scholarly journals Simplified SAGE II ozone data usage rules

2020 ◽  
Author(s):  
Stefanie Kremser ◽  
Larry W. Thomason ◽  
Leroy J. Bird
Keyword(s):  
Visual Inspection ◽  
Ad Hoc ◽  
Stratospheric Aerosol ◽  
Data Set ◽  
Screening Criteria ◽  
Data Usage ◽  
Ozone Data ◽  
Ozone Measurement ◽  
Stratospheric Composition

Abstract. High quality satellite-based measurements are crucial to the assessment of global stratospheric composition change. The Stratospheric Aerosol and Gas Experiment II (SAGE II) provides to date the longest, continuous data set of vertically resolved ozone and aerosol extinction coefficients and therefore, remains a cornerstone of understanding and detecting long-term ozone variability and trends in the stratosphere. Despite its stability, SAGE II measurements must be screened for outliers that are a result of excessive aerosol emitted into the atmosphere and that degrade inferences of change. Current methods for SAGE II ozone measurement quality assurance consist of multiple ad-hoc, sometimes conflicting rules, leading to too much valuable data that are being removed or outliers being missed. In this work, the SAGE II ozone data set version 7.00 is used to develop and present a new set of screening recommendations and to compare the output to the screening recommendations currently used. Applying current recommendations to SAGE II ozone lead to unexpected features, such as removing ozone values around zero if the relative error is used as a screening criteria, leading to biases in monthly mean zonal mean ozone concentrations. Most of these current recommendations were developed based on "visual inspection", leading to inconsistent rules that might not be applicable at every altitude and latitude. Here, a set of new screening recommendations is presented that take into account the knowledge about how the measurements were made. The number of screening recommendations is reduced to three, which mainly remove ozone values that are affected by high aerosol loading and therefore are not reliable measurements. More data remain when applying these new recommendations compared to the rules that are currently being used, leading to more data being available for scientific studies. The SAGE II ozone data set used here is publicly available at https://doi.org/10.5281/zenodo.3710518. The complete SAGE II version 7.0 data set, which includes other variables in addition to ozone, is available at https://eosweb.larc.nasa.gov/project/sage2/sage2_v7_table, https://doi.org/10.5067/ERBS/SAGEII/SOLAR_BINARY_L2-V7.0 (SAGE II Science Team, 2012; Damadeo et al., 2013).

scholarly journals Simplified SAGE II ozone data usage rules

2020 ◽  
Vol 12 (2) ◽  
pp. 1419-1435
Author(s):  
Stefanie Kremser ◽  
Larry W. Thomason ◽  
Leroy J. Bird
Keyword(s):  
Visual Inspection ◽  
Ad Hoc ◽  
Stratospheric Aerosol ◽  
Data Set ◽  
Extinction Coefficients ◽  
Data Usage ◽  
Ozone Data ◽  
Ozone Measurement ◽  
Stratospheric Composition

Abstract. High-quality satellite-based measurements are crucial to the assessment of global stratospheric composition change. The Stratospheric Aerosol and Gas Experiment II (SAGE II) provides the longest, continuous data set of vertically resolved ozone and aerosol extinction coefficients to date and therefore remains a cornerstone of understanding and detecting long-term ozone variability and trends in the stratosphere. Despite its stability, SAGE II measurements must be screened for outliers that are a result of excessive aerosol emitted into the atmosphere and that degrade inferences of change. Current methods for SAGE II ozone measurement quality assurance consist of multiple ad hoc and sometimes conflicting rules, leading to too much valuable data being removed or outliers being missed. In this work, the SAGE II ozone data set version 7.00 is used to develop and present a new set of screening recommendations and to compare the output to the screening recommendations currently used. Applying current recommendations to SAGE II ozone leads to unexpected features, such as removing ozone values around zero if the relative error is used as a screening criterion, leading to biases in monthly mean zonal mean ozone concentrations. Most of these current recommendations were developed based on “visual inspection”, leading to inconsistent rules that might not be applicable at every altitude and latitude. Here, a set of new screening recommendations is presented that take into account the knowledge of how the measurements were made. The number of screening recommendations is reduced to three, which mainly remove ozone values that are affected by high aerosol loading and are therefore not reliable measurements. More data remain when applying these new recommendations compared to the rules that are currently being used, leading to more data being available for scientific studies. The SAGE II ozone data set used here is publicly available at https://doi.org/10.5281/zenodo.3710518 (Kremser et al., 2020). The complete SAGE II version 7.00 data set, which includes other variables in addition to ozone, is available at https://eosweb.larc.nasa.gov/project/sage2/sage2_v7_table (last access: December 2019), https://doi.org/10.5067/ERBS/SAGEII/SOLAR_BINARY_L2-V7.0 (SAGE II Science Team, 2012; Damadeo et al., 2013).

Retrievals of Atmospheric Carbonyl Sulfide from IASI

2021 ◽  
Author(s):  
Michael P. Cartwright ◽  
Jeremy J. Harrison ◽  
David P. Moore
Keyword(s):  
Gross Primary Production ◽  
Carbonyl Sulfide ◽  
Optimal Estimation ◽  
Stratospheric Aerosol ◽  
Data Set ◽  
Spatial Coverage ◽  
Retrieval Scheme ◽  
The University ◽  
Fresh Insight

<p>Carbonyl sulfide (OCS) is the most abundant sulfur containing gas in the atmosphere and is an important source of stratospheric aerosol. Furthermore, it has been shown that OCS can be used as a proxy for photosynthesis, which is a powerful tool in quantifying global gross primary production. While considerable improvements have been made in our understanding of the location and magnitude of OCS fluxes over the past few decades, recent studies highlight the need for a new satellite dataset to help reduce the uncertainties in current estimations. The Infrared Atmospheric Sounding Interferometer (IASI) instruments on-board the MetOp satellites offer over 14 years of nadir viewing radiance measurements with excellent spatial coverage. Given that there are currently three IASI instruments in operation, there is the potential for a significantly larger OCS dataset than is currently available elsewhere. Retrievals of OCS from these IASI radiances have been made using an adapted version of the University of Leicester IASI Retrieval Scheme (ULIRS). OCS total column amounts are calculated from profiles retrieved on a 31-layer equidistant pressure grid, using an optimal estimation approach for microwindows in the range 2000 – 2100 cm<sup>-1</sup> wavenumbers. Sensitivity of the measurements peak in the mid-troposphere, between 5 – 10 km.</p><p>The outlook of this work is to produce a long-term OCS satellite observational data set that provides fresh insight to the spatial distribution and trend of atmospheric OCS. Here, we present subsets of data in the form of case studies for different geographic regions and time periods.</p>

scholarly journals Effects of polar stratospheric clouds in the Nimbus 7 LIMS Version 6 data set

2016 ◽  
Vol 9 (7) ◽  
pp. 2927-2946 ◽  
Author(s):  
Ellis Remsberg ◽  
V. Lynn Harvey
Keyword(s):  
Stratospheric Aerosol ◽  
Transport Processes ◽  
The Arctic ◽  
Additional Parameter ◽  
Polar Stratospheric Clouds ◽  
Data Set ◽  
Screening Criteria ◽  
Temperature Thresholds ◽  
Level 3 ◽  
Stratospheric Clouds

Abstract. The historic Limb Infrared Monitor of the Stratosphere (LIMS) measurements of 1978–1979 from the Nimbus 7 satellite were re-processed with Version 6 (V6) algorithms and archived in 2002. The V6 data set employs updated radiance registration methods, improved spectroscopic line parameters, and a common vertical resolution for all retrieved parameters. Retrieved profiles are spaced about every 1.6° of latitude along orbits and include the additional parameter of geopotential height. Profiles of O3 are sensitive to perturbations from emissions of polar stratospheric clouds (PSCs). This work presents results of implementing a first-order screening for effects of PSCs using simple algorithms based on vertical gradients of the O3 mixing ratio. Their occurrences are compared with the co-located, retrieved temperatures and related to the temperature thresholds needed for saturation of H2O and/or HNO3 vapor onto PSC particles. Observed daily locations where the major PSC screening criteria are satisfied are validated against PSCs observed with the Stratospheric Aerosol Monitor (SAM) II experiment also on Nimbus 7. Remnants of emissions from PSCs are characterized for O3 and HNO3 following the screening. PSCs may also impart a warm bias in the co-located LIMS temperatures, but by no more than 1–2 K at the altitudes of where effects of PSCs are a maximum in the ozone; thus, no PSC screening was applied to the V6 temperatures. Minimum temperatures vary between 187 and 194 K and often occur 1 to 2 km above where PSC effects are first identified in the ozone (most often between about 21 and 28 hPa). Those temperature–pressure values are consistent with conditions for the existence of nitric acid trihydrate (NAT) mixtures and to a lesser extent of super-cooled ternary solution (STS) droplets. A local, temporary uptake of HNO3 vapor of order 1–3 ppbv is indicated during mid-January for the 550 K surface. Seven-month time series of the distributions of LIMS O3 and HNO3 are shown based on their gridded Level 3 data following the PSC screening. Zonal coefficients of both species are essentially free of effects from PSCs on the 550 K surface, based on their average values along PV contours and in terms of equivalent latitude. Remnants of PSCs are still present in O3 on the 450 K surface during mid-January. It is judged that the LIMS Level 3 data are of good quality for analyzing the larger-scale, stratospheric chemistry and transport processes during the Arctic winter of 1978–1979.

scholarly journals Volcanic impact on the climate – the stratospheric aerosol load in the period 2006–2015

2018 ◽  
Vol 18 (15) ◽  
pp. 11149-11169 ◽  
Author(s):  
Johan Friberg ◽  
Bengt G. Martinsson ◽  
Sandra M. Andersson ◽  
Oscar S. Sandvik
Keyword(s):  
Radiative Forcing ◽  
Volcanic Eruptions ◽  
Stratospheric Aerosol ◽  
Temperature Threshold ◽  
Data Set ◽  
Volcanic Impact ◽  
Almost All ◽  
Stratospheric Clouds ◽  
Correct Data

Abstract. We present a study on the stratospheric aerosol load during 2006–2015, discuss the influence from volcanism and other sources, and reconstruct an aerosol optical depth (AOD) data set in a resolution of 1∘ latitudinally and 8 days timewise. The purpose is to include the “entire” stratosphere, from the tropopause to the almost particle-free altitudes of the midstratosphere. A dynamic tropopause of 1.5 PVU was used, since it enclosed almost all of the volcanic signals in the CALIOP data set. The data were successfully cleaned from polar stratospheric clouds using a temperature threshold of 195 K. Furthermore, a method was developed to correct data when the CALIOP laser beam was strongly attenuated by volcanic aerosol, preventing a negative bias in the AOD data set. Tropospheric influence, likely from upwelling dust, was found in the extratropical transition layer in spring. Eruptions of both extratropical and tropical volcanoes that injected aerosol into the stratosphere impacted the stratospheric aerosol load for up to a year if their clouds reached lower than 20 km altitude. Deeper-reaching tropical injections rose in the tropical pipe and impacted it for several years. Our AODs mostly compare well to other long-term studies of the stratospheric AOD. Over the years 2006–2015, volcanic eruptions increased the stratospheric AOD on average by ∼40 %. In absolute numbers the stratospheric AOD and radiative forcing amounted to 0.008 and −0.2 W m−2, respectively.

scholarly journals Merging of ozone profiles from SCIAMACHY, OMPS and SAGE II observations to study stratospheric ozone changes

2019 ◽  
Vol 12 (4) ◽  
pp. 2423-2444
Author(s):  
Carlo Arosio ◽  
Alexei Rozanov ◽  
Elizaveta Malinina ◽  
Mark Weber ◽  
John P. Burrows
Keyword(s):  
Time Series ◽  
Stratospheric Ozone ◽  
Multivariate Regression Analysis ◽  
Stratospheric Aerosol ◽  
Montreal Protocol ◽  
Inversion Algorithm ◽  
Data Set ◽  
Large Variability ◽  
Stratospheric Temperature

Abstract. This paper presents vertically and zonally resolved merged ozone time series from limb measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) and the Ozone Mapping and Profiler Suite (OMPS) Limb Profiler (LP). In addition, we present the merging of the latter two data sets with zonally averaged profiles from Stratospheric Aerosol and Gas Experiment (SAGE) II. The retrieval of ozone profiles from SCIAMACHY and OMPS-LP is performed using an inversion algorithm developed at the University of Bremen. To optimize the merging of these two time series, we use data from the Microwave Limb Sounder (MLS) as a transfer function and we follow two approaches: (1) a conventional method involving the calculation of deseasonalized anomalies and (2) a “plain-debiasing” approach, generally not considered in previous similar studies, which preserves the seasonal cycles of each instrument. We find a good correlation and no significant drifts between the merged and MLS time series. Using the merged data set from both approaches, we apply a multivariate regression analysis to study ozone changes in the 20–50 km range over the 2003–2018 period. Exploiting the dense horizontal sampling of the instruments, we investigate not only the zonally averaged field, but also the longitudinally resolved long-term ozone variations, finding an unexpected and large variability, especially at mid and high latitudes, with variations of up to 3 %–5 % per decade at altitudes around 40 km. Significant positive linear trends of about 2 %–4 % per decade were identified in the upper stratosphere between altitudes of 38 and 45 km at mid latitudes. This is in agreement with the predicted recovery of upper stratospheric ozone, which is attributed to both the adoption of measures to limit the release of halogen-containing ozone-depleting substances (Montreal Protocol) and the decrease in stratospheric temperature resulting from the increasing concentration of greenhouse gases. In the tropical stratosphere below 25 km negative but non-significant trends were found. We compare our results with previous studies and with short-term trends calculated over the SCIAMACHY period (2002–2012). While generally a good agreement is found, some discrepancies are seen in the tropical mid stratosphere. Regarding the merging of SAGE II with SCIAMACHY and OMPS-LP, zonal mean anomalies are taken into consideration and ozone trends before and after 1997 are calculated. Negative trends above 30 km are found for the 1985–1997 period, with a peak of −6 % per decade at mid latitudes, in agreement with previous studies. The increase in ozone concentration in the upper stratosphere is confirmed over the 1998–2018 period. Trends in the tropical stratosphere at 30–35 km show an interesting behavior: over the 1998–2018 period a negligible trend is found. However, between 2004 and 2011 a negative long-term change is detected followed by a positive change between 2012 and 2018. We attribute this behavior to dynamical changes in the tropical middle stratosphere.

scholarly journals Assessment of Odin-OSIRIS ozone measurements from 2001 to the present using MLS, GOMOS, and ozone sondes

2013 ◽  
Vol 6 (2) ◽  
pp. 3819-3857 ◽  
Author(s):  
C. Adams ◽  
A. E. Bourassa ◽  
V. Sofieva ◽  
L. Froidevaux ◽  
C. A. McLinden ◽  
...  
Keyword(s):  
Infrared Imaging ◽  
Imaging System ◽  
Data Sets ◽  
Validation Data ◽  
Data Set ◽  
Long Term Stability ◽  
Ozone Data ◽  
High Bias ◽  
The Stability

Abstract. The Optical Spectrograph and InfraRed Imaging System (OSIRIS) was launched aboard the Odin satellite in 2001 and is continuing to take limb-scattered sunlight measurements of the atmosphere. This work aims to characterize and assess the stability of the OSIRIS 11 yr v5.0x ozone data set. Three validation data sets were used: the v2.2 Microwave Limb Sounder (MLS) and v6 Global Ozone Monitoring of Occultation on Stars (GOMOS) satellite data records, and ozone sonde measurements. Global mean percent differences between coincident OSIRIS and validation measurements are within 5% of zero at all altitude layers above 18.5 km for MLS, above 21.5 km for GOMOS, and above 17.5 km for ozone sondes. Below 17.5 km, OSIRIS measurements agree with ozone sondes within 5% and are well-correlated (R > 0.75) with them. For low OSIRIS optics temperatures (< 16 °C), OSIRIS ozone measurements are biased low by up 6% compared with the validation data sets for 25.5–40.5 km. Biases between OSIRIS ascending and descending node measurements were investigated and were found to be related to aerosol retrievals below 27.5 km. Above 30 km, agreement between OSIRIS and the validation data sets was related to the OSIRIS retrieved albedo, which measures apparent upwelling, with a high bias for in OSIRIS data with large albedos. In order to assess the long-term stability of OSIRIS measurements, global average drifts relative to the validation data sets were calculated and were found to be < 3% per decade for comparisons against MLS for 19.5–36.5 km, GOMOS for 18.5–54.5 km, and ozone sondes for 12.5–22.5 km, and within error of 3% per decade at most altitudes. Above 36.5 km, the relative drift for OSIRIS versus MLS ranged from ~ 0–6%, depending on the data set used to convert MLS data to the OSIRIS altitude versus number density grid. Overall, this work demonstrates that the OSIRIS 11 yr ozone data set from 2001 to the present is suitable for trend studies.

scholarly journals Search for evidence of trend slow-down in the long-term TOMS/SBUV total ozone data record: the importance of instrument drift uncertainty

2006 ◽  
Vol 6 (12) ◽  
pp. 4057-4065 ◽  
Author(s):  
R. S. Stolarski ◽  
S. M. Frith
Keyword(s):  
Time Series ◽  
Total Ozone ◽  
Rate Of Change ◽  
Data Set ◽  
Ozone Data ◽  
Data Record ◽  
Cusum Analysis ◽  
Statistical Time ◽  
Drift Uncertainty

Abstract. We have developed a merged ozone data set (MOD) for the period October 1978 through June 2006 combining total ozone measurements (Version 8 retrieval) from the TOMS (Nimbus 7, Earth Probe) and SBUV/SBUV2 (Nimbus 7, NOAA 9/11/16) series of satellite instruments. We use the MOD data set to search for evidence of ozone recovery in response to the observed leveling off of chlorine and bromine compounds in the stratosphere. A crucial step in any time series analysis is the evaluation of uncertainties. In addition to the standard statistical time series uncertainties, we evaluate the possible instrument drift uncertainty for the MOD data set. We combine these two sources of uncertainty and apply them to a cumulative sum of residuals (CUSUM) analysis for trend slow-down. For the extra-polar mean between 60° S and 60° N, the apparent slow-down in trend is found to be clearly significant if instrument uncertainties are ignored. When instrument uncertainties are added, the slow-down becomes marginally significant at the 2σ level. For the mid-latitudes of the northern hemisphere (30° to 60° N) the trend slow-down is highly significant at the 2σ level, while in the southern hemisphere the trend slow-down has yet to meet the 2σ significance criterion. The rate of change of chlorine/bromine compounds is similar in both hemispheres, and we expect the ozone response to be similar in both hemispheres as well. The asymmetry in the trend slow-down between hemispheres likely reflects the influence of dynamical variability, and thus a clearly statistically significant response of total ozone to the leveling off of chlorine and bromine in the stratosphere is not yet indicated.

scholarly journals Assessment of Odin-OSIRIS ozone measurements from 2001 to the present using MLS, GOMOS, and ozonesondes

2014 ◽  
Vol 7 (1) ◽  
pp. 49-64 ◽  
Author(s):  
C. Adams ◽  
A. E. Bourassa ◽  
V. Sofieva ◽  
L. Froidevaux ◽  
C. A. McLinden ◽  
...  
Keyword(s):  
Infrared Imaging ◽  
Imaging System ◽  
Data Sets ◽  
Validation Data ◽  
Data Set ◽  
Long Term Stability ◽  
Ozone Data ◽  
The Stability ◽  
Global Mean

Abstract. The Optical Spectrograph and InfraRed Imaging System (OSIRIS) was launched aboard the Odin satellite in 2001 and is continuing to take limb-scattered sunlight measurements of the atmosphere. This work aims to characterize and assess the stability of the OSIRIS 11 yr v5.0x ozone data set. Three validation data sets were used: the v2.2 Microwave Limb Sounder (MLS) and v6 Global Ozone Monitoring by Occultation of Stars (GOMOS) satellite data records, and ozonesonde measurements. Global mean percent differences between coincident OSIRIS and validation measurements are within 5% at all altitudes above 18.5 km for MLS, above 21.5 km for GOMOS, and above 17.5 km for ozonesondes. Below 17.5 km, OSIRIS measurements agree with ozonesondes within 5% and are well-correlated (R > 0.75) with them. For low OSIRIS optics temperatures (< 16 °C), OSIRIS ozone measurements have a negative bias of 1–6% compared with the validation data sets for 25.5–40.5 km. Biases between OSIRIS ascending and descending node measurements were investigated and found to be related to aerosol retrievals below 27.5 km. Above 30 km, agreement between OSIRIS and the validation data sets was related to the OSIRIS retrieved albedo, which measures apparent upwelling, with a positive bias in OSIRIS data with large albedos. In order to assess the long-term stability of OSIRIS measurements, global average drifts relative to the validation data sets were calculated and were found to be < 3% per decade for comparisons with MLS for 19.5–36.5 km, GOMOS for 18.5–54.5 km, and ozonesondes for 12.5–22.5 km. Above 36.5 km, the relative drift for OSIRIS versus MLS ranged from ~ 0 to 6% per decade, depending on the data set used to convert MLS data to the OSIRIS altitude versus number density grid. Overall, this work demonstrates that the OSIRIS 11 yr ozone data set from 2001 to the present is suitable for trend studies.

scholarly journals Validation of ozone monthly zonal mean profiles obtained from the version 8.6 Solar Backscatter Ultraviolet algorithm

2013 ◽  
Vol 13 (14) ◽  
pp. 6887-6905 ◽  
Author(s):  
N. A. Kramarova ◽  
S. M. Frith ◽  
P. K. Bhartia ◽  
R. D. McPeters ◽  
S. L. Taylor ◽  
...  
Keyword(s):  
Potential Effect ◽  
Stratospheric Aerosol ◽  
Data Set ◽  
Long Term Stability ◽  
Record Data ◽  
Data Record ◽  
The Mean ◽  
Climate Studies ◽  
Combined Data

Abstract. We present the validation of ozone profiles from a number of Solar Backscatter Ultraviolet (SBUV and SBUV/2) instruments that were recently reprocessed using an updated (version 8.6) algorithm. The SBUV data record spans a 41 yr period from 1970 to 2011 with a 5 yr gap in the 1970s. The ultimate goal is to create a consistent, well-calibrated data set of ozone profiles that can be used for climate studies and trend analyses. SBUV ozone profiles have been intensively validated against satellite profile measurements from the Microwave Limb Sounders (MLS) (on board the UARS and Aura satellites) and the Stratospheric Aerosol and Gas Experiment (SAGE II) and ground-based observations from the microwave spectrometers, lidars, Umkehr instruments and balloon-borne ozonesondes. In the stratosphere between 25 and 1 hPa the mean biases and standard deviations are mostly within 5% for monthly zonal mean ozone profiles. Above and below this layer the vertical resolution of the SBUV algorithm decreases. We combine several layers of data in the troposphere/lower stratosphere to account for the lower resolution. The bias in the SBUV tropospheric/lower stratospheric combined layer relative to similarly integrated columns from Aura MLS, ozonesonde and Umkehr instruments varies within 5%. We also estimate the drift of the SBUV instruments and their potential effect on the long-term stability of the combined data record. Data from the SBUV instruments that collectively cover the 1980s and 2000s are very stable, with drifts mostly less than 0.5% per year. The features of individual SBUV(/2) instruments are discussed and recommendations for creating a merged SBUV data set are provided.

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