The semi-annual oscillation (SAO) in the upper troposphere and lower stratosphere (UTLS)

Shangguan, Ming; Wang, Wuke

doi:10.5194/acp-22-9499-2022

Cited by 3 publications

(1 citation statement)

References 60 publications

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“…On an extended timescale, anomalies in stratospheric circulation patterns descending to the troposphere induce extensive surface cold outbreaks [7]. Over seasonal or semi-annual scales, a linkage exists between the semi-annual oscillation (SAO) signal of temperatures in the mid-latitude upper-troposphere-lower-stratosphere region and the SAO signal of sea surface temperatures in extratropical regions [31]. Furthermore, events involving Rossby wave breaking near the tropopause contribute to the exchange of materials between the stratosphere and troposphere [32,33], representing a distinct facet of their interaction.…”

Section: Introductionmentioning

confidence: 99%

Types of Coupling between the Stratospheric Polar Vortex and Tropospheric Polar Vortex, and Tropospheric Circulation Anomalies Associated with Each Type in Boreal Winter

Han,

Shi,

Guo

2023

Remote Sensing

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Fifty years of daily ERA5 reanalysis data are employed to investigate the linkages between the strength of the stratospheric polar vortex and the tropospheric polar vortex during the boreal winter. The strong coupling events, anomalies in both the stratospheric and tropospheric polar vortices, can be classified into four configurations, each representing the distinct characteristics of planetary wave vertical propagation and tropospheric circulation anomalies. The findings reveal the following patterns: (1) Strong stratospheric polar vortex and weak tropospheric polar vortex periods are associated with anomalous downward E-P flux from the stratosphere to the troposphere, predominantly induced by planetary waves 1 and 2. Warm anomalies occur along the North Atlantic coasts, while cold anomalies are evident over Eastern Europe and East Asia at the surface. (2) Weak stratospheric polar vortex and strong tropospheric polar vortex periods exhibit anomalous upward E-P flux in high latitudes, with dominant wave 1, and anomalous downward E-P flux in the middle latitudes, dominated by wave 2. Warm anomalies are observed over North America, Western Europe, and the northern side of the Gulf of Oman at the surface. (3) Strong stratospheric polar vortex and strong tropospheric polar vortex periods feature anomalous downward E-P flux in high latitudes, dominated by wave 1, and anomalous upward E-P flux in middle latitudes, with a wave 2 predominance. Warm anomalies prevail over Northeast Asia, Southern Europe, and North America at the surface. (4) Weak stratospheric polar vortex and weak tropospheric polar vortex periods display anomalous upward E-P flux in mid-to-high latitudes, predominantly with wave 1. In contrast to the tropospheric circulation anomalies observed in the third category, this pattern results in the presence of cold anomalies over Northeast Asia, Southern Europe, and North America.

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Section: Introductionmentioning

confidence: 99%

Types of Coupling between the Stratospheric Polar Vortex and Tropospheric Polar Vortex, and Tropospheric Circulation Anomalies Associated with Each Type in Boreal Winter

Han,

Shi,

Guo

2023

Remote Sensing

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Study on long term troposphere lower stratosphere temperature (TLST) trend in tropical and subtropical northern hemisphere using ground based and COSMIC satellite data

Negash,

Raju

2024

Journal of Atmospheric and Solar-Terrestrial Physics

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Analysis of Temperature Semi-Annual Oscillations (SAO) in the Middle Atmosphere

Shangguan

Wang

2023

Remote Sensing

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The middle atmosphere plays an important role in the research of various dynamical and energy processes. Microwave Limb Sounder (MLS), reanalyses and model simulations with NCAR’s Whole Atmosphere Community Climate Model (WACCM) data in the range between 100 and 0.1 hPa from 2005 to 2020 have been analyzed with a focus on the temperature semi-annual oscillations (SAO). Significant SAO of temperature is prominent in the tropical region (20°S–20°N) around 1–3 hPa, which is consistent with previous studies. We also found significant SAO in the northern hemisphere (NH) high latitudes between 8 and 0.3 hPa and southern hemisphere (SH) high latitudes between 0.5 and 0.1 hPa, which has been of less concern in previous studies. The thermal budget based on MERRA2 and simulations is used to explain the mechanism of SAO in the middle atmosphere. In the tropics, the two temperature peaks are mainly determined by radiative processes. In the NH high latitudes of the stratosphere, the temperature peak in January is mainly related to dynamical processes, while the temperature peak in July is determined by a combination of dynamical and radiative processes. In the NH high latitudes of the lower mesosphere, the first peak in June is primarily associated with dynamical and radiative processes, while the second peak in December is primarily associated with the dynamical processes. In the SH high latitudes of the lower mesosphere, the first temperature peak in July is mainly due to dynamical processes while the second temperature peak in December is mainly due to radiative processes. Various features are present in the SH and NH high latitude SAO in the lower mesosphere. Furthermore, we performed model simulations with and without SAO in sea surface temperatures (SST-SAO) to study the connection between SST and temperature SAO. WACCM6 results indicate that the SAO in the middle atmosphere is partially affected by the existence of an SST-SAO. By removing SAO in SST, the PSD magnitude of the SAO decreases in the tropical region and increases in the polar region. The amplitudes of total heating rates are also modified. The WACCM experiment confirms the relationship between SST-SAO and temperature SAO in the middle atmosphere.

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The semi-annual oscillation (SAO) in the upper troposphere and lower stratosphere (UTLS)

Cited by 3 publications

References 60 publications

Types of Coupling between the Stratospheric Polar Vortex and Tropospheric Polar Vortex, and Tropospheric Circulation Anomalies Associated with Each Type in Boreal Winter

Types of Coupling between the Stratospheric Polar Vortex and Tropospheric Polar Vortex, and Tropospheric Circulation Anomalies Associated with Each Type in Boreal Winter

Study on long term troposphere lower stratosphere temperature (TLST) trend in tropical and subtropical northern hemisphere using ground based and COSMIC satellite data

Analysis of Temperature Semi-Annual Oscillations (SAO) in the Middle Atmosphere

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