Tropical forecasting at ECMWF: The influence of physical parametrization on the mean structure of forecasts and analyses

TIEDTKE, M; Heckley, W. A.; Slingo, Julia

doi:10.1256/smsqj.48105

Cited by 71 publications

(55 citation statements)

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“…To overcome this deficiency, the diffusive processes in the shallow convection were added to the TDK scheme. This scheme is described by the following diffusive terms for large scale (grid mean) dry static energy S and specific humidity q (Tiedtke et al 1988):…”

Section: A Bottom-heavy Diffusivity In the Shallow Convection Schemementioning

confidence: 99%

Improving MJO simulation by enhancing the interaction between boundary layer convergence and lower tropospheric heating

Yang

Wang

2018

Clim Dyn

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It has been a great challenge for global weather and climate models to simulate realistic Madden-Julian Oscillation (MJO) while keeping global energy and water balance unaffected. This work demonstrates that, in the Nanjing University of Information Science and Technology Earth System Model, enhanced boundary layer (BL) convergence feedback to the lower tropospheric heating in both the modified Tidtke (TDK) and relaxed Arakawa-Schubert (RAS) convective schemes have significantly improved the quality of MJO simulation in terms of both the eastward propagation and three-dimensional dynamic and thermodynamic structures. The modifications to the TDK and RAS schemes include (a) a BL depth-dependent convective inhibition, and (b) a bottom-heavy diffusivity in the shallow convection scheme. To understand how these modifications improved the MJO simulation, we applied dynamics-oriented diagnostics to reveal the critical role of the interaction between the lower-tropospheric heating and the BL convergence. The modified schemes enhance the lower-tropospheric diabatic heating to the east of the MJO convective center, which leads to increased Kelvin wave easterly winds. The strengthened MJO easterly winds reinforce the BL moisture convergence to the east of the MJO center and therefore result in increased upward transports of moisture and heat from the BL to the free atmosphere, which further moisten and destabilize the lower troposphere and thereby increase the lower-tropospheric heating. The positive feedback between the BL convergence and lower tropospheric heating improves MJO eddy available potential energy generation to the east of major convection and promotes MJO eastward propagation. The results indicate that correct simulation of the heating induced by shallow and/ or congestus clouds and its interaction with BL dynamics is critical for realistic simulation of the MJO as suggested by the trio-interaction theory.

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Section: A Bottom-heavy Diffusivity In the Shallow Convection Schemementioning

confidence: 99%

Improving MJO simulation by enhancing the interaction between boundary layer convergence and lower tropospheric heating

Yang

Wang

2018

Clim Dyn

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“…The thermodynamic structure of the cloud is given by (4). The cloud-base closure needs particular care since it prescribes the initial cloudy plume properties and represents the ventilation of the sub-cloud layer (Tiedtke et al 1988). Betts (1976) introduced a closure of the mass flux at cloud base to describe the coupling between two layers.…”

Section: The Edmf Parametrizationmentioning

confidence: 99%

“…Because the mass-flux term is always active, one avoids discontinuities in model integration associated with switching between the turbulence and convection parametrizations. It also avoids the need of making rather ad hoc extrapolations of the mass flux at cloud base towards the surface (Tiedtke et al 1988).…”

Section: Introductionmentioning

confidence: 99%

An eddy‐diffusivity/mass‐flux parametrization for dry and shallow cumulus convection

Soares

Miranda

Siebesma

et al. 2004

Quart J Royal Meteoro Soc

182

239

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SUMMARYRecently, a new consistent way of parametrizing simultaneously local and non-local turbulent transport for the convective atmospheric boundary layer has been proposed and tested for the clear boundary layer. This approach assumes that in the convective boundary layer the subgrid-scale fluxes result from two different mixing scales: small eddies, that are parametrized by an eddy-diffusivity approach, and thermals, which are represented by a mass-flux contribution. Since the interaction between the cloud layer and the underlying sub-cloud layer predominantly takes place through strong updraughts, this approach offers an interesting avenue of establishing a unified description of the turbulent transport in the cumulus-topped boundary layer. This paper explores the possibility of such a new approach for the cumulus-topped boundary layer. In the sub-cloud and cloud layers, the mass-flux term represents the effect of strong updraughts. These are modelled by a simple entraining parcel, which determines the mean properties of the strong updraughts, the boundary-layer height, the lifting condensation level and cloud top. The residual smaller-scale turbulent transport is parametrized with an eddy-diffusivity approach that uses a turbulent kinetic energy closure. The new scheme is implemented and tested in the research model MesoNH.

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“…Moist processes are obviously important for the modeling of clouds, precipitation, radiation, and latent heat release. The moisture field depends on parameterized physical processes (Tiedtke et al 1988;Gregory 1996;Tiedke 1993;Jakob and Klein 1999;Beljaars and Viterbo 1998), which can have substantial uncertainties, but it also depends on the large-scale motion, particularly the vertical motion. One way of assessing the model is by looking at systematic differences between forecasts and analyses.…”

Section: Modeling Aspects and Validationmentioning

confidence: 99%

Assimilation and Modeling of the Atmospheric Hydrological Cycle in the ECMWF Forecasting System

Andersson¹,

Bauer²,

Beljaars³

et al. 2005

Bull. Amer. Meteor. Soc.

147

122

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ECMWF's preparations for cloud and rain assimilation encompass development of linearized physics, improved satellite data utilization, a new humidity analysis, and another look at the "spindown" problem. European, American, and Japanese satellite agencies have a number of Earth-observation missions with the objective of providing improved measurements of components of the global hydrological cycle-clouds, precipitation, soil moisture, and water vapor-from a range of operational platforms in both polar and geostationary orbits. Significant development of data assimilation methods will be necessary to make full use of both the existing and new types of observations of the water cycle. The small-scale

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Tropical forecasting at ECMWF: The influence of physical parametrization on the mean structure of forecasts and analyses

Cited by 71 publications

References 0 publications

Improving MJO simulation by enhancing the interaction between boundary layer convergence and lower tropospheric heating

Improving MJO simulation by enhancing the interaction between boundary layer convergence and lower tropospheric heating

An eddy‐diffusivity/mass‐flux parametrization for dry and shallow cumulus convection

Assimilation and Modeling of the Atmospheric Hydrological Cycle in the ECMWF Forecasting System

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