scholarly journals Toward a combined SAGE II-HALOE aerosol climatology: an evaluation of HALOE version 19 stratospheric aerosol extinction coefficient observations

2012 ◽  
Vol 12 (17) ◽  
pp. 8177-8188 ◽  
Author(s):  
L. W. Thomason
Keyword(s):  
Extinction Coefficient ◽  
Stratospheric Aerosol ◽  
Substantial Improvement ◽  
Data Sets ◽  
Aerosol Extinction ◽  
Scientific Applications ◽  
Quality Product ◽  
Coefficient Measurement ◽  
Derived Data ◽  
Aerosol Extinction Coefficient

Abstract. Herein, the Halogen Occultation Experiment (HALOE) aerosol extinction coefficient data is evaluated in the low aerosol loading period after 1996 as the first necessary step in a process that will eventually allow the production of a combined HALOE/SAGE II (Stratospheric Aerosol and Gas Experiment) aerosol climatology of derived aerosol products including surface area density. Based on these analyses, it is demonstrated that HALOE's 3.46 μm is of good quality above 19 km and suitable for scientific applications above that altitude. However, it is increasingly suspect at lower altitudes and should not be used below 17 km under any circumstances after 1996. The 3.40 μm is biased by about 10% throughout the lower stratosphere due to the failure to clear NO2 but otherwise appears to be a high quality product down to 15 km. The 2.45 and 5.26 μm aerosol extinction coefficient measurements are clearly biased and should not be used for scientific applications after the most intense parts of the Pinatubo period. Many of the issues in the aerosol data appear to be related to either the failure to clear some interfering gas species or doing so poorly. For instance, it is clear that the 3.40 μm aerosol extinction coefficient measurements can be improved through the inclusion of an NO2 correction and could, in fact, end up as the highest quality overall HALOE aerosol extinction coefficient measurement. It also appears that the 2.45 and 5.26 μm channels may be improved by updating the Upper Atmosphere Pilot Database which is used as a resource for the removal of gas species otherwise not available from direct HALOE measurements. Finally, a simple model to demonstrate the promise of mixed visible/infrared aerosol extinction coefficient ensembles for the retrieval of bulk aerosol properties demonstrates that a combined HALOE/SAGE II aerosol climatology is feasible and may represent a substantial improvement over independently derived data sets.

scholarly journals Toward a combined SAGE II-HALOE aerosol climatology: an evaluation of HALOE version 19 stratospheric aerosol extinction coefficient observations

2012 ◽  
Vol 12 (6) ◽  
pp. 13933-13965
Author(s):  
L. W. Thomason
Keyword(s):  
Extinction Coefficient ◽  
Stratospheric Aerosol ◽  
Substantial Improvement ◽  
Data Sets ◽  
Aerosol Extinction ◽  
Scientific Applications ◽  
Quality Product ◽  
Coefficient Measurement ◽  
Derived Data ◽  
Aerosol Extinction Coefficient

Abstract. Herein, the Halogen Occultation Experiment (HALOE) aerosol extinction coefficient data is evaluated in the low aerosol loading period after 1996 as the first necessary step in a process that will eventually allow the production of a combined HALOE/SAGE II (Stratospheric Aerosol and Gas Experiment) aerosol climatology of derived aerosol products including surface area density. Based on these analyses, it is demonstrated that HALOE's 3.46 μm is of good quality above 19 km and suitable for scientific applications above that altitude. However, it is increasingly suspect at lower altitudes and should not be used below 17 km under any circumstances. The 3.40 μm is biased by about 10% throughout the lower stratosphere due to the failure to clear NO2 but otherwise appears to be a high quality product down to 15 km. The 2.45 and 5.26 μm aerosol extinction coefficient measurements are clearly biased and should not be used for scientific applications after the most intense parts of the Pinatubo period. Many of the issues in the aerosol data appear to be related to either the failure to clear some interfering gas species or doing so poorly. For instance, it is clear that the 3.40 μm aerosol extinction coefficient measurements can be improved through the inclusion of an NO2 correction and could, in fact, end up as the highest quality overall HALOE aerosol extinction coefficient measurement. It also appears that the 2.45 and 5.26 μm channels may be improved by updating the Upper Atmosphere Pilot Database which is used as a resource for the removal of gas species otherwise not available from direct HALOE measurements. Finally, a simple model to demonstrate the promise of mixed visible/infrared aerosol extinction coefficient ensembles for the retrieval of bulk aerosol properties demonstrates that a combined HALOE/SAGE II aerosol climatology is feasible and may represent a substantial improvement over independently derived data sets.

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

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.

scholarly journals An evaluation of the SAGE III version 4 aerosol extinction coefficient and water vapor data products

2010 ◽  
Vol 10 (5) ◽  
pp. 2159-2173 ◽  
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 ◽  
Target Range ◽  
Data Sets ◽  
Aerosol Extinction ◽  
Data Products ◽  
Mean Differences ◽  
Aerosol Extinction Coefficient

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 mission's primary aerosol target 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. SAGE III water vapor data does not appear to be affected by aerosol loading in the stratosphere.

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

2020 ◽  
Author(s):  
Larry W. Thomason ◽  
Mahesh Kovilakam ◽  
Anja Schmidt ◽  
Christian von Savigny ◽  
Travis Knepp ◽  
...  
Keyword(s):  
Size Distribution ◽  
Extinction Coefficient ◽  
Volcanic Eruptions ◽  
Stratospheric Aerosol ◽  
Global Climate Models ◽  
Aerosol Size Distribution ◽  
Aerosol Layer ◽  
Aerosol Extinction ◽  
Volcanic Event ◽  
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 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.

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

2021 ◽  
Vol 21 (2) ◽  
pp. 1143-1158 ◽  
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.

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

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.

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

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.

Sign in / Sign up

Export Citation Format

Share Document