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SUMMARY:Interannual variability in the tropical lower stratosphere - Aliso
 n Ming\, DAMTP
DTSTART:20220307T130000Z
DTEND:20220307T140000Z
UID:TALK170960@talks.cam.ac.uk
CONTACT:Prof. Jerome Neufeld
DESCRIPTION:The tropical lower stratosphere is the primary region by which
  air enters the stratosphere from the troposphere and this region exerts a
  strong control on the properties of the upwelling air and hence the wider
  stratosphere. In this talk\, I will focus on the large inter‐annual var
 iability in temperatures. To understand how this variability arises\, the 
 temperature changes are decomposed into dynamical and radiative contributi
 ons using a radiative calculation perturbed with changes in dynamical heat
 ing\, trace gases and aerosol optical depth. The temperature timeseries ob
 tained is highly correlated with a de‐seasonalized reanalaysis dataset (
 ERA5). Ozone and dynamical heating contributions are found to be equally i
 mportant\, with water vapor\, stratospheric aerosols\, and carbon dioxide 
 playing smaller roles. Prominent aspects of the temperature timeseries are
  closely reproduced\, including the 1991 Pinatubo volcanic eruption\, the 
 year‐2000 water vapor drop\, and the 2016 Quasi‐biennial oscillation (
 QBO) disruption. Below 20 hPa\, ozone is primarily controlled by transport
  and is positively correlated to the upwelling. This ozone‐transport fee
 dback acts to increase the temperature response to a change in upwelling b
 y providing an additional ozone‐induced radiative temperature change. Th
 is can be quantified as an enhancement of the dynamical heating of about 2
 0% at 70 hPa. A Principal Oscillation Pattern (POP) analysis is used to es
 timate the contribution of the ozone QBO (±1 K at 70 hPa). The non‐QBO 
 ozone variability is also shown to be significant. Using the QBO leading P
 OP timeseries as representative of the regular QBO signal\, the QBO 2016 d
 isruption is shown to have an anomalously large radiative impact on temper
 ature due to the ozone change ( > 3 K at 70 hPa).
LOCATION:MR5\, CMS
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