Variability of the aerosol content in the tropical lower stratosphere from 2013 to 2019 as influenced by moderate volcanic eruptions

2021 ◽  
Author(s):  
Mariam Tidiga ◽  
Gwenaël Berthet ◽  
Fabrice Jegou ◽  
Adriana Bossolasco ◽  
Corinna Kloss ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Climate Model ◽  
Volcanic Eruptions ◽  
Climate Trends ◽  
Asian Monsoon Region ◽  
Microphysical Properties ◽  
Radiative Impact ◽  
Decadal Climate ◽  
The Tropics

<p>The cumulative impacts of frequent moderate-magnitude eruptions on stratospheric aerosols were identified among the factors in recent decadal climate trends. Moderate volcanic eruptions are a recurrent source of sulfur dioxide (SO2) in the Upper Troposphere and Lower Stratosphere (UTLS) region and the resulting formation of sulfuric acid aerosol particles from the SO2 emitted provides sites for chemical reactions leading to enhancement of stratospheric optical depth (SAOD) and ozone depletion. Modelling properly the volcanic aerosol content and its evolution in this region is important for radiative impact issues. In this work, we explore the variability of the tropical UTLS aerosol content between 2013 and 2019, a period which was particularly impacted by moderate tropical and mid-latitude volcanic eruptions. For that purpose, space-borne observations from OMPS (version 2, datasets from GES DISC), and IASI, together with simulations by the Whole Atmosphere Community Climate Model (WACCM) coupled with the Community Aerosol and Radiation Model for Atmospheres (CARMA), are used. Different model sensitive experiments, particularly for the injection altitude and timing, have been conducted to evaluate how the model captures the aerosol plume in terms of content, optical and microphysical properties, transport and residence time. We find that the decay of the Calbuco and Kelud plumes observed by OMPS version 2 is well reproduced by the model. Comparisons with unique datasets in the tropical southern hemisphere from the NDACC Maïdo observatory (Reunion Island, France, 20.5°S, 55.5°E) show good agreement between the lidar SAOD observations and WACCM-CARMA SAOD simulations although we observe a difference in the altitude of the maximum aerosol concentration between the model and the in situ profile after Calbuco eruption in April 2015. A particular focus is also made on recent eruptions like Raikoke, Ambae and Ulawun. The plume of the Ambae volcano (15°S, 167°E) which erupted in July 2018 is shown to propagate to the northern hemisphere with some influence until summer 2019 in the Asian monsoon region. For the year 2019, we investigate how the Ulawun (5°S, 151°E; ~0.14 Tg of SO2) tropical eruption and the Raikoke mid-latitude eruption (48°N, 153°E; ~1.5Tg of SO2), have influenced the aerosol burden in the tropics.</p>

scholarly journals Observing the climate impact of large wildfires on stratospheric temperature

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Matthias Stocker ◽  
Florian Ladstädter ◽  
Andrea K. Steiner
Keyword(s):  
Lower Stratosphere ◽  
Volcanic Eruptions ◽  
Satellite Observation ◽  
Atmospheric Temperature ◽  
Climate Impact ◽  
Atmospheric Composition ◽  
Temperature Structure ◽  
Climate Trends ◽  
Short Term ◽  
Climate Signal

AbstractWildfires are expected to become more frequent and intense in the future. They not only pose a serious threat to humans and ecosystems, but also affect Earth’s atmosphere. Wildfire plumes can reach into the stratosphere, but little is known about their climate impact. Here, we reveal observational evidence that major wildfires can have a severe impact on the atmospheric temperature structure and short-term climate in the stratosphere. Using advanced satellite observation, we find substantial warming of up to 10 K of the lower stratosphere within the wildfire plumes during their early development. The short-term climate signal in the lower stratosphere lasts several months and amounts to 1 K for the Northern American wildfires in 2017, and up to striking 3.5 K for the Australian wildfires in 2020. This is stronger than any signal from recent volcanic eruptions. Such extreme events affect atmospheric composition and climate trends, underpinning their importance for future climate.

scholarly journals Triggering Global Climate Transitions through Volcanic Eruptions

2019 ◽  
Vol 32 (12) ◽  
pp. 3727-3742 ◽  
Author(s):  
Mukund Gupta ◽  
John Marshall ◽  
David Ferreira
Keyword(s):  
Sea Ice ◽  
Hysteresis Loop ◽  
Time Scales ◽  
Climate Model ◽  
Global Climate ◽  
Deep Ocean ◽  
Volcanic Eruptions ◽  
Cold Climate ◽  
Cold State ◽  
The Tropics

Abstract A coupled climate model with idealized representations of atmosphere, ocean, sea ice, and land is used to investigate transitions between global climate equilibria. The model supports the presence of climates with limited ice cover (Warm), a continuum of climates in which sea ice extends down into the midlatitudes and the tropics (Cold), together with a completely ice-covered earth (Snowball). Transitions between these states are triggered through volcanic eruptions, where the radiative effect of stratospheric sulfur emissions is idealized as an impulse reduction in incoming solar radiation. Snowball transitions starting from the Cold state are more favorable than from the Warm state, because less energy must be extracted from the system. However, even when starting from a Cold climate, Toba-like volcanic events (cooling of order −100 W m−2) must be sustained continuously for several decades to glaciate the entire planet. When the deep ocean is involved, the volcanic response is characterized by relaxation time scales spanning hundreds to thousands of years. If the interval between successive eruptions is significantly shorter (years to decades) than the ocean’s characteristic time scales, the cumulative cooling can build over time and initiate a state transition. The model exhibits a single hysteresis loop that connects all three climate equilibria. When starting from a Snowball, the model cannot access the Cold branch without first transitioning to an ice-free climate and completing the hysteresis loop. By contrast, a Cold state, when warmed, transitions to the Warm equilibrium without any hysteresis.

scholarly journals Aerosol microphysics simulations of the Mt. Pinatubo eruption with the UKCA composition-climate model

2014 ◽  
Vol 14 (2) ◽  
pp. 2799-2855 ◽  
Author(s):  
S. S. Dhomse ◽  
K. M. Emmerson ◽  
G. W. Mann ◽  
N. Bellouin ◽  
K. S. Carslaw ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Climate Model ◽  
Particle Growth ◽  
Climate Impacts ◽  
Spatial And Temporal Variation ◽  
Test Case ◽  
Pinatubo Eruption ◽  
High Bias ◽  
Aerosol Properties

Abstract. We have enhanced the capability of a microphysical aerosol-chemistry module to simulate the atmospheric aerosol and precursor gases for both tropospheric and stratospheric conditions. Using the Mount Pinatubo eruption (June 1991) as a test case, we evaluate simulated aerosol properties in a composition-climate model against a range of satellite and in-situ observations. Simulations are performed assuming an injection of 20 Tg SO2 at 19–27 km in tropical latitudes, without any radiative feedback from the simulated aerosol. In both quiescent and volcanically perturbed conditions, simulated aerosol properties in the lower stratosphere show reasonable agreement with the observations. The model captures the observed timing of the maximum aerosol optical depth (AOD) and its decay timescale in both tropics and Northern Hemisphere (NH) mid-latitudes. There is also good qualitative agreement with the observations in terms of spatial and temporal variation of the aerosol effective radius (Reff), which peaks 6–8 months after the eruption. However, the model shows significant biases against some observational data sets. Simulated AOD and Surface Area Density (SAD) in the tropics are substantially higher than the gap-filled satellite data products during the first 6 months after the eruption. The model shows consistently weaker enhancement in Reff compared to satellite and in-situ measurements. Simulated aerosol particle size distribution is also compared to NH mid-latitude in-situ balloon sounding measurements of size-resolved number concentrations. Before the eruption, the model captures the observed profiles of lower stratospheric particle number concentrations with radii larger than 5, 150 and 250 nm (N5, N150 and N250) very well. However, in the first 6 months after the eruption, the model shows high bias in N5 concentrations in the lower stratosphere, suggesting too strong nucleation. Following particle growth via condensation and coagulation, this bias in the finest particles propagates into a factor 2 high bias in N150. Our comparison suggests that new particle formation in the initial phase of large eruptions, and subsequent particle growth to optically-active sizes, might be playing an important role in determining the magnitude of the climate impacts from volcanoes like Pinatubo.

scholarly journals An In-Flight Calibration Method for Near-Real-Time Humidity Measurements with the Airborne MOZAIC Sensor

2008 ◽  
Vol 25 (5) ◽  
pp. 656-666 ◽  
Author(s):  
Herman G. J. Smit ◽  
Andreas Volz-Thomas ◽  
Manfred Helten ◽  
Werner Paetz ◽  
Dieter Kley
Keyword(s):  
Real Time ◽  
Lower Stratosphere ◽  
Potential Temperature ◽  
Calibration Method ◽  
Measured Temperature ◽  
Humidity Measurements ◽  
The Tropics ◽  
Selection Of ◽  
Good Agreement

Abstract A new in-flight calibration (IFC) method is described for the humidity sensor flown routinely since 1994 on the Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft (MOZAIC) program’s aircraft. The IFC method corrects the potential drift of the sensor offset at zero relative humidity, which is the critical parameter in determining the uncertainty of the measurements. The sensor offset is determined from the measurements themselves as obtained during periods when the aircraft is flying in the lower stratosphere at or above the hygropause, where the H2O mixing ratio reaches well-defined minimum values of about 5 ppmv and the contribution of atmospheric H2O to the sensor signal is minimal. The selection of stratospheric data is achieved with the help of potential temperature, which can be calculated in situ from measured temperature and pressure. The IFC method is capable of providing humidity measurements in near–real time with an uncertainty of ±8% RH at the surface and ±7% RH in the upper troposphere. For validation, the IFC method was applied to 5 yr of archived raw signals from the MOZAIC aircraft. The resulting humidity data are in good agreement (within 2% RH) with the original MOZAIC data that used monthly pre- and postflight calibrations of the sensor. The standard deviation of the differences varies with altitude between ±4% and ±6% RH, which is comparable to the accuracy of the MOZAIC laboratory calibrations. Compared to MOZAIC operation based on monthly calibrations in the laboratory, the use of IFC will substantially reduce the efforts for maintenance and thus will enable operation of the sensor on a large fleet of in-service aircraft for near-real-time measurements of humidity in the troposphere. Because the IFC method will not work on aircraft that never enter the lower stratosphere, for example, aircraft that fly exclusively regional routes or in the tropics, regular offline calibrations will remain important for such aircraft.

scholarly journals Understanding Recent Stratospheric Climate Change

2009 ◽  
Vol 22 (8) ◽  
pp. 1934-1943 ◽  
Author(s):  
David W. J. Thompson ◽  
Susan Solomon
Keyword(s):  
Climate Change ◽  
Large Scale ◽  
Lower Stratosphere ◽  
Climate Model ◽  
Longwave Radiation ◽  
Volcanic Eruptions ◽  
Stratospheric Temperature ◽  
Ozone Trends ◽  
Global Mean

Abstract The long-term, global-mean cooling of the lower stratosphere stems from two downward steps in temperature, both of which are coincident with the cessation of transient warming after the volcanic eruptions of El Chichón and Mount Pinatubo. Previous attribution studies reveal that the long-term cooling is linked to ozone trends, and modeling studies driven by a range of known forcings suggest that the steps reflect the superposition of the long-term cooling with transient variability in upwelling longwave radiation from the troposphere. However, the long-term cooling of the lower stratosphere is evident at all latitudes despite the fact that chemical ozone losses are thought to be greatest at middle and polar latitudes. Further, the ozone concentrations used in such studies are based on either 1) smooth mathematical functions fit to sparsely sampled observations that are unavailable during postvolcanic periods or 2) calculations by a coupled chemistry–climate model. Here the authors provide observational analyses that yield new insight into three key aspects of recent stratospheric climate change. First, evidence is provided that shows the unusual steplike behavior of global-mean stratospheric temperatures is dependent not only upon the trend but also on the temporal variability in global-mean ozone immediately following volcanic eruptions. Second, the authors argue that the warming/cooling pattern in global-mean temperatures following major volcanic eruptions is consistent with the competing radiative and chemical effects of volcanic eruptions on stratospheric temperature and ozone. Third, it is revealed that the contrasting latitudinal structures of recent stratospheric temperature and ozone trends are consistent with large-scale increases in the stratospheric overturning Brewer–Dobson circulation.

scholarly journals Evaluation of ECMWF ERA-40 temperature and wind in the lower tropical stratosphere since 1988 from past long-duration balloon measurements

2007 ◽  
Vol 7 (13) ◽  
pp. 3399-3409 ◽  
Author(s):  
T. Christensen ◽  
B. M. Knudsen ◽  
J.-P. Pommereau ◽  
G. Letrenne ◽  
A. Hertzog ◽  
...  
Keyword(s):  
Wind Speed ◽  
Lower Stratosphere ◽  
Equatorial Region ◽  
Satellite Measurements ◽  
Operational Analysis ◽  
Long Duration ◽  
The Tropics ◽  
Recent Evaluation ◽  
Balloon Measurements

Abstract. The temperature and wind of the ECMWF ERA-40 reanalysis in the tropical lower stratosphere during the period 1988–2001 has been evaluated by comparison with independent in situ measurements of 21 IR Montgolfier and superpressure long-duration balloon flights performed by CNES from Pretoria (26° S) in South Africa in 1988–1989, Latacunga (1° S) in Ecuador in 1991–1998 and Bauru (22° S) in Brazil in 2000–2001. The ERA-40 temperature displays a bias varying progressively from +1.16 K in 1988–1989, to +0.26 K in 1994–1996 and −0.46 K after 1998, the latter being fully consistent with recent evaluations of ECMWF operational analysis from radio occultation and in situ long-duration balloon observations. The amplitude of the bias and its evolution are very similar to the results of a previous evaluation from radiosondes in 1991–2003, suggesting that the origin of the drift of ERA-40 might be mainly due to errors in the series of satellite measurements of MSU, replaced by AMSU in 1998, assimilated in the model. The ERA-40 zonal wind speed in the lower stratosphere appears slightly overestimated by 0.7–1.0 m/s on average in both the tropics and equatorial region, that is by 5–10% compared to the average 10–20 m/s wind speed. This bias, fully consistent with a recent evaluation of ECMWF operational analysis in 2004, is found constant during the whole 1988–2001 period, suggesting a shortfall in the variabililty of ERA-40 horizontal winds in the lower stratosphere in the tropics and the equatorial region. Finally calculated trajectories using ERA-40, frequently used for analysing field observations, are found in error compared to that of the balloons by ±500 km after 5 days and ±1000 km after 10 days.

Volcanic influence on STRATOCLIM aircraft observations 2017 in the Asian Monsoon, studies with the transient CCM EMAC

2020 ◽  
Author(s):  
Christoph Brühl ◽  
Hans Schlager ◽  
Ralf Weigel ◽  
Oliver Appel ◽  
Stephan Borrmann ◽  
...  
Keyword(s):  
Asian Monsoon ◽  
Lower Stratosphere ◽  
Climate Model ◽  
Explosive Eruptions ◽  
Volcanic Material ◽  
Aircraft Observations ◽  
Sensitivity Studies ◽  
Volcanic Influence ◽  
Monsoon Dynamics

<p>Results from a transient 28 year simulation with the chemistry climate model EMAC with interactive modal aerosol scheme nudged to observed tropospheric meteorology (ERA-Interim) which includes about 500 volcanic SO<sub>2</sub> injections are compared with in situ aircraft observations in the UT/LS in the Asian Monsoon anticyclone. Enhanced SO<sub>2</sub> observed by STRATOMAS and enhanced sulfate aerosol observed by ERICA in the LS point to impact of several explosive eruptions of the Indonesian volcano Sinabung during summer 2017 seen by the OSIRIS satellite instrument. This is supported by freshly nucleated particles observed by COPAS in the UTLS. We present several sensitivity studies with EMAC with different assumptions on the injection patterns in comparison to the observations in July/August 2017.  <br>The monsoon dynamics distributes the volcanic material together with Asian pollution into the global lower stratosphere.</p>

scholarly journals Absence of internal multidecadal and interdecadal oscillations in climate model simulations

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Michael E. Mann ◽  
Byron A. Steinman ◽  
Sonya K. Miller
Keyword(s):  
Climate Model ◽  
Southern Oscillation ◽  
Low Frequency ◽  
Climate Trends ◽  
Internal Oscillation ◽  
Model Simulations ◽  
Control Climate ◽  
Climate Model Simulations ◽  
Decadal Climate ◽  
And Control

AbstractFor several decades the existence of interdecadal and multidecadal internal climate oscillations has been asserted by numerous studies based on analyses of historical observations, paleoclimatic data and climate model simulations. Here we use a combination of observational data and state-of-the-art forced and control climate model simulations to demonstrate the absence of consistent evidence for decadal or longer-term internal oscillatory signals that are distinguishable from climatic noise. Only variability in the interannual range associated with the El Niño/Southern Oscillation is found to be distinguishable from the noise background. A distinct (40–50 year timescale) spectral peak that appears in global surface temperature observations appears to reflect the response of the climate system to both anthropogenic and natural forcing rather than any intrinsic internal oscillation. These findings have implications both for the validity of previous studies attributing certain long-term climate trends to internal low-frequency climate cycles and for the prospect of decadal climate predictability.

scholarly journals Global cloud top height retrieval using SCIAMACHY limb spectra: model studies and first results

2016 ◽  
Vol 9 (2) ◽  
pp. 793-815 ◽  
Author(s):  
Kai-Uwe Eichmann ◽  
Luca Lelli ◽  
Christian von Savigny ◽  
Harjinder Sembhi ◽  
John P. Burrows
Keyword(s):  
Lower Stratosphere ◽  
Michelson Interferometer ◽  
Volcanic Eruptions ◽  
Cirrus Clouds ◽  
Detection Sensitivity ◽  
Retrieval Algorithm ◽  
Transfer Model ◽  
Aerosol Layer ◽  
Cloud Detection ◽  
The Tropics

Abstract. Cloud top heights (CTHs) are retrieved for the period 1 January 2003 to 7 April 2012 using height-resolved limb spectra measured with the SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY) on board ENVISAT (ENVIronmental SATellite). In this study, we present the retrieval code SCODA (SCIAMACHY cloud detection algorithm) based on a colour index method and test the accuracy of the retrieved CTHs in comparison to other methods. Sensitivity studies using the radiative transfer model SCIATRAN show that the method is capable of detecting cloud tops down to about 5 km and very thin cirrus clouds up to the tropopause. Volcanic particles can be detected that occasionally reach the lower stratosphere. Upper tropospheric ice clouds are observable for a nadir cloud optical thickness (COT)  ≥  0.01, which is in the subvisual range. This detection sensitivity decreases towards the lowermost troposphere. The COT detection limit for a water cloud top height of 5 km is roughly 0.1. This value is much lower than thresholds reported for passive cloud detection methods in nadir-viewing direction. Low clouds at 2 to 3 km can only be retrieved under very clean atmospheric conditions, as light scattering of aerosol particles interferes with the cloud particle scattering. We compare co-located SCIAMACHY limb and nadir cloud parameters that are retrieved with the Semi-Analytical CloUd Retrieval Algorithm (SACURA). Only opaque clouds (τN,c > 5) are detected with the nadir passive retrieval technique in the UV–visible and infrared wavelength ranges. Thus, due to the frequent occurrence of thin clouds and subvisual cirrus clouds in the tropics, larger CTH deviations are detected between both viewing geometries. Zonal mean CTH differences can be as high as 4 km in the tropics. The agreement in global cloud fields is sufficiently good. However, the land–sea contrast, as seen in nadir cloud occurrence frequency distributions, is not observed in limb geometry. Co-located cloud top height measurements of the limb-viewing Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on ENVISAT are compared for the period from January 2008 to March 2012. The global CTH agreement of about 1 km is observed, which is smaller than the vertical field of view of both instruments. Lower stratospheric aerosols from volcanic eruptions occasionally interfere with the cloud retrieval and inhibit the detection of tropospheric clouds. The aerosol impact on cloud retrievals was studied for the volcanoes Kasatochi (August 2008), Sarychev Peak (June 2009), and Nabro (June 2011). Long-lasting aerosol scattering is detected after these events in the Northern Hemisphere for heights above 12.5 km in tropical and polar latitudes. Aerosol top heights up to about 22 km are found in 2009 and the enhanced lower stratospheric aerosol layer persisted for about 7 months. In August 2009 about 82 % of the lower stratosphere between 30 and 70° N was filled with scattering particles and nearly 50 % in October 2008.

scholarly journals Time varying changes in the simulated structure of the Brewer Dobson Circulation

2016 ◽  
Author(s):  
Chaim I. Garfinkel ◽  
Valentina Aquila ◽  
Darryn W. Waugh ◽  
Luke D. Oman
Keyword(s):  
Structural Changes ◽  
Climate Models ◽  
Climate Model ◽  
Volcanic Eruptions ◽  
Residual Circulation ◽  
The Past ◽  
Earth Observing System ◽  
Long Time ◽  
System Chemistry

Abstract. A series of simulations using the NASA Goddard Earth Observing System Chemistry-Climate Model are analyzed in order to assess changes in the Brewer-Dobson Circulation (BDC) over the past 55 years. When trends are computed over the past 55 years, the BDC accelerates throughout the stratosphere, consistent with previous modeling results. However, over the second half of the simulations (i.e. since the late 1980s), the model simulates structural changes in the BDC as the temporal evolution of the BDC varies between regions in the stratosphere. In the mid-stratosphere in the mid-latitude Northern Hemisphere, the BDC decelerates in a simulation despite increases in greenhouse gas concentrations and warming sea surface temperatures. This deceleration is reminiscent of changes inferred from satellite instruments and in-situ measurements. In contrast, the BDC in the lower-stratosphere continues to accelerate. The main forcing agents for the recent slowdown in the mid-stratosphere appear to be declining ODS concentrations and the timing of volcanic eruptions. Changes in both age of air and the tropical upwelling of the residual circulation are similar. We therefore clarify that the statement that is often made that climate models simulate a decreasing age throughout the stratosphere only applies over long time periods, and is not the case for the past 25 years when we have most tracer measurements.

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