Dr Natalie Ratcliffe: Publications

Evaluating dust storms modeled at kilometer-scale resolution in the ECOMIP initiative

(2026)

Authors:

Martina Klose, Andreas Baer, Rumeng Li, Noel M Chawang, Natalie Ratcliffe, Sebastian Vergara Palacio

Abstract:

Advanced kilometer-scale resolution modeling offers unprecedented detail of atmospheric processes and properties, including of mineral dust. At kilometer-scale model resolutions, deep moist convective processes do not have to be parameterized any more, but can be represented explicitly at the grid resolution. These processes are very effective in transporting heat, moisture, and energy within the atmosphere and therefore have strong impacts on weather phenomena, such as wind storms. Mineral dust emission is a threshold process that depends non-linearly upon surface wind intensity, which means that the accuracy at which models represent surface winds, together with land-surface properties, is key to estimating dust emissions. A spectacular and intense type of dust storm, i.e. haboob dust storms, is caused by the cold pool outflow of moist convection. We therefore expect that the explicit representation of moist convection in kilometer-scale simulations is particularly beneficial for dust modeling. Determining whether kilometer-scale models can meet this expectation, demands in-depth evaluation against observations. This evaluation is now enabled through novel satellite missions, such as the Earth Cloud Aerosol and Radiation Explorer (EarthCARE). Here we present results of kilometer-scale simulations conducted with two models, ICON-ART and ICON-HAM-lite, both including an interactive dust representation. We investigate, for example, evaporative cooling and vertical velocities associated with moist convection as drivers of dust emission. We compare our results against observations from EarthCARE and ORCESTRA (Organized Convection and EarthCARE Studies over the Tropical Atlantic), and against results from other models in the framework of the EarthCARE-ORCESTRA Model Intercomparison Project (ECOMIP). Our results show fascinating detail of mineral dust processes, enabling novel insights into the mineral dust cycle, for example, a globally consistent characterization of haboob properties and impacts.

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New processes to counteract sedimentation of coarse dust particles are required for climate models to agree with observations

(2026)

Authors:

Natalie Ratcliffe, Claire Ryder, Nicolas Bellouin, Martina Klose, Stephanie Woodward, Anthony Jones, Ben Johnson, Lisa-Maria Wieland, Andreas Baer, Josef Gasteiger, Bernadett Weinzierl

Abstract:

Recent observations show that large mineral dust particles are more abundant in the atmosphere than expected and travel further than their mass and theoretical rapid deposition allow for. The presence of these large particles alters the impact of dust on Earth’s radiative budget, carbon and hydrological cycles, and human health. Research into the impacts of the mechanisms influencing large dust particle lifetime in models is vital in ascertaining how large dust particles travel thousands of kilometres further than expected. We employ a series of model simulations to better understand the long-range transport of large particles from the Sahara to the West Atlantic. We present results from two models—HadGEM3A and ICON-ART—which are run at differing resolutions and with different dust representations (size bins and lognormal modes). Observations are used to verify long-range transport in model simulations, including in-situ aircraft observations at the Sahara, Canary Islands, Cape Verde, and Caribbean. Coarse particle mass loading (validated against observations) is limited by excessively rapid deposition in both models, but is further limited in ICON-ART by a reduced size-range representation, with the coarsest mode having a mean diameter by mass of 14.2 µm, whereas the maximum dust size in HadGEM3A extends to 63.2 µm. The sensitivity of large particle long-range transport to sedimentation, convective and turbulent mixing, shortwave absorption, and impaction scavenging are tested in global HadGEM3A climate simulations. A reduction in sedimentation by 80% is required to bring the modelled large particle transport into agreement with aircraft observations. None of the other processes tested were able to make the multiple order of magnitude changes to long-range large particle concentration in the model required for agreement with the observations. Convective and turbulent mixing in the model have minimal impact on large particle long-range transport, but are key in controlling the vertical distribution in the Saharan air layer and marine boundary layer, respectively. This work adds to the growing body of evidence that points to processes involved in large mineral dust transport and deposition which are not represented accurately or at all in models, which counteract the sedimentation of large particles in the real-world.

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New processes to counteract sedimentation of coarse dust particles are required for climate models to agree with aircraft observations

(2025)

Authors:

Natalie G Ratcliffe, Claire L Ryder, Nicolas Bellouin, Anthony Jones, Ben Johnson, Stephanie Woodward, Lisa-Maria Wieland, Josef Gasteiger, Bernadett Weinzierl

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Supplementary material to "New processes to counteract sedimentation of coarse dust particles are required for climate models to agree with aircraft observations"

(2025)

Authors:

Natalie G Ratcliffe, Claire L Ryder, Nicolas Bellouin, Anthony Jones, Ben Johnson, Stephanie Woodward, Lisa-Maria Wieland, Josef Gasteiger, Bernadett Weinzierl

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The Mass Extinction Coefficient for Dust: challenges in the link between mass and optical properties for models, reanalyses, in-situ and satellite observations

(2025)

Authors:

Claire Ryder, Natalie Ratcliffe, Alcide Zhao, Nicolas Bellouin, Laura Wilcox, Helen Dacre, Clément Bézier, Vassilis Amiridis, Eleni Marinou, Emmanouil Proestakis, Bernadett Weinzierl, Stephanie Woodward, Ben Johnson, Anthony Jones

Abstract:

The latest range of CMIP6 model dust simulations shows a greater diversity than previous generations of models in terms of dust emission, deposition, burden and dust optical depth (DOD) (Zhao et al., 2022). Validation of dust models is crucial for understanding the impact of dust on climate and climate change, as well as for quantifying socio-economic and health impacts of dust.While models (and reanalyses) mostly provide output in terms of mass, satellite observations used for model validation are optical measurements. Thus we require good knowledge of the dust mass extinction coefficient (MEC) to successfully validate our dust models. However, the MEC is intricately linked to the dust size distribution, fraction of coarse particles and composition, all of which may vary regionally, in the vertical and in time.This presentation will provide a perspective on some recent efforts exploring the challenges in model validation relating to dust size, composition, optical depth and dust mass loading in climate models (Zhao et al., 2024; Ratcliffe et al., 2024), reanalyses (Ryder et al., 2024), space-borne lidar, space-borne optical depth and in-situ measurements, demonstrating the critical importance and uncertainty of the dust MEC.ReferencesRatcliffe, N.G., Ryder, C.L., Bellouin, N., Woodward, S., Jones, A., Johnson, B., Wieland, L.-M., Dollner, M., Gasteiger, J., Weinzierl, B. Long range transport of coarse mineral dust: an evaluation of the Met Office Unified Model against aircraft observations, Atmos. Chem. Phys., 24, 12161–12181, https://doi.org/10.5194/acp-24-12161-2024, 2024.Ryder, C.L., Bézier, C., Dacre, H., Clarkson, R., Amiridis, V., Marinou, E., Proestakis, E., Kipling, Z., Benedetti, A., Parrington, M., Rémy, S., Vaughan, M., Aircraft Engine Dust Ingestion at Global Airports, https://doi.org/10.5194/nhess-24-2263-2024, 24, 7, Natural Hazards and Earth System Science, 2024.Zhao, A., Ryder, C.L., Wilcox, L., How well do the CMIP6 models simulate dust aerosols?, Atmos. Chem. Phys., 22, 2095–2119, https://doi.org/10.5194/acp-22-2095-2022, 2022.Zhao, A., Wilcox, L., Ryder, C.L., The key role of atmospheric absorption in the Asian Summer Monsoon response to dust emissions in CMIP6 models, Atmos. Chem. Phys., https://doi.org/10.5194/acp-24-13385-2024, 2024.

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Dr Natalie Ratcliffe

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Evaluating dust storms modeled at kilometer-scale resolution in the ECOMIP initiative

Authors:

Abstract:

New processes to counteract sedimentation of coarse dust particles are required for climate models to agree with observations

Authors:

Abstract:

New processes to counteract sedimentation of coarse dust particles are required for climate models to agree with aircraft observations

Authors:

Supplementary material to "New processes to counteract sedimentation of coarse dust particles are required for climate models to agree with aircraft observations"

Authors:

The Mass Extinction Coefficient for Dust: challenges in the link between mass and optical properties for models, reanalyses, in-situ and satellite observations

Authors:

Abstract:

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Dr Natalie Ratcliffe

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Evaluating dust storms modeled at kilometer-scale resolution in the ECOMIP initiative

Authors:

Abstract:

New processes to counteract sedimentation of coarse dust particles are required for climate models to agree with observations

Authors:

Abstract:

New processes to counteract sedimentation of coarse dust particles are required for climate models to agree with aircraft observations

Authors:

Supplementary material to "New processes to counteract sedimentation of coarse dust particles are required for climate models to agree with aircraft observations"

Authors:

The Mass Extinction Coefficient for Dust: challenges in the link between mass and optical properties for models, reanalyses, in-situ and satellite observations

Authors:

Abstract: