Regional Characteristics of Variability in the Northern Hemisphere Wintertime Polar Front Jet and Subtropical Jet in Observations and CMIP6 Models

Liu, Xinhuiyu; Grise, Kevin M.; Schmidt, Daniel F.; Davis, Robert E.

doi:10.1029/2021jd034876

Cited by 8 publications

(4 citation statements)

References 73 publications

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“…In addition, the PDO phase change from positive to negative is related to a poleward expansion of the Hadley Cell [39,94], which drives the STJ in the same direction. This argument is supported by studies that have shown that the Northern Hemisphere Pacific STJ is mostly modulated by central Pacific SST variability [58,89,[102][103][104][105]. In summary, numerical experiments in which Arctic warming is induced by the loss of sea-ice have a consistent but limited Arctic influence on the STJ latitudinal position over Europe, North America and the North Atlantic basin.…”

Section: Discussionmentioning

confidence: 61%

Regional Responses of the Northern Hemisphere Subtropical Jet Stream to Reduced Arctic Sea Ice Extent

Solis

Thompson

Groß

2022

Climate

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The effect of Arctic sea ice loss on the boreal winter regional trends of wind speed and latitudinal position of the Northern Hemisphere subtropical jet stream (STJ) in 1980–2012 is investigated. Two sets of global simulations with reduced Arctic sea ice extent are analyzed: simulations that, south of 70 N, use a climatological annual cycle of the sea surface temperature (SST) and a second set that uses full SST variability. Results with the climatological SST have a significant but weak response of the STJ wind speed and latitudinal position to the warmer Arctic: the wind speed generally decreases and the jet core is displaced equatorward. However, in the realistic SST simulations, the effect of Arctic warming is only slightly evident in a small equatorward shift of the jet over the Atlantic basin. Over the Pacific basin the STJ is mostly driven by tropical and mid-latitude SST variability, with little influence from the Arctic region. A weakening and poleward shift of the STJ that is observed in the realistic SST simulations over the Pacific basin is attributed to negative SST trends in the tropical Pacific and the consequent weakening of the mid-latitude meridional gradient of geopotential height in the upper troposphere.

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Section: Discussionmentioning

confidence: 61%

Regional Responses of the Northern Hemisphere Subtropical Jet Stream to Reduced Arctic Sea Ice Extent

Solis

Thompson

Groß

2022

Climate

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“…Previous studies have shown that simulate a larger warm pool area in the present day and predicted an excessive warming in the future in the eastern tropical Pacific due to intensified ocean stratification (Park et al, 2022). Liu et al showed that CMIP6 multi‐model mean reproduces the warm pool size well, but there is large spread among models, with models with smaller warm pool areas (larger biases) tending to simulate weaker WTP SST (Liu & Grise, 2023). Therefore, there are still significant biases in the current model simulations of climate variability in the Pacific region.…”

Section: Introductionmentioning

confidence: 99%

Interhemispheric propagation of seasonal sea surface temperature fluctuations over the western Pacific in CMIP6

Wei,

Sun,

Guo

et al. 2024

Intl Journal of Climatology

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Interannual sea surface temperature (SST) variability in the western Pacific is a critical research topic in climate change, as it can significantly impact regional and global weather patterns. Previous observational studies have shown that SST in the southwestern Pacific (SWP) can effectively serve as a precursor signal for SST in the western tropical Pacific (WTP). In this study, we evaluate and compare the modelling capabilities of 32 CMIP6 models to simulate the relationship between SWP and WTP SST. The results indicate that while some CMIP6 models can simulate the spatial connection and physical processes between the SWP and WTP, there are significant intermodel differences. Specifically, the models that best simulate the cross‐equatorial propagation of SWP SST anomalies are those that accurately simulate the cross‐equatorial wind anomalies induced by SWP SST anomalies, highlighting the key role of wind‐evaporation‐SST feedback in SST propagation. Further analysis reveals that the intermodel spread in cross‐equatorial SST propagation is attributable to model biases in simulating climatological SST and wind speed. Models with warm climatological equatorial SST and strong wind speeds provide favourable conditions for the cross‐equatorial propagation of SWP‐related SST anomalies towards the north. Warm SST and strong inter‐season wind speeds near the equator facilitate the northward propagation of the SWP warm signal, leading to increased warming in the WTP.

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“…This technique has been applied to constrain CMIP6 ensemble projections of surface temperature and precipitation. Several studies have used emergent constraints to reduce projection uncertainty at the global scale (Liu & Grise, 2023; Nijsse et al, 2020; Shiogama et al, 2022; Tokarska et al, 2020) and regional scale (Chai et al, 2022; Chen et al, 2020; Hu et al, 2021). The reliability ensemble averaging (REA) approach, as introduced by Giorgi and Mearns (2002), assigns weights to each model based on reliability criteria, including the “model performance” and “model convergence” criteria.…”

Section: Introductionmentioning

confidence: 99%

Optimal reliability ensemble averaging approach for robust climate projections over China

Gao,

Yu,

Zhou

et al. 2024

Intl Journal of Climatology

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Accurate simulation and reliable projection of temperature and precipitation over China under climate change is important for proposing adaptation measures for future natural ecosystems. This study proposes a novel method to construct an optimal reliability ensemble averaging (REA) subset from the Coupled Model Intercomparison Project Phase 6 (CMIP6) based on their historical performance in simulating temperature and precipitation across different subregions. The optimal REA ensemble outperforms the multi‐model ensemble mean (MMEM) and single optimal model in reproducing the spatial patterns of historical annual mean temperature and precipitation over China from 1985 to 2014. Under the examined Shared Socioeconomic Pathway scenarios (SSP1‐2.6, SSP2‐4.5 and SSP5‐8.5), the REA projects persistent warming and increased precipitation towards the end of the 21st century, intensifying under higher emissions. Nationwide mean temperature rises of 1.39, 2.69 and 5.05°C, and precipitation increases of 9%, 10% and 20% are projected in the long‐term (2081–2100) relative to 1995–2014 under SSP1‐2.6, SSP2‐4.5 and SSP5‐8.5 scenarios, respectively. Northwestern China and the Tibetan Plateau are expected to experience amplified warming and precipitation increases, respectively. Compared to the MMEM, the REA generally indicates reduced warming but larger precipitation increases, especially over the Tibetan Plateau under higher‐emissions scenarios. The REA exhibits lower projection uncertainty than the MMEM for both temperature and precipitation, primarily attributed to reduced internal variability. The novel optimal framework for REA shows the potential for extracting robust regional climate information applicable to different subregions of China. This study may contribute to new comprehension of future climate change over China.

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Regional Characteristics of Variability in the Northern Hemisphere Wintertime Polar Front Jet and Subtropical Jet in Observations and CMIP6 Models

Cited by 8 publications

References 73 publications

Regional Responses of the Northern Hemisphere Subtropical Jet Stream to Reduced Arctic Sea Ice Extent

Regional Responses of the Northern Hemisphere Subtropical Jet Stream to Reduced Arctic Sea Ice Extent

Interhemispheric propagation of seasonal sea surface temperature fluctuations over the western Pacific in CMIP6

Optimal reliability ensemble averaging approach for robust climate projections over China

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