Response of trace gases to the disrupted 2015–2016 quasi-biennial oscillation

Abstract. The quasi-biennial oscillation (QBO) is a quasiperiodic alternation between easterly and westerly zonal winds in the tropical stratosphere, propagating downward from the middle stratosphere to the tropopause with a period that varies from 24 to 32 months ( ∼  28 months on average). The QBO wind oscillations affect the distribution of chemical constituents, such as ozone (O3), water vapor (H2O), nitrous oxide (N2O), and hydrochloric acid (HCl), through the QBO-induced meridional circulation. In the 2015–2016 winter, radiosonde observations revealed an anomaly in the downward propagation of the westerly phase, which was disrupted by the upward displacement of the westerly phase from ∼  30 hPa up to 15 hPa and the sudden appearance of easterlies at 40 hPa. Such a disruption is unprecedented in the observational record from 1953 to the present. In this study we show the response of trace gases to this QBO disruption using O3, HCl, H2O, and temperature from the Aura Microwave Limb Sounder (MLS) and total ozone measurements from the Solar Backscatter Ultraviolet (SBUV) Merged Ozone Data Set (MOD). Results reveal the development of positive anomalies in stratospheric equatorial O3 and HCl over ∼  50–30 hPa in May–September of 2016 and a substantial decrease in O3 in the subtropics of both hemispheres. The SBUV observations show near-record low levels of column ozone in the subtropics in 2016, resulting in an increase in the surface UV index during northern summer. Furthermore, cold temperature anomalies near the tropical tropopause result in a global decrease in stratospheric water vapor.

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Response of Trace Gases to the Disrupted 2015–2016 Quasi-Biennial Oscillation

10.5194/acp-2017-76 ◽

2017 ◽

Author(s):

Olga V. Tweedy ◽

Natalya A. Kramarova ◽

Susan E. Strahan ◽

Paul A. Newman ◽

Lawrence Coy ◽

...

Keyword(s):

Water Vapor ◽

Chemical Constituents ◽

Trace Gases ◽

Quasi Biennial Oscillation ◽

Data Set ◽

Uv Index ◽

Stratospheric Water Vapor ◽

Northern Summer ◽

Tropical Tropopause ◽

Biennial Oscillation

Abstract. The quasi-biennial oscillation (QBO) is a quasi-periodic alternation between easterly and westerly zonal winds in the tropical stratosphere, propagating downward from the middle stratosphere to the tropopause with a period that varies from 24 to 32 months (∼28 months on average). The QBO wind oscillations affect the distribution of chemical constituents, such as ozone (O3), water vapor (H2O), nitrous oxide (N2O) and hydrochloric acid (HCl), through the QBO induced meridional circulation. In the 2015–2016 winter, radiosonde observations revealed an anomaly in the downward propagation of the westerly phase, which was disrupted by the upward displacement of the westerly phase from ∼30 hPa up to 15 hPa, and the sudden appearance of easterlies at 40 hPa. Such a disruption is unprecedented in the observational record from 1953–present. In this study we show the response of trace gases to this QBO disruption using O3, HCl, H2O and temperature from the Aura Microwave Limb Sounder (MLS) and total ozone measurements from the Solar Backscatter Ultraviolet (SBUV) Merged Ozone Data Set (MOD). Results reveal development of positive anomalies in stratospheric equatorial O3 and HCl over ∼50–30 hPa in May–September of 2016 and a substantial decrease in O3 in the subtropics of both hemispheres. The SBUV observations show near record low levels of column ozone in the subtropics in 2016, resulting in an increase of surface UV index during northern summer. Furthermore, cold temperature anomalies near the tropical tropopause result in a global decrease in stratospheric water vapor.

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Contribution of different processes to changes in tropical lower-stratospheric water vapor in chemistry–climate models

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-8031-2017 ◽

2017 ◽

Vol 17 (13) ◽

pp. 8031-8044 ◽

Cited By ~ 12

Author(s):

Kevin M. Smalley ◽

Andrew E. Dessler ◽

Slimane Bekki ◽

Makoto Deushi ◽

Marion Marchand ◽

...

Keyword(s):

Water Vapor ◽

Regression Model ◽

21St Century ◽

Climate Models ◽

Quasi Biennial Oscillation ◽

Tropical Tropopause Layer ◽

Stratospheric Water Vapor ◽

Tropical Tropopause ◽

The Impact

Abstract. Variations in tropical lower-stratospheric humidity influence both the chemistry and climate of the atmosphere. We analyze tropical lower-stratospheric water vapor in 21st century simulations from 12 state-of-the-art chemistry–climate models (CCMs), using a linear regression model to determine the factors driving the trends and variability. Within CCMs, warming of the troposphere primarily drives the long-term trend in stratospheric humidity. This is partially offset in most CCMs by an increase in the strength of the Brewer–Dobson circulation, which tends to cool the tropical tropopause layer (TTL). We also apply the regression model to individual decades from the 21st century CCM runs and compare them to a regression of a decade of observations. Many of the CCMs, but not all, compare well with these observations, lending credibility to their predictions. One notable deficiency is that most CCMs underestimate the impact of the quasi-biennial oscillation on lower-stratospheric water vapor. Our analysis provides a new and potentially superior way to evaluate model trends in lower-stratospheric humidity.

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Effects of tropical deep convection on interannual variability of tropical tropopause layer water vapor

10.5194/acp-2017-951 ◽

2017 ◽

Cited By ~ 1

Author(s):

Hao Ye ◽

Andrew E. Dessler ◽

Wandi Yu

Keyword(s):

Water Vapor ◽

Interannual Variability ◽

Deep Convection ◽

Tropospheric Temperature ◽

Quasi Biennial Oscillation ◽

Tropical Tropopause Layer ◽

Tropical Tropopause ◽

Tropical Deep Convection ◽

The Impact ◽

Biennial Oscillation

Abstract. Water vapor interannual variability in the tropical tropopause layer (TTL) is investigated using satellite observations and model simulations. We breakdown the influences of the Brewer-Dobson circulation (BDC), the quasi-biennial oscillation (QBO), and the tropospheric temperature (ΔT) as a function of latitude and longitude using a 2-dimensional multivariable linear regression. This allows us to examine the spatial distribution of the impact on TTL water vapor from these physical processes. In agreement with expectation, we find that the impacts from the BDC and QBO act on TTL water vapor by changing TTL temperature. For ΔT, we find that TTL temperatures alone cannot explain the influence. We hypothesize a moistening role for the evaporation of convective ice from increased deep convection as troposphere warms. Tests with simulations from GEOSCCM and a corresponding trajectory model support this hypothesis.

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Variability of the Brewer-Dobson circulation's meridional and vertical branch using Aura/MLS water vapor

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-21291-2012 ◽

2012 ◽

Vol 12 (8) ◽

pp. 21291-21320 ◽

Cited By ~ 1

Author(s):

T. Flury ◽

D. L. Wu ◽

W. G. Read

Keyword(s):

Time Series ◽

Water Vapor ◽

Lower Stratosphere ◽

Meridional Circulation ◽

Time Lag ◽

Quasi Biennial Oscillation ◽

Stratospheric Water Vapor ◽

One Year ◽

The Tropics ◽

Biennial Oscillation

Abstract. We use Aura/MLS stratospheric water vapor measurements to infer interannual variations in the speed of the Brewer-Dobson circulation (BDC) from 2004 to 2011. Stratospheric water vapor (H2O) is utilized as a tracer for dynamics and we follow its path along the vertical and meridional branch of the BDC from the tropics to mid-latitudes. We correlate one year time series of H2O in the lower stratosphere at two subsequent altitude levels (68 hPa, ~18.8 km and 56 hPa, ~19.9 km at the Equator) and determine the time lag for best correlation. The same calculation is made on the horizontal on the 100 hPa (~16.6 km) level by correlating the H2O time series at the Equator with the ones at 40° N and 40° S. From these lag coefficients we derive the vertical and horizontal speeds of the BDC in the tropics and extra-tropics respectively. We observe a clear interannual variability of the vertical and horizontal branch. The variability reflects signatures of the Quasi Biennial Oscillation (QBO). Our measurements confirm the QBO meridional circulation anomalies and show that the speed variations in the two branches of the BDC are out of phase and fairly well anti-correlated. Maximum ascent rates are found during the QBO easterly phase. We also find that the transport towards the Northern Hemisphere (NH) is on the average two times faster than to the Southern Hemisphere (SH) with a mean speed of 1.15 m s−1 at 100 hPa. Furthermore, the speed towards the NH shows much more variability with an amplitude of about 21% whilst the speed towards the SH varies by only 10%. An amplitude of 21% is also observed in the variability of the ascent rate at the Equator which is on the average 0.2 mm s−1 and hence about 5000 times slower than the meridional branch.

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Response of stratospheric water vapor and ozone to the unusual timing of El Niño and the QBO disruption in 2015–2016

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-13055-2018 ◽

2018 ◽

Vol 18 (17) ◽

pp. 13055-13073 ◽

Cited By ~ 16

Author(s):

Mohamadou Diallo ◽

Martin Riese ◽

Thomas Birner ◽

Paul Konopka ◽

Rolf Müller ◽

...

Keyword(s):

Water Vapor ◽

El Niño ◽

Lower Stratosphere ◽

El Nino ◽

Trace Gases ◽

Enso Event ◽

Quasi Biennial Oscillation ◽

Stratospheric Water Vapor ◽

Enso Events ◽

The Impact

Abstract. The stratospheric circulation determines the transport and lifetime of key trace gases in a changing climate, including water vapor and ozone, which radiatively impact surface climate. The unusually warm El Niño–Southern Oscillation (ENSO) event aligned with a disrupted Quasi-Biennial Oscillation (QBO) caused an unprecedented perturbation to this circulation in 2015–2016. Here, we quantify the impact of the alignment of these two phenomena in 2015–2016 on lower stratospheric water vapor and ozone from satellite observations. We show that the warm ENSO event substantially increased water vapor and decreased ozone in the tropical lower stratosphere. The QBO disruption significantly decreased global lower stratospheric water vapor and tropical ozone from early spring to late autumn. Thus, this QBO disruption reversed the lower stratosphere moistening triggered by the alignment of the warm ENSO event with westerly QBO in early boreal winter. Our results suggest that the interplay of ENSO events and QBO phases will be crucial for the distributions of radiatively active trace gases in a changing future climate, when increasing El Niño-like conditions and a decreasing lower stratospheric QBO amplitude are expected.

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Impact of stratospheric major warmings and the quasi‐biennial oscillation on the variability of stratospheric water vapor

Geophysical Research Letters ◽

10.1002/2015gl064443 ◽

2015 ◽

Vol 42 (11) ◽

pp. 4599-4607 ◽

Cited By ~ 13

Author(s):

Mengchu Tao ◽

Paul Konopka ◽

Felix Ploeger ◽

Martin Riese ◽

Rolf Müller ◽

...

Keyword(s):

Water Vapor ◽

Quasi Biennial Oscillation ◽

Stratospheric Water Vapor ◽

Biennial Oscillation

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Modeling upper tropospheric and lower stratospheric water vapor anomalies

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-9653-2013 ◽

2013 ◽

Vol 13 (4) ◽

pp. 9653-9679 ◽

Cited By ~ 1

Author(s):

M. R. Schoeberl ◽

A. E. Dessler ◽

T. Wang

Keyword(s):

Water Vapor ◽

Lower Stratosphere ◽

Calculation Model ◽

Vapor Concentration ◽

Cold Temperatures ◽

Tropical Tropopause Layer ◽

Stratospheric Water Vapor ◽

Tropical Tropopause ◽

Minimum Displacement ◽

Asian Monsoons

Abstract. The domain-filling, forward trajectory calculation model developed by Schoeberl and Dessler (2011) is used to further investigate processes that produce upper tropospheric and lower stratospheric water vapor anomalies. We examine the pathways parcels take from the base of the tropical tropopause layer (TTL) to the lower stratosphere. Most parcels found in the lower stratosphere arise from East Asia, the Tropical West Pacific (TWP) and the Central/South America. The belt of TTL parcel origins is very wide compared to the final dehydration zones near the top of the TTL. This is due to the convergence of rising air as a result of the stronger diabatic heating near the tropopause relative to levels above and below. The observed water vapor anomalies – both wet and dry – correspond to regions where parcels have minimal displacement from their initialization. These minimum displacement regions include the winter TWP and the Asian and American monsoons. To better understand the stratospheric water vapor concentration we introduce the water vapor spectrum and investigate the source of the wettest and driest components of the spectrum. We find that the driest air parcels that originate below the TWP, moving upward to dehydrate in the TWP cold upper troposphere. The wettest air parcels originate at the edges of the TWP as well as the summer American and Asian monsoons. The wet air parcels are important since they skew the mean stratospheric water vapor distribution toward higher values. Both TWP cold temperatures that produce dry parcels as well as extra-TWP processes that control the wet parcels determine stratospheric water vapor.

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Processes Controlling Tropical Tropopause Temperature and Stratospheric Water Vapor in Climate Models

Journal of Climate ◽

10.1175/jcli-d-15-0075.1 ◽

2015 ◽

Vol 28 (16) ◽

pp. 6516-6535 ◽

Cited By ~ 29

Author(s):

Steven C. Hardiman ◽

Ian A. Boutle ◽

Andrew C. Bushell ◽

Neal Butchart ◽

Mike J. P. Cullen ◽

...

Keyword(s):

Water Vapor ◽

Climate Models ◽

Atmospheric Composition ◽

Stratospheric Water Vapor ◽

Vertical Advection ◽

Radiative Processes ◽

Microphysical Properties ◽

Tropical Tropopause ◽

The Tropics ◽

Tropopause Temperature

Abstract A warm bias in tropical tropopause temperature is found in the Met Office Unified Model (MetUM), in common with most models from phase 5 of CMIP (CMIP5). Key dynamical, microphysical, and radiative processes influencing the tropical tropopause temperature and lower-stratospheric water vapor concentrations in climate models are investigated using the MetUM. A series of sensitivity experiments are run to separate the effects of vertical advection, ice optical and microphysical properties, convection, cirrus clouds, and atmospheric composition on simulated tropopause temperature and lower-stratospheric water vapor concentrations in the tropics. The numerical accuracy of the vertical advection, determined in the MetUM by the choice of interpolation and conservation schemes used, is found to be particularly important. Microphysical and radiative processes are found to influence stratospheric water vapor both through modifying the tropical tropopause temperature and through modifying upper-tropospheric water vapor concentrations, allowing more water vapor to be advected into the stratosphere. The representation of any of the processes discussed can act to significantly reduce biases in tropical tropopause temperature and stratospheric water vapor in a physical way, thereby improving climate simulations.

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Revisiting the factors that drive interannual variability in stratospheric entry water vapour

10.5194/egusphere-egu2020-5231 ◽

2020 ◽

Author(s):

Shlomi Ziskin Ziv ◽

Chaim I. Garfinkel

Keyword(s):

Water Vapor ◽

Interannual Variability ◽

Large Scale ◽

Trace Gases ◽

Transport Processes ◽

Tropospheric Temperature ◽

Stratospheric Water Vapor ◽

Cold Point ◽

Stratospheric Trace Gases

<p>Understanding the sinks, sources and transport processes of stratospheric trace gases can improve our prediction of mid to long term climate change. In this study we consider the processes that lead to variability in stratospheric water vapor. We perform a Multiple Linear Regression(MLR) on the SWOOSH combined anomaly filled water vapor product with ENSO, QBO, BDC, mid-tropospheric temperature, and CH4 as predictors, in an attempt to find the factors that most succinctly explain observed water vapor variability. We also consider the fraction of entry water vapor variability that can be accounted for by variations of the cold point temperature as an upper bound on how much water vapor variability is predictable from large scale processes. Several periods in which the MLR fails to account for interannual variability are treated as case studies in order to better understand variability in entry water not governed by these large scale processes.</p>

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