Comparison of Some Schemes for Nonhydrostatic Models with Orography

Ikawa, Motohki

doi:10.2151/jmsj1965.66.5_753

Cited by 45 publications

(41 citation statements)

References 28 publications

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“…The numerical model is basically the same as Ikawa et al (1987) unless specifically mentioned; subgrid turbulent mixing terms are parameterized based on Klemp and Wilhelmson (1978) and Deardorff (1980); for the time integration, E-HI-VI scheme (Ikawa, 1988b) is used with the time averaging parameter of the implicit scheme, *< 0.5 (see Table 1. Specifications of 5 kinds of hydrometeors in the model.…”

Section: Numerical Model and Parameterization Of Cloud Microphysicsmentioning

confidence: 99%

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Numerical Modeling of the Convective Snow Cloud over the Sea of Japan

Ikawa¹,

Mizuno²,

Matsuo³

et al. 1991

Journal of the Meteorological Society of Japan

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A bulk parameterization scheme of cloud microphysics which predicts not only the number concentrations of cloud ice and snow but also that of graupel, in addition to the mixing ratios of six water species (water vapor, cloud water, rain, cloud ice, ;snow and graupel), is developed. This scheme is applied to the 3-dimensional simulation of the convective snow cloud observed over the Sea of Japan on Feb. 4, 1989, with a cloud top temperature at -20*.In the simulation where conventional parameters are used for Fletcher's deposition/sorption nucleation, Bigg's freezing of cloud droplets and the Hallet-Mossop rime-splinter secondary production of ice crystals, the maximum of number concentration of ice particles is about 5 *104/m3, 1/4 of the observed counterpart (2 *105/m3). Radar reflectivity is larger by 10 dBZ than observation. Other aspects appear to be well reproduced by the model at least qualitatively. Precipitation formation in the simulated cloud is examined, and it is found to be consistent with observational studies.Sensitivity experiments to the amplification of various ice nucleation rates are conducted to simulate the cloud more realistically and to see the effects of the increase of the number concentration of ice crystals on the precipitation formation of the convective cloud. The increase in the number concentration of ice crystals to the value of 105*106/m3 results in the increase of snow in mass and number and the decrease of radar reflectivity. The further increase in the number concentration of ice crystals to the value (107/m3) results in suppression of precipitation, glaciation of cloud with little cloud water and suspension of abundant snow in the air. These experiments give some support to the possibility of suppressing the precipitation by overseeding.Some merits of predicting number concentrations of ice particles are discussed. In the simulation, the intercept parameters of the inverse exponential size distribution functions for snow and graupel, Nos and Nog, are found to be more dependent on the stage of the cloud development than on the precipitation rate. This feature cannot be reproduced by the model with the prescribed Nos and Nog. For a more realistic simulation of clouds, a more reliable knowledge about ice nucleation is crucial.

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Section: Numerical Model and Parameterization Of Cloud Microphysicsmentioning

confidence: 99%

“…Specifications of 5 kinds of hydrometeors in the model. Ikawa, 1988b) and the coefficient for the Robert-Asselin time filter, *=0.15.…”

Section: Numerical Model and Parameterization Of Cloud Microphysicsmentioning

confidence: 99%

Numerical Modeling of the Convective Snow Cloud over the Sea of Japan

Ikawa¹,

Mizuno²,

Matsuo³

et al. 1991

Journal of the Meteorological Society of Japan

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“…The numerical model is a 2-dimensional nonhydrostatic model, the same as described by Ikawa (1988); it is based mainly on Clark (1977); the terrain-following coordinate is used such as where zs is the mountain shape function and H the domain height; the advective term in the flux form is used; for subgrid-scale turbulence, the turbulent closure model (Kiemp and Wilhelmson, 1978) is used; no water vapour or radiation or heat flux from outside are included. Governing equations are as follows: -years (1971-1975) and that given to the model as the initial profile (right; o-o) for 4-layered fluid are also shown.…”

Section: Numerical Model and Experimental Designmentioning

confidence: 99%

“…For some experiments (mainly L1 experiments (Table 3)), *=0 is used, and for other experiments (mainly L4 (Table 2) and L2 (Table 4) experiments), *=1 and the E-HI-VI time integration scheme (elastic, horizontally and vertically implicit; Ikawa, 1988) is used.…”

Section: Numerical Model and Experimental Designmentioning

confidence: 99%

“…The specifications of the experiments for the homogeneous fluid (L1 experiments) are different from the L4 experiments described in section 3, and the same as described in section 3 of Ikawa (1988); N=0.01/s, U=4m/s; p=1 kg/m3 are specified to realize the Boussinesq homogeneous fluid. It is noted that in the Boussinesq fluid, WICL of the n=0 mode always occurs before that of the n=1 mode.…”

Section: Experiments With the Homogeneous Fluidmentioning

confidence: 99%

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A Numerical Study of a Dynamically Induced Foehn Observed in the Abashiri-Ohmu Area

Ikawa¹,

Nagasawa²

1989

Journal of the Meteorological Society of Japan

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Observations are given for the foehn event which occurred in the Abashiri-Ohmu area (N44.3, E143.5), Hokkaido, northern Japan, on 12 May 1975. A numerical investigation is made of the foehn, using a 2-dimensional nonhydrostatic model.The foehn is well simulated, even without any diabatic heating in the presence of an inversion layer below 900hPa. This foehn is confirmed to be dynamically induced, and is an unsteady, highly nonlinear phenomenon. It is accompanied by an atmospheric bore (a shock-like disturbance propagating upstream) and an internal hydraulic jump (a shock-like disturbance propagating downstream), but no wave breaking (wave induced critical layer). The foehn of a homogeneous fluid (with constant mean velocity U and constant Brunt-Vaisala frequency N) is also simulated. It is accompanied by wave breaking and hydraulic jump, but no bore.A foehn index (a non-dimensionalized potential temperature rise on the lee slope) is introduced, and its dependence on the inverse Froude number (Nh/U) is examined for the 4-layered fluid of the Abashiri-Ohmu case and the homogeneous fluid. The critical mountain height for the occurrence of the foehn is found to be lower in the presence of an inversion layer below 900hPa than in the absence of an inversion layer.In addition, the foehn event in the Abashiri-Ohmu area is compared with that of the European Alps (Hoinka, 1985).

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Numerical analyses of Runge–Kutta implicit–explicit schemes for horizontally explicit, vertically implicit solutions of atmospheric models

Lock

Wood

Weller

2014

Quart J Royal Meteoro Soc

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With the prospect of exascale computing, computational methods requiring only local data become especially attractive. Consequently, the typical domain decomposition of atmospheric models means horizontally explicit, vertically implicit (HEVI) time-stepping schemes warrant further attention. In this analysis, Runge-Kutta implicit-explicit schemes from the literature are analysed for their stability and accuracy using a von Neumann stability analysis of two linear systems. Attention is paid to the numerical phase to indicate the behaviour of phase and group velocities. Where the analysis is tractable, analytically derived expressions are considered. For more complicated cases, amplification factors have been numerically generated and the associated amplitudes and phase diagnosed. Analysis of a system describing acoustic waves has necessitated attributing the three resultant eigenvalues to the three physical modes of the system. To do so, a series of algorithms has been devised to track the eigenvalues across the frequency space. The result enables analysis of whether the schemes exactly preserve the non-divergent mode; and whether there is evidence of spurious reversal in the direction of group velocities or asymmetry in the damping for the pair of acoustic modes. Frequency ranges that span next-generation high-resolution weather models to coarse-resolution climate models are considered; and a comparison is made of errors accumulated from multiple stability-constrained shorter time-steps from the HEVI scheme with a single integration from a fully implicit scheme over the same time interval.Two schemes, 'Trap2(2,3,2)' and 'UJ3(1,3,2)', both already used in atmospheric models, are identified as offering consistently good stability and representation of phase across all the analyses. Furthermore, according to a simple measure of computational cost, 'Trap2(2,3,2)' is the least expensive.

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Comparison of Some Schemes for Nonhydrostatic Models with Orography

Cited by 45 publications

References 28 publications

Numerical Modeling of the Convective Snow Cloud over the Sea of Japan

Numerical Modeling of the Convective Snow Cloud over the Sea of Japan

A Numerical Study of a Dynamically Induced Foehn Observed in the Abashiri-Ohmu Area

Numerical analyses of Runge–Kutta implicit–explicit schemes for horizontally explicit, vertically implicit solutions of atmospheric models

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