scholarly journals On the climatological probability of the vertical propagation of stationary planetary waves

2016 ◽  
Vol 16 (13) ◽  
pp. 8447-8460 ◽  
Author(s):  
Khalil Karami ◽  
Peter Braesicke ◽  
Miriam Sinnhuber ◽  
Stefan Versick
Keyword(s):  
Wave Propagation ◽  
Climate Model ◽  
Reanalysis Data ◽  
Planetary Waves ◽  
Superior Performance ◽  
Wave Number ◽  
Wave Numbers ◽  
Membership Value ◽  
Environmental Prediction ◽  
Strong Vortex

Abstract. We introduce a diagnostic tool to assess a climatological framework of the optimal propagation conditions for stationary planetary waves. Analyzing 50 winters using NCEP/NCAR (National Center for Environmental Prediction/National Center for Atmospheric Research) reanalysis data we derive probability density functions (PDFs) of positive vertical wave number as a function of zonal and meridional wave numbers. We contrast this quantity with classical climatological means of the vertical wave number. Introducing a membership value function (MVF) based on fuzzy logic, we objectively generate a modified set of PDFs (mPDFs) and demonstrate their superior performance compared to the climatological mean of vertical wave number and the original PDFs. We argue that mPDFs allow an even better understanding of how background conditions impact wave propagation in a climatological sense. As expected, probabilities are decreasing with increasing zonal wave numbers. In addition we discuss the meridional wave number dependency of the PDFs which is usually neglected, highlighting the contribution of meridional wave numbers 2 and 3 in the stratosphere. We also describe how mPDFs change in response to strong vortex regime (SVR) and weak vortex regime (WVR) conditions, with increased probabilities of the wave propagation during WVR than SVR in the stratosphere. We conclude that the mPDFs are a convenient way to summarize climatological information about planetary wave propagation in reanalysis and climate model data.

scholarly journals On the climatological probability of the vertical propagation of stationary planetary waves

2015 ◽  
Vol 15 (22) ◽  
pp. 32289-32321
Author(s):  
K. Karami ◽  
P. Braesicke ◽  
M. Sinnhuber ◽  
S. Versick
Keyword(s):  
Wave Propagation ◽  
Climate Model ◽  
Reanalysis Data ◽  
Planetary Waves ◽  
Superior Performance ◽  
Wave Number ◽  
Refractive Indices ◽  
Wave Numbers ◽  
Membership Value ◽  
Strong Vortex

Abstract. We introduce a diagnostic tool to assess in a climatological framework the optimal propagation conditions for stationary planetary waves. Analyzing 50 winters using NCEP/NCAR reanalysis data we derive probability density functions (PDFs) of positive refractive indices as a function of zonal and meridional wave numbers. We contrast this quantity with classical climatological means of the refractive index. Introducing a Membership Value Function (MVF) based on fuzzy logic, we objectively generate a modified set of PDFs (mPDFs) and demonstrate their superior performance compared to the climatological mean of refractive indices and the original PDFs. We argue that mPDFs allow an even better understanding of how background conditions impact wave propagation in a climatological sense. As expected, probabilities are decreasing with increasing zonal wave numbers. In addition we discuss the meridional wave number dependency of the PDFs which is usually neglected, highlighting the contribution of meridional wave numbers 2 and 3 in the stratosphere. We also describe how mPDFs change in response to strong vortex regime (SVR) and weak vortex regime (WVR) conditions, with increased probabilities during WVR than SVR in the stratosphere. We conclude that the mPDFs are a convenient way to summarize climatological information about planetary wave propagation in reanalysis and climate model data.

scholarly journals Climatic variability of the mean flow and stationary planetary waves in the NCEP/NCAR reanalysis data

2008 ◽  
Vol 26 (5) ◽  
pp. 1233-1241 ◽  
Author(s):  
A. Yu. Kanukhina ◽  
E. V. Suvorova ◽  
L. A. Nechaeva ◽  
E. K. Skrygina ◽  
A. I. Pogoreltsev
Keyword(s):  
Lower Stratosphere ◽  
Climatic Variability ◽  
Reanalysis Data ◽  
Planetary Waves ◽  
Lower Atmosphere ◽  
Wave Number ◽  
Mean Flow ◽  
The Mean ◽  
The 1960S ◽  
Environmental Prediction

Abstract. NCEP/NCAR (National Center for Environmental Prediction – National Center for Atmospheric Research) data have been used to estimate the long-term variability of the mean flow, temperature, and Stationary Planetary Waves (SPW) in the troposphere and lower stratosphere. The results obtained show noticeable climatic variabilities in the intensity and position of the tropospheric jets that are caused by temperature changes in the lower atmosphere. As a result, we can expect that this variability of the mean flow will cause the changes in the SPW propagation conditions. The simulation of the SPW with zonal wave number m=1 (SPW1), performed with a linearized model using the mean flow distributions typical for the 1960s and for the beginning of 21st century, supports this assumption and shows that during the last 40 years the amplitude of the SPW1 in the stratosphere and mesosphere increased substantially. The analysis of the SPW amplitudes extracted from the geopotential height and zonal wind NCEP/NCAR data supports the results of simulation and shows that during the last years there exists an increase in the SPW1 activity in the lower stratosphere. These changes in the amplitudes are accompanied by increased interannual variability of the SPW1, as well. Analysis of the SPW2 activity shows that changes in its amplitude have a different sign in the northern winter hemisphere and at low latitudes in the southern summer hemisphere. The value of the SPW2 variability differs latitudinally and can be explained by nonlinear interference of the primary wave propagation from below and from secondary SPW2.

Harmonic Wave Propagation in a Periodically Layered, Infinite Elastic Body: Plane Strain, Analytical Results

1979 ◽  
Vol 46 (1) ◽  
pp. 113-119 ◽  
Author(s):  
T. J. Delph ◽  
G. Herrmann ◽  
R. K. Kaul
Keyword(s):  
Wave Propagation ◽  
Asymptotic Behavior ◽  
Plane Strain ◽  
Elastic Body ◽  
Harmonic Wave ◽  
Wave Number ◽  
Periodic Medium ◽  
Frequency Wave ◽  
Wave Numbers ◽  
Band Characteristic

The problem of harmonic wave propagation in an unbounded, periodically layered elastic body in a state of plane strain is examined. The dispersion spectrum is shown to be governed by the roots of an 8 × 8 determinant, and represents a surface in frequency-wave number space. The spectrum exhibits the typical stopping band characteristic of wave propagation in a periodic medium. The dispersion equation is shown to uncouple along the ends of the Brillouin zones, and also in the case of wave propagation normal to the layering. The significance of this uncoupling is examined. Also, the asymptotic behavior of the spectrum for large values of the wave numbers is investigated.

scholarly journals Zonal wave numbers 1-5 in planetary waves from the TOMS total ozone at 65° S

2005 ◽  
Vol 23 (5) ◽  
pp. 1565-1573 ◽  
Author(s):  
A. Grytsai ◽  
Z. Grytsai ◽  
A. Evtushevsky ◽  
G. Milinevsky ◽  
N. Leonov
Keyword(s):  
Total Ozone ◽  
General Circulation ◽  
Middle Atmosphere ◽  
Polar Vortex ◽  
Planetary Waves ◽  
Wave Number ◽  
Stratospheric Polar Vortex ◽  
Term Change ◽  
Wave Numbers ◽  
The Difference

Abstract. Planetary waves in the total ozone at the southern latitude of 65° S are studied to obtain the main characteristics of the zonal wave numbers 1–5. The TOMS total ozone data were used to analyze the amplitude and periodicity variations of the five spectral components during August-December of 1979–2003. A presence of the shorter period of waves 1–3 in 1996 (7 days) in comparison with 2002 (8–12 days) is revealed which can be attributed to the distinction in conditions of typical and anomalously weak stratospheric polar vortex, probably, a strong and weak mean zonal wind. The interannual variations of the monthly and 5-month mean amplitudes of the zonal wave numbers 1–5 are described. Wave 1 has the largest amplitude in October (up to 139 DU in 2000) and increasing amplitude trend (15 DU/decade for October 1979–2003). The 5-month mean amplitudes averaged over 1979–2003 are 53.6, 29.9, 15.5, 10.5, and 7.8 DU for the wave number sequence 1, 2, 3, 4 and 5, respectively. For the stationary components the amplitudes are 38.3, 4.8, 1.8, 1.2, 0.7 DU, respectively. Thus, the stationary component of wave 1 and the traveling one of waves 2–5 are predominant. The tendencies in a long-term change in the wave number amplitude can be explained by taking into account the degree of wave deformation of the stratospheric polar vortex edge, net meridional displacements of the lower stratosphere air, and the difference between the total ozone loss and negative trends in the polar and mid-latitude regions. Keywords. General circulation – Middle atmosphere dynamics – Waves and tides

scholarly journals Downscaling Of Precipitation Using Statistical Downscaling Model and Multiple Linear Regression Over Rajasthan State

2019 ◽  
Vol 14 (1) ◽  
pp. 68-98
Author(s):  
Poonam Mahla ◽  
A.K. Lohani ◽  
V. K. Chandola ◽  
Aradhana Thakur ◽  
C.D. Mishra ◽  
...  
Keyword(s):  
Linear Regression ◽  
Multiple Linear Regression ◽  
Statistical Downscaling ◽  
Climate Model ◽  
Regional Climate ◽  
Reanalysis Data ◽  
Rainfall Variation ◽  
Mean Climate ◽  
Environmental Prediction ◽  
Hadley Centre

Statistical downscaling method is mainly practised to relate atmospheric circulation to surface variables for forecast and prediction of the regional climate. As we know in Rajasthan drought is the foremost problem due to scanty of rainfall. The core objective of the present study stands to prognosis rainfall variation also assess the recital of Multiple Linear Regression (MLR) to access the variation in rainfall. The data were analyzed using higher resolution atmospheric data which includes daily National Centers for Environmental Prediction (NCEP)/ National Center for Atmospheric Research (NCAR) reanalysis data and daily mean climate model result intended for A2 and B2 scenarios of the Hadley Centre Climate Model (HadCM3) model. The period from 1961-1990 used as a baseline due to the availability of adequate period which is required to establish a reliable climatology. Results of the study show an increasing trend of future precipitation tended for both A2 and B2 scenarios. From the study, it has been found that MLR model is more superior to downscale precipitation in most districts under study area.

scholarly journals Planetary waves in a coupled chemistry-climate model: analysis techniques and comparison with reanalysis data

2005 ◽  
Vol 5 (3) ◽  
pp. 2559-2598
Author(s):  
F. Mager ◽  
M. Dameris
Keyword(s):  
Large Scale ◽  
Vertical Structure ◽  
Climate Model ◽  
Polar Vortex ◽  
Reanalysis Data ◽  
Planetary Waves ◽  
Transient Waves ◽  
Reanalysis Dataset ◽  
Analysis Techniques ◽  
The Impact

Abstract. This paper presents several analysis techniques relating to large-scale atmospheric waves. Such analysis tools allow the extraction of planetary waves from reanalysis or model datasets, and can contribute to a detailed insight into the forcing, propagation, and vertical structure of planetary waves, and their dynamic impact on the atmosphere. The different tools presented here use time series of space Fourier coefficients in order to extract transient and stationary wave parts by zonal wavenumbers, and to quantify their dynamic effect in the form of sensible heat and momentum fluxes. In this work, they have been applied to model results from the coupled chemistry-climate model ECHAM4.L39(DLR)/CHEM (E39/C) (Hein et al., 2001) and to the ERA-15 reanalysis dataset from ECMWF. We show that E39/C qualitatively matches the variance distribution and vertical structure of transient waves from reanalysis data; quantitative differences can be traced back to the horizontal model resolution and the modelled zonal winds. The modelled polar vortex during Northern Hemisphere winter has previously been shown to be colder and more stable than observed (Hein et al., 2001; Schnadt et al., 2002; a possible explanation is that in the model experiment, a reduced heat flux by long transient waves at high latitudes disturbs and warms the polar vortex less than ERA-15 suggests, thereby leading to an overestimated stationary wavenumber 1 in E39/C. The results show that the tools used are well suited to investigate and estimate the impact of various dynamic processes related to large-scale waves.

scholarly journals Intraseasonal Ensemble Forecasting for the Brazilian Northeastern

2019 ◽  
Vol 41 ◽  
pp. 10
Author(s):  
Cleber Souza Corrêa ◽  
Fabricio Pereira Harter ◽  
Gerson Luiz Camillo
Keyword(s):  
Climate Model ◽  
Regional Climate ◽  
Surface Wind ◽  
Reanalysis Data ◽  
Ensemble Prediction ◽  
Weather Forecasts ◽  
Ensemble Techniques ◽  
Ensemble Estimation ◽  
Environmental Prediction ◽  
Wind Intensity

This preliminary analysis, uses simulations performed by the National Centers for Environmental Prediction (NCEP) coupled forecast system model version 2 (CFSv2) /regional climate model RegCM-4.6, allowed to be observed in this work, the data analyzed were the information of the surface wind intensity, by the analysis and comparison of the simulations carried out for the Alcântara region on the coast of the state of Maranhão. These simulations were stored in the period from February to June 2018. The analysis sought to validate with ERA5 reanalysis data from the European Center for Medium-Range Weather Forecasts (ECMWF). The observed result shows great potential for use of prediction ensemble techniques, since in the observed results the smallest anomalies were observed in the intraseasonal ensemble prediction to the Alcântara region in the intensity wind, in comparison to the simulation without being ensemble, presenting greater deviations and when closer to the forecast, in itself, greater deviations presented. The intraseasonal Ensemble estimation ends up filtering the terms of high frequency, being the best estimate and presenting intraseasonal predictions more balanced.

Infrared spectra and substituent effects in 2-(3-, and 4-substituted phenylmethylene)-1,3-cycloheptanediones

1983 ◽  
Vol 48 (2) ◽  
pp. 586-595 ◽  
Author(s):  
Alexander Perjéssy ◽  
Pavol Hrnčiar ◽  
Ján Šraga
Keyword(s):  
Substituent Effects ◽  
Phenyl Group ◽  
Wave Number ◽  
Vibrational Coupling ◽  
Wave Numbers ◽  
Stretching Vibration ◽  
Stretching Vibrations ◽  
The Relationship ◽  
Derivatives Of ◽  
Effect Of Structure

The wave numbers of the fundamental C=O and C=C stretching vibrations, as well as that of the first overtone of C=O stretching vibration of 2-(3-, and 4-substituted phenylmethylene)-1,3-cycloheptanediones and 1,3-cycloheptanedione were measured in tetrachloromethane and chloroform. The spectral data were correlated with σ+ constants of substituents attached to phenyl group and with wave number shifts of the C=O stretching vibration of substituted acetophenones. The slope of the linear dependence ν vs ν+ of the C=C stretching vibration of the ethylenic group was found to be more than two times higher than that of the analogous correlation of the C=O stretching vibration. Positive values of anharmonicity for asymmetric C=O stretching vibration can be considered as an evidence of the vibrational coupling in a cyclic 1,3-dicarbonyl system similarly, as with derivatives of 1,3-indanedione. The relationship between the wave numbers of the symmetric and asymmetric C=O stretching vibrations indicates that the effect of structure upon both vibrations is symmetric. The vibrational coupling in 1,3-cycloheptanediones and the application of Seth-Paul-Van-Duyse equation is discussed in relation to analogous results obtained for other cyclic 1,3-dicarbonyl compounds.

Long-term variation of water vapor content and precipitation in the Haihe river basin

2014 ◽  
Vol 6 (2) ◽  
pp. 341-351 ◽  
Author(s):  
Chun Chang ◽  
Ping Feng ◽  
Fawen Li ◽  
Yunming Gao
Keyword(s):  
Water Vapor ◽  
River Basin ◽  
Reanalysis Data ◽  
Water Vapor Content ◽  
Haihe River Basin ◽  
Haihe River ◽  
Annual Water ◽  
Environmental Prediction ◽  
High Consistency ◽  
The Haihe River Basin

Based on the Haihe river basin National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis data from 1948 to 2010 and the precipitation data of 53 hydrological stations during 1957–2010, this study analyzed the variation of water vapor content and precipitation, and investigated the correlation between them using several statistical methods. The results showed that the annual water vapor content decreased drastically from 1948 to 2010. It was comparatively high from the late 1940s to the late 1960s and depreciated from the early 1970s. From the southeast to the northwest of the Haihe river basin, there was a decrease in water vapor content. For vertical distribution, water vapor content from the ground to 700 hPa pressure level accounted for 72.9% of the whole atmospheric layer, which indicated that the water vapor of the Haihe river basin was mainly in the air close to the ground. The precipitation in the Haihe river basin during 1957–2010 decreased very slightly. According to the correlation analysis, the precipitation and water vapor content changes showed statistically positive correlation, in addition, their break points were both in the 1970s. Furthermore, the high consistency between the precipitation efficiency and precipitation demonstrates that water vapor content is one of the important factors in the formation of precipitation.

On wave dispersion characteristics of fluid-conveying smart nanotubes considering surface elasticity and flexoelectricity approach

2020 ◽  
pp. 095440622096561
Author(s):  
Amir-Reza Asghari Ardalani ◽  
Ahad Amiri ◽  
Roohollah Talebitooti ◽  
Mir Saeed Safizadeh
Keyword(s):  
Wave Propagation ◽  
Strain Gradient ◽  
Surface Elasticity ◽  
Shear Deformation Theory ◽  
Wave Dispersion ◽  
Strain Gradient Theory ◽  
Wave Number ◽  
Gradient Theory ◽  
Specific Domain ◽  
Size Dependent

Wave dispersion response of a fluid-carrying piezoelectric nanotube is studied in this paper utilizing an improved model for piezoelectric materials which capture a new effect known as flexoelectricity in conjunction with the surface elasticity. For this aim, a higher order shear deformation theory is employed to model the problem. Furthermore, strain gradient effect as well as nonlocal effect is taken into consideration throughout using the nonlocal strain gradient theory (NSGT). Surface elasticity is also considered to make an accurate size-dependent formulation. Additionally, a non-compressible and non-viscous fluid is taken into consideration to model the flow effect. The wave propagation solution is then implemented to the governing equations obtained by Hamiltonian’s approach. The phase velocity and group velocity of the nanotube is determined for three wave modes (i.e. shear, longitudinal and bending waves) to study the influence of various involved factors including strain gradient, nonlocality, flexoelectricity and surface elasticity and flow velocity on the wave dispersion curves. Results reveal a considerable effect of the flexoelectric phenomenon on the wave propagation properties especially at a specific domain of the wave number. The size-dependency of this effect is disclosed. Overall, it is found that the flexoelectricity exhibits a substantial influence on wave dispersion properties of the smart fluid-conveying systems. Hence, such size-dependent effect should be considered to achieve exact and accurate knowledge on wave propagation characteristics of the system.

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