A perturbed parameter ensemble of HadGEM3-GC3.05 coupled model projections: part 1: selecting the parameter combinations

Sexton, David M. H.; McSweeney, C.; Rostron, John; Yamazaki, Kiroku; Booth, Ben B. B.; Murphy, James M.; Regayre, Leighton A.; Johnson, Jill S.; Karmalkar, Ambarish V.

doi:10.1007/s00382-021-05709-9

Cited by 40 publications

(55 citation statements)

References 76 publications

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“…The 15-member PPE was based on the GC3.05 configuration of the UK Met Office Global Coupled Model (Williams et al 2017), a fully coupled version of the UK Met Office model featuring atmosphere and land (Walters et al 2017), ocean (Storkey et al 2017), and sea ice (Ridley et al 2017) components. Perturbations and the process for constructing the PPE used in UKCP Global is discussed in Sexton et al (2021) and the performance of the PPE is discussed in Yamazaki et al (2021). The 13 CMIP5 models were selected representing 12 different modelling groups, including a previous configuration of the UK Met Office model, HadGEM2; the selection was based on work by McSweeney et al (2015), which is summarised in Murphy et al (2018).…”

Section: Ukcpmentioning

confidence: 99%

Investigation of future climate change over the British Isles using weather patterns

et al. 2021

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For those involved in planning for regional and local scale changes in future climate, there is a requirement for climate information to be available in a context more usually associated with meteorological timescales. Here we combine a tool used in numerical weather prediction, the 30 weather patterns produced by the Met Office, which are already applied operationally to numerical weather prediction models, to assess changes in the UK Climate Projections (UKCP) Global ensemble. Through assessing projected changes in the frequency of the weather patterns at the end of the 21st Century, we determine that future changes in large-scale circulation tend towards an increase in winter of weather patterns associated with cyclonic and westerly wind conditions at the expense of more anticyclonic, settled/blocked weather patterns. In summer, the results indicate a shift towards an increase in dry settled weather types with a corresponding reduction in the wet and windy weather types. Climatologically this suggests a shift towards warmer, wetter winters and warmer, drier summers; which is consistent with the headline findings from the UK Climate Projections 2018. This paper represents the first evaluation of weather patterns analysis within UKCP Global. It provides a detailed assessment of the changes in these weather patterns through the 21st Century and how uncertainty in emissions, structural and perturbed parameters affects these results. We show that the use of these weather patterns in tandem with the UKCP projections is useful for future work investigating changes in a range of weather-related climate features such as extreme precipitation.

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Section: Ukcpmentioning

confidence: 99%

Investigation of future climate change over the British Isles using weather patterns

et al. 2021

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“…To examine when this signal emerges, the combined frequency of the predominantly summer type patterns (1-6) is plotted against the combined frequency of the predominantly winter type patterns (25)(26)(27)(28)(29)(30) for the lowest and highest emissions scenarios for UKCP Global RCP 2.6 and RCP 8.5 respectively (Fig. 6).…”

Section: Future Climate Signal In Weather Regimesmentioning

confidence: 99%

Future Extension Of The UK Summer And Its Impact On Autumn Precipitation

Cotterill

Pope

Stott

2022

Preprint

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Research into weather circulation changes over the UK for future climate has mainly focused on changes in the Summer and Winter seasons, with less analysis on seasonality and the transition seasons. Using the 30 Met Office weather patterns we examine the influence of climate change on seasonality through atmospheric circulation using a number of climate models. Changes in seasonality are important as they can have large impacts on many sectors including agriculture, energy and tourism. This paper finds a noticeable increase in Autumn over the UK in the frequency of drier summer-type regimes and a decrease in stormy winter types that emerge as early as the 2020s. The change in circulation signal once isolated from the overall signal is responsible for a 4-12% decrease in Autumn mean rainfall on average for England by the end of this century (where the values in the range are dependent on the emissions scenario). This change is projected over English regions that are already experiencing water stress, and with predictions of drier summers over the UK in future, this could further increase drought risk. The change in circulation in Autumn also moderates the large increase in the number of large-scale extreme daily rainfall events over the same regions predicted due to climate change. While climate models replicate the frequency of the 30 weather patterns well for all seasons, large differences remain between the strength of circulation signal changes simulated by models even though the general trend is in agreement.

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“…Each ensemble member has a horizontal resolution of approximately 60km at mid-latitudes (called 'N216') and was run for a 200-year period from 1900-2100, using CMIP5 historical forcings and future scenarios consistent with RCP8.5 emissions (accounting for carbon cycle uncertainties). The latter was assessed using idealised forcing experiments in atmosphere-only simulations, where diversity in climate feedbacks, aerosol and CO2 forcings, and regional precipitation and temperature responses were targeted (Sexton et al 2021). The plausibility of the variants was assessed in a variety of historical and present-day experiments e.g.…”

Section: Base Model and Parameter Perturbationsmentioning

confidence: 99%

“…for example, to study present-day climate performance (e.g. Yokohata et al 2013;Sexton et al 2019Sexton et al , 2021; climate feedbacks and sensitivities (e.g. Sanderson 2011;Collins et al 2011;Karmalkar et al 2019;Rostron et al 2020;Tsushima et al 2020); emergent constraints (e.g.…”

Section: Introductionmentioning

confidence: 99%

Evaluation and projections of the East Asian summer monsoon in a perturbed parameter ensemble

Rostron

Sexton

Furtado

et al. 2022

Preprint

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The East Asian summer monsoon (EASM) is a dominant driver of East Asian climate, with variations in its strength potentially impacting the livelihoods of millions of people. Understanding, predicting and assessing uncertainties in these variations is therefore an important area of research. Here, we present a study of the projected 21st Century changes in the EASM using a ‘perturbed parameter ensemble’ (PPE) of HadGEM3-GC3.05 coupled climate models, which samples uncertainties arising from differences in model parameter values. We show that while the present-day performance of PPE members for leading order EASM metrics is comparable to CMIP5 models in many respects, the PPE also exposes model biases which exist for most, if not all, parameter combinations. These ‘structural’ model biases are found mainly in the low-level circulation over the South China Sea and west Pacific. We also show that future changes in regional circulation and precipitation are projected consistently across the PPE members. A more detailed moisture budget analysis of the precipitation changes in a region covering the Yangtze River valley shows that both dynamic and thermodynamic changes contribute to an increase in precipitation over the 21st century, but that the spread in this response across the PPE is mainly due to spread in the dynamic responses. We also discuss how the information provided by the PPE may be used in practice, considering the plausibility of the models, and giving examples of ways to sub-select ensemble members to capture the diversity in the moisture budget changes.

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A perturbed parameter ensemble of HadGEM3-GC3.05 coupled model projections: part 1: selecting the parameter combinations

Cited by 40 publications

References 76 publications

Investigation of future climate change over the British Isles using weather patterns

Investigation of future climate change over the British Isles using weather patterns

Future Extension Of The UK Summer And Its Impact On Autumn Precipitation

Evaluation and projections of the East Asian summer monsoon in a perturbed parameter ensemble

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