Modifications of the quasi-biennial oscillation by a geoengineering perturbation of the stratospheric aerosol layer

2014 ◽  
Vol 41 (5) ◽  
pp. 1738-1744 ◽  
Author(s):  
V. Aquila ◽  
C. I. Garfinkel ◽  
P.A. Newman ◽  
L.D. Oman ◽  
D.W. Waugh
Keyword(s):  
Stratospheric Aerosol ◽  
Aerosol Layer ◽  
Quasi Biennial Oscillation ◽  
Biennial Oscillation

scholarly journals Quasi-biennial oscillation of the tropical stratospheric aerosol layer

2015 ◽  
Vol 15 (10) ◽  
pp. 5557-5584 ◽  
Author(s):  
R. Hommel ◽  
C. Timmreck ◽  
M. A. Giorgetta ◽  
H. F. Graf
Keyword(s):  
Seasonal Variations ◽  
Stratospheric Aerosol ◽  
Static Balance ◽  
Aerosol Layer ◽  
Mixing Ratio ◽  
Quasi Biennial Oscillation ◽  
Mixing Ratios ◽  
Vertical Extent ◽  
Biennial Oscillation ◽  
Stratospheric Aerosols

Abstract. This study describes how aerosol in an aerosol-coupled climate model of the middle atmosphere is influenced by the quasi-biennial oscillation (QBO) during times when the stratosphere is largely unperturbed by volcanic material. In accordance with satellite observations, the vertical extent of the stratospheric aerosol layer in the tropics is modulated by the QBO by up to 6 km, or ~ 35% of its mean vertical extent between 100–7 hPa (about 16–33 km). Its largest vertical extent lags behind the occurrence of strongest QBO westerlies. The largest reduction lags behind maximum QBO easterlies. Strongest QBO signals in the aerosol surface area (30 %) and number densities (up to 100% e.g. in the Aitken mode) are found in regions where aerosol evaporates, that is above the 10 hPa pressure level (~ 31 km). Positive modulations are found in the QBO easterly shear, negative modulations in the westerly shear. Below 10 hPa, in regions where the aerosol mixing ratio is largest (50–20 hPa, or ~ 20–26 km), in most of the analysed parameters only moderate statistically significant QBO signatures (< 10%) have been found. QBO signatures in the model prognostic aerosol mixing ratio are significant at the 95% confidence level throughout the tropical stratosphere where modelled mixing ratios exceed 0.1 ppbm. In some regions of the tropical lower stratosphere the QBO signatures in other analysed parameters are partly not statistically significant. Peak-to-peak amplitudes of the QBO signature in the prognostic mixing ratios are up to twice as large as seasonal variations in the region where aerosols evaporate and between 70–30 hPa. Between the tropical tropopause and 70 hPa the QBO signature is relatively weak and seasonal variations dominate the variability of the simulated Junge layer. QBO effects on the upper lid of the tropical aerosol layer turn the quasi-static balance between processes maintaining the layer's vertical extent into a cyclic balance when considering this dominant mode of atmospheric variability. Global aerosol-interactive models without a QBO are only able to simulate the quasi-static balance state. To assess the global impact of stratospheric aerosols on climate processes, those partly nonlinear relationships between the QBO and stratospheric aerosols have to be taken into account.

scholarly journals Differences in the QBO response to stratospheric aerosol modification depending on injection strategy and species

2020 ◽  
Author(s):  
Henning Franke ◽  
Ulrike Niemeier ◽  
Daniele Visioni
Keyword(s):  
Stratospheric Ozone ◽  
Stratospheric Aerosol ◽  
Adverse Side Effect ◽  
Aerosol Layer ◽  
Quasi Biennial Oscillation ◽  
Thermal Wind ◽  
Highly Sensitive ◽  
Maximum Warming ◽  
Biennial Oscillation ◽  
Injection Strategies

Abstract. A known adverse side effect of stratospheric aerosol modification (SAM) is the modification of the quasi-biennial oscillation (QBO), which is caused by the stratospheric heating associated with an artificial aerosol layer. Multiple studies found the QBO to slow down or even completely vanish for point-like injections of SO2 at the equator. The cause for this was found to be a modification of the thermal wind balance and a stronger tropical upwelling. For other injection strategies, different responses of the QBO have been observed. It has not yet been presented a theory which is able to explain those differences in a comprehensive manner, which is further complicated by the fact that the simulated QBO response is highly sensitive to the used model even under identical boundary conditions. Therefore, within this study we investigate the response of the QBO to SAM for three different injection strategies (point-like injection at the equator, point-like injection at 30° N and 30° S simultaneously, and areal injection into a 60° wide belt along the equator). Our simulations confirm that the QBO response significantly depends on the injection location. Based on the thermal wind balance, we demonstrate that this dependency is explained by differences in the meridional structure of the aerosol-induced stratospheric warming, i.e. the location and meridional extension of the maximum warming. Additionally, we also tested two different injection species (SO2 and H2SO4). The QBO response is qualitatively similar for both investigated injection species. Comparing the results to corresponding results of a second model, we further demonstrate the generality of our theory as well as the importance of an interactive treatment of stratospheric ozone for the simulated QBO response.

scholarly journals Differences in the quasi-biennial oscillation response to stratospheric aerosol modification depending on injection strategy and species

2021 ◽  
Vol 21 (11) ◽  
pp. 8615-8635
Author(s):  
Henning Franke ◽  
Ulrike Niemeier ◽  
Daniele Visioni
Keyword(s):  
Stratospheric Ozone ◽  
Stratospheric Aerosol ◽  
Adverse Side Effect ◽  
Aerosol Layer ◽  
Quasi Biennial Oscillation ◽  
Thermal Wind ◽  
Highly Sensitive ◽  
Maximum Warming ◽  
Biennial Oscillation ◽  
Injection Strategies

Abstract. A known adverse side effect of stratospheric aerosol modification (SAM) is the alteration of the quasi-biennial oscillation (QBO), which is caused by the stratospheric heating associated with an artificial aerosol layer. Multiple studies found the QBO to slow down or even completely vanish for point-like injections of SO2 at the Equator. The cause for this was found to be a modification of the thermal wind balance and a stronger tropical upwelling. For other injection strategies, different responses of the QBO have been observed. A theory which is able to explain those differences in a comprehensive manner has not yet been presented. This is further complicated by the fact that the simulated QBO response is highly sensitive to the used model even under identical boundary conditions. Therefore, within this study we investigate the response of the QBO to SAM for three different injection strategies (point-like injection at the Equator, point-like injection at 30∘ N and 30∘ S simultaneously, and areal injection into a 60∘ wide belt along the Equator). Our simulations confirm that the QBO response significantly depends on the injection location. Based on the thermal wind balance, we demonstrate that this dependency is explained by differences in the meridional structure of the aerosol-induced stratospheric warming, i.e., the location and meridional extension of the maximum warming. Additionally, we also tested two different injection species (SO2 and H2SO4). The QBO response is qualitatively similar for both investigated injection species. Comparing the results to corresponding results of a second model, we further demonstrate the generality of our theory as well as the importance of an interactive treatment of stratospheric ozone for the simulated QBO response.

scholarly journals Quasi-biennial oscillation of the tropical stratospheric aerosol layer

2014 ◽  
Vol 14 (11) ◽  
pp. 16243-16290 ◽  
Author(s):  
R. Hommel ◽  
C. Timmreck ◽  
M. A. Giorgetta ◽  
H. F. Graf
Keyword(s):  
Climate Model ◽  
Middle Atmosphere ◽  
Stratospheric Aerosol ◽  
Dominant Mode ◽  
Static Balance ◽  
Aerosol Layer ◽  
Quasi Biennial Oscillation ◽  
Volcanic Material ◽  
Biennial Oscillation ◽  
Stratospheric Aerosols

Abstract. This study describes how aerosol in an aerosol-coupled climate model of the middle atmosphere is influenced by the quasi-biennial oscillation (QBO) during times when the stratosphere is largely unperturbed from volcanic material. In accordance with satellite observations, the tropical stratospheric aerosol load is predominately influenced by QBO induced anomalies in the vertical advection. Large impacts are seen in the size of aerosols, in particular in the region where aerosol evaporates. This turns the quasi-static balance between processes maintaining the vertical extent of the Junge layer in the tropics into a cyclic balance when considering this dominant mode of atmospheric variability. Global aerosol-interactive models without a QBO are only able to simulate the quasi-static balance state. To assess the global impact of stratospheric aerosols on climate processes, those partly non-linear relationships between the QBO and stratospheric aerosols have to be taken into account.

scholarly journals Stratospheric aerosol evolution after Pinatubo simulated with a coupled size-resolved aerosol–chemistry–climate model, SOCOL-AERv1.0

2018 ◽  
Vol 11 (7) ◽  
pp. 2633-2647 ◽  
Author(s):  
Timofei Sukhodolov ◽  
Jian-Xiong Sheng ◽  
Aryeh Feinberg ◽  
Bei-Ping Luo ◽  
Thomas Peter ◽  
...  
Keyword(s):  
Climate Model ◽  
Reference Model ◽  
Volcanic Eruptions ◽  
Global Scale ◽  
Stratospheric Aerosol ◽  
Atmospheric Effects ◽  
Aerosol Layer ◽  
Aerosol Chemistry ◽  
Quasi Biennial Oscillation ◽  
Aerosol Parameters

Abstract. We evaluate how the coupled aerosol–chemistry–climate model SOCOL-AERv1.0 represents the influence of the 1991 eruption of Mt. Pinatubo on stratospheric aerosol properties and atmospheric state. The aerosol module is coupled to the radiative and chemical modules and includes comprehensive sulfur chemistry and microphysics, in which the particle size distribution is represented by 40 size bins with radii spanning from 0.39 nm to 3.2 µm. SOCOL-AER simulations are compared with satellite and in situ measurements of aerosol parameters, temperature reanalyses, and ozone observations. In addition to the reference model configuration, we performed series of sensitivity experiments looking at different processes affecting the aerosol layer. An accurate sedimentation scheme is found to be essential to prevent particles from diffusing too rapidly to high and low altitudes. The aerosol radiative feedback and the use of a nudged quasi-biennial oscillation help to keep aerosol in the tropics and significantly affect the evolution of the stratospheric aerosol burden, which improves the agreement with observed aerosol mass distributions. The inclusion of van der Waals forces in the particle coagulation scheme suggests improvements in particle effective radius, although other parameters (such as aerosol longevity) deteriorate. Modification of the Pinatubo sulfur emission rate also improves some aerosol parameters, while it worsens others compared to observations. Observations themselves are highly uncertain and render it difficult to conclusively judge the necessity of further model reconfiguration. The model revealed problems in reproducing aerosol sizes above 25 km and also in capturing certain features of the ozone response. Besides this, our results show that SOCOL-AER is capable of predicting the most important global-scale atmospheric effects following volcanic eruptions, which is also a prerequisite for an improved understanding of solar geoengineering effects from sulfur injections to the stratosphere.

scholarly journals 35 years of stratospheric aerosol measurements at Garmisch-Partenkirchen: from Fuego to Eyjafjallajökull, and beyond

2012 ◽  
Vol 12 (9) ◽  
pp. 23135-23193 ◽  
Author(s):  
T. Trickl ◽  
H. Giehl ◽  
H. Jäger ◽  
H. Vogelmann
Keyword(s):  
Volcanic Eruptions ◽  
Stratospheric Aerosol ◽  
Saharan Dust ◽  
Positive Trend ◽  
Aerosol Layer ◽  
Quasi Biennial Oscillation ◽  
Mauna Loa ◽  
Background Period ◽  
Lidar Measurements ◽  
Volcanic Impact

Abstract. The powerful backscatter lidar at Garmisch-Partenkirchen (Germany) has almost continually delivered backscatter coefficients of the stratospheric aerosol since 1976. The time series is dominated by signals from the particles injected into or formed in the stratosphere due to major volcanic eruptions, in particular those of El Chichon (Mexico, 1982) and Mt. Pinatubo (Philippines, 1991). The volcanic aerosol disappears within about five years, the removal from the stratosphere being modulated by the phase of the quasi-biennial oscillation. Here, we focus more on the long-lasting background period since the late 1990s and 2006, in view of processes maintaining a residual lower-stratospheric aerosol layer in absence of major eruptions, as well as the period of moderate volcanic impact afterwards. During the long background period the stratospheric backscatter coefficients reached a level even below that observed in the late 1970s. This suggests that the predicted potential influence of the strongly growing air traffic on the stratospheric aerosol loading is very low. Some correlation may be found with single strong forest-fire events, but the average influence of biomass burning seems to be quite limited. No positive trend in background aerosol can be resolved over a period as long as that observed by lidar at Mauna Loa or Boulder. This suggests being careful with invoking Asian air pollution as the main source as found in the literature. Rather an impact of previously missed volcanic eruptions on the stratospheric aerosol must be taken into consideration. A key observation in this regard was that of the plume from the Icelandic volcano Eyjafjallajökull above Garmisch-Partenkirchen (April 2010) due to the proximity of that source. The top altitude of the ash next to the source was reported just as roughly 9.3 km, but the lidar measurements revealed enhanced stratospheric aerosol up to 14.5 km. Our analysis suggests for two, perhaps three, of the four measurement days the presence of a stratospheric contribution from Iceland related to quasi-horizontal transport, contrasting the strongly descending lower layers entering Central Europe. The backscatter coefficients within the first 2 km above the tropopause exceed the stratospheric background by a factor of three to four. In addition, Asian and Saharan dust layers were identified in the free troposphere, Asian dust most likely even in the stratosphere. The number of minor mid-latitude eruptions has gradually increased during the past ten years. We conclude that, although their stratospheric contribution could not be clearly identified above our site they can sum up for forming some minor background. Clear stratospheric signatures were only seen in the case of eruptions reaching higher altitudes.

scholarly journals Sensitivity of the radiative forcing by stratospheric sulfur geoengineering to the amount and strategy of the SO<sub>2</sub>injection studied with the LMDZ-S3A model

2018 ◽  
Vol 18 (4) ◽  
pp. 2769-2786 ◽  
Author(s):  
Christoph Kleinschmitt ◽  
Olivier Boucher ◽  
Ulrich Platt
Keyword(s):  
Radiative Forcing ◽  
General Circulation ◽  
Volcanic Eruptions ◽  
Stratospheric Aerosol ◽  
Aerosol Layer ◽  
Quasi Biennial Oscillation ◽  
Detailed Model ◽  
Mass Unit ◽  
Modelling Studies ◽  
Injection Rates

Abstract. The enhancement of the stratospheric sulfate aerosol layer has been proposed as a method of geoengineering to abate global warming. Previous modelling studies found that stratospheric aerosol geoengineering (SAG) could effectively compensate for the warming by greenhouse gases on the global scale, but also that the achievable cooling effect per sulfur mass unit, i.e. the forcing efficiency, decreases with increasing injection rate. In this study we use the atmospheric general circulation model LMDZ with the sectional aerosol module S3A to determine how the forcing efficiency depends on the injected amount of SO2, the injection height, and the spatio-temporal pattern of injection. We find that the forcing efficiency may decrease more drastically for larger SO2 injections than previously estimated. As a result, the net instantaneous radiative forcing does not exceed the limit of –2 W m−2 for continuous equatorial SO2 injections and it decreases (in absolute value) for injection rates larger than 20 Tg S yr−1. In contrast to other studies, the net radiative forcing in our experiments is fairly constant with injection height (in a range 17 to 23 km) for a given amount of SO2 injected. Also, spreading the SO2 injections between 30∘ S and 30∘ N or injecting only seasonally from varying latitudes does not result in a significantly larger (i.e. more negative) radiative forcing. Other key characteristics of our simulations include a consequent stratospheric heating, caused by the absorption of solar and infrared radiation by the aerosol, and changes in stratospheric dynamics, with a collapse of the quasi-biennial oscillation at larger injection rates, which has impacts on the resulting spatial aerosol distribution, size, and optical properties. But it has to be noted that the complexity and uncertainty of stratospheric processes cause considerable disagreement among different modelling studies of stratospheric aerosol geoengineering. This may be addressed through detailed model intercomparison activities, as observations to constrain the simulations of stratospheric aerosol geoengineering are not available and analogues (such as volcanic eruptions) are imperfect.

scholarly journals Trends in stratospheric ozone derived from merged SAGE II and Odin-OSIRIS satellite observations

2014 ◽  
Vol 14 (6) ◽  
pp. 7113-7140 ◽  
Author(s):  
A. E. Bourassa ◽  
D. A. Degenstein ◽  
W. J. Randel ◽  
J. M. Zawodny ◽  
E. Kyrölä ◽  
...  
Keyword(s):  
Southern Oscillation ◽  
Stratospheric Ozone ◽  
Stratospheric Aerosol ◽  
Basis Functions ◽  
Quasi Biennial Oscillation ◽  
Tropical Tropopause ◽  
Infrared Imager ◽  
Ozone Profile ◽  
Biennial Oscillation

Abstract. Stratospheric ozone profile measurements from the Stratospheric Aerosol and Gas Experiment (SAGE) II satellite instrument (1984–2005) are combined with those from the Optical Spectrograph and InfraRed Imager System (OSIRIS) instrument on the Odin satellite (2001–Present) to quantify interannual variability and decadal trends in stratospheric ozone between 60° S and 60° N. These data are merged into a multi-instrument, long-term stratospheric ozone record (1984–present) by analyzing the measurements during the overlap period of 2002–2005 when both satellite instruments were operational. The variability in the deseasonalized time series is fit using multiple linear regression with predictor basis functions including the quasi-biennial oscillation, El Niño-Southern Oscillation index, solar activity proxy, and the pressure at the tropical tropopause, in addition to two linear trends (one before and one after 1997), from which the decadal trends in ozone are derived. From 1984–1997, there are statistically significant negative trends of 5–10% per decade throughout the stratosphere between approximately 30–50 km. From 1997–present, a statistically significant recovery of 3–8% per decade has taken place throughout most of the stratosphere with the notable exception between 40° S–40° N below approximately 22 km where the negative trend continues. The recovery is not significant between 25–35 km altitude when accounting for a conservative estimate of instrument drift.

scholarly journals Trend and variability in ozone in the tropical lower stratosphere over 2.5 solar cycles observed by SAGE II and OSIRIS

2013 ◽  
Vol 13 (6) ◽  
pp. 16661-16697 ◽  
Author(s):  
C. E. Sioris ◽  
C. A. McLinden ◽  
V. E. Fioletov ◽  
C. Adams ◽  
J. M. Zawodny ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Southern Oscillation ◽  
Stratospheric Ozone ◽  
Stratospheric Aerosol ◽  
Tropopause Height ◽  
Solar Cycles ◽  
Quasi Biennial Oscillation ◽  
Infrared Imager ◽  
Biennial Oscillation ◽  
Temporal Overlap

Abstract. We are able to replicate previously reported decadal trends in the tropical lower stratospheric ozone anomaly based on Stratospheric Aerosol and Gas Experiment II observations. We have extended the satellite-based ozone anomaly time series to the present (December 2012) by merging SAGE II with OSIRIS (Optical Spectrograph and Infrared Imager System) and correcting for the small bias (~0.5%) between them, determined using their temporal overlap of 4 yr. Analysis of the merged dataset (1984–2012) shows a statistically significant negative trend at all altitudes in the 18–25 km range reaching (−6.5 ± 1.8)% decade−1 at 18.5 km, with underlying strong variations due to El Niño–Southern Oscillation, the Quasi–Biennial Oscillation, and tropopause height.

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