SCISAT-1, also known as the Atmospheric Chemistry Experiment, is a satellite mission for remote sensing of the Earth's atmosphere, launched on 12 August 2003. The primary instrument on the satellite ...is a 0.02 cm(-1) resolution Fourier-transform spectrometer operating in the mid-IR (750-4400 cm(-1)). We describe the approach developed for the retrieval of atmospheric temperature and pressure from the troposphere to the lower thermosphere as well as the strategy for the retrievals of volume-mixing ratio profiles of atmospheric species.
Atlas of ACE spectra of clouds and aerosols Lecours, Michael J.; Bernath, Peter F; Sorensen, Jason J ...
Journal of quantitative spectroscopy & radiative transfer,
December 2022, 2022-12-00, Volume:
292
Journal Article
Peer reviewed
Open access
•Atmospheric chemistry Experiment, ACE.•Characteristic IR solar absorption spectroscopy of clouds and aerosol particles.•Cloud and aerosol particle spectral analysis and modeling.•Satellite remote ...sensing by Fourier transform infrared spectroscopy.
Clouds and aerosols play a vital role in the Earth's climate. Detecting polar mesospheric clouds, polar stratospheric clouds and aerosols is useful for monitoring climate change and atmospheric chemistry. ACE (Atmospheric Chemistry Experiment) satellite data are used to provide an infrared spectral atlas of polar mesospheric clouds, three types of polar stratospheric clouds (nitric acid trihydrate, sulfuric/nitric acid ternary solutions, and ice), cirrus clouds, stratospheric smoke from fires and sulfate aerosols. Most of the example spectra have been modeled using the appropriate optical constants and the calculated extinction of sunlight by the particles.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The report of an IUPAC Task Group, formed in 2011 on “Intensities and line shapes in high-resolution spectra of water isotopologues from experiment and theory” (Project No. 2011-022-2-100), on line ...profiles of isolated high-resolution rotational-vibrational transitions perturbed by neutral gas-phase molecules is presented. The well-documented inadequacies of the Voigt profile (VP), used almost universally by databases and radiative-transfer codes, to represent pressure effects and Doppler broadening in isolated vibrational-rotational and pure rotational transitions of the water molecule have resulted in the development of a variety of alternative line-profile models. These models capture more of the physics of the influence of pressure on line shapes but, in general, at the price of greater complexity. The Task Group recommends that the partially Correlated quadratic-Speed-Dependent Hard-Collision profile (pCqSD-HCP) should be adopted as the appropriate model for high-resolution spectroscopy. For simplicity this should be called the Hartmann–Tran profile (HTP). The HTP is sophisticated enough to capture the various collisional contributions to the isolated line shape, can be computed in a straightforward and rapid manner, and reduces to simpler profiles, including the Voigt profile, under certain simplifying assumptions.
The distributions of the four most abundant isotopologues and isotopomers (N2O, 15NNO, N15NO, and NN18O) of nitrous oxide have been measured in the Earth's stratosphere by infrared remote sensing ...with the Atmospheric Chemistry Experiment (ACE) Fourier transform spectrometer. These satellite observations have provided a near‐global picture of N2O isotopic fractionation. The relative abundances of the heavier species increase with altitude and with latitude in the stratosphere as the air becomes older. The heavy isotopologues are enriched by 20–30% in the upper stratosphere and even more over the poles. These observations are in general agreement with model predictions made with the Whole Atmosphere Community Climate Model (WACCM). A detailed 3‐D chemical transport model is needed to account for the global isotopic distributions of N2O and to infer sources and sinks.
Key Points
Near‐global observations of atmospheric NNO, 15NNO, N15NO, and NN18O were made with ACE satellite
Isotopic fractionation was modeled with WACCM
Relative stratospheric abundances of the heavier isotopologues and isotopomers are enhanced at higher altitudes and over the poles
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Infrared aerosol spectra derived from Atmospheric Chemistry Experiment measurements following the June 2019 Raikoke volcanic eruption are used to evaluate the composition of stratospheric aerosols in ...the Arctic. A blanket of aerosols, spanning an altitude range from the tropopause (8–11 km) to 20 km, persisted in the stratosphere over northern latitudes for many months. The aerosols within this blanket were almost exclusively sulfates. The percentage of sulfuric acid in the aerosols decreased over time, dropping below 50% H2SO4 concentration at some altitudes by March 2020. Contrary to previous reports, the aerosol blanket was not comprised of smoke particles.
Plain Language Summary
Particles in the atmosphere were measured from a satellite‐based instrument following the 2019 eruption of the Raikoke volcano. These particles were found to be predominately liquid droplets containing a mixture of sulfuric acid and water. A thick blanket of the particles settled over northern regions and lasted for months. Contrary to previous reports, particles in this blanket did not consist of smoke from intense fires that occurred shortly after the volcano's eruption.
Key Points
Following the Raikoke eruption, a layer of sulfate aerosols developed in the stratosphere over northern latitudes, persisting for months
Aerosol composition and physical properties were derived from measurements by the Atmospheric Chemistry Experiment
No evidence of stratospheric smoke was found in the Arctic region, contradicting previous reports
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
This study presents upper troposphere–lower stratosphere (UTLS) water vapour and ozone climatologies generated from 14 years (June 2004 to May 2018) of measurements made by three Canadian ...limb-viewing satellite instruments: the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS), the Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation (MAESTRO), and the Optical Spectrograph and InfraRed Imaging System (OSIRIS; ozone only). This selection of instruments was chosen to explore the capability of these Canadian instruments in representing the UTLS and to enable analysis of the impact of different measurement sampling patterns. The water vapour and ozone climatologies have been constructed using tropopause-relative potential temperature and equivalent-latitude coordinates in an effort to best represent the distribution of these two gases in the UTLS, which is characterized by a high degree of dynamic and geophysical variability. Zonal-mean multiyear-mean climatologies are provided with 5∘ equivalent latitude and 10 K potential temperature spacing and have been constructed on a monthly, seasonal (3-month), and yearly basis. These climatologies are examined in-depth for two 3-month periods, December–January–February and June–July–August, and are compared to reference climatologies constructed from the Canadian Middle Atmosphere Model 39-year specified dynamics (CMAM39-SD) run, subsampled to the times and locations of the satellite measurements, in order to evaluate the consistency of water vapour and ozone between the datasets. Specifically, this method of using a subsampled model addresses the impact of each instrument's measuring pattern and allows for the quantification of the influence of different measurement patterns on multiyear climatologies. This in turn permits a more consistent evaluation of the distributions of these two gas species, as assessed through the differences between the model and measurement climatologies. For water vapour, the average absolute relative difference between CMAM39-SD and ACE-FTS differed between the two versions of ACE-FTS by less than 8 %, while the MAESTRO climatologies were found to differ by 15 %–41 % from ACE-FTS, depending on the version of ACE-FTS and the season. When considering the ozone climatologies, those constructed from the two ACE-FTS versions agreed to within 2 % overall, and the OSIRIS ozone climatologies agreed with these to within 10 %. The MAESTRO ozone climatologies differ from those from ACE-FTS and OSIRIS by 30 %–35 % and 25 %, respectively, albeit with regions of better agreement within the UTLS. These findings indicate that this set of Canadian limb sounders yields generally similar water vapour and ozone distributions in the UTLS, with some exceptions for MAESTRO depending on the season and gas species.
In this paper, we present a new climatology based on the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) version 3.5 data set from February 2004 to February 2013. This ...extends the ACE-FTS climatology to include profile information in the mesosphere and carbon-containing species in the upper troposphere and lower stratosphere. Climatologies of 21 species, based on nine years of observations, are calculated, providing the most comprehensive and self-consistent climatology available from limb-viewing satellite measurements. Pressure levels from the upper troposphere to the mesosphere and lower thermosphere are included with ~3 to 4km vertical resolution up to 10−4hPa (~105km). Volume mixing ratio values are filtered prior to the climatology estimation using the ACE-FTS data quality recommendations. The multi-year mean climatology contains zonal mean profiles for monthly and three-monthly (DJF, MAM, JJA, and SON) periods. These are provided with 5-degree spacing in either latitude or equivalent latitude. Also, the local daytime and nighttime distributions are provided separately for nitrogen-containing species, enabling diurnal differences to be investigated. Based on this climatology, examples of typical spatiotemporal patterns for trace gases in the mesosphere and for carbon-containing gases in the upper troposphere and lower stratosphere are discussed.
•A new global climatology has been produced from the ACE-FTS v3.5 data set.•Fields are on pressure levels that extend from upper troposphere up to mesosphere.•Seven carbon-containing species are now provided with 14 ACE-FTS baseline gases.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
In order to validate satellite measurements of
atmospheric composition, it is necessary to understand the range of random
and systematic uncertainties inherent in the measurements. On occasions
where ...measurements from two different satellite instruments do not agree
within those estimated uncertainties, a common explanation is that the
difference can be assigned to geophysical variability, i.e., differences due
to sampling the atmosphere at different times and locations. However, the
expected geophysical variability is often left ambiguous and rarely
quantified. This paper describes a case study where the geophysical
variability of O3 between two satellite instruments – ACE-FTS
(Atmospheric Chemistry Experiment – Fourier Transform Spectrometer) and
OSIRIS (Optical Spectrograph and InfraRed Imaging System) – is estimated
using simulations from climate models. This is done by sampling the models
CMAM (Canadian Middle Atmosphere Model), EMAC (ECHAM/MESSy Atmospheric
Chemistry), and WACCM (Whole Atmosphere Community Climate Model) throughout
the upper troposphere and stratosphere at times and geolocations of
coincident ACE-FTS and OSIRIS measurements. Ensemble mean values show that
in the lower stratosphere, O3 geophysical variability tends to be
independent of the chosen time coincidence criterion, up to within 12 h; and
conversely, in the upper stratosphere geophysical variation tends to be
independent of the chosen distance criterion, up to within 2000 km. It was
also found that in the lower stratosphere, at altitudes where there is the
greatest difference between air composition inside and outside the polar
vortex, the geophysical variability in the southern polar region can be
double of that in the northern polar region. This study shows that the
ensemble mean estimates of geophysical variation can be used when comparing
data from two satellite instruments to optimize the coincidence criteria,
allowing for the use of more coincident profiles while providing an estimate
of the geophysical variation within the comparison results.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Line-of-sight wind profiles are derived from Doppler shifts in infrared solar occultation measurements from the Atmospheric Chemistry Experiment Fourier transform spectrometers (ACE-FTS), the primary ...instrument on SCISAT, a satellite-based mission for monitoring the Earth’s atmosphere. Comparisons suggest a possible eastward bias from 20 m/s to 30 m/s in ACE-FTS results above 80 km relative to some datasets but no persistent bias relative to other datasets. For instruments operating in a limb geometry, looking through a wide range of altitudes, smearing of the Doppler effect along the line of sight can impact the measured signal, particularly for saturated absorption lines. Implications of Doppler effect smearing are investigated for forward model calculations and volume mixing ratio retrievals. Effects are generally small enough to be safely ignored, except for molecules having a large overhang in their volume mixing ratio profile, such as carbon monoxide.
In September–October 2015, El Niño‐driven weather conditions led to one of the most intense Indonesian peatland burning events in recent history. Consequently, an unprecedented amount of hydrogen ...cyanide (HCN) was emitted from Southeast Asia and transported into the upper troposphere and lower stratosphere, which was then transported by the general circulation from the tropics to polar latitudes. By early 2016, the daily mean concentrations of HCN in the lower stratosphere at all latitudes, as measured by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE‐FTS) instrument, were the largest on record for the region, on the order of 40–90% greater than the climatological mean and ~40% greater than the 2007 El Niño‐driven values. By December 2016, levels of polar HCN in the lower stratosphere were still on the order 10–20% greater than the climatological mean. These ACE‐FTS measurements are thus vital for interpreting ground‐based and nadir satellite measurements of HCN made during 2016 and could be used to help validate tropospheric‐stratospheric exchange in climate models.
Key Points
ACE‐FTS observes extreme concentrations of HCN in lower stratosphere in 2016
HCN concentrations in the lower stratosphere are the largest values on record
Enhancements linked to El Niño‐driven high temperatures, drought in Southeast Asia
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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