Effect of Spatial Variation of Convective Adjustment Time on the Madden–Julian Oscillation: A Theoretical Model Analysis

This study investigates the moisture and wave feedbacks in the Madden–Julian oscillation (MJO) dynamics by applying the general three-way interaction theoretical model. The three-way interaction model can reproduce observed large-scale characteristics of the MJO in terms of horizontal quadrupole-vortex structure, vertically tilted structure led by planetary boundary layer (PBL) convergence, slow eastward propagation with a period of 30–90 days, and planetary-scale circulation. The moisture feedback effects can be identified in this model by using diagnostic thermodynamic and momentum equations, and the wave feedback effects are investigated by using a diagnostic moisture equation. The moisture feedback is found to be responsible for producing the MJO dispersive modes when the convective adjustment process is slow. The moisture feedback mainly acts to reduce the frequency and growth rate of the short waves, while leaving the planetary waves less affected, so neglecting the moisture feedback is a good approximation for the wavenumber-1 MJO. The wave feedback is shown to slow down the eastward propagation and increase the growth rate of the planetary waves. The wave feedback becomes weak when the convective adjustment time increases, so neglecting the wave feedback is a good approximation for the MJO dynamics during a slow adjustment process. Sensitivities of these two feedbacks to other parameters are also discussed. These theoretical findings suggest that the two feedback processes, and thus the behaviors of the simulated MJO mode, should be sensitive to the parameters used in cumulus parameterizations.

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More on the Scale Dependence of the Predictability of Precipitation Patterns: Extension to the 2009–13 CAPS Spring Experiment Ensemble Forecasts

Monthly Weather Review ◽

10.1175/mwr-d-16-0362.1 ◽

2017 ◽

Vol 145 (9) ◽

pp. 3625-3646 ◽

Cited By ~ 13

Author(s):

Madalina Surcel ◽

Isztar Zawadzki ◽

M. K. Yau ◽

Ming Xue ◽

Fanyou Kong

Keyword(s):

Large Scale ◽

Forecast Error ◽

Quasi Equilibrium ◽

Relative Role ◽

Ensemble Forecasts ◽

Adjustment Time ◽

Convective Adjustment ◽

Microphysical Parameterization ◽

Microphysical Parameterization Scheme

This paper analyzes the scale and case dependence of the predictability of precipitation in the Storm-Scale Ensemble Forecast (SSEF) system run by the Center for Analysis and Prediction of Storms (CAPS) during the NOAA Hazardous Weather Testbed Spring Experiments of 2008–13. The effect of different types of ensemble perturbation methodologies is quantified as a function of spatial scale. It is found that uncertainties in the large-scale initial and boundary conditions and in the model microphysical parameterization scheme can result in the loss of predictability at scales smaller than 200 km after 24 h. Also, these uncertainties account for most of the forecast error. Other types of ensemble perturbation methodologies were not found to be as important for the quantitative precipitation forecasts (QPFs). The case dependences of predictability and of the sensitivity to the ensemble perturbation methodology were also analyzed. Events were characterized in terms of the extent of the precipitation coverage and of the convective-adjustment time scale [Formula: see text], an indicator of whether convection is in equilibrium with the large-scale forcing. It was found that events characterized by widespread precipitation and small [Formula: see text] values (representative of quasi-equilibrium convection) were usually more predictable than nonequilibrium cases. No significant statistical relationship was found between the relative role of different perturbation methodologies and precipitation coverage or [Formula: see text].

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Effects of peg’s positions of low‐registered strings on acoustic gain by a stage riser: Theoretical model analysis

The Journal of the Acoustical Society of America ◽

10.1121/1.4787046 ◽

2006 ◽

Vol 120 (5) ◽

pp. 3011-3011

Author(s):

Shinsuke Nakanishi

Keyword(s):

Theoretical Model ◽

Model Analysis

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Research on Dynamic Design Method Based on Measuring Information for Printing Press

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.174.290 ◽

2010 ◽

Vol 174 ◽

pp. 290-294

Author(s):

Yi Ming Wang ◽

Bang She Chen ◽

Yan Li ◽

Shao Hua Zhang

Keyword(s):

Theoretical Model ◽

Dynamic Characteristics ◽

High Speed ◽

Design Method ◽

Model Analysis ◽

Printing Press ◽

Vibration Measurement ◽

Dynamic Design ◽

Analysis Experiment ◽

Printing Machine

Printing machinery’s reliability is one of the most important index parameter and good dynamic characteristics are essential for high speed printing press. The dynamic characteristic is predictable for printing machine with dynamic design. With the complexity of printing technique and printing machine, information, such as load on components is lack, leading to the difficulty of dynamic model solving and further more the dynamic parameters needs to be verified. Firstly, according to the dynamic design method, a dynamic design process based on measuring information for printing machine was put forward. Secondly, on the basis of principle and structure analysis to typical printing machine, dynamic characteristics measurement item and method was determined. With a wallboard of a two-color offset press acting as an example, the utilizing method was illustrated through dynamic modeling, theoretical model analysis, experiment model analysis based on vibration measurement and comparing the theoretical and experimental results. Finally, a Dynamic Design Assistant Platform based Vibration Measurement for Printing Machine was developed and had been used in 10 kinds of printing machine measurement and analysis. The conclusion shows that the tolerance of the theoretical model analysis results and experiment results is allowed. A new approach for new printing machine design and optimal design for existed printing machine is given.

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Nitrogen deposition and atmospheric CO2 interactions on fine root dynamics in temperate forests: a theoretical model analysis

Global Change Biology ◽

10.1046/j.1365-2486.2002.00481.x ◽

2002 ◽

Vol 8 (5) ◽

pp. 486-503 ◽

Cited By ~ 25

Author(s):

Daniel P. Rasse

Keyword(s):

Theoretical Model ◽

Nitrogen Deposition ◽

Fine Root ◽

Temperate Forests ◽

Model Analysis ◽

Atmospheric Co2 ◽

Root Dynamics ◽

Fine Root Dynamics

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A Dynamically Computed Convective Time Scale for the Kain–Fritsch Convective Parameterization Scheme

Monthly Weather Review ◽

10.1175/mwr-d-14-00251.1 ◽

2015 ◽

Vol 143 (6) ◽

pp. 2105-2120 ◽

Cited By ~ 16

Author(s):

O. Russell Bullock ◽

Kiran Alapaty ◽

Jerold A. Herwehe ◽

John S. Kain

Keyword(s):

Time Scale ◽

Radiation Effects ◽

Convective Available Potential Energy ◽

Wrf Model ◽

Grid Cell ◽

Grid Spacing ◽

Convective Parameterization ◽

Convective Clouds ◽

Adjustment Time ◽

Convective Adjustment

Abstract Many convective parameterization schemes define a convective adjustment time scale τ as the time allowed for dissipation of convective available potential energy (CAPE). The Kain–Fritsch scheme defines τ based on an estimate of the advective time period for deep convective clouds within a grid cell, with limits of 1800 and 3600 s, based on practical cloud-lifetime considerations. In simulations from the Weather Research and Forecasting (WRF) Model using 12-km grid spacing, the value of τ often defaults to the lower limit, resulting in relatively rapid thermodynamics adjustments and high precipitation rates. Herein, a new computation for τ in the Kain–Fritsch scheme is implemented based on the depth of the buoyant layer and the convective velocity scale. This new τ formulation is applied using 12- and 36-km model grid spacing in conjunction with a previous modification that takes into account the radiation effects of parameterized convective clouds. The dynamically computed convective adjustment time scale is shown to reduce the precipitation bias by approximately 15% while also providing improved simulations of inland rainfall from tropical storms.

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