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F. A. Gifford

MARC~1977 NOTES AND CORRESPONDENCE 311NOTES AND CORRESPONDENCETropospheric Relative Diffusion Observations F. A. GIrrO~Atmospheric Turbulence and Di~usion Laboratory, NOAA, Oak Ridge, Tenn.10 September 1976ABSTRACT Data on relative atmospheric diffusion, that is, the spreading by diffusion of puffs or particle pairs (e.g.,of balloons) relative to their mutual center of mass, are

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Erich Becker
and
Ulrike Burkhardt

1. Introduction Atmospheric circulation models that resolve synoptic-scale waves need to contain horizontal diffusion in order to prevent the accumulation of enstrophy and kinetic energy at the smallest resolved scales. Horizontal diffusion (other equivalent terms are lateral or scale-selective horizontal damping), therefore, offsets the enstrophy cascade in the free atmosphere and helps to parameterize the dissipation of kinetic energy at unresolved scales ( Tung and Orlando 2003 ). In the

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Richard Rotunno
and
George H. Bryan

, hereafter BR09b) , using an axisymmetric numerical model with fixed external parameters, conducted a systematic study of the dependence of simulated nearly steady hurricane intensity on the internal modeling parameters. BR09b found the strongest sensitivity of simulated structure and maximum intensity coming from the parameterized diffusion. In the present article, the authors take a closer look at this sensitivity through budget analysis of the BR09b numerical simulations and comparison of these

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Carmen J. Nappo
,
K. Shankar Rao
, and
Jerold A. Herwehe

JULY 1989 NAPPO, RAO AND HERWEHE 617Pollutant Transport and Diffusion in Katabatic FlowsCARMEN J. NAPPO, K. SHANKAR RAO AND JEROLD A. HERWEHE*Atmospheric Turbulence and Diffusion Division, NOAA /ARL, Oak Ridge, Tennessee(Manuscript received 17 February 1988, in final form 24 June 1988)ABSTRACT The characteristics of pollutant transport and diffusion of a passive contaminant in a two

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C. Liu
,
Y. Liu
, and
H. Xu

1. Introduction The evolution of a many-body system like the atmosphere in nonequilibrium involves the irreversible physical processes such as diffusion within the system. A proper description of diffusion is of critical importance for a numerical weather prediction (NWP) model. In the early NWP models ( Cheng 1975 ), the second-order diffusion schemes were, indeed, introduced as a dissipative term similar to viscosity into a prognostic equation. During the 1980s some models progressed to the

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Olivier Pannekoucke
and
Laurent Vezard

. Different models exist for correlation matrix and among them, the diagonal assumption in spectral space ( Courtier et al. 1998 ), which leads to homogeneous correlation functions. Amid the heterogeneous correlation models, one can cite the diagonal assumption in wavelet space ( Fisher 2003 ), the recursive filter approach ( Purser et al. 2003a , b ), and the diffusion equation ( Weaver and Courtier 2001 ). The formulation based on the diffusion equation is now considered. It appears that along the

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Xiaogang Wu
and
Mu Mu

been many studies about THC (e.g. Rahmstorf 2000 ; Marshall et al. 2001 ; Clark et al. 2002 ; Wunsch and Ferrari 2004 ; Dahl et al. 2005 ; Sévellec et al 2007 , among others), and box models are one of useful tools for solving the problems of THC ( Stommel 1961 ; Rooth 1982 ; Welander 1982 ; Whitehead 1995 ; Rahmstorf 1996 , and many others). However, there is a disadvantage that most box models have ignored: the effect of horizontal diffusion (HD), which may arise as a result of

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Steven R. Hanna

588 JOURNAL OF APPLIED METEOROLOGYRelative Diffusion of Tetroon Pairs During Convective Conditions~ Sr~wN R. HAm~AA~mosph~ri~ Turbul~ ~r Di~u~ion L~bora~n'y, ~fOAA, Oak Ridge, Ten~. 37850 (Manuscript received 25 August 1975, in revised form 15 Apri! 1976) Observations of the relative diffusion o! 13 sets of tetroon pa~rs in the mixed layer during convective conditions in eastern Tennessee are reported. The root-mean-square separation S is

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Jason C. Knievel
,
George H. Bryan
, and
Joshua P. Hacker

1. Introduction One of the strengths of the Advanced Research core of the Weather Research and Forecasting (WRF) model is its high effective resolution. This results in simulations whose energy spectra begin to decay at shorter wavelengths than do the spectra of simulations by some other numerical weather prediction models ( Skamarock 2004 ). The WRF model’s high effective resolution is achieved partly through the scale-selective diffusion implicit in the model’s advection schemes ( Skamarock

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Tiziano Tirabassi
,
Daniela Buske
,
Davidson M. Moreira
, and
Marco T. Vilhena

1. Introduction The Eulerian approach for modeling the concentration of contaminants in a turbulent flow in the planetary boundary layer (PBL) is widely used in the field of air pollution studies. The simplicity of the K theory of turbulent diffusion has led to the frequent use of this theory as the mathematical basis for simulating air pollution dispersion. Dry deposition refers to the transfer of air pollution (gas and particles) to the ground, where it is removed. The various transfer

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