Cloud detection in the upper troposphere‐lower stratosphere region via ACE imagers: A qualitative study

Dodion, J.; Fussen, D.; Vanhellemont, F.; Bingen, Christine; Mateshvili, Nina; Gilbert, K. L.; Skelton, R.; Turnbull, D. N.; McLeod, Sean D.; Boone, C. D.; Walker, Kaley A.; Bernath, P. F.

doi:10.1029/2006jd007160

Cited by 11 publications

(10 citation statements)

References 19 publications

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“…As already explained, solar images are rotated about their sun centroids before transmittance is calculated. However, when clouds are present, the solar disk is not well defined and has a very irregular shape (Dodion et al, 2007). It is possible, therefore, that the calculated rotation angle is not correct and erroneous transmittance profiles result.…”

Section: Discussionmentioning

confidence: 96%

“…This feature allows the identification of particle/cloud types by the use of the observed morphology (cloud shape, layer dimensions). Initial studies on this topic have already been performed by Dodion et al (2007). The subject of this paper is the comparison of the aerosol and cloud extinction profiles that are derived from the two ACE imager measurements, with results from four satellite occultation instruments (SAGE II, SAGE III, POAM III and GOMOS) and one limb sounder (OSIRIS).…”

Section: Introductionmentioning

confidence: 99%

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Aerosol extinction profiles at 525 nm and 1020 nm derived from ACE imager data: comparisons with GOMOS, SAGE II, SAGE III, POAM III, and OSIRIS

Vanhellemont

Tétard²,

Bourassa

et al. 2008

Atmos. Chem. Phys.

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Abstract. The Canadian ACE (Atmospheric Chemistry Experiment) mission is dedicated to the retrieval of a large number of atmospheric trace gas species using the solar occultation technique in the infrared and UV/visible spectral domain. However, two additional solar disk imagers (at 525 nm and 1020 nm) were added for a number of reasons, including the retrieval of aerosol and cloud products. In this paper, we present first comparison results for these imager aerosol/cloud optical extinction coefficient profiles, with the ones derived from measurements performed by 3 solar occultation instruments (SAGE II, SAGE III, POAM III), one stellar occultation instrument (GOMOS) and one limb sounder (OSIRIS). The results indicate that the ACE imager profiles are of good quality in the upper troposphere/lower stratosphere, although the aerosol extinction for the visible channel at 525 nm contains a significant negative bias at higher altitudes, while the relative differences indicate that ACE profiles are almost always too high at 1020 nm. Both problems are probably related to ACE imager instrumental issues.

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Section: Discussionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Aerosol extinction profiles at 525 nm and 1020 nm derived from ACE imager data: comparisons with GOMOS, SAGE II, SAGE III, POAM III, and OSIRIS

Vanhellemont

Tétard²,

Bourassa

et al. 2008

Atmos. Chem. Phys.

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“…It also allows for three‐dimensional mapping of this relatively long‐lived volcanic plume. Previous work on cloud heights from ACE Imager extinctions relied on visual inspection [ Dodion et al , 2007]. This method was limiting since:…”

Section: Methodsmentioning

confidence: 99%

Atmospheric Chemistry Experiment (ACE) observations of aerosol in the upper troposphere and lower stratosphere from the Kasatochi volcanic eruption

Sioris¹,

Boone²,

Bernath³

et al. 2010

J. Geophys. Res.

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Near‐infrared (NIR) atmospheric extinction profile observations from the Atmospheric Chemistry Experiment (ACE) Imager and from Measurements of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation (MAESTRO) are presented, illustrating the impact of the Kasatochi volcanic eruption in August 2008 on the aerosol loading of the upper troposphere and lower stratosphere in the subsequent months. In September 2008, profiles of NIR extinction show a significant increase relative to each of the previous four Septembers (2004–2007). The aerosol enhancement is observable up to 18.5 km in Northern Hemisphere NIR extinction data, and peaks at 9.5 km in the extratropics, where the extinction is ∼8 times the normal September value. The particulate matter in the troposphere is quickly dispersed over the Northern Hemisphere during September 2008 and vanishes by the end of November 2008. An upper layer, initially in the extratropical lower stratosphere, persists through March 2009, descending with time into the troposphere where, by coagulation of sulphate aerosol, the size of the particles increases with time.

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“…The images are already being put to use in the detection and identification of cirrus and polar stratospheric clouds [ Dodion et al , 2007], and their atmospheric extinction profiles are supporting the remote sensing of biomass burning [ Rinsland et al , 2006]. Because ACE imager data are now in demand and still in a preliminary processing state, it seems necessary to provide a description of the imagers so that the data may be better understood.…”

Section: Introductionmentioning

confidence: 99%

The onboard imagers for the Canadian ACE SCISAT‐1 mission

Gilbert¹,

Turnbull²,

Walker³

et al. 2007

J. Geophys. Res.

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[1] The Atmospheric Chemistry Experiment (ACE) onboard the Canadian Space Agency's SCISAT-1 satellite has been in orbit since August of 2003. Its broad objective is to study the problem of stratospheric ozone depletion, particularly in the Arctic. The main instruments are two spectrometers, one an infrared Fourier Transform Spectrometer and the other a dual optical spectrophotometer sensitive in the UV and visible. Also included are two filtered imagers used to measure altitude profiles of atmospheric extinction and detect thin clouds. The nominal center wavelengths of the filters are 525 nm for the visible (VIS) imager and 1020 nm for the near-infrared (NIR) imager. With the decommissioning of other satellite instruments used to monitor global aerosols [i.e., Stratospheric Aerosol and Gas Experiment II (SAGE II), SAGE III, Polar Ozone and Aerosol Measurement (POAM) III, Halogen Occultation Experiment (HALOE)], the imagers provide much needed continuity in this data record. The data product from the imagers is still, however, in a preliminary state. Funding restrictions in the prelaunch period were responsible for an incomplete characterization of the imagers' optics and electronics and prevented corrections being made for the problems found during testing. Postlaunch data analysis to correct for image artifacts is ongoing. A comparison with coincidental measurements from SAGE II shows that systematic errors from the preliminary analysis are within 5 and 20% for the VIS and NIR imagers, respectively, for uninverted profiles of optical depth. Despite the preliminary nature of the imager results, a paper describing the imagers and the initial operational data processing code is timely because the data are already being used.

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Cloud detection in the upper troposphere‐lower stratosphere region via ACE imagers: A qualitative study

Cited by 11 publications

References 19 publications

Aerosol extinction profiles at 525 nm and 1020 nm derived from ACE imager data: comparisons with GOMOS, SAGE II, SAGE III, POAM III, and OSIRIS

Aerosol extinction profiles at 525 nm and 1020 nm derived from ACE imager data: comparisons with GOMOS, SAGE II, SAGE III, POAM III, and OSIRIS

Atmospheric Chemistry Experiment (ACE) observations of aerosol in the upper troposphere and lower stratosphere from the Kasatochi volcanic eruption

The onboard imagers for the Canadian ACE SCISAT‐1 mission

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