Impact of extremely warm Tibetan Plateau in spring on the rare rainfall anomaly pattern in the regions west and east to Plateau in late summer 2022

Li, Zhangqun; Xiao, Ziniu; Ling, Jian

doi:10.1016/j.atmosres.2023.106797

“…Meanwhile, the rising trend of H may, at least partly, be responsible for the frequent occurrence of "extremely strong" subtropical high events in recent years, such as the extremely strong WNPSH events in 2020 (e.g., Takaya et al 2020;Qiao et al 2021;Zhou et al 2021;Shi and Fang 2022), 2021 (Ke et al 2022;Ma et al 2022;Zhang et al 2022b) and 2022 (Chen and Li 2023;Li et al 2023;Tang et al 2023;Zhang et al 2023) based on H anomaly or characteristic H contour. This is because a recent year is compared with a "climate normal" based on past decades in attribution studies, and the strong rising trend of H may push the H anomaly (and also the anomalous AI for subtropical high) in recent years toward a positive anomaly in comparison to a past "climate normal" (Livezey et al 2007;Arguez and Vose 2011;Rahmstorf and Coumou 2011;Hansen et al 2012).…”

Section: Relating Past and Future Evolution Of H To Ts Changementioning

confidence: 99%

“…Meanwhile, an "extremely strong" subtropical high has frequently been reported in recent years. For example, the summertime WNPSH was reported to be exceptionally strong and extended farther westward than normal in 2020 (e.g., Takaya et al 2020;Qiao et al 2021;Zhou et al 2021;Shi and Fang 2022), as well as in 2021 (Ke et al 2022;Ma et al 2022;Zhang et al 2022b) and 2022 (Chen and Li 2023;Li et al 2023;Zhang et al 2023). In the summer of 2022, maybe for the first time, the characteristic contour of H=5880 gpm covered the Tibetan Plateau and encircled the globe, possibly indicating an extremely strong subtropical high and drawing wide attention from the research community (Mallapaty 2022;Chen and Li 2023;Zhang et al 2023).…”

Section: Introductionmentioning

confidence: 99%

Rising geopotential height under global warming

He,

Chen,

Collins

et al. 2024

Clim Dyn

0

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Geopotential height (H) is a widely used metric for atmospheric circulation. H has been reported to be rising under global warming, but the amplitude and mechanism of this rise are not clear. Based on reanalysis datasets and climate models participating in CMIP6, this study quantitatively evaluates the sensitivity of H to global mean surface air temperature (Ts), i.e., dH/dTs. Reanalysis datasets and model simulations consistently show that dH/dTs increases monotonically with altitude in the troposphere, with a global averaged value of about 24.5 gpm/K at 500 hPa, which overwhelms the interannual H variability. Diagnosis based on the hypsometric equation shows that the rise in H is dominated by temperature-driven expansion, i.e., expansion of the air column due to warming-induced reduction of air density, while moisture-driven expansion and the surface pressure effect play only minor roles. Therefore, the magnitude of dH/dTs is determined largely by a vertical integration of the warming profile below the pressure level. Since the anthropogenic forced rise in H is rather horizontally uniform and proportional to Ts change, past and projected future changes in the global H field at each pressure level can be reproduced by change in Ts multiplied by a constant historical dH/dTs value. The spatially uniform rise in H reproduces the past and projected future expansion of the widely used H=5880 gpm contour at 500 hPa, suggesting that it does not indicate enhancement of the subtropical high but is simply caused by thermal expansion of the atmosphere.

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“…The 2022 extreme heatwave was also associated with decreased spring snow cover on the Qinghai-Tibetan Plateau and reduced rainfall over Southwest China (Figure S9 in Supporting Information S1). The anomalous Tibetan Plateau warming in spring associated with reduced snow cover could drive the northeastward shift of the South Asian high (SAH) and the northwestward movement of the WPSH (Li et al, 2023). The overlap of the SAH and the WPSH in the vertical direction could further favor the high-pressure anomalies in the summer, leading to long-lived heatwaves in central-eastern China (Li et al, 2021).…”

Section: Atmospheric Circulation Patterns Associated With the 2022 Ex...mentioning

confidence: 99%

How Unexpected Was the 2022 Summertime Heat Extremes in the Middle Reaches of the Yangtze River?

Hua

¹

,

Dai

²

,

Qin

³

et al. 2023

Geophysical Research Letters

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The 2022 heatwave in China featured record‐shattering high temperatures, raising questions about its origin and possible link to global warming. Here we show that the maximum temperature anomalies over Central China reached 13.1°C in the summer of 2022, which is ∼4.2σ above the 1981–2010 mean with a return period of tens of thousands of years. Our results suggested that the persistent high‐pressure anomaly and associated extreme heatwave likely resulted mainly from internal variability, although anthropogenic warming has increased the probability of such extreme heatwaves. We also estimate that the 2022‐like heatwave becomes six to seven times more likely under persistent high‐pressure conditions when compared to stochastic circulation states. Due to a shift toward warmer mean temperatures and a flattening of the probability distribution function, such rare extreme heatwaves are projected to become much more common at a global warming level of 4°C, occurring once about every 8.5 years.

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“…Meanwhile, the rising trend of H may, at least partly, be responsible for the frequent occurrence of "extremely strong" subtropical high events in recent years, such as the extremely strong WNPSH events in 2020 (e.g., Takaya et al 2020;Qiao et al 2021;Zhou et al 2021;Shi and Fang 2022), 2021 (Ke et al 2022;Ma et al 2022;Zhang et al 2022b) and 2022 (Chen and Li 2023;Li et al 2023;Tang et al 2023;Zhang et al 2023) based on H anomaly or characteristic H contour. This is because a recent year is compared with a "climate normal" based on past decades in attribution studies, and the strong rising trend of H may push the H anomaly (and also the anomalous AI for subtropical high) in recent years toward a positive anomaly in comparison to a past "climate normal" (Livezey et al 2007;Arguez and Vose 2011;Rahmstorf and Coumou 2011;Hansen et al 2012).…”

Section: Relating Past and Future Evolution Of H To Ts Changementioning

confidence: 99%

Rising geopotential height under global warming

He,

Chen,

Collins

et al. 2023

Preprint

0

View full text Add to dashboard Cite

Geopotential height (H) is a widely used metric for atmospheric circulation. H has been reported to be rising under global warming, but the amplitude and mechanism of this rise are not clear. Based on reanalysis datasets and climate models participating in CMIP6, this study quantitatively evaluates the sensitivity of H to global mean surface air temperature (Ts), i.e., dH/dTs. Reanalysis datasets and model simulations consistently show that dH/dTs increases monotonically with altitude in the troposphere, with a global averaged value of about 24.5 gpm/K at 500 hPa, which overwhelms the interannual H variability. Diagnosis based on the hypsometric equation shows that the rise in H is dominated by temperature-driven expansion, i.e., expansion of the air column due to warming-induced reduction of air density, while moisture-driven expansion and the surface pressure effect play only minor roles. Therefore, the magnitude of dH/dTs is determined largely by a vertical integration of the warming profile below the pressure level. Since the anthropogenic forced rise in H is rather horizontally uniform and proportional to Ts change, past and projected future changes in the global H field at each pressure level can be reproduced by change in Ts multiplied by a constant historical dH/dTs value. The spatially uniform rise in H reproduces the past and projected future expansion of the widely used H=5880 gpm contour at 500 hPa, suggesting that it does not indicate enhancement of the subtropical high but is simply caused by thermal expansion of the atmosphere.

show abstract

Impact of extremely warm Tibetan Plateau in spring on the rare rainfall anomaly pattern in the regions west and east to Plateau in late summer 2022

Cited by 7 publications

References 56 publications

Rising geopotential height under global warming

Rising geopotential height under global warming

How Unexpected Was the 2022 Summertime Heat Extremes in the Middle Reaches of the Yangtze River?

Rising geopotential height under global warming

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