scholarly journals MJO Simulation Diagnostics

2009 ◽  
Vol 22 (11) ◽  
pp. 3006-3030 ◽  
Keyword(s):  
Model Performance ◽  
Diagnostic Techniques ◽  
Life Cycles ◽  
Global Circulation ◽  
Orthogonal Function ◽  
Global Circulation Models ◽  
Wide Range ◽  
Weather And Climate ◽  
The Mean

Abstract The Madden–Julian oscillation (MJO) interacts with and influences a wide range of weather and climate phenomena (e.g., monsoons, ENSO, tropical storms, midlatitude weather), and represents an important, and as yet unexploited, source of predictability at the subseasonal time scale. Despite the important role of the MJO in climate and weather systems, current global circulation models (GCMs) exhibit considerable shortcomings in representing this phenomenon. These shortcomings have been documented in a number of multimodel comparison studies over the last decade. However, diagnosis of model performance has been challenging, and model progress has been difficult to track, because of the lack of a coherent and standardized set of MJO diagnostics. One of the chief objectives of the U.S. Climate Variability and Predictability (CLIVAR) MJO Working Group is the development of observation-based diagnostics for objectively evaluating global model simulations of the MJO in a consistent framework. Motivation for this activity is reviewed, and the intent and justification for a set of diagnostics is provided, along with specification for their calculation, and illustrations of their application. The diagnostics range from relatively simple analyses of variance and correlation to more sophisticated space–time spectral and empirical orthogonal function analyses. These diagnostic techniques are used to detect MJO signals, to construct composite life cycles, to identify associations of MJO activity with the mean state, and to describe interannual variability of the MJO.

scholarly journals On the Role of Entrainment in the Fate of Cumulus Thermals

2018 ◽  
Vol 75 (11) ◽  
pp. 3911-3924 ◽  
Author(s):  
Daniel Hernandez-Deckers ◽  
Steven C. Sherwood
Keyword(s):  
Initial Conditions ◽  
Cloud Base ◽  
Entrainment Rate ◽  
Moist Convection ◽  
Key Factors ◽  
Global Circulation ◽  
Ascent Rate ◽  
Global Circulation Models ◽  
Large Eddy

Abstract Mixing is one of the most important processes associated with atmospheric moist convection. It determines the two-way interaction between clouds and their environment, thus having a direct impact on the time evolution of convection. The fractional entrainment rate ε—the main parameter related to mixing—is often parameterized in global circulation models as a function of updraft properties, and at the same time has a strong influence on how convection evolves. Within the framework of cumulus thermal vortices in large-eddy simulations of convection, here we first investigate the validity of some of the most common parameterizations of ε, and then investigate how relevant ε is for the fate of these thermals. We find that 1/R, where R is a measure of the thermal’s radius, best parameterizes ε, but it explains only about 20% of the total variance. On the other hand, we find that both ε and favorable initial conditions—including high initial saturated fraction of the thermals—are key factors that affect the thermals’ ascent rate, mean buoyancy, and distance traveled. The lifetimes of thermals, however, seem not to be affected significantly by either ε or initial conditions, which supports the view of cumulus convection as a succession of many short-lived thermals. Finally, our results suggest that for the majority of in-cloud cumulus thermals the important role of environmental moisture in the deepening of convection results mainly from providing the initial moisture for the short-lived thermals as they initiate at different altitudes above cloud base, rather than favoring their buoyancy as they rise through it.

scholarly journals Hierarchical Porous Polyamide 6 by Solution Foaming: Synthesis, Characterization and Properties

Polymers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1310 ◽  
Author(s):  
Liang Wang ◽  
Yu-Ke Wu ◽  
Fang-Fang Ai ◽  
Jie Fan ◽  
Zhao-Peng Xia ◽  
...  
Keyword(s):  
Large Scale ◽  
Polyamide 6 ◽  
Solution Concentration ◽  
The Novel ◽  
Foaming Agent ◽  
Hierarchical Porous ◽  
Wide Range ◽  
The Mean ◽  
Novel Strategy

Porous polym er materials have received great interest in both academic and industrial fields due to their wide range of applications. In this work, a porous polyamide 6 (PA6) material was prepared by a facile solution foaming strategy. In this approach, a sodium carbonate (SC) aqueous solution acted as the foaming agent that reacted with formic acid (FA), generating CO2 and causing phase separation of polyamide (PA). The influence of the PA/FA solution concentration and Na2CO3 concentration on the microstructures and physical properties of prepared PA foams were investigated, respectively. PA foams showed a hierarchical porous structure along the foaming direction. The mean pore dimension ranged from hundreds of nanometers to several microns. Low amounts of sodium salt generated from a neutralization reaction played an important role of heterogeneous nucleation, which increased the crystalline degree of PA foams. The porous PA materials exhibited low thermal conductivity, high crystallinity and good mechanical properties. The novel strategy in this work could produce PA foams on a large scale for potential engineering applications.

Wind of Change: Atmospheric wind retrieval and its implications for hot Jupiters

2020 ◽  
Author(s):  
Julia Seidel ◽  
David Ehrenreich ◽  
Vincent Bourrier ◽  
Lorenzo Pino ◽  
Aurelien Wyttenbach ◽  
...  
Keyword(s):  
High Spectral Resolution ◽  
Wind Retrieval ◽  
Hot Jupiters ◽  
Global Circulation ◽  
Hot Gas ◽  
Global Circulation Models ◽  
Pressure Profiles ◽  
Profile Fitting ◽  
Wide Range ◽  
Hot Jupiter

<p><span>The sodium doublet is one of the most powerful probes of exoplanet atmospheric properties when observed in transmission spectroscopy during transits. Recent high-spectral resolution observations of the sodium doublet in hot gas giants allowed us to resolve the line shape, opening the way for extracting atmospheric properties using line-profile fitting. </span></p><p><span>Using the MERC code (Seidel et al. 2020a), a retrieval tool to determine temperature-pressure profiles and high-altitude winds in exoplanet thermospheres, we have studied the curiously broadened sodium signatures of various hot Jupiters. We have updated the MERC code to a quasi 3D treatment of the atmosphere (Seidel et al. 2020c, in prep.) and analysed three hot Jupiters, spanning a wide range of this class of exoplanets (see figure). Using the sodium signature of three examples - WASP-76b (a highly irradiated ultra-hot Jupiter, Seidel et al. 2019), KELT-11b (a puffy hot Jupiter, Mounzer et al. 2020, in prep.), and lastly HD189733b (one of the most studied hot Jupiters to date, Wyttenbach et al. 2015) - we explore possible trends in the atmospheric structure of hot Jupiters.</span></p><p><span>We will first introduce the new quasi 3D retrieval of MERC, and proceed to show that high-velocity winds in the thermosphere are one possible explanation of the broadened sodium features seen in hot Jupiters. We plan to highlight various caveats and present likely origin scenarios for the observed wind patterns. We will then put these results in the context of past studies using global circulation models (GCMs) on hot Jupiters.</span></p><p><img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.2223b4ea02fe54080292951/sdaolpUECMynit/0202CSPE&app=m&a=0&c=4c9f1f886978a365f195c38f0ef4783d&ct=x&pn=gnp.elif" alt=""></p>

scholarly journals Is Precipitation a Good Metric for Model Performance?

2019 ◽  
Vol 100 (2) ◽  
pp. 223-233 ◽  
Author(s):  
Francisco J. Tapiador ◽  
Rémy Roca ◽  
Anthony Del Genio ◽  
Boris Dewitte ◽  
Walt Petersen ◽  
...  
Keyword(s):  
Quantitative Measurement ◽  
Climate Models ◽  
Model Performance ◽  
Model Verification ◽  
Verification And Validation ◽  
Weather And Climate ◽  
Model Verification And Validation ◽  
Global Precipitation Mission ◽  
Global Precipitation

AbstractPrecipitation has often been used to gauge the performances of numerical weather and climate models, sometimes together with other variables such as temperature, humidity, geopotential, and clouds. Precipitation, however, is singular in that it can present a high spatial variability and probably the sharpest gradients among all meteorological fields. Moreover, its quantitative measurement is plagued with difficulties, and there are even notable differences among different reference datasets. Several additional issues sometimes lead to questions about its usefulness in model validation. This essay discusses the use of precipitation for model verification and validation and the crucial role of highly precise and reliable satellite estimates, such as those from NASA’s Global Precipitation Mission Core Observatory.

Instability and Bifurcation Behavior of Orthotropic S-FGM Plates Under Lateral Stochastic Loads Considering Variation of Material Properties

2016 ◽  
Vol 16 (03) ◽  
pp. 1450108 ◽  
Author(s):  
Majid Abedi ◽  
Alireza Asnafi
Keyword(s):  
Material Property ◽  
Material Properties ◽  
Nonlinear Behavior ◽  
Mean Value ◽  
Effective Parameters ◽  
Wide Range ◽  
The Mean ◽  
Stochastic Loads ◽  
Bifurcation Behavior

In this paper, all the parameters affecting the nonlinear behavior of S-FGM plates under lateral stochastic white noise excitations are investigated. First the governing equation for a general S-FGM plate is derived for the assumed problem. Then it is rewritten by introducing some nondimensional parameters such that the results are applicable for a wide range of plates. Without loss of generality and using an example, the effective parameters on the instability and bifurcation of the transverse vibration of plates are studied, including the mean value of the lateral load with the in-plane forces and the material property. Especially, the role of material property is highlighted and some analogical figures are drawn to compare the behavior of the FGM plates with the homogenous ones. It is shown that the material property can affect the behavior of instability and bifurcation of the plate and its occurrence.

scholarly journals The Resolution Sensitivity of Northern Hemisphere Blocking in Four 25-km Atmospheric Global Circulation Models

2017 ◽  
Vol 30 (1) ◽  
pp. 337-358 ◽  
Author(s):  
Reinhard Schiemann ◽  
Marie-Estelle Demory ◽  
Len C. Shaffrey ◽  
Jane Strachan ◽  
Pier Luigi Vidale ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Horizontal Resolution ◽  
Model Ensemble ◽  
Grid Spacing ◽  
Atmospheric Blocking ◽  
Global Circulation ◽  
Global Circulation Models ◽  
Northern European ◽  
The Mean ◽  
Mean State

The aim of this study is to investigate if the representation of Northern Hemisphere blocking is sensitive to resolution in current-generation atmospheric global circulation models (AGCMs). An evaluation is conducted of how well atmospheric blocking is represented in four AGCMs whose horizontal resolution is increased from a grid spacing of more than 100 km to about 25 km. It is shown that Euro-Atlantic blocking is simulated overall more credibly at higher resolution (i.e., in better agreement with a 50-yr reference blocking climatology created from the reanalyses ERA-40 and ERA-Interim). The improvement seen with resolution depends on the season and to some extent on the model considered. Euro-Atlantic blocking is simulated more realistically at higher resolution in winter, spring, and autumn, and robustly so across the model ensemble. The improvement in spring is larger than that in winter and autumn. Summer blocking is found to be better simulated at higher resolution by one model only, with little change seen in the other three models. The representation of Pacific blocking is not found to systematically depend on resolution. Despite the improvements seen with resolution, the 25-km models still exhibit large biases in Euro-Atlantic blocking. For example, three of the four 25-km models underestimate winter northern European blocking frequency by about one-third. The resolution sensitivity and biases in the simulated blocking are shown to be in part associated with the mean-state biases in the models’ midlatitude circulation.

Performance of the k-kL model for aerodynamics applications

2019 ◽  
Vol 30 (8) ◽  
pp. 3985-4011
Author(s):  
Nikhil Kalkote ◽  
Ashutosh Kumar ◽  
Ashwani Assam ◽  
Vinayak Eswaran
Keyword(s):  
Unstructured Grid ◽  
Model Performance ◽  
Length Scale ◽  
Mean Flow ◽  
Complex Flow ◽  
High Lift ◽  
Content Type ◽  
Aerodynamic Flows ◽  
Wide Range ◽  
The Mean

Purpose The purpose of this paper is to study the predictability of the recently proposed length scale-based two-equation k-kL model for external aerodynamic flows such as those also encountered in the high-lift devices. Design/methodology/approach The two-equation k-kL model solves the transport equations of turbulent kinetic energy (TKE) and the product of TKE and the integral length scale to obtain the effect of turbulence on the mean flow field. In theory, the use of governing equation for length scale (kL) along with the TKE promises applicability in a wide range of applications in both free-shear and wall-bounded flows with eddy-resolving capability. Findings The model is implemented in the in-house unstructured grid computational fluid dynamics solver to investigate its performance for airfoils in difficult-to-predict situations, including stalling and separation. The numerical findings show the good capability of the model in handling the complex flow physics in the external aerodynamic computations. Originality/value The model performance is studied for stationary turbulent external aerodynamic flows, using five different airfoils, including two multi-element airfoils in high-lift configurations which, in the knowledge of the authors, have not been simulated with k-kL model until now.

scholarly journals Increased water deficit decreases Douglas fir growth throughout western US forests

2016 ◽  
Vol 113 (34) ◽  
pp. 9557-9562 ◽  
Author(s):  
Christina M. Restaino ◽  
David L. Peterson ◽  
Jeremy Littell
Keyword(s):  
Tree Mortality ◽  
Vapor Pressure Deficit ◽  
Douglas Fir ◽  
Evaporative Demand ◽  
Global Circulation ◽  
Global Circulation Models ◽  
Western Us ◽  
The Mean ◽  
Related Stress ◽  
Global Carbon

Changes in tree growth rates can affect tree mortality and forest feedbacks to the global carbon cycle. As air temperature increases, evaporative demand also increases, increasing effective drought in forest ecosystems. Using a spatially comprehensive network of Douglas fir (Pseudotsuga menziesii) chronologies from 122 locations that represent distinct climate environments in the western United States, we show that increased temperature decreases growth via vapor pressure deficit (VPD) across all latitudes. Using an ensemble of global circulation models, we project an increase in both the mean VPD associated with the lowest growth extremes and the probability of exceeding these VPD values. As temperature continues to increase in future decades, we can expect deficit-related stress to increase and consequently Douglas fir growth to decrease throughout its US range.

scholarly journals THE ROLE OF MIRNAS IN TYMORIGENESIS.LITERATURE REVIEW.

2019 ◽  
pp. 11-18
Author(s):  
I.S. Brodetskyi
Keyword(s):  
Stem Cells ◽  
Diagnostic Techniques ◽  
Response To Therapy ◽  
The Body ◽  
Advanced Technology ◽  
Biological Processes ◽  
Mesenchymal Transition ◽  
Tumor Identification ◽  
Wide Range

Introduction. There are many diagnostic techniques in modern medicine, that enable preoperative and postoperative human neoplasms verification (identification).There are a number of postoperative diagnostic techniques, namely his to pathological, immunohistochemical and genetic one. The last-mentioned is rather popular. One of the genetic approaches in tumor diagnostics is the examination of the role of microRNA molecules. The aim of our work is to reveal the role of microRNA molecules on tumor genesis in accordance with the literature review. Research findings.A microRNA is a small non-coding RNA consisting of approximately 22 nucleotides andit is found in all eukaryotic cells. Up to now, we know about 2588 microRNAs. The review of the majority of literature sources has shown, that microRNA molecules may impact on significant biological processes: cell cycle control, apoptosis, metabolism, cellular development and differentiation along with the development of the wide range of diseases: neurodegenerative, metabolic disorders and cancer. Furthermore, they may regulate carcinoma-dependent processes – proliferation, apoptosis, migration, invasion, play a crucial role in stem cells differentiation and control cancer stem cells formation and obtaining of the epithelial-to-mesenchymal transition phenotype, which is directly connected with drug resistance. Using of microRNA profiles we can differentiate sound and cancer tissues, identify the tissue`s origin and distinguish different subtypes of certain cancer or even specific oncogenic deviations (abnormities) and prognosticate the result or response to therapy. Nowadays, its usage in human neoplasms diagnostics made it possible to create a promising area in malignant tumor treatment that in addition to chemotherapy extends lifespan of oncology patients. And the examination of the role of microRNA on such processes as apoptosis and interaction with cytokines makes it possible to know about new mechanisms of pathogenesis in the development of the majority of tumors and particularly salivary gland tumors (pleomorphic adenomas). The ability of the microRNA identification in various biological fluids (blood, saliva) allows us to receive further information regarding one or another pathology and the examination of tumor biopsy for the presence of these markers helps us to increase the probability of tumor verification. Treatment development with usage of exosomal microRNA for the regeneration of damaged organs of an adult offers new opportunities in the therapy of various diseases. Conclusions. Thus, genetic tumor research methods (microRNA) are an advanced technology that allows us to increase tumor identification, to make an impact on different biological processes, to differentiate and classify the most of tumors of the body, and to adopt state-of-the-art medicines and prognosticate the result or response to therapy.

The Problem of Identifying and Modeling the Relationship between Monetary Factor and Inflation in the Russian Economy

2008 ◽  
pp. 61-76
Author(s):  
A. Porshakov ◽  
A. Ponomarenko
Keyword(s):  
Money Supply ◽  
Money Demand ◽  
Russian Economy ◽  
Long Run ◽  
Complex Approach ◽  
Wide Range ◽  
Long Time ◽  
The Relationship ◽  
Supply Side Factors

The role of monetary factor in generating inflationary processes in Russia has stimulated various debates in social and scientific circles for a relatively long time. The authors show that identification of the specificity of relationship between money and inflation requires a complex approach based on statistical modeling and involving a wide range of indicators relevant for the price changes in the economy. As a result a model of inflation for Russia implying the decomposition of inflation dynamics into demand-side and supply-side factors is suggested. The main conclusion drawn is that during the recent years the volume of inflationary pressures in the Russian economy has been determined by the deviation of money supply from money demand, rather than by money supply alone. At the same time, monetary factor has a long-run spread over time impact on inflation.

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