Observations of middle atmospheric seasonal variations and study of atmospheric oscillations at equatorial regions

Patel, Nisha; Sharma, Som; Joshi, Vaidehi; Kumar, Prashant; Ojha, Narendra; Kumar, Kondapalli Niranjan; Chandra, H.; Beig, Gufran

doi:10.1016/j.jastp.2019.105066

Cited by 1 publication

(1 citation statement)

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“…The QBO temperature signal in the TTL is relatively small (±0.5 K at the CPT) compared to the corresponding stratospheric variations (±4 K at 25 km) and maximizes between 10°S to 10°N (e.g., Randel & Wu, 2015). In general, the QBO is zonally symmetric, however, studies have suggested some longitudinal variations in middle stratospheric temperature (Patel et al, 2019) and wind (Hamilton et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Zonal Asymmetry of the QBO Temperature Signal in the Tropical Tropopause Region

Tegtmeier

Anstey

Davis

et al. 2020

Geophysical Research Letters

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The quasi-biennial oscillation (QBO) of the equatorial zonal wind leads to zonally symmetric temperature variations in the stratosphere that descend downward. Here we investigate the QBO-induced temperature anomalies in the tropical tropopause layer (TTL) and detect pronounced longitudinal variations of the signal. In addition, the QBO temperature anomalies show a strong seasonal variability. The magnitude of these seasonal and longitudinal QBO variations is comparable to the magnitude of the well-known zonal mean QBO signal in the TTL. At the cold point tropopause, the strongest QBO variations of around ±1.6 K are found over regions of active convection such as the West Pacific and Africa during boreal winter. The weakest QBO variations of ±0.25 K are detected over the East Pacific during boreal summer, while the zonal mean signal ranges around ±0.7 K. The longitudinal variations are associated with enhanced convective activity that occurs during QBO cold phases and locally enhances the cold anomalies. Plain Language Summary Temperatures in the tropical stratosphere, the atmospheric region between 20°S and 20°N and above 18 km, oscillate between colder and warmer conditions with a full cycle taking about 28 months on average. Observations over the last decades have shown that the strength of this so-called quasi-biennial oscillation of stratospheric temperature is similar for all longitudes within the tropics. The temperature variations extend downward into the region that connects the stratosphere with troposphere. We show that in this transition region between the two atmospheric layers, the temperature oscillations can be stronger or weaker depending on the geographical position along the equator. Especially strong temperature oscillations are found over regions of frequently occurring thunderstorms such as the West Pacific and Africa. The fact that a stratospheric signal such as the quasi-biennial oscillation is linked with thunderstorms has implications for understanding how the upper atmosphere can impact tropical weather phenomena.

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Section: Introductionmentioning

confidence: 99%