Numerical Techniques for Global Atmospheric Models

Lauritzen, P. H.

doi:10.1007/978-3-642-11640-7

Cited by 48 publications

(8 citation statements)

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“…The numerical dissipation in this model introduced in section 2.2 (D u , Figure 10i) may be primarily due to the interpolation process in the semi-Lagrangian advection scheme [Jablonowski and Williamson, 2011] by which the dissipation resembles fourth-order hyperdiffusion (−K 4 ∇ 4 u) [Yao and Jablonowski, 2013]. The detailed structure and magnitudes of D u shown in Figure 10i match well with −K 4 4 u∕ z 4 when K 4 = 1.5 × 10 6 m 4 s −1 .…”

Section: Estimates Of the Qbo Forcingsmentioning

confidence: 57%

Contributions of equatorial wave modes and parameterized gravity waves to the tropical QBO in HadGEM2

Kim

Chun

2015

JGR Atmospheres

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The contributions of the equatorial waves to the quasi-biennial oscillation (QBO) are investigated using Hadley Centre Global Environment Model version 2 (HadGEM2). A gravity wave parameterization that couples its source spectrum to the convection is used. The equatorial wave modes are identified in the spectral domain, based on their distinct characteristics associated with momentum and heat fluxes. The Kelvin waves and parameterized gravity waves (PGWs) transport westerly momentum into the equatorial stratosphere by ∼0.35 and 0.8 mPa, respectively, while easterly momentum is carried primarily by the PGWs (∼0.75 mPa). The resolved inertio-gravity (IG) waves transport both easterly and westerly momentum by ∼0.2 mPa. In the lowermost stratosphere, gradual dissipation of the Kelvin waves occurs, and the remaining waves induce eastward forcing in the westerly shear layer by 3-5 m s −1 month −1 . The PGWs primarily dissipate within the sheared layer and provide large easterly and westerly forcing in the middle stratosphere (∼17 m s −1 month −1 ), while the forcing in the lower stratosphere is comparable to the Kelvin wave forcing. The IG wave forcing is small because of the small wave dissipation rate. The Rossby and mixed Rossby-gravity (MRG) waves contribute to the westerly-to-easterly QBO transition by ∼2 m s −1 month −1 . The magnitudes of the simulated Kelvin and Rossby wave forcings are comparable with the Modern-Era Retrospective Analysis for Research and Applications, whereas the MRG and IG wave forcings are underestimated in the lower stratosphere. Differences between the simulation and reanalysis and the uncertainties in both are discussed.

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Section: Estimates Of the Qbo Forcingsmentioning

confidence: 57%

Contributions of equatorial wave modes and parameterized gravity waves to the tropical QBO in HadGEM2

Kim

Chun

2015

JGR Atmospheres

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“…-Optimization of solver efficiency: even though the use of the KPP has simplified the code maintenance and may result in a higher numerical accuracy of the solution, it also caused a considerable slow-down of the numerical efficiency as compared to the EBI solver, as that solver had been optimized for tropospheric ozone chemistry in C-IFS-CB05. Solutions could be an optimization of the initial chemical time step for the KPP solver, depending on prevailing chemical and physical conditions, and an optimization of the automated solver code, which allows for a more efficient code structure (KP4, Jöckel et al, 2010).…”

Section: Discussionmentioning

confidence: 99%

C-IFS-CB05-BASCOE: stratospheric chemistry in the Integrated Forecasting System of ECMWF

et al. 2016

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“…Controlling the Nonlinear Term. We start from the expression (20) for H m k to obtain estimates on the nonlinear term in (14). By definition of E θ , ( 13), one has…”

Section: Galerkin Approximation and The Itō Trickmentioning

confidence: 99%

“…In this work we present a solution theory of 2-dimensional Primitive Equations in the hyperviscous setting D(∆) = −(−∆) θ , for large enough θ and a suitable stochastic forcing. The regularising effect of hyperviscosity for Navier-Stokes and Primitive Equations is well-understood in the deterministic setting, and it is often used in numerical simulations [20]; we refer to [19,22,23] and, more recently, [18] for a thorough discussion. The main contribution of the present paper is thus to introduce a Gaussian invariant measure in the context of 2-dimensional Primitive Equations, and then to exploit the techniques of [15] to provide a first well-posedness result for this singular SPDE in a hyperviscous setting.…”

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confidence: 99%