Implementation of a double moment cloud microphysics scheme in the UK met office regional numerical weather prediction model

Field, Paul R.; Hill, Adrian A.; Shipway, Ben; Furtado, Kalli; Wilkinson, Jonathan; Miltenberger, Annette K.; Gordon, Hamish; Grosvenor, Daniel P.; Stevens, Robin; Weverberg, Kwinten Van

doi:10.1002/qj.4414

Cited by 24 publications

(20 citation statements)

References 131 publications

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“…This is done through km‐scale simulations of 47 well‐observed CAO cases during the Cold‐Air Outbreaks in the Marine Boundary Layer Experiment (COMBLE) in Norway in 2020 (Geerts et al., 2022). All simulations were performed using a recently developed two‐moment microphysics scheme, CASIM (Field et al., 2022) in the UK Met Office Unified Model. The continuous ground‐based observations, collected at one site over a multi‐month period, provide a unique opportunity for a more statistically robust analysis, compared to single case studies observed by aircraft.…”

Section: Discussionmentioning

confidence: 99%

“…Experiment Description BM Baseline Simulation using Regional Atmosphere and Land 3 Configuration, with Bimodal macrophysics (Van Weverberg, Morcrette, Boutle, Furtado, & Field, 2021) and CASIM microphysics (Field et al, 2022), including modifications listed in Appendix A for consistent treatment of saturationdeparture between the macrophysics and the ice nucleation and deposition in the microphysics…”

Section: Model Experimentsmentioning

confidence: 99%

“…Originally, the PC2 scheme was coupled to the one-moment microphysics scheme of Wilson and Ballard (1999), with CF fro tendencies from nucleation, deposition, melting and sublimation, and liquid cloud (CF liq ) tendencies from nucleation, deposition and evaporation. This appendix provides PC2 tendency formulations when coupled to CASIM (Field et al, 2022). Note that while CASIM includes two separate categories for small ice and large aggregates, it only includes a single CF fro for both categories combined.…”

Section: Appendix B: Prognostic Cloud Fraction Tendencies Associated ...mentioning

confidence: 99%

“…This configuration builds on the Regional Atmosphere 2 (RAL2) configuration described in Bush et al (2022), using a blended turbulence boundary-layer parameterization (Boutle et al, 2014). The one-moment microphysics scheme with a single combined ice-snow category in RAL2 (Wilson & Ballard, 1999), was replaced in RAL3 by a new two-moment bulk microphysics scheme, CASIM (Cloud AeroSol Interacting Microphysics; Field et al, 2022). CASIM predicts mass and number density of cloud water, rain, snow aggregates, ice crystals and graupel and uses in-cloud values of water content and number concentration in its collection calculations, using cloud fractions obtained from the macrophysics parameterization.…”

Section: General Model Setupmentioning

confidence: 99%

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On the Role of Macrophysics and Microphysics in Km‐Scale Simulations of Mixed‐Phase Clouds During Cold Air Outbreaks

et al. 2023

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Mixed-phase clouds in polar cold-air outbreaks (CAOs) continue to pose a major challenge for regional atmospheric models (Abel et al., 2017;Field et al., 2017;Klein et al., 2009). The co-existence of ice and supercooled liquid in these clouds at temperatures well below the freezing point, challenges our understanding of the interaction between aerosol, microphysical and turbulent processes. Yet, it is imperative that progress be made in the representation of mixed-phase clouds, given their abundance over polar regions and their potentially important cloud-radiative feedbacks in a changing climate (Frey & Kay, 2018;Murray et al., 2021). Despite progress in the representation of the interaction of turbulent processes and microphysics (Field, Hill, et al., 2014;Korolev & Field, 2008), most atmospheric models still struggle to reproduce the observed amount of supercooled liquid in polar mixed-phase clouds (

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Section: Discussionmentioning

confidence: 99%

Section: Model Experimentsmentioning

confidence: 99%

Section: Appendix B: Prognostic Cloud Fraction Tendencies Associated ...mentioning

confidence: 99%

Section: General Model Setupmentioning

confidence: 99%

See 2 more Smart Citations

On the Role of Macrophysics and Microphysics in Km‐Scale Simulations of Mixed‐Phase Clouds During Cold Air Outbreaks

et al. 2023

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“…For details of the parameterisations schemes used in RAL1T see Bush et al (2020), which includes the full model description. In RAL3, the largest model upgrades compared with RAL1T are the introduction of the Cloud AeroSol Interacting Microphysics (CASIM) double-moment cloud microphysics scheme (Field et al, 2023) and the use of the bimodal large-scale cloud scheme (Van Weverberg et al, 2021). The RAL3 configuration is the latest version of the science configuration, whereas the RAL1T configuration produced near-real-time forecasts.…”

Section: Methodsmentioning

confidence: 99%

Extreme precipitation at Padang, Sumatra triggered by convectively coupled Kelvin waves

Senior,

Matthews,

Webber

et al. 2023

Quart J Royal Meteoro Soc

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Convectively coupled Kelvin waves (CCKWs) are tropical weather systems that travel eastward along the equatorial waveguide and have previously been linked to 90% of flooding events in Sumatra, Indonesia. Here, the processes through which CCKWs influence convection to produce extreme precipitation are investigated, with a focus on Padang, a city on the west coast of Sumatra. Extreme precipitation days at Padang, defined as days when the daily total precipitation exceeds the percentile, are found to be 59% more likely to occur given the presence of a CCKW. We find that CCKWs modulate the diurnal cycle to produce extreme precipitation. This is achieved firstly through providing low‐level moisture and convergence that acts to couple the Kelvin wave to the convection. Secondly, the CCKW acts to displace the convergence zone towards Padang, such that it experiences rainfall that persists throughout the night and peaks the following day in the early evening. We examine the case study of a CCKW that passed over Padang on August 21, 2017, bringing extreme precipitation that led to flooding in the West Sumatra region, recording a maximum daily accumulated rainfall of 137 mm. This case study showed remarkably similar characteristics in its propagation, structure, and precipitation patterns to composite studies of CCKWs. The performance of a suite of convection‐permitting configurations of the UK Met Office Unified Model (MetUM), embedded within a parameterised convection global model, in forecasting this CCKW is evaluated. In general, all configurations of the model capture this event reasonably well. We find that extending the western boundary of the high‐resolution model domain from 90°E to 65°E leads to a significantly improved forecast, as the CCKW development over the Indian Ocean is captured more accurately by the high‐resolution nested model, compared with the lower‐resolution global driving model.

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Utility of thermal remote sensing for evaluation of a high‐resolution weather model in a city

Hall,

Blunn,

Grimmond

et al. 2024

Quart J Royal Meteoro Soc

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Progress in high‐resolution numerical weather prediction (NWP) for urban areas will require new modelling approaches and extensive evaluation. Here, we exploit land surface temperature (LST) data from Landsat‐8 to assess 100 m resolution NWP for London (UK) on four cloud‐free days. The LST observations are directional radiometric temperatures with non‐negligible uncertainties. We consider the challenges of informative comparison between the Landsat LST and the NWP scheme's internal characterisation of the complete surface temperature. The LST spatial coverage allows large‐scale observation–model differences to be explored. In one case, obvious spatial artifacts in the NWP surface temperature are observed relative to the Landsat LST. These are found to be related to the NWP's initial method of downscaling of soil moisture using soil properties. Updated model runs have higher spatial correlation between model and Landsat LST. In cases where meteorological conditions favour the formation of horizontal convective rolls, warmer air temperatures associated with updraughts in the mixed layer extend inappropriately to the urban surface. This manifests as warm stripes in the model surface temperature that are not present in the Landsat LST. NWP–Landsat LST differences are larger in more built‐up areas on days nearer summer solstice. This is largely attributed to urban thermal anisotropy, as Landsat preferentially views warmer urban surfaces, whereas the model LST represents all surfaces. We evaluate two approaches to quantify this sampling effect, but further work is needed to fully constrain it and facilitate more informative model evaluation.

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Implementation of a double moment cloud microphysics scheme in the UK met office regional numerical weather prediction model

Cited by 24 publications

References 131 publications

On the Role of Macrophysics and Microphysics in Km‐Scale Simulations of Mixed‐Phase Clouds During Cold Air Outbreaks

On the Role of Macrophysics and Microphysics in Km‐Scale Simulations of Mixed‐Phase Clouds During Cold Air Outbreaks

Extreme precipitation at Padang, Sumatra triggered by convectively coupled Kelvin waves

Utility of thermal remote sensing for evaluation of a high‐resolution weather model in a city

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