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

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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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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Upwelling into the lower stratosphere forced by breaking tropical waves: evidence from chemical tracers

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-19571-2012 ◽

2012 ◽

Vol 12 (8) ◽

pp. 19571-19615 ◽

Cited By ~ 1

Author(s):

Z. Engida ◽

I. Folkins

Keyword(s):

Water Vapor ◽

Spatial Pattern ◽

Lower Stratosphere ◽

Time Window ◽

Time Windows ◽

Time Lag ◽

Time Lags ◽

Quasi Biennial Oscillation ◽

Stratospheric Water Vapor ◽

Temperature Anomalies

Abstract. Measurements from the Microwave Limb Sounder (MLS) on the 68 hPa pressure level from 1 January 2005 to 31 December 2010 are used to calculate the coherence between anomalies in the tropical mean mixing ratios of H2O, CO, and N2O, and 100 hPa temperature. We show that the fluctuations of lower stratospheric water vapor in the subseasonal and multiyear time windows are generated by different physical mechanisms. In the subseasonal time window, the spatial pattern of the coherence between 100 hPa temperature and water vapor, and the time lag, show that the variability in lower stratospheric water vapor is dominated by fluctuations in upwelling forced by the dissipation of tropical Rossby waves. In the multiyear time window, the variability of lower stratospheric water vapor is more strongly coherent with temperature fluctuations on the 100 hPa surface in regions where the annual mean temperature is colder than 194 K. In addition, the 68 hPa water vapor anomalies lag the 100 hPa temperature anomalies by roughly 140 days. In this time window, the variability of lower stratospheric water vapor is therefore dominated by changes in the temperature dependent dehydration efficiency which modulate the water vapor stratospheric entry mixing ratio. On subseasonal timescales, the spatial pattern of the coherence between 100 hPa temperature and 68 hPa CO anomalies is very similar to the pattern of coherence between 100 hPa temperature and the Real-time Multivariate MJO series 1 (RMM1) index of the Madden Julian Oscillation (MJO). The MJO therefore has a strong influence on the subseasonal variability of CO in the lower stratosphere. The subseasonal 68 hPa CO and H2O anomalies lag the 100 hPa temperature anomalies by 3.16 and 2.51 days, respectively. The similarity between the two time lags suggests that the subseasonal CO anomalies can also be attributed to changes in upwelling. The multiyear variability in lower stratospheric N2O appears to be dominated by the Quasi Biennial Oscillation (QBO).

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Interannual Variations of Stratospheric Water Vapor in MLS Observations and Climate Model Simulations

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-14-0164.1 ◽

2014 ◽

Vol 71 (11) ◽

pp. 4072-4085 ◽

Cited By ~ 15

Author(s):

Yoshio Kawatani ◽

Jae N. Lee ◽

Kevin Hamilton

Keyword(s):

Water Vapor ◽

Climate Model ◽

Coupled Model ◽

Vertical Gradient ◽

Quasi Biennial Oscillation ◽

Model Simulations ◽

Stratospheric Water Vapor ◽

Budget Analysis ◽

Climate Model Simulations ◽

Interannual Fluctuations

Abstract By analyzing the almost-decade-long record of water vapor measurements from the Microwave Limb Sounder (MLS) instrument on the NASA Aura satellite and by detailed diagnostic analysis of the results from state-of-the art climate model simulations, this study confirmed the conceptual picture of the interannual variation in equatorial stratospheric water vapor discussed in earlier papers (e.g., Geller et al.). The interannual anomalies in water vapor are strongly related to the dynamical quasi-biennial oscillation (QBO), and this study presents the first QBO composite of the time–height structure of the equatorial water vapor anomalies. The anomalies display upward propagation below about 10 hPa in a manner analogous to the annual “tape recorder” effect, but at higher levels they show clear downward propagation. This study examined these variations in the Model for Interdisciplinary Research on Climate (MIROC)-AGCM and in four models in phase 5 of the Coupled Model Intercomparison Project (CMIP5) that simulate realistic QBOs. Diagnostic budget analysis of the MIROC-AGCM data and comparisons among the CMIP5 model results demonstrate (i) the importance of temperature anomalies at the tropopause induced by the QBO for lower-stratospheric water vapor variations and (ii) that upper-stratospheric water vapor anomalies are largely driven by advection of the mean vertical gradient of water content by the QBO interannual fluctuations in the vertical wind.

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

10.5194/acp-2018-239 ◽

2018 ◽

Cited By ~ 1

Author(s):

Mohamadou Diallo ◽

Martin Riese ◽

Thomas Birner ◽

Paul Konopka ◽

Rolf Müller ◽

...

Keyword(s):

Water Vapor ◽

Greenhouse Gases ◽

El Niño ◽

Lower Stratosphere ◽

El Nino ◽

Enso Event ◽

Quasi Biennial Oscillation ◽

Stratospheric Water Vapor ◽

Enso Events ◽

The Impact

Abstract. The stratospheric circulation determines the transport and lifetime of key greenhouse gases, 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 increases water vapor and decreases ozone in the tropical lower stratosphere. The QBO disruption significantly decreases global lower stratospheric water vapor and tropical ozone from early spring to late autumn. Thus, this QBO disruption reverses 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 greenhouse gases in a changing future climate, when increasing El Niño-like conditions and decreasing lower stratospheric QBO amplitude are expected.

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Multi-timescale variations of modelled stratospheric water vapor derived from three modern reanalysis products

10.5194/acp-2019-39 ◽

2019 ◽

Author(s):

Mengchu Tao ◽

Paul Konopka ◽

Felix Ploeger ◽

Xiaolu Yan ◽

Jonathon S. Wright ◽

...

Keyword(s):

Water Vapor ◽

Lower Stratosphere ◽

Southern Oscillation ◽

Radiation Budget ◽

Lagrangian Model ◽

Linear Regression Method ◽

Positive Trend ◽

Volcanic Aerosol ◽

Quasi Biennial Oscillation ◽

Stratospheric Water Vapor

Abstract. Stratospheric water vapor (SWV) plays important roles in the radiation budget and ozone chemistry and is a valuable tracer for understanding stratospheric transport. Meteorological reanalyses provide variables necessary for simulating this transport; however, even recent reanalyses are subject to substantial uncertainties, especially in the stratosphere. It is therefore necessary to evaluate the consistency among SWV distributions simulated using different input reanalysis products. In this study, we evaluate the representation of SWV and its variations on multiple timescales using simulations over the period 1980–2013. Our simulations are based on the Chemical Lagrangian Model of the Stratosphere (CLaMS) driven by horizontal winds and diabatic heating rates from three recent reanalyses: ERA-Interim, JRA-55 and MERRA-2. We present an inter-comparison among these model results and observationally-based estimates, using a multiple linear regression method to study the annual cycle (AC), the quasi-biennial oscillation (QBO), and longer-term variability in monthly zonal-mean H2O mixing ratios forced by variations in the El-Nino–Southern Oscillation and the volcanic aerosol burden. We find reasonable consistency among simulations of the distribution and variability of SWV with respect to the AC and QBO. However, the amplitudes of both signals are systematically weaker in the lower and middle stratosphere when CLaMS is driven by MERRA-2 than when it is driven by ERA-Interim or JRA-55. This difference is primarily attributable to relatively slow tropical upwelling in the lower stratosphere in simulations based on MERRA-2. Two possible contributors of the slow tropical upwelling in the lower stratosphere are found to be the large long-wave radiative effect and the unique assimilation process in MERRA-2. The impacts of ENSO and volcanic aerosol on H2O entry variability are qualitatively consistent among the three simulations despite differences of 50–100 % in the magnitudes. Trends show larger discrepancies among the three simulations. CLaMS driven by ERA-Interim produces a neutral to slightly positive trend in H2O entry values over 1980–2013 (&plus;0.01 ppmv decade-1), while both CLaMS driven by JRA-55 and CLaMS driven by MERRA-2 produce negative trends but with significantly different magnitudes (−0.22 ppmv decade-1 and −0.08 ppmv decade-1, respectively).

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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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