Evidence for the predictability of changes in the stratospheric aerosol size following volcanic eruptions of diverse magnitudes using space-based instruments

Abstract. An analysis of multiwavelength stratospheric aerosol extinction coefficient data from the Stratospheric Aerosol and Gas Experiment II and III/ISS instruments is used to demonstrate a coherent relationship between the perturbation in extinction coefficient in an eruption's main aerosol layer and an apparent change in aerosol size distribution that spans multiple orders of magnitude in the stratospheric impact of a volcanic event. The relationship is measurement-based and does not rely on assumptions about the aerosol size distribution. We note limitations on this analysis including that the presence of significant amounts of ash in the main aerosol layer may significantly modulate these results. Despite this limitation, these findings represent a unique opportunity to verify the performance of interactive aerosol models used in Global Climate Models and Earth System Model and may suggest an avenue for improving aerosol extinction coefficient measurements from single channel observations such the Optical Spectrograph and Infrared Imager System as they rely on a priori assumptions about particle size.

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Evidence for the predictability of changes in the stratospheric aerosol size following volcanic eruptions of diverse magnitudes using space-based instruments

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-1143-2021 ◽

2021 ◽

Vol 21 (2) ◽

pp. 1143-1158 ◽

Cited By ~ 1

Author(s):

Larry W. Thomason ◽

Mahesh Kovilakam ◽

Anja Schmidt ◽

Christian von Savigny ◽

Travis Knepp ◽

...

Keyword(s):

Extinction Coefficient ◽

Climate Models ◽

Single Channel ◽

Volcanic Eruptions ◽

Stratospheric Aerosol ◽

Global Climate Models ◽

Aerosol Size Distribution ◽

Aerosol Layer ◽

Aerosol Extinction ◽

Aerosol Extinction Coefficient

Abstract. An analysis of multiwavelength stratospheric aerosol extinction coefficient data from the Stratospheric Aerosol and Gas Experiment II and III/ISS instruments is used to demonstrate a coherent relationship between the perturbation in extinction coefficient in an eruption's main aerosol layer and the wavelength dependence of that perturbation. This relationship spans multiple orders of magnitude in the aerosol extinction coefficient of stratospheric impact of volcanic events. The relationship is measurement-based and does not rely on assumptions about the aerosol size distribution. We note limitations on this analysis including that the presence of significant amounts of ash in the main sulfuric acid aerosol layer and other factors may significantly modulate these results. Despite these limitations, the findings suggest an avenue for improving aerosol extinction coefficient measurements from single-channel observations such as the Optical Spectrograph and Infrared Imager System as they rely on a prior assumptions about particle size. They may also represent a distinct avenue for the comparison of observations with interactive aerosol models used in global climate models and Earth system models.

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Evaluation of the OMPS/LP stratospheric aerosol extinction product using SAGE III/ISS observations

Atmospheric Measurement Techniques ◽

10.5194/amt-13-3471-2020 ◽

2020 ◽

Vol 13 (6) ◽

pp. 3471-3485

Author(s):

Zhong Chen ◽

Pawan K. Bhartia ◽

Omar Torres ◽

Glen Jaross ◽

Robert Loughman ◽

...

Keyword(s):

Size Distribution ◽

Pearson Correlation ◽

Volcanic Eruptions ◽

Stratospheric Aerosol ◽

Aerosol Size Distribution ◽

Retrieval Algorithm ◽

Aerosol Layer ◽

Aerosol Extinction ◽

Extinction Time ◽

Altitude Range

Abstract. The Ozone Mapping and Profiler Suite Limb Profiler (OMPS/LP) has been taking limb-scattered measurements since April 2012. It is designed to produce ozone and aerosol vertical profiles at a 1.6 km vertical resolution over the entire sunlit globe. The Version 1.5 (V1.5) aerosol extinction retrieval algorithm provides aerosol extinction profiles using observed radiances at 675 nm. The algorithm assumes Mie theory and a gamma function aerosol size distribution for the stratospheric aerosol that is derived from results calculated by the Community Aerosol and Radiation Model for Atmospheres (CARMA). In this paper, we compare V1.5 LP aerosol profiles with SAGE III/ISS solar occultation observations for the period from June 2017 to May 2019, when both measurements were available to evaluate our ability to characterize background aerosol conditions. Overall, LP extinction profiles agree with SAGE III/ISS data to within ±25 % for altitudes between 19 and 27 km, even during periods perturbed by volcanic eruptions or intense forest fires. In this altitude range, the slope parameter of linear fitting of LP extinction values with respect to SAGE III/ISS measurements is close to 1.0, with Pearson correlation coefficients of r≥0.95, indicating that the LP aerosol data are reliable in that altitude range. Comparisons of extinction time series show that both instruments capture the variability of the stratospheric aerosol layer quite well, and the differences between the two instruments vary from 0 % to ±25 % depending on altitude, latitude, and time. In contrast, we find erroneous seasonal variations in the OMPS/LP Version 1.5 dataset, which usually exist below 20 km in the Southern Hemisphere due to the lack of sensitivity to particles when the scattering angle (SA) is greater than 145∘. We also find that LP-retrieved extinction is systematically higher than SAGE III/ISS observations at altitudes above 28 km and systematically lower below 19 km in the tropics with significant biases up to ±13 %. This is likely due in part to the fact that the actual aerosol size distribution is altitude dependent. There are also other reasons related to cloud contamination, wavelength limitations, aerosol loading, and the influence of the viewing configuration.

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Evaluation of OMPS/LP Stratospheric Aerosol Extinction Product Using SAGE III/ISS Observations

10.5194/amt-2019-360 ◽

2019 ◽

Author(s):

Zhong Chen ◽

Pawan K. Bhartia ◽

Omar Torres ◽

Glen Jaross ◽

Robert Loughman ◽

...

Keyword(s):

Size Distribution ◽

Forest Fires ◽

Correlation Coefficients ◽

Volcanic Eruptions ◽

Stratospheric Aerosol ◽

Aerosol Size Distribution ◽

Retrieval Algorithm ◽

Aerosol Layer ◽

Aerosol Extinction ◽

Extinction Time

Abstract. The Ozone Mapping and Profiler Suite Limb Profiler (OMPS/LP) has been flying on the Suomi NPP satellite since October 2011. It is designed to produce ozone and aerosol vertical profiles at 1.6 km vertical resolution over the entire sunlit globe. The Version 1.5 (V1.5) aerosol extinction retrieval algorithm provides aerosol extinction profiles using observed radiances at 675 nm. The algorithm assumes Mie theory and a gamma function aerosol size distribution for the stratospheric aerosol that is derived from Community Aerosol and Radiation Model for Atmospheres (CARMA) calculated results and observations in April 2012. In this paper, we compare V1.5 LP aerosol profiles with SAGE III/ISS solar occultation observations for the period June 2017 – May 2019, when both measurements were available. Overall, LP extinction profiles agree with SAGE data to within ±25 % for the main aerosol layer between 19 and 27 km, even during periods perturbed by volcanic eruptions or intense forest fires. The slope parameter of linear fitting of LP extinctions with respect to SAGE measurements are close to 1.0, with Pearson's correlation coefficients of r ≥ 0.95, indicating that the LP aerosol data are reliable in that altitude range. Comparisons of extinction time series show a high degree of correlation between LP and SAGE, indicating that the LP retrieved extinction variability in time is robust. On the other hand, we find that LP retrieved extinction is systematically higher than SAGE observations at altitudes above 28 km and systematically lower below 19 km in the tropics. This is likely due in part to the fact that the actual aerosol size distribution is altitude dependent, while the assumed size distribution in the V1.5 retrieval is assumed to be altitude independent and so it may be less accurate for altitudes above 28 km and below 19 km where the size distribution is more variable. There are other reasons related to cloud contamination, wavelength limitations and the accuracy of both instruments at low aerosol loading.

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Retrieval of stratospheric aerosol size distribution parameters using satellite solar occultation measurements at three wavelengths

Atmospheric Measurement Techniques ◽

10.5194/amt-14-2345-2021 ◽

2021 ◽

Vol 14 (3) ◽

pp. 2345-2357

Author(s):

Felix Wrana ◽

Christian von Savigny ◽

Jacob Zalach ◽

Larry W. Thomason

Keyword(s):

Size Distribution ◽

Space Station ◽

Volcanic Eruptions ◽

Stratospheric Aerosol ◽

Aerosol Size Distribution ◽

Aerosol Layer ◽

Data Set ◽

Extinction Coefficients ◽

Solar Occultation ◽

Spatial Coverage

Abstract. In this work, a novel approach for the determination of the particle size distribution (PSD) parameters of stratospheric sulfate aerosols is presented. For this, ratios of extinction coefficients obtained from SAGE III/ISS (Stratospheric Aerosol and Gas Experiment III on the International Space Station) solar occultation measurements at 449, 756 and 1544 nm were used to retrieve the mode width and median radius of a size distribution assumed to be monomodal lognormal. The estimated errors at the peak of the stratospheric aerosol layer, on average, lie between 20 % and 25 % for the median radius and 5 % and 7 % for the mode width. The results are consistent in magnitude with other retrieval results from the literature, but a robust comparison is difficult, mainly because of differences in temporal and spatial coverage. Other quantities like number density and effective radius were also calculated. A major advantage of the described method over other retrieval techniques is that both the median radius and the mode width can be retrieved simultaneously, without having to assume one of them. This is possible due to the broad wavelength spectrum covered by the SAGE III/ISS measurements. Also, the presented method – being based on the analysis of three wavelengths – allows unique solutions for the retrieval of PSD parameters for almost all of the observed extinction spectra, which is not the case when using only two spectral channels. In addition, the extinction coefficients from SAGE III/ISS solar occultation measurements, on which the retrieval is based, are calculated without a priori assumptions about the PSD. For those reasons, the data produced with the presented retrieval technique may be a valuable contribution for a better understanding of the variability of stratospheric aerosol size distributions, e.g. after volcanic eruptions. While this study focuses on describing the retrieval method, and a future study will discuss the PSD parameter data set produced in depth, some exemplary results for background conditions in June 2017 are shown.

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Changes in stratospheric aerosol extinction coefficient after the 2018 Ambae eruption as seen by OMPS-LP and MAECHAM5-HAM

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-14871-2021 ◽

2021 ◽

Vol 21 (19) ◽

pp. 14871-14891

Author(s):

Elizaveta Malinina ◽

Alexei Rozanov ◽

Ulrike Niemeier ◽

Sandra Wallis ◽

Carlo Arosio ◽

...

Keyword(s):

Extinction Coefficient ◽

Radiative Forcing ◽

Volcanic Eruptions ◽

Stratospheric Aerosol ◽

Retrieval Algorithm ◽

Second Phase ◽

Aerosol Extinction ◽

Monitoring Instrument ◽

Aerosol Loading ◽

Aerosol Extinction Coefficient

Abstract. Stratospheric aerosols are an important component of the climate system. They not only change the radiative budget of the Earth but also play an essential role in ozone depletion. These impacts are particularly noticeable after volcanic eruptions when SO2 injected with the eruption reaches the stratosphere, oxidizes, and forms stratospheric aerosol. There have been several studies in which a volcanic eruption plume and the associated radiative forcing were analyzed using climate models and/or data from satellite measurements. However, few have compared vertically and temporally resolved volcanic plumes using both measured and modeled data. In this paper, we compared changes in the stratospheric aerosol loading after the 2018 Ambae eruption observed by satellite remote sensing measurements and simulated by a global aerosol model. We use vertical profiles of the aerosol extinction coefficient at 869 nm retrieved at the Institute of Environmental Physics (IUP) in Bremen from OMPS-LP (Ozone Mapping and Profiling Suite – Limb Profiler) observations. Here, we present the retrieval algorithm and a comparison of the obtained profiles with those from SAGE III/ISS (Stratospheric Aerosol and Gas Experiment III on board the International Space Station). The observed differences are within 25 % for most latitude bins, which indicates a reasonable quality of the retrieved limb aerosol extinction product. The volcanic plume evolution is investigated using both monthly mean aerosol extinction coefficients and 10 d averaged data. The measurement results were compared with the model output from MAECHAM5-HAM (ECHAM for short). In order to simulate the eruption accurately, we use SO2 injection estimates from OMPS and OMI (Ozone Monitoring Instrument) for the first phase of eruption and the TROPOspheric Monitoring Instrument (TROPOMI) for the second phase. Generally, the agreement between the vertical and geographical distribution of the aerosol extinction coefficient from OMPS-LP and ECHAM is quite remarkable, in particular, for the second phase. We attribute the good consistency between the model and the measurements to the precise estimation of injected SO2 mass and height, as well as to the nudging to ECMWF ERA5 reanalysis data. Additionally, we compared the radiative forcing (RF) caused by the increase in the aerosol loading in the stratosphere after the eruption. After accounting for the uncertainties from different RF calculation methods, the RFs from ECHAM and OMPS-LP agree quite well. We estimate the tropical (20∘ N to 20∘ S) RF from the second Ambae eruption to be about −0.13 W m−2.

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Changes in stratospheric aerosol extinction coefficient after the 2018 Ambae eruption as seen by OMPS-LP and ECHAM5-HAM

10.5194/acp-2020-749 ◽

2020 ◽

Author(s):

Elizaveta Malinina ◽

Alexei Rozanov ◽

Ulrike Niemeier ◽

Sandra Peglow ◽

Carlo Arosio ◽

...

Keyword(s):

Extinction Coefficient ◽

Radiative Forcing ◽

Volcanic Eruptions ◽

Stratospheric Aerosol ◽

Retrieval Algorithm ◽

Volcanic Plume ◽

Second Phase ◽

Aerosol Extinction ◽

Aerosol Loading ◽

Aerosol Extinction Coefficient

Abstract. Stratospheric aerosols are an important component of the climate system. They not only change the radiative budget of the Earth but also play an essential role in ozone depletion. Most noticeable those effects are after volcanic eruptions when SO2 injected with the eruption reaches the stratosphere, oxidizes and forms stratospheric aerosol. There have been several studies, where a volcanic eruption plume and the associated radiative forcing were analyzed using climate models. Besides, volcanic eruptions were studied using the data from satellite measurements; however, studies combining both models and measurement data are rare. In this paper, we compared changes in the stratospheric aerosol loading after the 2018 Ambae eruption observed by satellite remote sensing measurements and by a global aerosol model. We use vertical profiles of aerosol extinction coefficient at 869 nm retrieved at IUP Bremen from OMPS-LP (Ozone Mapping and Profiling Suite – Limb Profiler) observations. Here, we present the retrieval algorithm as well as a comparison of the obtained profiles with those from SAGE III/ISS (Stratospheric Aerosol and Gas Experiment III onboard International Space Station). The observed differences are within 25 % for the most latitude bins, which indicates a reasonable quality of the retrieved limb aerosol extinction product. The volcanic plume evolution is investigated using both: monthly mean aerosol extinction coefficients and 10-day averaged data. The measurement results were compared with the model output from ECHAM5-HAM. In order to simulate the eruption accurately, we use SO2 injections estimates from OMPS and OMI for the first phase of eruption and TROPOMI for the second phase. Generally, the agreement between the vertical and geographical distribution of the aerosol extinction coefficient from OMPS-LP and ECHAM is quite remarkable, in particular, for the second phase. We attribute the good consistency between the model and the measurements to the precise estimation of injected SO2 mass and height as well as through nudging to ECMWF reanalysis data. Additionally, we compared the radiative forcing (RF) caused by the increase of the aerosol loading in the stratosphere after the eruption. After accounting for the uncertainties from different RF calculation methods, the RFs from ECHAM and OMPS-LP agree quite well. We estimate the tropical (20° N to 20° S) RF from the second Ambae eruption to be about −0.13 W/m2.

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Climate Data Records of GOMOS/AerGOM stratospheric aerosol extinction coefficient for the Copernicus Climate Change Service: last developments and validation

10.5194/egusphere-egu21-7971 ◽

2021 ◽

Author(s):

Christine Bingen ◽

Charles Robert ◽

Filip Vanhellemont ◽

Nina Mateshvili

Keyword(s):

Climate Change ◽

Extinction Coefficient ◽

Volcanic Eruptions ◽

Stratospheric Aerosol ◽

Radiative Properties ◽

Medium Size ◽

Aerosol Extinction ◽

Climate Data ◽

Level 2 ◽

Aerosol Extinction Coefficient

Stratospheric aerosol extinction coefficient data derived from GOMOS using the AerGOM algorithm are one of the aerosol products provided to the Copernicus Climate Change Services (C3S).The stellar occultation instrument GOMOS, which sounded the atmosphere in the UV-visible-near IR range on board ENVISAT during the period 2002-2012 was a pioneering instrument, relying on a large number of stars with varying magnitude and temperature making the data inversion challenging. An algorithm called AerGOM was developed as an alternative to the operational algorithm to optimize the retrieval of aerosol properties, and this dataset has been continuously improved since then.A main milestone of this evolution was the elaboration of Level 3 gridded datasets in the framework of the ESA Aerosol_CCI project. This dataset provides aerosol radiative properties with as main quantity the aerosol extinction coefficient between 350 and 750 nm with a better resolution (bins with 5&#176; latitude and 60&#176; longitude intervals, 5-day time periods) than the usual monthly zonal mean. It is therefore better suited to describe the signature of events such as medium-size volcanic eruptions.Afterward, an extended exploration of the AerGOM performance in the retrieval of trace gases such as ozone, nitrogen dioxide and nitrogen trioxide led to an adaptation of the retrieval scheme in order to improve the retrieved gaseous species.The outcome of this exploration performed in the framework of the ESA Living Planet project EXPANSION is now exploited to improve again the Level 2 aerosol extinction coefficient, and the resultant Climate Data Record (CDR) delivered to C3S.We present here the latest developments in the aerosol extinction coefficient retrieval from GOMOS using AerGOM, and show how we use the improvement of the inversion of gas species to derived the new version of the GOMOS extinction product in Level 2, and the C3S CDR. The validation of the AerGOM dataset with respect to datasets from several contemporary missions such as SAGE II, SAGE III, and OSIRIS is also presented.

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Retrieval of stratospheric aerosol size distribution parameters using SAGE-III/ISS extinction measurements at three wavelengths

10.5194/amt-2020-277 ◽

2020 ◽

Cited By ~ 1

Author(s):

Felix Wrana ◽

Christian von Savigny ◽

Jacob Zalach ◽

Larry W. Thomason

Keyword(s):

Size Distribution ◽

A Priori ◽

Volcanic Eruptions ◽

Stratospheric Aerosol ◽

Aerosol Size Distribution ◽

Aerosol Layer ◽

Data Set ◽

Extinction Coefficients ◽

Solar Occultation ◽

Spatial Coverage

Abstract. In this work a novel approach to determine the particle size distribution (PSD) parameters of stratospheric sulfate aerosols is presented. For this, ratios of extinction coefficients obtained from SAGE III/ISS solar occultation measurements at 449 nm, 756 nm and 1544 nm were used to retrieve the mode width and median radius of a size distribution assumed to be monomodal lognormal. The estimated errors at the peak of the stratospheric aerosol layer on average lie between 20 % and 25 % for the median radius and 5 % and 7 % for the mode width. The results are consistent in magnitude with other retrieval results from the literature, but a robust comparison is difficult, mainly because of differences in temporal and spatial coverage. Other quantities like number density and effective radius were also calculated. A major advantage of the described method over other retrieval techniques is that both the median radius and the mode width can be retrieved simultaneously, without having to assume one of them, due to the broad wavelength spectrum covered by the SAGE III/ISS measurements. Also the extinction coefficients from SAGE III/ISS solar occultation measurements, on which the retrieval is based, are calculated without a priori assumptions about the PSD. For those reasons, the data produced with the presented retrieval technique may be a valuable contribution to better understand the variability of stratospheric aerosol size distributions, e.g. after volcanic eruptions. While this study focuses on describing the retrieval method and a future study will discuss the PSD parameter data set produced in depth, some exemplary results for background conditions in June 2017 are shown.

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An evaluation of the SAGE III Version 4 aerosol extinction coefficient and water vapor data products

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-22177-2009 ◽

2009 ◽

Vol 9 (5) ◽

pp. 22177-22222

Author(s):

L. W. Thomason ◽

J. R. Moore ◽

M. C. Pitts ◽

J. M. Zawodny ◽

E.-W. Chiou

Keyword(s):

Water Vapor ◽

Extinction Coefficient ◽

Stratospheric Aerosol ◽

Data Sets ◽

Aerosol Extinction ◽

Data Products ◽

Mean Differences ◽

Aerosol Extinction Coefficient ◽

Polar Ozone

Abstract. Herein, we provide an assessment of the data quality of Stratospheric Aerosol and Gas Experiment (SAGE III) Version 4 aerosol extinction coefficient and water vapor data products. The evaluation is based on comparisons with data from four instruments: SAGE II, the Polar Ozone and Aerosol Measurement (POAM III), the Halogen Occultation Experiment (HALOE), and the Microwave Limb Sounder (MLS). Since only about half of the SAGE III channels have a direct comparison with measurements by other instruments, we have employed some empirical techniques to evaluate measurements at some wavelengths. We find that the aerosol extinction coefficient measurements at 449, 520, 755, 869, and 1021 nm are reliable with accuracies and precisions on the order of 10% in the primary aerosol range of 15 to 25 km. We also believe this to be true of the aerosol measurements at 1545 nm though we cannot exclude some positive bias below 15 km. We recommend use of the 385 nm measurements above 16 km where the accuracy is on par with other aerosol channels. The 601 nm measurement is much noisier (~20%) than other channels and we suggest caution in the use of these data. We believe that the 676 nm data are clearly defective particularly above 20 km (accuracy as poor as 50%) and the precision is also low (~30%). We suggest excluding this channel under most circumstances. The SAGE III Version 4 water vapor data product appears to be high quality and is recommended for science applications in the stratosphere below 45 km. In this altitude range, the mean differences with all four corroborative data sets are no bigger than 15% and often less than 10% with exceptional agreement with POAM III and MLS. Above 45 km, it seems likely that SAGE III water vapor values are increasingly too large and should be used cautiously or avoided. We believe that SAGE III meets its preflight goal of 15% accuracy and 10% precision between 15 and 45 km. We do not currently recommend limiting the SAGE III water vapor data utility in the stratosphere by aerosol loading.

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Stratospheric aerosol particle size information in Odin-OSIRIS limb scatter spectra

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-6-5065-2013 ◽

2013 ◽

Vol 6 (3) ◽

pp. 5065-5099

Author(s):

L. A. Rieger ◽

A. E. Bourassa ◽

D. A. Degenstein

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Imaging System ◽

Stratospheric Aerosol ◽

Retrieval Algorithm ◽

Aerosol Layer ◽

Aerosol Extinction ◽

Model Calculations ◽

Size Information

Abstract. The Optical Spectrograph and InfraRed Imaging System (OSIRIS) on-board the Odin satellite has now taken over a decade of limb scatter measurements that have been used to retrieve the Version 5 stratospheric aerosol extinction product. This product is retrieved using a representative particle size distribution to calculate scattering cross sections and scattering phase functions for the forward model calculations. In this work the information content of OSIRIS measurements with respect to stratospheric aerosol is systematically examined for the purpose of retrieving particle size information along with the extinction coefficient. The benefit of using measurements at different wavelengths and scattering angles in the retrieval is studied and it is found that incorporation of the 1530 nm radiance measurement is key for a robust retrieval of particle size information. It is also found that using OSIRIS measurements at different solar geometries simultaneously provides little additional benefit. Based on these results, an improved aerosol retrieval algorithm is developed that couples the retrieval of aerosol extinction and mode radius of a log-normal particle size distribution. Comparison of these results with coincident measurements from SAGE III show agreement in retrieved extinction to within approximately 10% over the bulk of the aerosol layer, which is comparable to Version 5. The retrieved particle size, when converted to Ångström coefficient, shows good qualitative agreement with SAGE II measurements made at somewhat shorter wavelengths.

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