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

2016 ◽  
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 dataset 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 K and 194 K and occur at or just above where the PSC effects are first identified in the ozone (most often between about 21 hPa to 28 hPa). Those temperature-pressure values are consistent with conditions for saturation and formation of supercooled ternary solution (STS) droplets and/or nitric acid trihydrate (NAT) aerosols. A temporary uptake of HNO3 vapor by about 2–3 ppbv is indicated in mid-January downwind of and at pressure-altitudes where effects of PSCs are found. Seven-month, time series of the distributions of LIMS O3 and HNO3 are shown based on their gridded Level 3 data following the screening. The zonal coefficients of both O3 and HNO3 are essentially free of effects from PSCs on the 550 K surface as averaged at equivalent latitudes. Remnants of PSCs are still present in O3 during mid-January on the 450 K surface. 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 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 Chemical analysis of refractory stratospheric aerosol particles collected within the arctic vortex and inside polar stratospheric clouds

2016 ◽  
Author(s):  
Martin Ebert ◽  
Ralf Weigel ◽  
Konrad Kandler ◽  
Gebhard Günther ◽  
Sergej Molleker ◽  
...  
Keyword(s):  
Aerosol Particles ◽  
Stratospheric Aerosol ◽  
The Arctic ◽  
Late Winter ◽  
General Tendency ◽  
Polar Stratospheric Clouds ◽  
Metal Mixtures ◽  
Air Masses ◽  
Size And Morphology ◽  
Stratospheric Clouds

Abstract. Stratospheric aerosol particles with diameters larger than about 10 nm were collected within the arctic vortex during two polar flight campaigns: RECONCILE in winter 2010 and ESSenCe in winter 2011. Impactors were installed on board of the aircraft M-55 Geophysica, which was operated from Kiruna, Sweden. Flights were performed in a height of up to 21 km and some of the particle samples were taken within distinct polar stratospheric clouds (PSC). The chemical composition, size and morphology of refractory particles were analyzed by scanning electron microscopy and energy-dispersive X-ray microanalysis. During ESSenCe no refractory particles with diameters above 500 nm were sampled. In total 116 small silicate-, Fe-rich-, Pb-rich and aluminum oxide spheres were found. In contrast to ESSenCe early winter, during the late winter RECONCILE mission the air masses were subsiding inside the Arctic winter vortex from upper stratosphere and mesosphere, thus initializing a transport of refractory aerosol particles into the lower stratosphere. During RECONCILE 759 refractory particles with diameters above 500 nm were found consisting of silicates, silicate/carbon mixtures, Fe-rich particles, Ca-rich particles and complex metal mixtures. In the size range below 500 nm additionally the presence of soot was proven. While the data base is still sparse, the general tendency of a lower abundance of refractory particles during PSC events compared to non-PSC situations was observed. The detection of such large refractory particles in the stratosphere, and the fact that these particles were not observed in the particle samples (upper size limit about 5 µm) taken during PSC events, strengthen the hypothesis that such particles are present in the polar stratosphere in late winter and that they can provide a surface for heterogeneous condensation during PSC formation.

scholarly journals Chemical analysis of refractory stratospheric aerosol particles collected within the arctic vortex and inside polar stratospheric clouds

2016 ◽  
Vol 16 (13) ◽  
pp. 8405-8421 ◽  
Author(s):  
Martin Ebert ◽  
Ralf Weigel ◽  
Konrad Kandler ◽  
Gebhard Günther ◽  
Sergej Molleker ◽  
...  
Keyword(s):  
Aerosol Particles ◽  
Stratospheric Aerosol ◽  
The Arctic ◽  
Late Winter ◽  
General Tendency ◽  
Polar Stratospheric Clouds ◽  
Metal Mixtures ◽  
Air Masses ◽  
Size And Morphology ◽  
Stratospheric Clouds

Abstract. Stratospheric aerosol particles with diameters larger than about 10 nm were collected within the arctic vortex during two polar flight campaigns: RECONCILE in winter 2010 and ESSenCe in winter 2011. Impactors were installed on board the aircraft M-55 Geophysica, which was operated from Kiruna, Sweden. Flights were performed at a height of up to 21 km and some of the particle samples were taken within distinct polar stratospheric clouds (PSCs). The chemical composition, size and morphology of refractory particles were analyzed by scanning electron microscopy and energy-dispersive X-ray microanalysis. During ESSenCe no refractory particles with diameters above 500 nm were sampled. In total 116 small silicate, Fe-rich, Pb-rich and aluminum oxide spheres were found. In contrast to ESSenCe in early winter, during the late-winter RECONCILE mission the air masses were subsiding inside the Arctic winter vortex from the upper stratosphere and mesosphere, thus initializing a transport of refractory aerosol particles into the lower stratosphere. During RECONCILE, 759 refractory particles with diameters above 500 nm were found consisting of silicates, silicate ∕ carbon mixtures, Fe-rich particles, Ca-rich particles and complex metal mixtures. In the size range below 500 nm the presence of soot was also proven. While the data base is still sparse, the general tendency of a lower abundance of refractory particles during PSC events compared to non-PSC situations was observed. The detection of large refractory particles in the stratosphere, as well as the experimental finding that these particles were not observed in the particle samples (upper size limit ∼  5 µm) taken during PSC events, strengthens the hypothesis that such particles are present in the lower polar stratosphere in late winter and have provided a surface for heterogeneous nucleation during PSC formation.

Record springtime stratospheric ozone depletion at 80°N in 2020

2021 ◽  
Author(s):  
Ramina Alwarda ◽  
Kristof Bognar ◽  
Kimberly Strong ◽  
Martyn Chipperfield ◽  
Sandip Dhomse ◽  
...  
Keyword(s):  
Ozone Depletion ◽  
Transport Model ◽  
Stratospheric Ozone ◽  
Polar Vortex ◽  
The Arctic ◽  
Optical Absorption Spectroscopy ◽  
Chemical Transport Model ◽  
Polar Stratospheric Clouds ◽  
Ozone Loss ◽  
Stratospheric Clouds

<p>The Arctic winter of 2019-2020 was characterized by an unusually persistent polar vortex and temperatures in the lower stratosphere that were consistently below the threshold for the formation of polar stratospheric clouds (PSCs). These conditions led to ozone loss that is comparable to the Antarctic ozone hole. Ground-based measurements from a suite of instruments at the Polar Environment Atmospheric Research Laboratory (PEARL) in Eureka, Canada (80.05°N, 86.42°W) were used to investigate chemical ozone depletion. The vortex was located above Eureka longer than in any previous year in the 20-year dataset and lidar measurements provided evidence of polar stratospheric clouds (PSCs) above Eureka. Additionally, UV-visible zenith-sky Differential Optical Absorption Spectroscopy (DOAS) measurements showed record ozone loss in the 20-year dataset, evidence of denitrification along with the slowest increase of NO<sub>2</sub> during spring, as well as enhanced reactive halogen species (OClO and BrO). Complementary measurements of HCl and ClONO<sub>2</sub> (chlorine reservoir species) from a Fourier transform infrared (FTIR) spectrometer showed unusually low columns that were comparable to 2011, the previous year with significant chemical ozone depletion. Record low values of HNO<sub>3</sub> in the FTIR dataset are in accordance with the evidence of PSCs and a denitrified atmosphere. Estimates of chemical ozone loss were derived using passive ozone from the SLIMCAT offline chemical transport model to account for dynamical contributions to the stratospheric ozone budget.</p>

scholarly journals Denitrification, dehydration and ozone loss during the Arctic winter 2015/2016

2017 ◽  
Author(s):  
Farahnaz Khosrawi ◽  
Oliver Kirner ◽  
Björn-Martin Sinnhuber ◽  
Sören Johansson ◽  
Michael Höpfner ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Stratospheric Ozone ◽  
Satellite Observations ◽  
The Arctic ◽  
Cold Pool ◽  
Polar Stratospheric Clouds ◽  
Airborne Measurements ◽  
Ozone Loss ◽  
Polar Stratosphere ◽  
Stratospheric Clouds

Abstract. The Arctic winter 2015/2016 was one of the coldest stratospheric winters in recent years. A stable vortex formed by early December and the early winter was exceptionally cold. Cold pool temperatures dropped below the Nitric Acid Trihydrate (NAT) existence temperature of about 195 K, thus allowing Polar Stratospheric Clouds (PSCs) to form. The low temperatures in the polar stratosphere persisted until early March allowing chlorine activation and catalytic ozone destruction. Satellite observations indicate that sedimentation of PSC particles led to denitrification as well as dehydration of stratospheric layers. Model simulations of the Arctic winter 2015/2016 nudged toward European Center for Medium-Range Weather Forecasts (ECMWF) analyses data were performed with the atmospheric chemistry–climate model ECHAM5/MESSy Atmospheric Chemistry (EMAC) for the Polar Stratosphere in a Changing Climate (POLSTRACC) campaign. POLSTRACC is a High Altitude and LOng Range Research Aircraft (HALO) mission aimed at the investigation of the structure, composition and evolution of the Arctic Upper Troposphere and Lower Stratosphere (UTLS). The chemical and physical processes involved in Arctic stratospheric ozone depletion, transport and mixing processes in the UTLS at high latitudes, polar stratospheric clouds as well as cirrus clouds are investigated. In this study an overview of the chemistry and dynamics of the Arctic winter 2015/2016 as simulated with EMAC is given. Further, chemical-dynamical processes such as denitrification, dehydration and ozone loss during the Arctic winter 2015/2016 are investigated. Comparisons to satellite observations by the Aura Microwave Limb Sounder (Aura/MLS) as well as to airborne measurements with the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) performed on board of HALO during the POLSTRACC campaign show that the EMAC simulations are in fairly good agreement with observations. We derive a maximum polar stratospheric O3 loss of ~ 2 ppmv or 100 DU in terms of column in mid March. The stratosphere was denitrified by about 8 ppbv HNO3 and dehydrated by about 1 ppmv H2O in mid to end of February. While ozone loss was quite strong, but not as strong as in 2010/2011, denitrification and dehydration were so far the strongest observed in the Arctic stratosphere in the at least past 10 years.

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.

A three-dimensional model comparison of PSC processing during the Arctic winters of 1991/1992 and 1992/1993

1994 ◽  
Vol 12 (4) ◽  
pp. 342-354 ◽  
Author(s):  
M. P. Chipperfield
Keyword(s):  
Model Comparison ◽  
Transport Model ◽  
Three Dimensional ◽  
Polar Vortex ◽  
The Arctic ◽  
Three Dimensional Model ◽  
Polar Stratospheric Clouds ◽  
Ozone Loss ◽  
Stratospheric Clouds ◽  
Compare And Contrast

Abstract. A three-dimensional transport model has been used to compare and contrast the extent of processing by polar stratospheric clouds during the northern hemisphere winters of 1991/1992 and 1992/1993. The model has also been used to compare the potential for ozone loss between these two winters. The TOMCAT off-line model is forced using meteorological analyses from the ECMWF. During winter 1992/1993 polar stratospheric clouds (PSCs) in the model persisted into late February/early March, which is much later than in 1991/1992. This persistence of PSCs should have resulted in much more ozone loss in the later winter. Interestingly, however, the extent of PSC processing and ozone loss was greater in January 1992 than January 1993. In January 1992 PSCs occurred at the edge of a distorted polar vortex whilst in January 1993 the PSCs were located at the centre of a much more zonally symmetrical vortex. In March 1993, distortions of the vortex led to the tearing off of vortex air and its mixing into midlatitudes.

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