then exist. Moreover, in damping material waveguides, each mode of the scattered field has its own attenuation. Viscoelastic material characterization has been widely investigated by many authors in the past, but very few are treating multimodal scattering by discontinuities in viscoelastic guide. The scattering of a pure fundamental mode incident on a trough in a viscoelastic plate is investigated in this paper, over a relatively large frequency range, with up to five scattered modes. A hybrid two-dimensional finite element and modal projection method is used, based on modal orthogonality, to obtain the relative energy fluxes of each mode. Experiments are also made to validate the numerical predictions.
•The imperfect interface is modeled by Jones spring model.•Spring stiffness is obtained by comparison between analytical model and finite elements method.•The detection of corrugation effects is led ...by inspecting guided waves in plates.
The influence of surface imperfections on the propagation of guided waves in an immersed elastic plate can be interpreted by means of a rheological model. The corrugated surface is modeled by a very thin interface, similar to a Jones spring model, which replaces the continuity boundary conditions at the liquid – corrugated solid-plate interface. As the surrounding liquid is considered to be perfect, only one complex stiffness is used for the model of Jones. The selection of the plate guided mode and the test frequency are motivated by the detectability and non-interference with other modes. The spring stiffness is obtained by a best fit procedure, between the analytical solution and the results obtained by the finite elements method (FEM). One way ensuring the agreement of the two approaches, rheological and FEM, is to consider angular resonances provided by the transmission coefficients. Small changes in the parameters of the roughness keep the positions of the angular resonances of the plate practically unchanged, while at the same time large variations of the half width of the transmission coefficient curve is observed. The effect of corrugation parameters on the guided modes in the plate can be predicted by using the rheological model with the deduced spring complex stiffness.
This paper describes the second major release of the Earth System Model Evaluation Tool (ESMValTool), a community diagnostic and performance metrics tool for the evaluation of Earth system models ...(ESMs) participating in the Coupled Model Intercomparison Project (CMIP). Compared to version 1.0, released in 2016, ESMValTool version 2.0 (v2.0) features a brand new design, with an improved interface and a revised preprocessor. It also features a significantly enhanced diagnostic part that is described in three companion papers. The new version of ESMValTool has been specifically developed to target the increased data volume of CMIP Phase 6 (CMIP6) and the related challenges posed by the analysis and the evaluation of output from multiple high-resolution or complex ESMs. The new version takes advantage of state-of-the-art computational libraries and methods to deploy an efficient and user-friendly data processing. Common operations on the input data (such as regridding or computation of multi-model statistics) are centralized in a highly optimized preprocessor, which allows applying a series of preprocessing functions before diagnostics scripts are applied for in-depth scientific analysis of the model output. Performance tests conducted on a set of standard diagnostics show that the new version is faster than its predecessor by about a factor of 3. The performance can be further improved, up to a factor of more than 30, when the newly introduced task-based parallelization options are used, which enable the efficient exploitation of much larger computing infrastructures. ESMValTool v2.0 also includes a revised and simplified installation procedure, the setting of user-configurable options based on modern language formats, and high code quality standards following the best practices for software development.
The effects of periodicity perturbations in underwater phononic crystal layers composed of noninterpenetrating rows of identical shells are investigated. The results for one row are obtained by using ...a multiple scattering method between shells. Then, taking into account the multiple reflections and transmissions between two adjacent rows, a Debye series method is used to calculate the reflection and transmission coefficients by a finite number of rows. The paper focuses on three kinds of perturbations: (i) variation of the inner radius of shells from row to row, (ii) increase in the spacing from row to row and of the number of rows, and (iii) substitution of simple steel rows by steel-polyethylene bilayers. It is shown by studying the transmission coefficient that the case (i) permits the insertion of narrow pass bands in the stop band while the two other cases (ii) and (iii) widen the stop band. The study intends to model simple underwater acoustic filters.
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