Comparisons between Stratospheric Aerosol and Gas Experiment II and microwave limb sounder ozone measurements and aliasing of SAGE II ozone trends in the lower stratosphere

1996 ◽  
Vol 101 (D6) ◽  
pp. 10061-10075 ◽  
Author(s):  
D. M. Cunnold ◽  
H. Wang ◽  
W. P. Chu ◽  
L. Froidevaux
2016 ◽  
Author(s):  
Fabrice Chane Ming ◽  
Damien Vignelles ◽  
Fabrice Jegou ◽  
Gwenael Berthet ◽  
Jean-Batiste Renard ◽  
...  

Abstract. Coupled balloon-borne observations of Light Optical Aerosol Counter (LOAC), M10 meteorological global positioning system (GPS) sondes, ozonesondes and GPS radio occultation data, are examined to identify gravity-wave (GW) induced fluctuations on tracer gases and on the vertical distribution of stratospheric aerosol concentrations during the 2013 ChArMEx (Chemistry-Aerosol Mediterranean Experiment) campaign. Observations reveal signatures of GWs with short vertical wavelengths less than 4 km in dynamical parameters and tracer constituents which are also correlated with the presence of thin layers of strong local enhancements of aerosol concentrations in the upper troposphere and the lower stratosphere. In particular, this is evident from a case study above Ile du Levant (43.02 °N, 6.46 °E) on 26–29 July 2013. Observations show a strong activity of dominant mesoscale inertia GWs with horizontal and vertical wavelengths of 370–510 km and 2–3 km respectively, and periods of 10–13 h propagating southward at altitudes of 13–20 km and eastward above 20 km during 27–28 July which is also captured by the European Center for Medium range Weather Forecasting (ECMWF) analyses. Ray-tracing experiments indicate the jet-front system to be the source of observed GWs. Simulated vertical profiles of dynamical parameters with large stratospheric vertical wind maximum oscillations ± 40 mms−1 are produced for the dominant mesoscale GW using the simplified linear GW theory. Parcel advection method reveals signatures of GWs in the ozone mixing ratio and the specific humidity. Simulated vertical wind perturbations of the dominant GW and small-scale perturbations of aerosol concentration (aerosol size of 0.2–0.7 μm) are in phase in the lower stratosphere. Present results support the importance of vertical wind perturbations in the GW-aerosol relation. The observed mesoscale GW induces a strong modulation of the amplitude of tracer gases and the stratospheric aerosol background.


2017 ◽  
Author(s):  
Laura Revell ◽  
Andrea Stenke ◽  
Beiping Luo ◽  
Stefanie Kremser ◽  
Eugene Rozanov ◽  
...  

Abstract. To simulate the impacts of volcanic eruptions on the stratosphere, chemistry-climate models that do not include an online aerosol module require temporally and spatially resolved aerosol size parameters for heterogeneous chemistry and aerosol radiative properties as a function of wavelength. For phase 1 of the Chemistry-Climate Model Initiative (CCMI-1) and, later, for phase 6 of the Coupled Model Intercomparison Project (CMIP6) two such stratospheric aerosol data sets were compiled, whose functional capability and representativeness are compared here. For CCMI-1, the SAGE-4λ data set was compiled, which hinges on the measurements at four wavelengths of the SAGE (Stratospheric Aerosol and Gas Experiment) II satellite instrument and uses ground-based Lidar measurements for gap-filling immediately after the Mt. Pinatubo eruption, when the stratosphere was optically opaque for SAGE II. For CMIP6, the new SAGE-3λ data set was compiled, which excludes the least reliable SAGE II wavelength and uses CLAES (Cryogenic Limb Array Etalon Spectrometer) measurements on UARS, the Upper Atmosphere Research Satellite, for gap-filling following the Mt. Pinatubo eruption instead of ground-based Lidars. Here, we performed SOCOLv3 (Solar Climate Ozone Links version 3) chemistry-climate model simulations of the recent past (1986–2005) to investigate the impact of the Mt. Pinatubo eruption in 1991 on stratospheric temperature and ozone and how this response differs depending on which aerosol data set is applied. The use of SAGE-4λ results in heating and ozone loss being overestimated in the lower stratosphere compared to observations in the post-eruption period by approximately 3 K and 0.2 ppmv, respectively. However, less heating occurs in the model simulations based on SAGE-3λ, because the improved gap-filling procedures after the eruption lead to less aerosol loading in the tropical lower stratosphere. As a result, simulated temperature anomalies in the model simulations based on SAGE-3λ for CMIP6 are in excellent agreement with MERRA and ERA-Interim reanalyses in the post-eruption period. Less heating in the simulations with SAGE-3λ means that the rate of tropical upwelling does not strengthen as much as it does in the simulations with SAGE-4λ, which limits dynamical uplift of ozone and therefore provides more time for ozone to accumulate in tropical mid-stratospheric air. Ozone loss following the Mt. Pinatubo eruption is overestimated by 0.1 ppmv in the model simulations based on SAGE-3λ, which is a better agreement with observations than in the simulations based on SAGE-4λ. Overall, the CMIP6 stratospheric aerosol data set, SAGE-3λ, allows SOCOLv3 to more accurately simulate the post-Pinatubo eruption period.


2006 ◽  
Vol 24 (8) ◽  
pp. 2091-2103 ◽  
Author(s):  
S. Fadnavis ◽  
G. Beig

Abstract. To investigate the effects of decadal solar variability on ozone and temperature in the tropical stratosphere, along with interconnections to other features of the middle atmosphere, simultaneous data obtained from the Halogen Occultation Experiment (HALOE) aboard the Upper Atmospheric Research Satellite (UARS) and the Stratospheric Aerosol and Gas Experiment II (SAGE II) aboard the Earth Radiation Budget Satellite (ERBS) during the period 1992–2004 have been analyzed using a multifunctional regression model. In general, responses of solar signal on temperature and ozone profiles show good agreement for HALOE and SAGE~II measurements. The inferred annual-mean solar effect on temperature is found to be positive in the lower stratosphere (max 1.2±0.5 K / 100 sfu) and near stratopause, while negative in the middle stratosphere. The inferred solar effect on ozone is found to be significant in most of the stratosphere (2±1.1–4±1.6% / 100 sfu). These observed results are in reasonable agreement with model simulations. Solar signals in ozone and temperature are in phase in the lower stratosphere and they are out of phase in the upper stratosphere. These inferred solar effects on ozone and temperature are found to vary dramatically during some months, at least in some altitude regions. Solar effects on temperature are found to be negative from August to March between 9 mb–3 mb pressure levels while solar effects on ozone are maximum during January–March near 10 mb in the Northern Hemisphere and 5 mb–7 mb in the Southern Hemisphere.


2017 ◽  
Vol 30 (7) ◽  
pp. 2523-2534 ◽  
Author(s):  
Lorenzo M. Polvani ◽  
Lei Wang ◽  
Valentina Aquila ◽  
Darryn W. Waugh

The impact of ozone-depleting substances on global lower-stratospheric temperature trends is widely recognized. In the tropics, however, understanding lower-stratospheric temperature trends has proven more challenging. While the tropical lower-stratospheric cooling observed from 1979 to 1997 has been linked to tropical ozone decreases, those ozone trends cannot be of chemical origin, as active chlorine is not abundant in the tropical lower stratosphere. The 1979–97 tropical ozone trends are believed to originate from enhanced upwelling, which, it is often stated, would be driven by increasing concentrations of well-mixed greenhouse gases. This study, using simple arguments based on observational evidence after 1997, combined with model integrations with incrementally added single forcings, argues that trends in ozone-depleting substances, not well-mixed greenhouse gases, have been the primary driver of temperature and ozone trends in the tropical lower stratosphere until 1997, and this has occurred because ozone-depleting substances are key drivers of tropical upwelling and, more generally, of the entire Brewer–Dobson circulation.


2013 ◽  
Vol 13 (3) ◽  
pp. 7061-7079 ◽  
Author(s):  
J.-B. Renard ◽  
S. N. Tripathi ◽  
M. Michael ◽  
A. Rawal ◽  
G. Berthet ◽  
...  

Abstract. Electrified aerosols have been observed in the lower troposphere and in the mesosphere, but have never been detected in the stratosphere and upper troposphere. We present measurements of aerosols during a balloon flight to an altitude of ~24 km. The measurements were performed with an improved version of the STAC aerosol counter dedicated to the search for charged aerosols. It is found that most of the aerosols are charged in the upper troposphere for altitudes below 10 km and in the stratosphere for altitudes above 20 km. On the contrary, the aerosols seem to be uncharged between 10 km and 20 km. Model calculations are used to quantify the electrification of the aerosols with a stratospheric aerosol-ion model. The percentages of charged aerosols obtained with model calculations are in excellent agreement with the observations below 10 km and above 20 km. On the other hand, the model cannot reproduce the absence of detected electrification in the lower stratosphere, such that a distinct unknown process in this altitude range inhibits electrification. The presence of sporadic transient layers of electrified aerosol in the upper troposphere and in the stratosphere could have significant implications for sprite formation.


2020 ◽  
Author(s):  
Mahesh Kovilakam ◽  
Larry Thomason ◽  
Nicholas Ernest ◽  
Landon Rieger ◽  
Adam Bourassa ◽  
...  

Abstract. A robust stratospheric aerosol climate data record enables the depiction of the radiative forcing of this highly variable component of climate. Since stratospheric aerosol also plays a key role in the chemical processes leading to ozone depletion, stratosphere is one of the crucial parameters in understanding climate change in the past and potential changes in the future. As a part of Stratospheric-tropospheric Processes and their Role in Climate (SPARC) Stratospheric Sulfur and its Role in Climate (SSiRC) activity, the Global Space-based Stratospheric Aerosol Climatology (GloSSAC) was created (Thomason et al., 2018) to support the World Climate Research Programme (WCRP)’s Coupled Model Intercomparison Project Phase 6 (CMIP6) (Zanchettin et al., 2016). This data set is a follow-on to one created as a part of Stratosphere-Troposphere Process and their Role in Climate Project (SPARC)’s Assessment of Stratospheric Aerosol Properties (ASAP) activity(SPARC, 2006) and a data created for Chemistry-Climate Model Initiative (CCMI) in 2012 (Eyring and Lamarque, 2012). Herein, we discuss changes to the original release version including those as a part of v1.1 that was released in September 2018 that primarily corrects an error in the conversion of Cryogenic Limb Array Etalon Spectrometer (CLAES) data to Stratospheric Aerosol and Gas Experiment (SAGE) II wavelengths, and the new release, v2.0. Version 2.0 is focused on improving the post-SAGE II era (after 2005) with the goal to mitigate elevated aerosol extinction in the lower stratosphere at mid and high latitudes noted in v1.0 as noted in Thomason et al. (2018). Changes include the use of version 7.0 of Optical Spectrograph and InfraRed Imaging System(OSIRIS), the recently released Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) Lidar Level 3 Stratospheric Aerosol profile monthly product, and the new addition of SAGE III/ISS. Although, the version 7.0 OSIRIS data is substantially improved at its native wavelength of 750 nm, conversion to 525 nm using a constant Angstrom exponent often results in disagreements with SAGEII/ SAGE III/ISS overlap measurements. We, therefore use an observed relationship between OSIRIS extinction at 750 nm and SAGEII/SAGE III/ISS extinction at 525 nm to derive Altitude-Latitude based monthly climatology of Angstrom exponent to compute extinction at 525 nm, resulting in a better agreement between OSIRIS and SAGE measurements. We employ a similar approach to convert OSIRIS 750 nm extinction to 1020 nm extinction for the post-SAGEII period. Additionally, we incorporate the recently released standard CALIPSO stratospheric aerosol profile monthly product into GloSSAC with an improved conversion technique of 532 nm backscatter coefficient to extinction using an observed relationship between OSIRIS 525 nm extinction and CALIPSO 532 nm backscatter. We also investigate for any cloud contamination in OSIRIS/standard CALIPSO stratospheric aerosol product, which may have caused apparent enhancement in the aerosol extinction particularly in the lower stratosphere. SAGE III/ISS data is also incorporated in GloSSAC to extend the climatology to the present and to test the approach used to correct OSIRIS/CALIPSO data. The GloSSAC v2.0 netcdf file is accessible at https://doi.org/10.5067/glossac-l3-v2.0 (Thomason, 2020).


Author(s):  
Thumeka Mkololo ◽  
Nkanyiso Mbatha ◽  
Sivakumar Venkataraman ◽  
Nelson Begue ◽  
Gerrie Coetzee ◽  
...  

This study aims to investigate the Stratosphere-Troposphere Exchange (STE) events and ozone trends over Irene (25.5°S, 28.1°E). Twelve years of ozonesondes data (2000–2007, 2012–2015) from Irene station operating in the framework of the Southern Hemisphere Additional Ozonesodes (SHADOZ) was used to study the troposphere (0–16 km) and stratosphere (17– 28 km) ozone (O3) vertical profiles. Ozone profiles were grouped into three categories (2000–2003, 2004–2007 and 2012–2015) and average composites were calculated for each category. Fifteen O3 enhancement events were identified over the study period. These events were observed in all seasons (one event in summer, four events in autumn, five events in winter and five events in spring), however, they predominantly occur in winter and spring. The STE events presented here are observed to be influenced by the Southern Hemisphere polar vortex. During the STE events, the advected potential vorticity maps assimilated using Modélisation Isentrope du transport Méso–échelle de l’Ozone Stratosphérique par Advection (MIMOSA) model for the 350 K (~12–13 km) isentropic level indicated a transport of high latitude air masses which seems to be responsible for the reduction of the O3 mole fractions at the lower stratosphere over Irene which takes place at the same time with the enhancement of ozone in the upper troposphere. In general, the stratosphere is dominated by higher Modern Retrospective Analysis for Research Application (MERRA-2) potential vorticity (PV) values compared to the troposphere. However, during the STE events, higher PV values from the stratosphere were observed to intrude the troposphere. Ozone decline was observed from 12 km to 24 km with highest decline occurring from 14 km to 18 km. An average decrease of 6.0 and 9.1% was calculated from 12 to 24 km in 2004–2007 and 2012–2015 respectively. The observed decline occurred in the upper troposphere and lower stratosphere with winter and spring showing more decline compared with summer and autumn.


2021 ◽  
Vol 21 (2) ◽  
pp. 989-1013
Author(s):  
Johannes Schneider ◽  
Ralf Weigel ◽  
Thomas Klimach ◽  
Antonis Dragoneas ◽  
Oliver Appel ◽  
...  

Abstract. We analyse aerosol particle composition measurements from five research missions between 2014 and 2018 to assess the meridional extent of particles containing meteoric material in the upper troposphere and lower stratosphere (UTLS). Measurements from the Jungfraujoch mountaintop site and a low-altitude aircraft mission show that meteoric material is also present within middle- and lower-tropospheric aerosol but within only a very small proportion of particles. For both the UTLS campaigns and the lower- and mid-troposphere observations, the measurements were conducted with single-particle laser ablation mass spectrometers with bipolar-ion detection, which enabled us to measure the chemical composition of particles in a diameter range of approximately 150 nm to 3 µm. The five UTLS aircraft missions cover a latitude range from 15 to 68∘ N, altitudes up to 21 km, and a potential temperature range from 280 to 480 K. In total, 338 363 single particles were analysed, of which 147 338 were measured in the stratosphere. Of these total particles, 50 688 were characterized by high abundances of magnesium and iron, together with sulfuric ions, the vast majority (48 610) in the stratosphere, and are interpreted as meteoric material immersed or dissolved within sulfuric acid. It must be noted that the relative abundance of such meteoric particles may be overestimated by about 10 % to 30 % due to the presence of pure sulfuric acid particles in the stratosphere which are not detected by the instruments used here. Below the tropopause, the observed fraction of the meteoric particle type decreased sharply with 0.2 %–1 % abundance at Jungfraujoch, and smaller abundances (0.025 %–0.05 %) were observed during the lower-altitude Canadian Arctic aircraft measurements. The size distribution of the meteoric sulfuric particles measured in the UTLS campaigns is consistent with earlier aircraft-based mass-spectrometric measurements, with only 5 %–10 % fractions in the smallest particles detected (200–300 nm diameter) but with substantial (> 40 %) abundance fractions for particles from 300–350 up to 900 nm in diameter, suggesting sedimentation is the primary loss mechanism. In the tropical lower stratosphere, only a small fraction (< 10 %) of the analysed particles contained meteoric material. In contrast, in the extratropics the observed fraction of meteoric particles reached 20 %–40 % directly above the tropopause. At potential temperature levels of more than 40 K above the thermal tropopause, particles containing meteoric material were observed in much higher relative abundances than near the tropopause, and, at these altitudes, they occurred at a similar abundance fraction across all latitudes and seasons measured. Above 440 K, the observed fraction of meteoric particles is above 60 % at latitudes between 20 and 42∘ N. Meteoric smoke particles are transported from the mesosphere into the stratosphere within the winter polar vortex and are subsequently distributed towards low latitudes by isentropic mixing, typically below a potential temperature of 440 K. By contrast, the findings from the UTLS measurements show that meteoric material is found in stratospheric aerosol particles at all latitudes and seasons, which suggests that either isentropic mixing is effective also above 440 K or that meteoric fragments may be the source of a substantial proportion of the observed meteoric material.


2020 ◽  
Author(s):  
Masatomo Fujiwara ◽  
Tetsu Sakai ◽  
Koichi Shiraishi ◽  
Yoichi Inai ◽  
Sergey Khaykin ◽  
...  

Abstract. Eastward airmass transport from the Asian summer monsoon (ASM) anticyclone in the upper troposphere and lower stratosphere (UTLS) often involves eastward shedding vortices, which can cover most of the Japanese archipelago. We investigated the aerosol characteristics of these vortices by analysing data from two lidar systems in Japan, at Tsukuba (36.1° N, 140.1° E) and Fukuoka (33.55° N, 130.36° E), during the summer of 2018. We observed several events with enhanced particle signals at Tsukuba at 15.5–18 km altitude (at or above the local tropopause) during August–September 2018, with a backscattering ratio of ~1.10 and particle depolarization of ~5 % (i.e., not spherical, but more spherical than ice crystals). These particle characteristics may be consistent with those of solid aerosol particles, such as ammonium nitrate. Each event had a timescale of a few days. During the same study period, we also observed similar enhanced particle signals in the lower stratosphere at Fukuoka. The upper troposphere is often covered by cirrus clouds at both lidar sites. Backward trajectory calculations for these sites for days with enhanced particle signals in the lower stratosphere and days without indicate that the former airmasses originated within the ASM anticyclone, and the latter more from edge regions. Reanalysis carbon-monoxide and satellite water-vapour data indicate that eastward shedding vortices were involved in the observed aerosol enhancements. Satellite aerosol data confirm that the period and latitudinal region were free from the direct influence of documented volcanic eruptions and high latitude forest fires. Our results indicate that the Asian Tropopause Aerosol Layer (ATAL) over the ASM region extends east towards Japan in association with the eastward shedding vortices, and that lidar systems in Japan can detect at least the lower stratospheric portion of the ATAL during periods when the lower stratosphere is undisturbed by volcanic eruptions and forest fires. The upper tropospheric portion of the ATAL is either depleted by tropospheric processes (convection and wet scavenging) during eastward transport or is obscured by much stronger cirrus cloud signals.


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