Preprints
https://doi.org/10.5194/egusphere-2023-2196
https://doi.org/10.5194/egusphere-2023-2196
13 Oct 2023
 | 13 Oct 2023

Moist bias in the Pacific upper troposphere and lower stratosphere (UTLS) in climate models affects regional circulation patterns

Felix Ploeger, Thomas Birner, Edward Charlesworth, Paul Konopka, and Rolf Müller

Abstract. Water vapour in the upper troposphere and lower stratosphere is a key radiative agent and crucial factor in the Earth's climate system. The largest observed moisture anomaly in the lower stratosphere occurs in boreal summer in the Asian monsoon region, but global climate models face problems with simulating this moisture pattern and show a common regional moist bias above the Pacific. We demonstrate from combination of climate model experiments and atmospheric observations that the enhanced moisture in the Pacific lower stratosphere critically impacts regional circulation systems by inducing local longwave cooling. Related impacts involve a strengthening of isentropic potential vorticity gradients, strengthened westerlies in the Pacific westerly duct region, and a zonally extended anticyclonic monsoon circulation. Hence, improving regional biases in climate model simulated stratospheric water vapour appears to be an important factor for improving simulation of regional circulation systems, in particular in the Asian monsoon and Pacific region.

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Journal article(s) based on this preprint

16 Feb 2024
| ACP Letters
| Highlight paper
Moist bias in the Pacific upper troposphere and lower stratosphere (UTLS) in climate models affects regional circulation patterns
Felix Ploeger, Thomas Birner, Edward Charlesworth, Paul Konopka, and Rolf Müller
Atmos. Chem. Phys., 24, 2033–2043, https://doi.org/10.5194/acp-24-2033-2024,https://doi.org/10.5194/acp-24-2033-2024, 2024
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

There is a very strong contrast between water vapor concentrations in the stratosphere (dry) and...
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We present a novel mechanism how regional anomalies in water vapour concentrations in the upper...
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