ACP - The semi-annual oscillation (SAO) in the upper troposphere

Abstract. Both the scientific and operational communities are increasingly interested in subseasonal to seasonal variations of weather and climate. The semi-annual oscillation (SAO) has been studied extensively at the surface as well as in the middle atmosphere (upper stratosphere and the lower mesosphere). However, the SAO in the upper troposphere and lower stratosphere (UTLS) has been less discussed. Here we find evident SAO of temperature in the UTLS (250–175 hPa) from the subtropics to middle latitudes (22.5–42.5∘) using high-quality satellite measurements, reanalysis data, and model simulations. We show the mechanism of its formation by an energy budget analysis. The temperature in the Northern Hemisphere (NH) UTLS shows the first peak in February according to the dynamical heating and shows the second peak in July due to the dynamical heating and moist processes. Similar to the NH, the austral winter time maximum temperature in the Southern Hemisphere (SH) is related to dynamical heating and the austral summer time maximum is related to both moisture and dynamical heating in the UTLS. Model simulations indicate that the SAO in the UTLS is partly affected by the existence of an SAO in sea surface temperatures (SSTs) in the SH mid-latitudes and weakly affected by the SAO in SSTs in the NH mid-latitudes.

A quasi-27-day oscillation activity from the troposphere to the mesosphere and lower thermosphere at low latitudes, Earth, Planets and Space

QBO Aliased Harmonics

Wave Forcing of the Quasi-Biennial Oscillation in the Max Planck Institute Earth System Model in: Journal of the Atmospheric Sciences Volume 71 Issue 6 (2014)

a) Buoyancy frequency (N 2 ) calculated from climatological annual

ACP - Representation of the equatorial stratopause semiannual oscillation in global atmospheric reanalyses

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PDF) Does the coupling of the semiannual oscillation with the quasi-biennial oscillation provide predictability of Antarctic sudden stratospheric warmings?

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A quasi-27-day oscillation activity from the troposphere to the mesosphere and lower thermosphere at low latitudes, Earth, Planets and Space

1: Long-term means of zonally asymmetric components of (a, top left) 2

Changing patterns in aerosol vertical distribution over South and East Asia

Interannual variability of mesopause zonal winds over Ascension Island: Coupling to the stratospheric QBO - Wit - 2013 - Journal of Geophysical Research: Atmospheres - Wiley Online Library

The Quasi-Biennial zonal wind Oscillation (QBO)

Semiannual Oscillation - an overview