scholarly journals SO<sub>2</sub> Retrieval from SCIAMACHY using the Weighting Function DOAS (WFDOAS) Technique: comparison with Standard DOAS retrieval

2008 ◽  
Vol 8 (3) ◽  
pp. 10817-10839 ◽  
Author(s):  
C. Lee ◽  
A. Richter ◽  
M. Weber ◽  
J. P. Burrows
Keyword(s):  
Rayleigh Scattering ◽  
Surface Albedo ◽  
Weighting Function ◽  
Spectral Interference ◽  
Optical Absorption Spectroscopy ◽  
Ultraviolet Region ◽  
Scanning Imaging ◽  
Technique Comparison ◽  
Ozone Column ◽  
Absorption Features

Abstract. Atmospheric SO2 can be measured by remote sensing of scattered sunlight from space, using its unique absorption features in the ultraviolet region. However, the sensitivity of the SO2 measurement depends critically on spectral interference, surface albedo and varies with wavelength as Rayleigh scattering increases at shorter wavelengths. The Weighting Function Differential Optical Absorption Spectroscopy (WFDOAS) method was used to solve these problems. The Ring spectra included in the WFDOAS fit were determined as a function of total ozone column density, solar zenith angle, surface albedo, and effective scene altitude. The WFDOAS SO2 retrieval from SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography) data onboard the ENVISAT satellite are presented here and compared to those of the Standard DOAS (SDOAS) method for cases of background conditions and volcanic eruption. The study demonstrates that the problems in the SO2 retrieval with SDOAS, such as the positive offsets over remote (clean) regions and the negative offsets at high solar zenith angles and high ozone, can be solved by the WFDOAS approach.

scholarly journals SO<sub>2</sub> Retrieval from SCIAMACHY using the Weighting Function DOAS (WFDOAS) technique: comparison with Standard DOAS retrieval

2008 ◽  
Vol 8 (20) ◽  
pp. 6137-6145 ◽  
Author(s):  
C. Lee ◽  
A. Richter ◽  
M. Weber ◽  
J. P. Burrows
Keyword(s):  
Rayleigh Scattering ◽  
Surface Albedo ◽  
Weighting Function ◽  
Spectral Interference ◽  
Optical Absorption Spectroscopy ◽  
Ultraviolet Region ◽  
Scanning Imaging ◽  
Technique Comparison ◽  
Ozone Column ◽  
Absorption Features

Abstract. Atmospheric SO2 can be measured by remote sensing of scattered sunlight from space, using its unique absorption features in the ultraviolet region. However, the sensitivity of the SO2 measurement depends critically on spectral interference, surface albedo and varies with wavelength as Rayleigh scattering increases at shorter wavelengths. The Weighting Function Differential Optical Absorption Spectroscopy (WFDOAS) method was used to pinpoint these problems and improve the retrieval. The Ring spectra included in the WFDOAS fit were determined as a function of total ozone column density, solar zenith angle, surface albedo, and effective scene altitude. The WFDOAS SO2 retrieval from SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography) data onboard the ENVISAT satellite are presented here and compared to those of the Standard DOAS (SDOAS) method for cases of background conditions and volcanic eruption. The study demonstrates the problems in the SO2 retrieval with SDOAS, such as the positive offsets over remote (clean) regions and the negative offsets at high solar zenith angles and high ozone, could be attributed to imperfect correction for the varying ozone dependence of the Ring effect and could be solved by the WFDOAS approach.

scholarly journals Stratospheric CH<sub>4</sub> and CO<sub>2</sub> profiles derived from SCIAMACHY solar occultation measurements

2015 ◽  
Vol 8 (11) ◽  
pp. 11467-11511 ◽  
Author(s):  
S. Noël ◽  
K. Bramstedt ◽  
M. Hilker ◽  
P. Liebing ◽  
J. Plieninger ◽  
...  
Keyword(s):  
Time Series ◽  
Weighting Function ◽  
Optical Absorption Spectroscopy ◽  
Data Sets ◽  
Solar Occultation ◽  
Scanning Imaging ◽  
Carbon Dioxide Co2 ◽  
Latitudinal Range ◽  
Total Column

Abstract. Stratospheric profiles of methane (CH4) and carbon dioxide (CO2) have been derived from solar occultation measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY). The retrieval is performed using a method called "Onion Peeling DOAS" (ONPD) which combines an onion peeling approach with a weighting function DOAS (Differential Optical Absorption Spectroscopy) fit. By use of updated pointing information and optimisation of the data selection and of the retrieval approach the altitude range for reasonable CH4 could be extended to about 17 to 45 km. Furthermore, the quality of the derived CO2 has been assessed such that now the first stratospheric profiles of CO2 from SCIAMACHY are available. Comparisons with independent data sets yield an estimated accuracy of the new SCIAMACHY stratospheric profiles of about 5–10 % for CH4 and 2–3 % for CO2. The accuracy of the products is currently mainly restricted by the appearance of unexpected vertical oscillations in the derived profiles which need further investigation. Using the improved ONPD retrieval, CH4 and CO2 stratospheric data sets covering the whole SCIAMACHY time series (August 2002–April 2012) and the latitudinal range between about 50 and 70° N have been derived. Based on these time series, CH4 and CO2 trends have been estimated, which are in reasonable agreement with total column trends for these gases. This shows that the new SCIAMACHY data sets can provide valuable information about the stratosphere.

scholarly journals Tropospheric column amount of ozone retrieved from SCIAMACHY limb–nadir-matching observations

2014 ◽  
Vol 7 (7) ◽  
pp. 2073-2096 ◽  
Author(s):  
F. Ebojie ◽  
C. von Savigny ◽  
A. Ladstätter-Weißenmayer ◽  
A. Rozanov ◽  
M. Weber ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Weighting Function ◽  
Anthropogenic Activities ◽  
European Space Agency ◽  
Optical Absorption Spectroscopy ◽  
Anthropogenic Activity ◽  
Ozone Monitoring Instrument ◽  
Space Agency ◽  
Tropospheric O3 ◽  
Scanning Imaging

Abstract. Tropospheric ozone (O3), has two main sources: transport from the stratosphere and photochemical production in the troposphere. It plays important roles in atmospheric chemistry and climate change. Its amount and destruction are being modified by anthropogenic activity. Global measurements are needed to test our understanding of its sources and sinks. In this paper, we describe the retrieval of tropospheric O3 columns (TOCs) from the combined limb and nadir observations (hereinafter referred to as limb–nadir-matching (LNM)) of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) instrument, which flew as part of the payload onboard the European Space Agency (ESA) satellite Envisat (2002–2012). The LNM technique used in this study is a residual approach that subtracts stratospheric O3 columns (SOCs), retrieved from the limb observations, from the total O3 columns (TOZs), derived from the nadir observations. The technique requires accurate knowledge of the SOCs, TOZs, tropopause height, and their associated errors. The SOCs were determined from the stratospheric O3 profiles retrieved in the Hartley and Chappuis bands from SCIAMACHY limb scattering measurements. The TOZs were also derived from SCIAMACHY measurements, but in this case from the nadir viewing mode using the Weighting Function Differential Optical Absorption Spectroscopy (WFDOAS) technique in the Huggins band. Comparisons of the TOCs from SCIAMACHY and collocated measurements from ozonesondes in both hemispheres between January 2003 and December 2011 show agreement to within 2–5 DU (1 DU = 2.69 × 1016 molecules cm−2). TOC values from SCIAMACHY have also been compared to the results from the Tropospheric Emission Spectrometer (TES) and from the LNM technique exploiting Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) data (hereinafter referred to as OMI/MLS). All compared data sets agree within the given data product error range and exhibit similar seasonal variations, which, however, differ in amplitude. The spatial distributions of tropospheric O3 in the SCIAMACHY LNM TOC product show characteristic variations related to stratosphere–troposphere exchange (STE) processes, anthropogenic activities and biospheric emissions.

scholarly journals Tropospheric column amount of ozone retrieved from SCIAMACHY limb-nadir-matching observations

2013 ◽  
Vol 6 (4) ◽  
pp. 7811-7865 ◽  
Author(s):  
F. Ebojie ◽  
C. von Savigny ◽  
A. Ladstätter-Weißenmayer ◽  
A. Rozanov ◽  
M. Weber ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Tropospheric Ozone ◽  
Weighting Function ◽  
European Space Agency ◽  
Optical Absorption Spectroscopy ◽  
Data Sets ◽  
Ozone Monitoring Instrument ◽  
Space Agency ◽  
Tropospheric O3 ◽  
Scanning Imaging

Abstract. Tropospheric ozone, O3, has two sources: transport from the stratosphere and photochemical production in the troposphere. It plays important roles in atmospheric chemistry and climate change. In this manuscript we describe the retrieval of tropospheric O3 columns from limb-nadir matching (LNM) observations of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) instrument, which flies as part of the payload onboard the European Space Agency (ESA) satellite Envisat. This retrieval technique is a residual approach that utilizes the subtraction of the stratospheric O3 columns, derived from the limb observations, from the total O3 columns, derived from the nadir observations. The technique requires accurate knowledge of the stratospheric O3 columns, the total O3 columns, tropopause height, and their associated errors. The stratospheric O3 columns were determined from the stratospheric O3 profile retrieved in the Hartley and Chappius bands, based on SCIAMACHY limb scattering measurements. The total O3 columns were also derived from SCIAMACHY measurements, in the nadir viewing mode using the Weighting Function Differential Optical Absorption Spectroscopy (WFDOAS) technique in the Huggins band. Comparisons of the tropospheric O3 columns from SCIAMACHY and collocated measurements from ozonesondes, in both hemispheres between January 2003 and December 2011 show agreement to within 2–5 DU (1 DU = 2.69 × 1016 molecules cm−2). Comparison of tropospheric O3 from SCIAMACHY with the results from ozonesondes, the Tropospheric Emission Spectrometer (TES), and the LNM method combining Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) data (hereinafter referred to as OMI/MLS), have been investigated. We find that all four retrieved data sets show agreement within the error bars and exhibit strong seasonal variation, which differs in amplitude. The spatial distribution of tropospheric ozone observed shows pollution plumes related to the release of precursors at the different seasons in both hemispheres.

scholarly journals Total ozone column from Ozone Mapping and Profiler Suite Nadir Mapper (OMPS-NM) measurements using the broadband weighting function fitting approach (WFFA)

2021 ◽  
Vol 14 (8) ◽  
pp. 5771-5789
Author(s):  
Andrea Orfanoz-Cheuquelaf ◽  
Alexei Rozanov ◽  
Mark Weber ◽  
Carlo Arosio ◽  
Annette Ladstätter-Weißenmayer ◽  
...  
Keyword(s):  
Total Ozone ◽  
Weighting Function ◽  
Optical Absorption Spectroscopy ◽  
Retrieval Algorithm ◽  
Polar Regions ◽  
Total Ozone Column ◽  
Function Fitting ◽  
Ozone Column ◽  
Good Agreement ◽  
Column Product

Abstract. A scientific total ozone column product from Ozone Mapping and Profiler Suite Nadir Mapper (OMPS-NM) observations and the retrieval algorithm are presented. The retrieval employs the weighting function fitting approach (WFFA), a modification of the weighting function differential optical absorption spectroscopy (WFDOAS) technique. The total ozone columns retrieved with WFFA are in very good agreement with other datasets. A mean difference of 0.3 % with respect to ground-based Brewer and Dobson measurements is observed. Seasonal and latitudinal variations are well represented and in agreement with other satellite datasets. The comparison of our product with the operational product of OMPS-NM indicates a mean bias of around zero. The comparison with the Tropospheric Monitoring Instrument products (S5P/TROPOMI) OFFL and WFDOAS shows a persistent negative bias of about −0.6 % for OFFL and −2.5 % for WFDOAS. Larger differences are only observed in the polar regions. This data product is intended to be used for trend analysis and the retrieval of tropospheric ozone combined with the OMPS limb profiler data.

scholarly journals Total ozone column retrieval from OMPS-NM measurements

2021 ◽  
Author(s):  
Andrea Orfanoz-Cheuquelaf ◽  
Alexei Rozanov ◽  
Mark Weber ◽  
Carlo Arosio ◽  
Annette Ladstätter-Weißenmayer ◽  
...  
Keyword(s):  
Total Ozone ◽  
Weighting Function ◽  
Optical Absorption Spectroscopy ◽  
Retrieval Algorithm ◽  
Polar Regions ◽  
Total Ozone Column ◽  
Function Fitting ◽  
Ozone Column ◽  
Good Agreement ◽  
Column Product

Abstract. A scientific total ozone column product from the Ozone Mapping and Profiler Suite Nadir Mapper (OMPS-NM) observations and its retrieval algorithm are presented. The retrieval employs the Weighting Function Fitting Approach (WFFA), a modification of the Weighting Function Differential Optical Absorption Spectroscopy (WFDOAS) technique. The total ozone columns retrieved with WFFA are in very good agreement with other datasets. A mean difference of 0.6 % with respect to ground-based Brewer and Dobson measurements is observed. Seasonal and latitudinal variations are well represented and in agreement with other satellite datasets. The comparison of our product with the scientific product of OMPS-NM indicate a mean bias of around 0.1 %. The comparison with the Tropospheric Monitoring Instrument products (S5P/TROPOMI) OFFL and WFDOAS, shows a persistent negative bias of about −0.5 % for OFFL and –2 % for WFDOAS. Larger differences are only observed in the polar regions. This data product is intended to be used for trend analysis and the retrieval of tropospheric ozone combined with the OMPS limb profiler data.

scholarly journals Stratospheric CH<sub>4</sub> and CO<sub>2</sub> profiles derived from SCIAMACHY solar occultation measurements

2016 ◽  
Vol 9 (4) ◽  
pp. 1485-1503 ◽  
Author(s):  
Stefan Noël ◽  
Klaus Bramstedt ◽  
Michael Hilker ◽  
Patricia Liebing ◽  
Johannes Plieninger ◽  
...  
Keyword(s):  
Time Series ◽  
Weighting Function ◽  
Optical Absorption Spectroscopy ◽  
Data Sets ◽  
Solar Occultation ◽  
Scanning Imaging ◽  
Carbon Dioxide Co2 ◽  
Latitudinal Range ◽  
Total Column

Abstract. Stratospheric profiles of methane (CH4) and carbon dioxide (CO2) have been derived from solar occultation measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY). The retrieval is performed using a method called onion peeling DOAS (ONPD), which combines an onion peeling approach with a weighting function DOAS (differential optical absorption spectroscopy) fit in the spectral region between 1559 and 1671 nm. By use of updated pointing information and optimisation of the data selection as well as of the retrieval approach, the altitude range for reasonable CH4 could be broadened from 20 to 40 km to about 17 to 45 km. Furthermore, the quality of the derived CO2 has been assessed such that now the first stratospheric profiles (17–45 km) of CO2 from SCIAMACHY are available. Comparisons with independent data sets yield an estimated accuracy of the new SCIAMACHY stratospheric profiles of about 5–10 % for CH4 and 2–3 % for CO2. The accuracy of the products is currently mainly restricted by the appearance of unexpected vertical oscillations in the derived profiles which need further investigation. Using the improved ONPD retrieval, CH4 and CO2 stratospheric data sets covering the whole SCIAMACHY time series (August 2002–April 2012) and the latitudinal range between about 50 and 70° N have been derived. Based on these time series, CH4 and CO2 trends have been estimated. CH4 trends above about 20 km are not significantly different from zero and the trend at 17 km is about 3 ppbv year−1. The derived CO2 trends show a general decrease with altitude with values of about 1.9 ppmv year−1 at 21 km and about 1.3 ppmv year−1 at 39 km. These results are in reasonable agreement with total column trends for these gases. This shows that the new SCIAMACHY data sets can provide valuable information about the stratosphere.

scholarly journals Spectral studies of ocean water using DOAS

2007 ◽  
Vol 4 (3) ◽  
pp. 459-489
Author(s):  
M. Vountas ◽  
T. Dinter ◽  
A. Bracher ◽  
J. P. Burrows ◽  
B. Sierk
Keyword(s):  
Spectral Studies ◽  
Optical Absorption Spectroscopy ◽  
Retrieval Technique ◽  
Phytoplankton Absorption ◽  
Visible Wavelengths ◽  
Scanning Imaging ◽  
Atmospheric Trace Gas ◽  
First Time ◽  
Chlorophyll Concentrations

Abstract. Methods enabling the retrieval of oceanic parameter from the space borne instrumentation Scanning Imaging Absorption Spectrometer for Atmospheric ChartographY (SCIAMACHY) using Differential Optical Absorption Spectroscopy (DOAS) are presented. SCIAMACHY onboard ENVISAT measures back scattered solar radiation at a spectral resolution (0.2 to 1.5 nm). The DOAS method was used for the first time to fit modelled Vibrational Raman Scattering (VRS) in liquid water and in situ measured phytoplankton absorption reference spectra to optical depths measured by SCIAMACHY. Spectral structures of VRS and phytoplankton absorption were clearly found in these optical depths. Both fitting approaches lead to consistent results. DOAS fits correlate with estimates of chlorophyll concentrations: low fit factors for VRS retrievals correspond to large chlorophyll concentrations and vice versa; large fit factors for phytoplankton absorption correspond with high chlorophyll concentrations and vice versa. From these results a simple retrieval technique taking advantage of both measurements is shown. First maps of global chlorophyll concentrations were compared to the corresponding MODIS measurements with very promising results. In addition, results from this study will be used to improve atmospheric trace gas DOAS-retrievals from visible wavelengths by including these oceanographic signatures.

scholarly journals Scattering and Absorption Cross-sections of Atmospheric Gases in the Ultraviolet-Visible Wavelength Range (307–725 nm)

2020 ◽  
Author(s):  
Quanfu He ◽  
Zheng Fang ◽  
Ofir Shoshamin ◽  
Steven S. Brown ◽  
Yinon Rudich
Keyword(s):  
Refractive Index ◽  
Wavelength Range ◽  
Cross Sections ◽  
Rayleigh Scattering ◽  
Dispersion Relations ◽  
Optical Absorption Spectroscopy ◽  
Absorption Cross ◽  
Atmospheric Gases ◽  
Scattering Cross ◽  
Scattering Cross Sections

Abstract. Accurate Rayleigh scattering and absorption cross-sections of atmospheric gases are essential for understanding the propagation of electromagnetic radiation in planetary atmospheres. Accurate extinction cross-sections are also essential for calibrating high finesse optical cavities and differential optical absorption spectroscopy and for accurate remote sensing. In this study, we measured the scattering and absorption cross-sections of carbon dioxide, nitrous oxide, sulfur hexafluoride, oxygen, and methane in the continuous wavelength range of 307–725 nm using Broadband Cavity Enhanced Spectroscopy (BBCES). The experimentally derived Rayleigh scattering cross-sections for CO2, N2O, SF6, O2, and CH4 agree with refractive index-based calculations, with a difference of 1.5 % and 1.1 %, 1.5 %, 2.9 %, and 1.4 % on average, respectively. The O2-O2 collision-induced absorption and absorption by methane are obtained with high precision at the 0.8 nm resolution of our BBCES instrument in the 307–725 nm wavelength range. New dispersion relations for N2O, SF6, and CH4 were derived using data in the UV-vis wavelength range. This study provides improved refractive index dispersion relations, n-based Rayleigh scattering cross-sections, and absorption cross-sections for these gases.

scholarly journals Validation of SCIAMACHY AMC-DOAS water vapour columns

2005 ◽  
Vol 5 (7) ◽  
pp. 1835-1841 ◽  
Author(s):  
S. Noël ◽  
M. Buchwitz ◽  
H. Bovensmann ◽  
J. P. Burrows
Keyword(s):  
Water Vapour ◽  
Visible Spectral Region ◽  
Optical Absorption Spectroscopy ◽  
Data Sets ◽  
Monthly Means ◽  
Data Set ◽  
Weather Forecasts ◽  
Microwave Imager ◽  
Scanning Imaging

Abstract. A first validation of water vapour total column amounts derived from measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) in the visible spectral region has been performed. For this purpose, SCIAMACHY water vapour data have been determined for the year 2003 using an extended version of the Differential Optical Absorption Spectroscopy (DOAS) method, called Air Mass Corrected (AMC-DOAS). The SCIAMACHY results are compared with corresponding water vapour measurements by the Special Sensor Microwave Imager (SSM/I) and with model data from the European Centre for Medium-Range Weather Forecasts (ECMWF). In confirmation of previous results it could be shown that SCIAMACHY derived water vapour columns are typically slightly lower than both SSM/I and ECMWF data, especially over ocean areas. However, these deviations are much smaller than the observed scatter of the data which is caused by the different temporal and spatial sampling and resolution of the data sets. For example, the overall difference with ECMWF data is only -0.05 g/cm2 whereas the typical scatter is in the order of 0.5 g/cm2. Both values show almost no variation over the year. In addition, first monthly means of SCIAMACHY water vapour data have been computed. The quality of these monthly means is currently limited by the availability of calibrated SCIAMACHY spectra. Nevertheless, first comparisons with ECMWF data show that SCIAMACHY (and similar instruments) are able to provide a new independent global water vapour data set.

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