scholarly journals SCIAMACHY Absorbing Aerosol Index – calibration issues and global results from 2002–2004

2005 ◽  
Vol 5 (3) ◽  
pp. 3367-3389 ◽  
Author(s):  
M. de Graaf ◽  
P. Stammes
Keyword(s):  
Good Representation ◽  
Correction Factors ◽  
Lookup Tables ◽  
Scanning Imaging ◽  
Aerosol Index ◽  
Reflectance Data ◽  
Absorption Spectrometer

Abstract. The validity of the Absorbing Aerosol Index (AAI) product from the SCanning Imaging Absorption SpectroMeter for Atmospheric CartograpHY (SCIAMACHY) is discussed. The operational SCIAMACHY AAI product suffers from calibration errors in the reflectance as measured by SCIAMACHY and design errors. Therefore, the AAI product was recalculated, compensating for the errors, with reflectance data from the start of measurements of SCIAMACHY until December 2004. Appropriate correction factors were determined for the UV to correct for the radiometric error in the SCIAMACHY reflectances. The algorithm was provided with LookUp Tables in which a good representation of polarisation effects was incorporated, as opposed to the LookUp Tables of the operational product, in which polarisation effects were not accounted for. The results are presented, their validity discussed, and compared to the operational product. The AAI is very sensitive to calibration errors and can be used to monitor calibration errors and changes. From 2004 onwards, the new SCIAMACHY AAI is suitable to add to the continuation of the long-term AAI record. Recommendations are given for improvement of the operational AAI product.

scholarly journals SCIAMACHY Absorbing Aerosol Index – calibration issues and global results from 2002–2004

2005 ◽  
Vol 5 (9) ◽  
pp. 2385-2394 ◽  
Author(s):  
M. de Graaf ◽  
P. Stammes
Keyword(s):  
Total Ozone ◽  
Computational Algorithm ◽  
Good Representation ◽  
Correction Factors ◽  
Total Ozone Mapping Spectrometer ◽  
Lookup Tables ◽  
Scanning Imaging ◽  
Aerosol Index ◽  
Reflectance Data

Abstract. The validity of the Absorbing Aerosol Index (AAI) product from the SCanning Imaging Absorption SpectroMeter for Atmospheric CartograpHY (SCIAMACHY) is discussed. The operational SCIAMACHY AAI product suffers from calibration errors in the reflectance as measured by SCIAMACHY and neglect of polarisation effects in the AAI computational algorithm. Therefore, the AAI product was recalculated, compensating for the errors, with reflectance data from the start of measurements of SCIAMACHY until December 2004. Appropriate correction factors were determined for the UV to correct for the radiometric error in the SCIAMACHY reflectances. The algorithm was provided with LookUp Tables in which a good representation of polarisation effects was incorporated, as opposed to the LookUp Tables of the operational product, in which polarisation effects were not accounted for. The results are presented, their validity discussed, and compared to the operational product and independent AAI data from the Total Ozone Mapping Spectrometer (TOMS). The AAI is very sensitive to calibration errors and can be used to monitor calibration errors and changes. The AAI is sensitive to sunglint and a correction flag used for the AAI is presented. From 2004 onwards, the new SCIAMACHY AAI is suitable to add to the continuation of the long-term AAI record. Important changes in the long-term AAI record due to instrument and algorithm changes are highlighted. Recommendations are given for improvement of the operational AAI product.

scholarly journals Deriving consistent long-term vegetation information from AVHRR reflectance data using a cover-triangle-based framework

2008 ◽  
Vol 112 (6) ◽  
pp. 2938-2949 ◽  
Author(s):  
Randall J. Donohue ◽  
Michael L. Roderick ◽  
Tim R. McVicar
Keyword(s):  
Reflectance Data

scholarly journals The semianalytical cloud retrieval algorithm for SCIAMACHY – I. The validation

2005 ◽  
Vol 5 (2) ◽  
pp. 1995-2015 ◽  
Author(s):  
A. A. Kokhanovsky ◽  
V. V. Rozanov ◽  
T. Nauss ◽  
C. Reudenbach ◽  
J. S. Daniel ◽  
...  
Keyword(s):  
Retrieval Algorithm ◽  
Look Up Table ◽  
Ozone Monitoring ◽  
Scanning Imaging ◽  
Using Data ◽  
The Look ◽  
Along Track ◽  
Spectrometer Data ◽  
Resolution Spectrometer ◽  
Absorption Spectrometer

Abstract. A recently developed cloud retrieval algorithm for the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) is briefly presented and validated using independent and well tested cloud retrieval techniques based on the look-up-table approach for MODeration resolutIon Spectrometer data. The results of the cloud top height retrievals using measurements in the oxygen A-band by an airborne crossed Czerny-Turner spectrograph and the Global Ozone Monitoring Experiment (GOME) instrument are compared with those obtained from airborne dual photography and retrievals using data from Along Track Scanning Radiometer (ATSR-2), respectively.

First year of real-time VOC measurements at the SIRTA facility (Paris region, France): diurnal and seasonal variabilities, impact of lockdowns on air quality

2021 ◽  
Author(s):  
Leïla Simon ◽  
Valérie Gros ◽  
Jean-Eudes Petit ◽  
François Truong ◽  
Roland Sarda-Esteve ◽  
...  
Keyword(s):  
Air Quality ◽  
Atmospheric Chemistry ◽  
Seasonal Variability ◽  
Anthropogenic Sources ◽  
First Year ◽  
Good Representation ◽  
Atmospheric Measurements ◽  
Paris Region ◽  
The Impact

<p>Volatile Organic Compounds (VOCs) have direct influences on air quality and climate. They also play a key role in atmospheric chemistry, as they are precursors of secondary pollutants, such as ozone (O<sub>3</sub>) and secondary organic aerosols (SOA).</p><p>Long-term datasets of in-situ atmospheric measurements are crucial to characterize the variability of atmospheric chemical composition. Online and continuous measurements of O<sub>3</sub>, NO<sub>x</sub> and aerosols have been achieved at the SIRTA-ACTRIS facility (Paris region, France), since 2012. Regarding VOCs, they have been measured there for several years thanks to bi-weekly samplings followed by offline Gas Chromatography analysis. However, this method doesn’t provide a good representation of the temporal variability of VOC concentrations. To tackle this issue, online VOC measurements using a Proton-Transfer-Reaction Quadrupole Mass-Spectrometer (PTR-Q-MS) have been started in January 2020.</p><p>The dataset acquired during the first year of online VOC measurements is analyzed, which gives insights on VOC seasonal variability. The additional long-term datasets obtained from co-located measurements (O<sub>3</sub>, NO<sub>x</sub>, aerosol physical and chemical properties, meteorological parameters) are also used for the sake of this study.</p><p>Due to Covid-19 pandemic, the year 2020 notably comprised a total lockdown in France in Spring, and a lighter one in Autumn. Therefore, a focus can be made on the impact of these lockdowns on the VOC variability and sources. To this end, the diurnal cycles of VOCs considered markers for anthropogenic sources are carefully investigated. Results notably indicate that markers for traffic and wood burning sources behave quite differently during the Spring lockdown in comparison to the other periods. A source apportionment analysis using positive matrix factorization allows to further document the seasonal variability of VOC sources and the impacts on air quality associated with the lockdown measures.</p>

scholarly journals Correcting the geomagnetic IHV index of the Eskdalemuir observatory

2006 ◽  
Vol 24 (12) ◽  
pp. 3411-3419 ◽  
Author(s):  
D. Martini ◽  
K. Mursula
Keyword(s):  
Magnetic Field ◽  
Data Center ◽  
Early Years ◽  
Correction Factors ◽  
Hourly Data ◽  
The World ◽  
Variability Index ◽  
The Magnetic Field ◽  
Long Term Studies

Abstract. We study here the recently proposed measure of local geomagnetic activity called the IHV (Inter-Hour Variability) index calculated for the Eskdalemuir (ESK) station. It was found earlier that the ESK IHV index depicts an artificial, step-like increase from 1931 to 1932. We show here that this increase is due to the fact that the values of the magnetic field components of the ESK observatory stored at the World Data Center are two-hour running averages of hourly data stored in ESK yearbooks. Two-hour averaging greatly reduces the variability of the data which leads to artificially small values of the IHV index in 1911–1931. We also study the effect of two-hour averaging upon hourly mean and spot values using 1-minute data available for recent years, and calculate the correction factors for the early years, taking into account the weak dependence of correction factors on solar activity. Using these correction factors, we correct the ESK IHV indices in 1912–1931, and revise the estimate of the centennial change based on them. The effect of correction is very significant: the centennial increase in the ESK IHV-raw (IHV-cor) index in 1912–2000 changes from 73.9% (134.4%) before correction to 10.3% (25.3%) thereafter, making the centennial increase at ESK quite similar to other mid-latitude stations. Obviously, earlier long-term studies based on ESK IHV values are affected by the correction and need to be revised. These results also strongly suggest that the ESK yearbook data should be digitized and the hourly ESK data at WDC should be replaced by them.

scholarly journals Multi-year comparison of stratospheric BrO vertical profiles retrieved from SCIAMACHY limb and ground-based UV-visible measurements

2009 ◽  
Vol 2 (1) ◽  
pp. 273-285 ◽  
Author(s):  
F. Hendrick ◽  
A. Rozanov ◽  
P. V. Johnston ◽  
H. Bovensmann ◽  
M. De Mazière ◽  
...  
Keyword(s):  
Cross Sections ◽  
Relative Difference ◽  
Early Spring ◽  
Vertical Profiles ◽  
Altitude Range ◽  
Comparison Results ◽  
Uv Visible ◽  
Scanning Imaging ◽  
Relative Differences ◽  
Absorption Spectrometer

Abstract. Vertical profiles of stratospheric bromine monoxide (BrO) retrieved daily from ENVISAT/SCIAMACHY (ENVIronmental SATellite/SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) limb scatter data and from ground-based UV-visible observations performed at Harestua (60° N, 11° E), Observatoire de Haute-Provence (44° N, 5.5° E), and Lauder (45° S, 170° E) are compared in the 15–27 km altitude range for the 2002–2006, 2005–2006, and 2002–2005 periods, respectively. At the three stations, the SCIAMACHY and ground-based UV-visible mean profiles agree reasonably well, with relative difference smaller than 23%. When comparing the BrO partial columns, the agreement obtained is good, with mean relative differences smaller than 11% and corresponding standard deviations in the 13–19% range. These comparison results are obtained, however, using different BrO cross sections in SCIAMACHY limb and ground-based UV-visible retrievals. The seasonal variation of the BrO columns at the three stations is consistently captured by both retrievals as well as large BrO column events occurring during the winter and early spring at Harestua which are associated with bromine activation.

scholarly journals Geophysical validation and long-term consistency between GOME-2/MetOp-A total ozone column and measurements from the sensors GOME/ERS-2, SCIAMACHY/ENVISAT and OMI/Aura

2012 ◽  
Vol 5 (9) ◽  
pp. 2169-2181 ◽  
Author(s):  
M. E. Koukouli ◽  
D. S. Balis ◽  
D. Loyola ◽  
P. Valks ◽  
W. Zimmer ◽  
...  
Keyword(s):  
Total Ozone ◽  
Satellite Monitoring ◽  
Total Ozone Column ◽  
Satellite Sensors ◽  
Data Processor ◽  
Ozone Monitoring ◽  
Scanning Imaging ◽  
Ozone Column ◽  
Seasonal Dependence

Abstract. The main aim of the paper is to assess the consistency of five years of Global Ozone Monitoring Experiment-2/Metop-A [GOME-2] total ozone columns and the long-term total ozone satellite monitoring database already in existence through an extensive inter-comparison and validation exercise using as reference Brewer and Dobson ground-based measurements. The behaviour of the GOME-2 measurements is being weighed against that of GOME (1995–2011), Ozone Monitoring Experiment [OMI] (since 2004) and the Scanning Imaging Absorption spectroMeter for Atmospheric CartograpHY [SCIAMACHY] (since 2002) total ozone column products. Over the background truth of the ground-based measurements, the total ozone columns are inter-evaluated using a suite of established validation techniques; the GOME-2 time series follow the same patterns as those observed by the other satellite sensors. In particular, on average, GOME-2 data underestimate GOME data by about 0.80%, and underestimate SCIAMACHY data by 0.37% with no seasonal dependence of the differences between GOME-2, GOME and SCIAMACHY. The latter is expected since the three datasets are based on similar DOAS algorithms. This underestimation of GOME-2 is within the uncertainty of the reference data used in the comparisons. Compared to the OMI sensor, on average GOME-2 data underestimate OMI_DOAS (collection 3) data by 1.28%, without any significant seasonal dependence of the differences between them. The lack of seasonality might be expected since both the GOME data processor [GDP] 4.4 and OMI_DOAS are DOAS-type algorithms and both consider the variability of the stratospheric temperatures in their retrievals. Compared to the OMI_TOMS (collection 3) data, no bias was found. We hence conclude that the GOME-2 total ozone columns are well suitable to continue the long-term global total ozone record with the accuracy needed for climate monitoring studies.

scholarly journals Analysis of global water vapour trends from satellite measurements in the visible spectral range

2007 ◽  
Vol 7 (4) ◽  
pp. 11761-11796 ◽  
Author(s):  
S. Mieruch ◽  
S. Noël ◽  
H. Bovensmann ◽  
J. P. Burrows
Keyword(s):  
Time Series ◽  
Water Vapour ◽  
Statistical Significance ◽  
Visible Spectral Range ◽  
Optical Absorption Spectroscopy ◽  
Data Set ◽  
Factors Affecting ◽  
Scanning Imaging ◽  
Global Water

Abstract. Global water vapour total column amounts have been retrieved from spectral data provided by the Global Ozone Monitoring Experiment (GOME) flying on ERS-2, which was launched in April 1995, and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) onboard ENVISAT launched in March 2002. For this purpose the Air Mass Corrected Differential Optical Absorption Spectroscopy (AMC-DOAS) approach has been used. The combination of the data from both instruments provides us with a long-term global data set spanning more than 11 years with the potential of extension up to 2020 by GOME-2 data, on Metop. Using linear and non-linear methods from time series analysis and standard statistics the trends of H2O contents and their errors have been calculated. In this study, factors affecting the trend such as the length of the time series, the magnitude of the variability of the noise, and the autocorrelation of the noise are investigated. Special emphasis has been placed on the calculation of the statistical significance of the observed trends, which reveal significant local changes of water vapour columns distributed over the whole globe.

Sign in / Sign up

Export Citation Format

Share Document