A new parametrization for the radiative properties of ice crystals: Comparison with existing schemes and impact in a GCM

Edwards, John M.; Havemann, Stephan; Thelen, Jean-Claude; Baran, Anthony J.

doi:10.1016/j.atmosres.2006.03.002

Cited by 99 publications

(78 citation statements)

References 42 publications

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“…It should be noted that in HiGEM and ERAI the representation of crystals and aggregates for radiative purposes differs, with snow not being radiatively active in ERAI. As such, the effective radii that are used in the temperature ranges relevant to these composites (230-245 K) differ (see Edwards et al (2007); Yang and Liou (1996) for HiGEM and ECMWF (2006); Ebert and Curry (1992); Heymsfield and Platt (1984) for ERAI). This inconsistency increases/ decreases the τ ice in HiGEM/ERAI relative to each other.…”

Section: Isccp Composite Storm Structurementioning

confidence: 99%

Using satellite and reanalysis data to evaluate the representation of latent heating in extratropical cyclones in a climate model

et al. 2016

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exhibit biases in cloud structure, with more clouds at lower altitudes than those observed in ISCCP in the warm conveyor belt region. As a result, latent heat release in ERAI is concentrated at lower altitudes. CloudSat indicates that much precipitation may be produced at too low an altitude in both HiGEM and ERAI, particularly ERAI, and neither capture observed variability in precipitation intensity. The potential vorticity structure in composite extratropical cyclones in HiGEM and ERAI is also compared. A more pronounced tropopause ridge evolves in HiGEM on the leading edge of the composite as compared to ERAI. One future area of research to be addressed is what impact these biases in the representation of latent heating have on climate projections produced by HiGEM. The biases found in ERAI indicate caution is required when using reanalyses to study cloud features and precipitation processes in extratropical cyclones or using reanalysis to evaluate climate models' ability to represent their structure.

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Section: Isccp Composite Storm Structurementioning

confidence: 99%

Using satellite and reanalysis data to evaluate the representation of latent heating in extratropical cyclones in a climate model

et al. 2016

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“…(See Edwards and Slingo (1996) for the liquid condensate parametrization based on Mie scattering. The ice crystal parametrization, based on ice aggregates, is described in Edwards et al (2007).) A treatment of the ozone absorption around 9.6 µm was found to be of little benefit in relation to the added cost and is not included.…”

Section: Incremental Time-stepping Scheme Implementationmentioning

confidence: 99%

Two fast radiative transfer methods to improve the temporal sampling of clouds in numerical weather prediction and climate models

Manners

Thelen

Petch

et al. 2009

Quart J Royal Meteoro Soc

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ABSTRACT:The high computational cost of calculating the radiative heating rates in numerical weather prediction (NWP) and climate models requires that calculations are made infrequently, leading to poor sampling of the fast-changing cloud field and a poor representation of the feedback that would occur. This paper presents two related schemes for improving the temporal sampling of the cloud field. Firstly, the 'split time-stepping' scheme takes advantage of the independent nature of the monochromatic calculations of the 'correlated-k' method to split the calculation into gaseous absorption terms that are highly dependent on changes in cloud (the optically thin terms) and those that are not (optically thick). The small number of optically thin terms can then be calculated more often to capture changes in the grey absorption and scattering associated with cloud droplets and ice crystals. Secondly, the 'incremental time-stepping' scheme uses a simple radiative transfer calculation using only one or two monochromatic calculations representing the optically thin part of the atmospheric spectrum. These are found to be sufficient to represent the heating rate increments caused by changes in the cloud field, which can then be added to the last full calculation of the radiation code. We test these schemes in an operational forecast model configuration and find a significant improvement is achieved, for a small computational cost, over the current scheme employed at the Met Office. The 'incremental time-stepping' scheme is recommended for operational use, along with a new scheme to correct the surface fluxes for the change in solar zenith angle between radiation calculations.

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“…Cloud ice crystals and water droplets are treated separately in the scheme. An ice cloud optical property scheme representing various non-spherical ice crystals developed by Edwards et al (2007) is used in the current version of ACCESS model.…”

Section: Radiationmentioning

confidence: 99%

Implementation of the initial ACCESS numerical weather prediction system

Puri¹,

Dietachmayer²,

Steinle³

et al. 2013

AMOJ

135

103

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The Australian Community Climate and Earth-System Simulator (ACCESS) is a coupled climate and earth system simulator being developed as a joint initiative of the Bureau of Meteorology and CSIRO in cooperation with the university community in Australia. The main aim of ACCESS is to develop a national approach to climate and weather prediction model development. Planning for ACCESS development commenced in 2005 and significant progress has been made subsequently. ACCESS-based numerical weather prediction (NWP) systems were implemented operationally by the Bureau in September 2009 and were marked by significantly increased forecast skill of close to one day for three-day forecasts over the previously operational systems. The fully-coupled ACCESS earth system model has been assembled and tested, and core runs have been completed and submitted for the Intergovernmental Panel for Climate Change (IPCC) Fifth Assessment Report. Significant progress has been made with ACCESS infrastructure including successful porting to both Solar and Vayu (National Computational Infrastructure (NCI)) machines and development of infrastructure to allow usage by university researchers. This paper provides a description of the NWP component of ACCESS and presents results from detailed verification of the system.

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A new parametrization for the radiative properties of ice crystals: Comparison with existing schemes and impact in a GCM

Cited by 99 publications

References 42 publications

Using satellite and reanalysis data to evaluate the representation of latent heating in extratropical cyclones in a climate model

Using satellite and reanalysis data to evaluate the representation of latent heating in extratropical cyclones in a climate model

Two fast radiative transfer methods to improve the temporal sampling of clouds in numerical weather prediction and climate models

Implementation of the initial ACCESS numerical weather prediction system

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