The development of a new dust uplift scheme in the Met Office Unified Model™

Ackerley, Duncan; Highwood, Eleanor J.; Harrison, Mark A.; McConnell, Claire; Joshi, Manoj; Walters, David; Milton, Sean; Greed, Glenn; Brooks, M. E.

doi:10.1002/met.141

Cited by 5 publications

(17 citation statements)

References 49 publications

(76 reference statements)

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“…This follows the implementation in a prior version of the HadGEM2 by Ackerley et al [2009Ackerley et al [ , 2012. While both schemes are based on Marticorena and Bergametti [1995] and Fécan et al [1999], the implementation of the threshold friction velocity is different.…”

Section: Alternative Dust Emission Schemementioning

confidence: 99%

Last glacial maximum radiative forcing from mineral dust aerosols in an Earth system model

et al. 2015

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The mineral dust cycle in preindustrial (PI) and Last Glacial Maximum (LGM) simulations with the Coupled Model Intercomparison Project Phase 5 model Hadley Centre Global Environment Model 2-Atmosphere (HadGEM2-A) is evaluated. The modeled global dust cycle is enhanced at the LGM, with larger emissions in the Southern Hemisphere, consistent with some previous studies. Two different dust uplift schemes within HadGEM2 both show a similar LGM/PI increase in total emissions (60% and 80%) and global loading (100% and 75%), but there is a factor of 3 difference in the top of the atmosphere net LGM-PI direct radiative forcing (−1.2 W m −2 and −0.4 W m −2 , respectively). This forcing is dominated by the short-wave effects in both schemes. Recent reconstructions of dust deposition fluxes suggest that the LGM increase is overestimated in the Southern Atlantic and underestimated over east Antarctica. The LGM dust deposition reconstructions do not strongly discern between these two dust schemes because deposition is dominated by larger (2-6 μm diameter) particles for which the two schemes show similar loading in both time periods. The model with larger radiative forcing shows a larger relative emissions increase of smaller particles. This is because of the size-dependent friction velocity emission threshold and different size distribution of the soil source particles compared with the second scheme. Size dependence of the threshold velocity is consistent with the theory of saltation, implying that the model with larger radiative forcing is more realistic. However, the large difference in radiative forcing between the two schemes highlights the size distribution at emission as a major uncertainty in predicting the climatic effects of dust cycle changes.

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Section: Alternative Dust Emission Schemementioning

confidence: 99%

Last glacial maximum radiative forcing from mineral dust aerosols in an Earth system model

et al. 2015

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“…where F soil is the fraction of bare soil within a grid box, C is an empirically derived constant of proportionality (defined in [25]), ρ * is the surface air density over land (kg m −3 ). M rel is the mass of dust in each bin relative to the total mass of dust at each grid point and is calculated from the silt, sand and clay fraction values taken from the International Geosphere-Biosphere Programme (IGBP) global soil data set [26], D is a globally uniform tuning parameter (set to 18 in these experiments following a series of test simulations) and TL is the "topographic low" source term (based on the work by [27]), which is calculated as:…”

Section: Dust Uplift Scheme 1: Climmentioning

confidence: 99%

“…Where H orog is half of the peak-to-trough height of the model surface elevation. The values in (3) (shown in Figure 1) were chosen following test experiments and are different to those used in [27] as a result of the lower resolution orography used in this study and the different dust uplift scheme (CLIM). The version of the horizontal flux used by [20] does not use the TL function used in this study.…”

Section: Dust Uplift Scheme 1: Climmentioning

confidence: 99%

A Comparison of Two Dust Uplift Schemes within the Same General Circulation Model

Ackerley

Joshi

Highwood

et al. 2012

Advances in Meteorology

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Aeolian dust modelling has improved significantly over the last ten years and many institutions now consistently model dust uplift, transport and deposition in general circulation models (GCMs). However, the representation of dust in GCMs is highly variable between modelling communities due to differences in the uplift schemes employed and the representation of the global circulation that subsequently leads to dust deflation. In this study two different uplift schemes are incorporated in the same GCM. This approach enables a clearer comparison of the dust uplift schemes themselves, without the added complexity of several different transport and deposition models. The global annual mean dust aerosol optical depths (at 550 nm) using two different dust uplift schemes were found to be 0.014 and 0.023—both lying within the estimates from the AeroCom project. However, the models also have appreciably different representations of the dust size distribution adjacent to the West African coast and very different deposition at various sites throughout the globe. The different dust uplift schemes were also capable of influencing the modelled circulation, surface air temperature, and precipitation despite the use of prescribed sea surface temperatures. This has important implications for the use of dust models in AMIP-style (Atmospheric Modelling Intercomparison Project) simulations and Earth-system modelling.

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“…A regional dust model system, LM-MUSCAT-DES, also has been developed during the 2006 Saharan Mineral Dust Experiment field campaign [Heinold et al, 2008], with a subsequent model evaluation revealing the benefits and the limitations of the model, such as inaccuracies in the location of dust sources and the description of specific meteorological features by the model. Recently, the Met Office Unified Model has been upgraded so as to include the dust emissions scheme based on the DEAD model [Ackerley et al, 2009]. The necessity for sand and dust storm prediction in East Asia has led to the development of CUACE/Dust operational forecasting system [Zhou et al, 2008]; the model evaluation revealed the significance of the utilization of detailed soil description.…”

Section: Introductionmentioning

confidence: 99%

An improved limited area model for describing the dust cycle in the atmosphere

Spyrou¹,

Mitsakou²,

Kallos³

et al. 2010

J. Geophys. Res.

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[1] During the last decade, several numerical schemes have been deployed for the simulation of mineral dust processes in the atmosphere. The developed models have various deficiencies in the representation of dust particle physical properties and effects on climate. On the basis of the present status of the dust modeling tools, a combined effort was devoted to upgrading the SKIRON/Dust forecasting system by incorporating new features for the description of the lower boundary characteristics of the atmospheric model and the dust aerosol properties. In this paper, the updated model version is presented along with sensitivity simulations and evaluation of the model results with available observational data. The analysis is separated into two main parts, namely, the improvements that correspond to the atmospheric modeling system SKIRON and the upgrading of the physical mechanisms incorporated in the dust transport submodel. The analysis showed that the incorporation of the new model correction schemes led to a better and more accurate representation of the processes concerning meteorology and dust properties. The new soil characterization schemes significantly improve the energy-partitioning predictions at the surface and therefore the boundary layer processes that play a substantial role in the determination of the dust production mechanisms. Significant differences were detected in the radiation balance between atmosphere and ground surface by incorporating statistical corrections for the description of terrain slopes and azimuths, mainly in areas with highly rough terrain. Finally, the more accurate description of the transported dust aerosol distribution (eight size bins) and the new dust production and deposition schemes led to more efficient determination of the dust particle optical properties (aerosol optical depths).Citation: Spyrou, C., C. Mitsakou, G. Kallos, P. Louka, and G. Vlastou (2010), An improved limited area model for describing the dust cycle in the atmosphere,

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The development of a new dust uplift scheme in the Met Office Unified Model™

Cited by 5 publications

References 49 publications

Last glacial maximum radiative forcing from mineral dust aerosols in an Earth system model

Last glacial maximum radiative forcing from mineral dust aerosols in an Earth system model

A Comparison of Two Dust Uplift Schemes within the Same General Circulation Model

An improved limited area model for describing the dust cycle in the atmosphere

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