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Daniel Hurtmans - One of the best experts on this subject based on the ideXlab platform.

  • validation of the IASI forli eumetsat ozone products using satellite gome 2 ground based brewer dobson saoz ftir and ozonesonde measurements
    Atmospheric Measurement Techniques, 2018
    Co-Authors: Anne Boynard, Catherine Wespes, Daniel Hurtmans, Katerina Garane, Florence Goutail, Juliette Hadjilazaro, M E Koukouli, Corinne Vigouroux, Arno Keppens, Jeanpierre Pommereau
    Abstract:

    Abstract. This paper assesses the quality of IASI (Infrared Atmospheric Sounding Interferometer)/Metop-A (IASI-A) and IASI/Metop-B (IASI-B) ozone ( O3 ) products (total and partial O3 columns) retrieved with the Fast Optimal Retrievals on Layers for IASI Ozone (FORLI- O3 ; v20151001) software for 9 years (2008–July 2017) through an extensive intercomparison and validation exercise using independent observations (satellite, ground-based and ozonesonde). Compared with the previous version of FORLI-O3 (v20140922), several improvements have been introduced in FORLI- O3 v20151001, including absorbance look-up tables recalculated to cover a larger spectral range, with additional numerical corrections. This leads to a change of ∼4  % in the total ozone column (TOC) product, which is mainly associated with a decrease in the retrieved O3 concentration in the middle stratosphere (above 30 hPa/25 km). IASI-A and IASI-B TOCs are consistent, with a global mean difference of less than 0.3 % for both daytime and nighttime measurements; IASI-A is slightly higher than IASI-B. A global difference of less than 2.4 % is found for the tropospheric (TROPO) O3 column product (IASI-A is lower than IASI-B), which is partly due to a temporary issue related to the IASI-A viewing angle in 2015. Our validation shows that IASI-A and IASI-B TOCs are consistent with GOME-2 (Global Ozone Monitoring Experiment-2), Dobson, Brewer, SAOZ (Systeme d'Analyse par Observation Zenithale) and FTIR (Fourier transform infrared) TOCs, with global mean differences in the range of 0.1 %–2 % depending on the instruments compared. The worst agreement with UV–vis retrieved TOC (satellite and ground) is found at the southern high latitudes. The IASI-A and ground-based TOC comparison for the period from 2008 to July 2017 shows the long-term stability of IASI-A, with insignificant or small negative drifts of 1 %–3 % decade −1 . The comparison results of IASI-A and IASI-B against smoothed FTIR and ozonesonde partial O3 columns vary with altitude and latitude, with the maximum standard deviation being seen for the 300–150 hPa column (20 %–40 %) due to strong ozone variability and large total retrievals errors. Compared with ozonesonde data, the IASI-A and IASI-B O3 TROPO column (defined as the column between the surface and 300 hPa) is positively biased in the high latitudes (4 %–5 %) and negatively biased in the midlatitudes and tropics (11 %–13 % and 16 %–19 %, respectively). The IASI-A-to-ozonesonde TROPO comparison for the period from 2008 to 2016 shows a significant negative drift in the Northern Hemisphere of - 8.6 ± 3.4  % decade −1 , which is also found in the IASI-A-to-FTIR TROPO comparison. When considering the period from 2011 to 2016, the drift value for the TROPO column decreases and becomes statistically insignificant. The observed negative drifts of the IASI-A TROPO O3 product (8 %–16 % decade −1 ) over the 2008–2017 period might be taken into consideration when deriving trends from this product and this time period.

  • Validation of the IASI FORLI/EUMETSAT ozone products using satellite (GOME-2), ground-based (Brewer–Dobson, SAOZ, FTIR) and ozonesonde measurements
    Atmospheric Measurement Techniques, 2018
    Co-Authors: Anne Boynard, Juliette Hadji-lazaro, Catherine Wespes, Daniel Hurtmans, Katerina Garane, Florence Goutail, M E Koukouli, Corinne Vigouroux, Arno Keppens, Jeanpierre Pommereau
    Abstract:

    This paper assesses the quality of IASI (Infrared Atmospheric Sounding Interferometer)/Metop-A (IASI-A) and IASI/Metop-B (IASI-B) ozone (O3) products (total and partial O3 columns) retrieved with the Fast Optimal Retrievals on Layers for IASI Ozone (FORLI-O3; v20151001) software for 9 years (2008–July 2017) through an extensive intercomparison and validation exercise using independent observations (satellite, ground-based and ozonesonde). Compared with the previous version of FORLI-O3 (v20140922), several improvements have been introduced in FORLI-O3 v20151001, including absorbance look-up tables recalculated to cover a larger spectral range, with additional numerical corrections. This leads to a change of ∼ 4% in the total ozone column (TOC) product, which is mainly associated with a decrease in the retrieved O3 concentration in the middle stratosphere (above 30hPa/25km). IASI-A and IASI-B TOCs are consistent, with a global mean difference of less than 0.3% for both daytime and nighttime measurements; IASI-A is slightly higher than IASI-B. A global difference of less than 2.4% is found for the tropospheric (TROPO) O3 column product (IASI-A is lower than IASI-B), which is partly due to a temporary issue related to the IASI-A viewing angle in 2015. Our validation shows that IASI-A and IASI-B TOCs are consistent with GOME-2 (Global Ozone Monitoring Experiment-2), Dobson, Brewer, SAOZ (Système d'Analyse par Observation Zénithale) and FTIR (Fourier transform infrared) TOCs, with global mean differences in the range of 0.1%–2% depending on the instruments compared. The worst agreement with UV–vis retrieved TOC (satellite and ground) is found at the southern high latitudes. The IASI-A and ground-based TOC comparison for the period from 2008 to July 2017 shows the long-term stability of IASI-A, with insignificant or small negative drifts of 1%–3%decade−1. The comparison results of IASI-A and IASI-B against smoothed FTIR and ozonesonde partial O3 columns vary with altitude and latitude, with the maximum standard deviation being seen for the 300–150hPa column (20%–40%) due to strong ozone variability and large total retrievals errors. Compared with ozonesonde data, the IASI-A and IASI-B O3 TROPO column (defined as the column between the surface and 300hPa) is positively biased in the high latitudes (4%–5%) and negatively biased in the midlatitudes and tropics (11%–13% and 16%–19%, respectively). The IASI-A-to-ozonesonde TROPO comparison for the period from 2008 to 2016 shows a significant negative drift in the Northern Hemisphere of −8.6±3.4%decade−1, which is also found in the IASI-A-to-FTIR TROPO comparison. When considering the period from 2011 to 2016, the drift value for the TROPO column decreases and becomes statistically insignificant. The observed negative drifts of the IASI-A TROPO O3 product (8%–16%decade−1) over the 2008–2017 period might be taken into consideration when deriving trends from this product and this time period.

  • What can be seen by IASI during pollution events in East Asia?
    2016
    Co-Authors: Maya George, Juliette Hadji-lazaro, Idir Bouarar, Sophie Bauduin, Anne Boynard, Catherine Wespes, Martin Van Damme, Cathy Clerbaux, Daniel Hurtmans, Simon Whitburn
    Abstract:

    With two IASI instruments flying on the MetOp-A and MetOp-B satellites, any location on Earth is now observed at least four times per day in the infrared spectral range. All cloud free observations are analysed in near real time mode, and a series of gases can be retrieved from the recorded spectra. We will present a detailed study of what can be detected by IASI during pollution events in East Asia. Record levels of CO, tropospheric O3, SO2 and NH3 are measured, and the reliability of the IASI observations will be investigated: what are the concentrations detected throughout the year and when pollution events occur, to what extent is it matching local PM observations, and what is the sensitivity of the IASI observations at the surface. An in-depth analysis will be presented for CO, with comparisons with IAGOS aircraft data and MOPITT v7 satellite data. IASI and MOPITT data are jointly assimilated in the Copernicus Atmospheric Monitoring Service (CAMS) to generate CO pollution forecasts. Examples above East Asia will be shown.

  • first characterization and validation of forli hno3 vertical profiles retrieved from IASI metop
    Atmospheric Measurement Techniques, 2016
    Co-Authors: Gaétane Ronsmans, Catherine Wespes, Bavo Langerock, Matthias Schneider, Frank Hase, J W Hannigan, Tobias Kerzenmacher, Emmanuel Mahieu, Dan Smale, Daniel Hurtmans
    Abstract:

    Abstract. Knowing the spatial and seasonal distributions of nitric acid (HNO3) around the globe is of great interest and allows us to comprehend the processes regulating stratospheric ozone, especially in the polar regions. Due to its unprecedented spatial and temporal sampling, the nadir-viewing Infrared Atmospheric Sounding Interferometer (IASI) is capable of sounding the atmosphere twice a day globally, with good spectral resolution and low noise. With the Fast Optimal Retrievals on Layers for IASI (FORLI) algorithm, we are retrieving, in near real time, columns as well as vertical profiles of several atmospheric species, among which is HNO3. We present in this paper the first characterization of the FORLI-HNO3 profile products, in terms of vertical sensitivity and error budgets. We show that the sensitivity of IASI to HNO3 is highest in the lower stratosphere (10–20 km), where the largest amounts of HNO3 are found, but that the vertical sensitivity of IASI only allows one level of information on the profile (degrees of freedom for signal, DOFS;  ∼  1). The sensitivity near the surface is negligible in most cases, and for this reason, a partial column (5–35 km) is used for the analyses. Both vertical profiles and partial columns are compared to FTIR ground-based measurements from the Network for the Detection of Atmospheric Composition Change (NDACC) to characterize the accuracy and precision of the FORLI-HNO3 product. The profile validation is conducted through the smoothing of the raw FTIR profiles by the IASI averaging kernels and gives good results, with a slight overestimation of IASI measurements in the upper troposphere/lower stratosphere (UTLS) at the six chosen stations (Thule, Kiruna, Jungfraujoch, Izana, Lauder and Arrival Heights). The validation of the partial columns (5–35 km) is also conclusive with a mean correlation of 0.93 between IASI and the FTIR measurements. An initial survey of the HNO3 spatial and seasonal variabilities obtained from IASI measurements for a 1-year (2011) data set shows that the expected latitudinal gradient of concentrations from low to high latitudes and the large seasonal variability in polar regions (cycle amplitude around 30 % of the seasonal signal, peak to peak) are well represented by IASI data.

  • seven years of IASI ozone retrievals from forli validation with independent total column and vertical profile measurements
    Atmospheric Measurement Techniques, 2016
    Co-Authors: Anne Boynard, Catherine Wespes, Daniel Hurtmans, Florence Goutail, Juliette Hadjilazaro, Sarah Safieddine, Mariliza E. Koukouli, Jérôme Bureau, Christophe Lerot, Jeanpierre Pommereau
    Abstract:

    Abstract. This paper presents an extensive intercomparison and validation for the ozone (O3) product measured by the two Infrared Atmospheric Sounding Interferometers (IASIs) launched on board the MetOp-A and MetOp-B satellites in 2006 and in 2012 respectively. IASI O3 total columns and vertical profiles obtained from Fast Optimal Retrievals on Layers for IASI (FORLI) v20140922 software (running up until recently) are validated against independent observations during the period 2008–2014 on a global scale. On average for the period 2013–2014, IASI-A and IASI-B total ozone columns (TOCs) retrieved using FORLI are consistent, with IASI-B providing slightly lower values with a global difference of only 0.2 ± 0.8 %. The comparison between IASI-A and IASI-B O3 vertical profiles shows differences within ± 2 % over the entire altitude range. Global validation results for 7 years of IASI TOCs from FORLI against the Global Ozone Monitoring Experiment-2 (GOME-2) launched on board MetOp-A and Brewer–Dobson data show that, on average, IASI overestimates the ultraviolet (UV) data by 5–6 % with the largest differences found in the southern high latitudes. The comparison with UV–visible SAOZ (Systeme d'Analyse par Observation Zenithale) measurements shows a mean bias between IASI and SAOZ TOCs of 2–4 % in the midlatitudes and tropics and 7 % at the polar circle. Part of the discrepancies found at high latitudes can be attributed to the limited information content in the observations due to low brightness temperatures. The comparison with ozonesonde vertical profiles (limited to 30 km) shows that on average IASI with FORLI processing underestimates O3 by  ∼  5–15 % in the troposphere while it overestimates O3 by ∼  10–40 % in the stratosphere, depending on the latitude. The largest relative differences are found in the tropical tropopause region; this can be explained by the low O3 amounts leading to large relative errors. In this study, we also evaluate an updated version of FORLI-O3 retrieval software (v20151001), using look-up tables recalculated to cover a larger spectral range using the latest HITRAN spectroscopic database (HITRAN 2012) and implementing numerical corrections. The assessment of the new O3 product with the same set of observations as that used for the validation exercise shows a correction of ∼  4 % for the TOC positive bias when compared to the UV ground-based and satellite observations, bringing the overall global comparison to ∼  1–2 % on average. This improvement is mainly associated with a decrease in the retrieved O3 concentration in the middle stratosphere (above 30 hPa/25 km) as shown by the comparison with ozonesonde data.

Cathy Clerbaux - One of the best experts on this subject based on the ideXlab platform.

  • Ten-year assessment of IASI radiance and temperature
    Remote Sensing, 2020
    Co-Authors: Marie Bouillon, Juliette Hadji-lazaro, Simon Whitburn, Thomas August, Sarah Safieddine, Lieven Clarisse, Marie Doutriaux-boucher, Dorothée Coppens, Elsa Jacquette, Cathy Clerbaux
    Abstract:

    The Infrared Atmospheric Sounding Interferometers (IASIs) are three instruments flying on board the Metop satellites, launched in 2006 (IASI-A), 2012 (IASI-B), and 2018 (IASI-C). They measure infrared radiance from the Earth and atmosphere system, from which the atmospheric composition and temperature can be retrieved using dedicated algorithms, forming the Level 2 (L2) product. The operational near real-time processing of IASI data is conducted by the EUropean organisation for the exploitation of METeorological SATellites (EUMETSAT). It has improved over time, but due to IASI's large data flow, the whole dataset has not yet been reprocessed backwards. A necessary step that must be completed before initiating this reprocessing is to uniformize the IASI radiance record (Level 1C), which has also changed with time due to various instrumental and software modifications. In 2019, EUMETSAT released a reprocessed IASI-A 2007-2017 radiance dataset that is consistent with both the L1C product generated after 2017 and with IASI-B. First, this study aimed to assess the changes in radiance associated with this update by comparing the operational and reprocessed datasets. The differences in the brightness temperature ranged from 0.02 K at 700 cm-1 to 0.1 K at 2200 cm-1. Additionally, two major updates in 2010 and 2013 were seen to have the largest impact. Then, we investigated the effects on the retrieved temperatures due to successive upgrades to the Level 2 processing chain. We compared IASI L2 with ERA5 reanalysis temperatures. We found differences of ~5-10 K at the surface and between 1 and 5 K in the atmosphere. These differences decreased abruptly after the release of the IASI L2 processor version 6 in 2014. These results suggest that it is not recommended to use the IASI inhomogeneous temperature products for trend analysis, both for temperature and trace gas trends.

  • What can be seen by IASI during pollution events in East Asia?
    2016
    Co-Authors: Maya George, Juliette Hadji-lazaro, Idir Bouarar, Sophie Bauduin, Anne Boynard, Catherine Wespes, Martin Van Damme, Cathy Clerbaux, Daniel Hurtmans, Simon Whitburn
    Abstract:

    With two IASI instruments flying on the MetOp-A and MetOp-B satellites, any location on Earth is now observed at least four times per day in the infrared spectral range. All cloud free observations are analysed in near real time mode, and a series of gases can be retrieved from the recorded spectra. We will present a detailed study of what can be detected by IASI during pollution events in East Asia. Record levels of CO, tropospheric O3, SO2 and NH3 are measured, and the reliability of the IASI observations will be investigated: what are the concentrations detected throughout the year and when pollution events occur, to what extent is it matching local PM observations, and what is the sensitivity of the IASI observations at the surface. An in-depth analysis will be presented for CO, with comparisons with IAGOS aircraft data and MOPITT v7 satellite data. IASI and MOPITT data are jointly assimilated in the Copernicus Atmospheric Monitoring Service (CAMS) to generate CO pollution forecasts. Examples above East Asia will be shown.

  • Spatial and temporal variability of stratospheric HNO 3 from IASI global measurements
    2016
    Co-Authors: Gaétane Ronsmans, Catherine Wespes, Cathy Clerbaux, Daniel Hurtmans, Bavo Langerock, Martine De Mazière, Pierre-françois Coheur
    Abstract:

    Nitric acid (HNO 3 ) plays a crucial role in the stratospheric ozone cycles but its spatial distribution was until recently only accessible from limb satellite measurements, with medium coverage and sampling. IASI provides since 2007 HNO 3 concentration distributions with unprecedented spatial and temporal sampling, which have not yet been exploited. In this presentation, we will first briefly review the characteristics of the HNO 3 profiles retrieved from IASI and we will show results from a validation exercise, in which the HNO 3 profiles and total columns from IASI are compared with those retrieved from ground-based measurements at several sites. We will then show and discuss the spatial distributions of HNO 3 IASI total and stratospheric columns and assess the seasonal and inter-annual variability of HNO 3 using the 8 years of IASI observations available. Preliminary results from a simple multivariable regression model applied to these time series will be shown to support the analysis and to identify the principal processes driving the variability of stratospheric HNO 3 . In this discussion focus will be given onto the polar regions, where the relation of HNO 3 to ozone will be investigated in greater details. With these results, the potential of using IASI for studying stratospheric chemistry will be more generally highlighted.

  • Validation of IASI NH3 columns at the single pixel scale from airborneand ground-based measurements
    2016
    Co-Authors: Mark A. Zondlo, Simon Whitburn, Cathy Clerbaux, Lieven Clarisse, Martin Van Damme, Pierre-françois Coheur
    Abstract:

    Ammonia (NH3) is an important gas phase precursor species for aerosols, and ammoniated aerosols are significant components of unhealthy fine particulate matter and also exhibit a net cooling effect on climate. IASI column NH3 measurements provide global coverage at ~ 100 km2 (nadir) and sub daily resolution. However, validation of IASI NH3 measurements has been limited due to a lack of in-situ measurements. Because of the short atmospheric lifetime of NH3 (~ day), large spatiotemporal gradients further complicate NH3 IASI validations. To address these concerns, we have conducted a pixel scale validation of daytime (cloud coverage < 25%) IASI NH3 columns from surface-, vehicle-, radiosonde-, and aircraft-based measurements during the 2014 NASA DISCOVER-AQ and NSF FRAPPE field experiments in northeast Colorado, USA (July-August 2014). This region includes a diverse range of validation environments such as agricultural areas (Platte River Valley), urban emissions (Denver metropolitan area), and relativelyclean mountain and prairie regions. To minimize horizontal gradients, a narrow spatial window of ±15 km from the IASI centroid was used (corresponding to temporal window of ± 1 hour at the mean boundary layer wind speed of 4 m s-1). Due to the spiral flight tracks of the NASA P3-B aircraft, a majority of the vertical profiles extended from near the ground (1.5 km MSL) to 5.5 km above sea level, the typical flight ceiling of the P3-B aircraft in DISCOVER-AQ. NH3 concentrations above the flight ceiling were assumed to be zero, consistent with the IASI a prior profile. A total of 58 IASI/in-situ-derived columns were identified within these constraints. The mean relative error of IASI NH3 columns was 15% lower than those derived from the in-situ measurements. Given the in-situ measurement uncertainties (~25%), mean IASI error (38%) for these cases, and the strong spatial NH3 gradients observed in this area, the agreement between IASI and insitu measurement columns is excellent. No systematic bias is observed over IASI column abundances from 8x1014 to 4.4x1016 molec cm-2. These results present the first pixel scale validation for IASI NH3 and are at column abundances one order of magnitude lower than previous work with the NASA AURA TES NH3 columns. Ongoing efforts will examine validations at higher NH3 column abundances in areas such as the San Joaquin Valley (USA), explore the agreement at different spatiotemporal windows, and quantify the agreement with improved retrieval algorithms.

  • Evaluation of IASI total ozone accuracy by comparisons with SAOZ and all other satellites measurements in the tropics and at mid-latitudes
    2016
    Co-Authors: Jeanpierre Pommereau, Florence Goutail, Andrea Pazmino, Cathy Clerbaux
    Abstract:

    High accuracy global total ozone measurements from space are key data for evaluating the amplitude of ozone depletion, understanding its contribution and consequences on climate change and predicting the future evolution of both ozone and climate. Long series of total ozone data are available, but showing still systematic significant differences between them. Here most recent data available from IASI A and B are compared to SAOZ NDACC UV-Vis ground-based measurements at several stations in the tropics and mid-latitudes, as well as all other satellites data available since the beginning of IASI operations in 2007. The list of satellites includes GOME, SCIAMACHY, GOME2 and OMI reprocessed with the GODFIT V3 (GOME-Type Direct FITing) algorithm developed in the frame of the ESA Ozone Climate Initiative (Lerot et al., 2014), the NASA SBUV v8.6 (McPeters et al., 2013), the NASA-AURA-OMIT and OMID (Levelt et al, 2007). According to these comparisons, the IASI A-B ozone columns are systematically overestimated by 2 - 6%, depending on the station and the satellite, and the difference between all of them is showing more or less seasonality of amplitude depending also on the satellite and the station. Mean biases are attributed to smaller ozone absorption cross-sections in the IR compared to the UV and visible and also to longitudinal ozone profiles variations ignored in most satellite retrievals. When corrected for mean biases, the seasonality of the differences between IASI, SAOZ and most others is generally smaller than ± 1% that is of the order of magnitude of the dispersion and thus random uncertainty of the measurements, except in a few specific cases: a) the presence of a larger 2-3% peak IASI-Sat difference in the monthly mean in May at OHP on both IASI A and B suggesting a retrieval error on all IASI data on that month but of totally unknown origin; b) a larger seasonality of the 4 CCI GOFDIT processed satellites compared to IASI and others suggesting a slight systematic error related to the use of zonal mean O3 profiles climatologies ignoring longitudinal variations; c) larger dispersion, seasonality and moreover opposite seasonality phase of NPP at southern midlatitudes indicative of an error in those data files in the southern hemisphere; d) and, finally, an overestimation of IASI ozone in Reunion Island in coincidence with hurricanes, suggesting that high altitude clouds are not properly removed in the IASI data sets. Shown in the presentation will be the illustration of the IASI- SAOZ- Sat differences at all SAOZ stations and possible explanations when significant differences are observed.

Juliette Hadji-lazaro - One of the best experts on this subject based on the ideXlab platform.

  • Ten-year assessment of IASI radiance and temperature
    Remote Sensing, 2020
    Co-Authors: Marie Bouillon, Juliette Hadji-lazaro, Simon Whitburn, Thomas August, Sarah Safieddine, Lieven Clarisse, Marie Doutriaux-boucher, Dorothée Coppens, Elsa Jacquette, Cathy Clerbaux
    Abstract:

    The Infrared Atmospheric Sounding Interferometers (IASIs) are three instruments flying on board the Metop satellites, launched in 2006 (IASI-A), 2012 (IASI-B), and 2018 (IASI-C). They measure infrared radiance from the Earth and atmosphere system, from which the atmospheric composition and temperature can be retrieved using dedicated algorithms, forming the Level 2 (L2) product. The operational near real-time processing of IASI data is conducted by the EUropean organisation for the exploitation of METeorological SATellites (EUMETSAT). It has improved over time, but due to IASI's large data flow, the whole dataset has not yet been reprocessed backwards. A necessary step that must be completed before initiating this reprocessing is to uniformize the IASI radiance record (Level 1C), which has also changed with time due to various instrumental and software modifications. In 2019, EUMETSAT released a reprocessed IASI-A 2007-2017 radiance dataset that is consistent with both the L1C product generated after 2017 and with IASI-B. First, this study aimed to assess the changes in radiance associated with this update by comparing the operational and reprocessed datasets. The differences in the brightness temperature ranged from 0.02 K at 700 cm-1 to 0.1 K at 2200 cm-1. Additionally, two major updates in 2010 and 2013 were seen to have the largest impact. Then, we investigated the effects on the retrieved temperatures due to successive upgrades to the Level 2 processing chain. We compared IASI L2 with ERA5 reanalysis temperatures. We found differences of ~5-10 K at the surface and between 1 and 5 K in the atmosphere. These differences decreased abruptly after the release of the IASI L2 processor version 6 in 2014. These results suggest that it is not recommended to use the IASI inhomogeneous temperature products for trend analysis, both for temperature and trace gas trends.

  • Validation of the IASI FORLI/EUMETSAT ozone products using satellite (GOME-2), ground-based (Brewer–Dobson, SAOZ, FTIR) and ozonesonde measurements
    Atmospheric Measurement Techniques, 2018
    Co-Authors: Anne Boynard, Juliette Hadji-lazaro, Catherine Wespes, Daniel Hurtmans, Katerina Garane, Florence Goutail, M E Koukouli, Corinne Vigouroux, Arno Keppens, Jeanpierre Pommereau
    Abstract:

    This paper assesses the quality of IASI (Infrared Atmospheric Sounding Interferometer)/Metop-A (IASI-A) and IASI/Metop-B (IASI-B) ozone (O3) products (total and partial O3 columns) retrieved with the Fast Optimal Retrievals on Layers for IASI Ozone (FORLI-O3; v20151001) software for 9 years (2008–July 2017) through an extensive intercomparison and validation exercise using independent observations (satellite, ground-based and ozonesonde). Compared with the previous version of FORLI-O3 (v20140922), several improvements have been introduced in FORLI-O3 v20151001, including absorbance look-up tables recalculated to cover a larger spectral range, with additional numerical corrections. This leads to a change of ∼ 4% in the total ozone column (TOC) product, which is mainly associated with a decrease in the retrieved O3 concentration in the middle stratosphere (above 30hPa/25km). IASI-A and IASI-B TOCs are consistent, with a global mean difference of less than 0.3% for both daytime and nighttime measurements; IASI-A is slightly higher than IASI-B. A global difference of less than 2.4% is found for the tropospheric (TROPO) O3 column product (IASI-A is lower than IASI-B), which is partly due to a temporary issue related to the IASI-A viewing angle in 2015. Our validation shows that IASI-A and IASI-B TOCs are consistent with GOME-2 (Global Ozone Monitoring Experiment-2), Dobson, Brewer, SAOZ (Système d'Analyse par Observation Zénithale) and FTIR (Fourier transform infrared) TOCs, with global mean differences in the range of 0.1%–2% depending on the instruments compared. The worst agreement with UV–vis retrieved TOC (satellite and ground) is found at the southern high latitudes. The IASI-A and ground-based TOC comparison for the period from 2008 to July 2017 shows the long-term stability of IASI-A, with insignificant or small negative drifts of 1%–3%decade−1. The comparison results of IASI-A and IASI-B against smoothed FTIR and ozonesonde partial O3 columns vary with altitude and latitude, with the maximum standard deviation being seen for the 300–150hPa column (20%–40%) due to strong ozone variability and large total retrievals errors. Compared with ozonesonde data, the IASI-A and IASI-B O3 TROPO column (defined as the column between the surface and 300hPa) is positively biased in the high latitudes (4%–5%) and negatively biased in the midlatitudes and tropics (11%–13% and 16%–19%, respectively). The IASI-A-to-ozonesonde TROPO comparison for the period from 2008 to 2016 shows a significant negative drift in the Northern Hemisphere of −8.6±3.4%decade−1, which is also found in the IASI-A-to-FTIR TROPO comparison. When considering the period from 2011 to 2016, the drift value for the TROPO column decreases and becomes statistically insignificant. The observed negative drifts of the IASI-A TROPO O3 product (8%–16%decade−1) over the 2008–2017 period might be taken into consideration when deriving trends from this product and this time period.

  • What can be seen by IASI during pollution events in East Asia?
    2016
    Co-Authors: Maya George, Juliette Hadji-lazaro, Idir Bouarar, Sophie Bauduin, Anne Boynard, Catherine Wespes, Martin Van Damme, Cathy Clerbaux, Daniel Hurtmans, Simon Whitburn
    Abstract:

    With two IASI instruments flying on the MetOp-A and MetOp-B satellites, any location on Earth is now observed at least four times per day in the infrared spectral range. All cloud free observations are analysed in near real time mode, and a series of gases can be retrieved from the recorded spectra. We will present a detailed study of what can be detected by IASI during pollution events in East Asia. Record levels of CO, tropospheric O3, SO2 and NH3 are measured, and the reliability of the IASI observations will be investigated: what are the concentrations detected throughout the year and when pollution events occur, to what extent is it matching local PM observations, and what is the sensitivity of the IASI observations at the surface. An in-depth analysis will be presented for CO, with comparisons with IAGOS aircraft data and MOPITT v7 satellite data. IASI and MOPITT data are jointly assimilated in the Copernicus Atmospheric Monitoring Service (CAMS) to generate CO pollution forecasts. Examples above East Asia will be shown.

  • Seven years of IASI ozone retrievals from FORLI: validation with independent total column and vertical profile measurements
    Atmospheric Measurement Techniques, 2016
    Co-Authors: Anne Boynard, Juliette Hadji-lazaro, Catherine Wespes, Daniel Hurtmans, Florence Goutail, Sarah Safieddine, Mariliza E. Koukouli, Jérôme Bureau, Christophe Lerot, Jeanpierre Pommereau
    Abstract:

    This paper presents an extensive inter-comparison and validation for the ozone (O3) product measured by the two Infrared Atmospheric Sounding Interferometers (IASI) launched onboard the Metop-A and Metop-B satellites in 2006 and in 2012, respectively. IASI O3 total columns and vertical profiles obtained from Fast Optimal Retrievals on Layers for IASI (FORLI-O3) v20140922 software (running up until recently) are validated against independent observations during the period 2008–2014 on a global scale. On average for the period 2013–2014, IASI-A and IASI-B TOCs retrieved using FORLI are consistent, with IASI-B providing slightly lower values with a global difference of only 0.2±0.8 %. The comparison between IASI-A and IASI-B O3 vertical profiles shows differences within ±2 % over the entire altitude range. Global validation results for seven years of IASI TOCs from FORLI against GOME-2/Metop-A, Dobson and Brewer data show that, on average, IASI overestimates the UV data by 5–6 % with the largest differences found in the Southern high latitudes. The comparison with UV-vis SAOZ measurements shows a mean bias between IASI and SAOZ TOCs of 2–4 % in the mid-latitudes and tropics, and 7 % at the polar circle. Part of the discrepancies found at high latitudes can be attributed to the limited information content in the observations, due to low brightness temperatures. The comparison with ozonesonde vertical profiles (limited to 30 km) shows that on average IASI with FORLI processing underestimates O3 by ~5–15 % in the troposphere while it overestimates O3 by ~10–40 % in the stratosphere depending on the latitude. In the Northern middle latitudes, the bias varies within ±20 % for the entire altitude range. The largest relative differences are found in the tropical tropopause region; this can be explained by the low O3 amounts leading to large relative errors. In this study, we also evaluate an updated version of FORLI-O3 retrieval software (v20151001), using look-up tables recalculated to cover a larger spectral range using the latest HITRAN spectroscopic database (HITRAN 2012), and implementing numerical corrections. The assessement of the new O3 product with the same set of observations as that used for the validation exercise shows a correction of ~4 % for the TOC positive bias when compared to the UV ground-based and satellite observations, bringing the overall global comparison to ~1–2 % on average. This improvement is mainly associated with a decrease in the retrieved O3 concentration in the stratosphere (above 30 hPa/25 km) as shown by the comparison with ozonesonde data.

  • Extending the satellite data record of tropospheric ozone profiles from Aura-TES to MetOp-IASI: characterisation of optimal estimation retrievals
    Atmospheric Measurement Techniques, 2014
    Co-Authors: H Oetjen, Cathy Clerbaux, Vivienne H Payne, S S Kulawik, Annmarie Eldering, J Worden, D P Edwards, H M Worden, G. L. Francis, Juliette Hadji-lazaro
    Abstract:

    We apply the Tropospheric Emission Spectrometer (TES) ozone retrieval algorithm to Infrared Atmospheric Sounding Instrument (IASI) radiances and characterise the uncertainties and information content of the retrieved ozone profiles. This study focuses on mid-latitudes for the year 2008. We validate our results by comparing the IASI ozone profiles to ozone sondes. In the sonde comparisons, we find a positive bias in the IASI ozone profiles in the UTLS region of up to 14% on average. For the described cases, the degrees of freedom for signal are on average 3.2, 0.3, 0.8, and 0.9 for the columns 0 km-top of atmosphere, (0-6) km, (0-11) km, and (8-16) km, respectively. We find that our biases with respect to sondes and our degrees of freedom for signal for ozone are comparable to previously published results from other IASI ozone algorithms. In addition to evaluating biases, we validate the retrieval errors by comparing predicted errors to the sample covariance matrix of the IASI observations themselves. For the predicted vs. empirical error comparison, we find that these errors are consistent and that the measurement noise and the interference of temperature and water vapour on the retrieval together mostly explain the empirically derived random errors. In general, the precision of the IASI ozone profiles is better than 20%.

Anne Boynard - One of the best experts on this subject based on the ideXlab platform.

  • validation of the IASI forli eumetsat ozone products using satellite gome 2 ground based brewer dobson saoz ftir and ozonesonde measurements
    Atmospheric Measurement Techniques, 2018
    Co-Authors: Anne Boynard, Catherine Wespes, Daniel Hurtmans, Katerina Garane, Florence Goutail, Juliette Hadjilazaro, M E Koukouli, Corinne Vigouroux, Arno Keppens, Jeanpierre Pommereau
    Abstract:

    Abstract. This paper assesses the quality of IASI (Infrared Atmospheric Sounding Interferometer)/Metop-A (IASI-A) and IASI/Metop-B (IASI-B) ozone ( O3 ) products (total and partial O3 columns) retrieved with the Fast Optimal Retrievals on Layers for IASI Ozone (FORLI- O3 ; v20151001) software for 9 years (2008–July 2017) through an extensive intercomparison and validation exercise using independent observations (satellite, ground-based and ozonesonde). Compared with the previous version of FORLI-O3 (v20140922), several improvements have been introduced in FORLI- O3 v20151001, including absorbance look-up tables recalculated to cover a larger spectral range, with additional numerical corrections. This leads to a change of ∼4  % in the total ozone column (TOC) product, which is mainly associated with a decrease in the retrieved O3 concentration in the middle stratosphere (above 30 hPa/25 km). IASI-A and IASI-B TOCs are consistent, with a global mean difference of less than 0.3 % for both daytime and nighttime measurements; IASI-A is slightly higher than IASI-B. A global difference of less than 2.4 % is found for the tropospheric (TROPO) O3 column product (IASI-A is lower than IASI-B), which is partly due to a temporary issue related to the IASI-A viewing angle in 2015. Our validation shows that IASI-A and IASI-B TOCs are consistent with GOME-2 (Global Ozone Monitoring Experiment-2), Dobson, Brewer, SAOZ (Systeme d'Analyse par Observation Zenithale) and FTIR (Fourier transform infrared) TOCs, with global mean differences in the range of 0.1 %–2 % depending on the instruments compared. The worst agreement with UV–vis retrieved TOC (satellite and ground) is found at the southern high latitudes. The IASI-A and ground-based TOC comparison for the period from 2008 to July 2017 shows the long-term stability of IASI-A, with insignificant or small negative drifts of 1 %–3 % decade −1 . The comparison results of IASI-A and IASI-B against smoothed FTIR and ozonesonde partial O3 columns vary with altitude and latitude, with the maximum standard deviation being seen for the 300–150 hPa column (20 %–40 %) due to strong ozone variability and large total retrievals errors. Compared with ozonesonde data, the IASI-A and IASI-B O3 TROPO column (defined as the column between the surface and 300 hPa) is positively biased in the high latitudes (4 %–5 %) and negatively biased in the midlatitudes and tropics (11 %–13 % and 16 %–19 %, respectively). The IASI-A-to-ozonesonde TROPO comparison for the period from 2008 to 2016 shows a significant negative drift in the Northern Hemisphere of - 8.6 ± 3.4  % decade −1 , which is also found in the IASI-A-to-FTIR TROPO comparison. When considering the period from 2011 to 2016, the drift value for the TROPO column decreases and becomes statistically insignificant. The observed negative drifts of the IASI-A TROPO O3 product (8 %–16 % decade −1 ) over the 2008–2017 period might be taken into consideration when deriving trends from this product and this time period.

  • Validation of the IASI FORLI/EUMETSAT ozone products using satellite (GOME-2), ground-based (Brewer–Dobson, SAOZ, FTIR) and ozonesonde measurements
    Atmospheric Measurement Techniques, 2018
    Co-Authors: Anne Boynard, Juliette Hadji-lazaro, Catherine Wespes, Daniel Hurtmans, Katerina Garane, Florence Goutail, M E Koukouli, Corinne Vigouroux, Arno Keppens, Jeanpierre Pommereau
    Abstract:

    This paper assesses the quality of IASI (Infrared Atmospheric Sounding Interferometer)/Metop-A (IASI-A) and IASI/Metop-B (IASI-B) ozone (O3) products (total and partial O3 columns) retrieved with the Fast Optimal Retrievals on Layers for IASI Ozone (FORLI-O3; v20151001) software for 9 years (2008–July 2017) through an extensive intercomparison and validation exercise using independent observations (satellite, ground-based and ozonesonde). Compared with the previous version of FORLI-O3 (v20140922), several improvements have been introduced in FORLI-O3 v20151001, including absorbance look-up tables recalculated to cover a larger spectral range, with additional numerical corrections. This leads to a change of ∼ 4% in the total ozone column (TOC) product, which is mainly associated with a decrease in the retrieved O3 concentration in the middle stratosphere (above 30hPa/25km). IASI-A and IASI-B TOCs are consistent, with a global mean difference of less than 0.3% for both daytime and nighttime measurements; IASI-A is slightly higher than IASI-B. A global difference of less than 2.4% is found for the tropospheric (TROPO) O3 column product (IASI-A is lower than IASI-B), which is partly due to a temporary issue related to the IASI-A viewing angle in 2015. Our validation shows that IASI-A and IASI-B TOCs are consistent with GOME-2 (Global Ozone Monitoring Experiment-2), Dobson, Brewer, SAOZ (Système d'Analyse par Observation Zénithale) and FTIR (Fourier transform infrared) TOCs, with global mean differences in the range of 0.1%–2% depending on the instruments compared. The worst agreement with UV–vis retrieved TOC (satellite and ground) is found at the southern high latitudes. The IASI-A and ground-based TOC comparison for the period from 2008 to July 2017 shows the long-term stability of IASI-A, with insignificant or small negative drifts of 1%–3%decade−1. The comparison results of IASI-A and IASI-B against smoothed FTIR and ozonesonde partial O3 columns vary with altitude and latitude, with the maximum standard deviation being seen for the 300–150hPa column (20%–40%) due to strong ozone variability and large total retrievals errors. Compared with ozonesonde data, the IASI-A and IASI-B O3 TROPO column (defined as the column between the surface and 300hPa) is positively biased in the high latitudes (4%–5%) and negatively biased in the midlatitudes and tropics (11%–13% and 16%–19%, respectively). The IASI-A-to-ozonesonde TROPO comparison for the period from 2008 to 2016 shows a significant negative drift in the Northern Hemisphere of −8.6±3.4%decade−1, which is also found in the IASI-A-to-FTIR TROPO comparison. When considering the period from 2011 to 2016, the drift value for the TROPO column decreases and becomes statistically insignificant. The observed negative drifts of the IASI-A TROPO O3 product (8%–16%decade−1) over the 2008–2017 period might be taken into consideration when deriving trends from this product and this time period.

  • What can be seen by IASI during pollution events in East Asia?
    2016
    Co-Authors: Maya George, Juliette Hadji-lazaro, Idir Bouarar, Sophie Bauduin, Anne Boynard, Catherine Wespes, Martin Van Damme, Cathy Clerbaux, Daniel Hurtmans, Simon Whitburn
    Abstract:

    With two IASI instruments flying on the MetOp-A and MetOp-B satellites, any location on Earth is now observed at least four times per day in the infrared spectral range. All cloud free observations are analysed in near real time mode, and a series of gases can be retrieved from the recorded spectra. We will present a detailed study of what can be detected by IASI during pollution events in East Asia. Record levels of CO, tropospheric O3, SO2 and NH3 are measured, and the reliability of the IASI observations will be investigated: what are the concentrations detected throughout the year and when pollution events occur, to what extent is it matching local PM observations, and what is the sensitivity of the IASI observations at the surface. An in-depth analysis will be presented for CO, with comparisons with IAGOS aircraft data and MOPITT v7 satellite data. IASI and MOPITT data are jointly assimilated in the Copernicus Atmospheric Monitoring Service (CAMS) to generate CO pollution forecasts. Examples above East Asia will be shown.

  • seven years of IASI ozone retrievals from forli validation with independent total column and vertical profile measurements
    Atmospheric Measurement Techniques, 2016
    Co-Authors: Anne Boynard, Catherine Wespes, Daniel Hurtmans, Florence Goutail, Juliette Hadjilazaro, Sarah Safieddine, Mariliza E. Koukouli, Jérôme Bureau, Christophe Lerot, Jeanpierre Pommereau
    Abstract:

    Abstract. This paper presents an extensive intercomparison and validation for the ozone (O3) product measured by the two Infrared Atmospheric Sounding Interferometers (IASIs) launched on board the MetOp-A and MetOp-B satellites in 2006 and in 2012 respectively. IASI O3 total columns and vertical profiles obtained from Fast Optimal Retrievals on Layers for IASI (FORLI) v20140922 software (running up until recently) are validated against independent observations during the period 2008–2014 on a global scale. On average for the period 2013–2014, IASI-A and IASI-B total ozone columns (TOCs) retrieved using FORLI are consistent, with IASI-B providing slightly lower values with a global difference of only 0.2 ± 0.8 %. The comparison between IASI-A and IASI-B O3 vertical profiles shows differences within ± 2 % over the entire altitude range. Global validation results for 7 years of IASI TOCs from FORLI against the Global Ozone Monitoring Experiment-2 (GOME-2) launched on board MetOp-A and Brewer–Dobson data show that, on average, IASI overestimates the ultraviolet (UV) data by 5–6 % with the largest differences found in the southern high latitudes. The comparison with UV–visible SAOZ (Systeme d'Analyse par Observation Zenithale) measurements shows a mean bias between IASI and SAOZ TOCs of 2–4 % in the midlatitudes and tropics and 7 % at the polar circle. Part of the discrepancies found at high latitudes can be attributed to the limited information content in the observations due to low brightness temperatures. The comparison with ozonesonde vertical profiles (limited to 30 km) shows that on average IASI with FORLI processing underestimates O3 by  ∼  5–15 % in the troposphere while it overestimates O3 by ∼  10–40 % in the stratosphere, depending on the latitude. The largest relative differences are found in the tropical tropopause region; this can be explained by the low O3 amounts leading to large relative errors. In this study, we also evaluate an updated version of FORLI-O3 retrieval software (v20151001), using look-up tables recalculated to cover a larger spectral range using the latest HITRAN spectroscopic database (HITRAN 2012) and implementing numerical corrections. The assessment of the new O3 product with the same set of observations as that used for the validation exercise shows a correction of ∼  4 % for the TOC positive bias when compared to the UV ground-based and satellite observations, bringing the overall global comparison to ∼  1–2 % on average. This improvement is mainly associated with a decrease in the retrieved O3 concentration in the middle stratosphere (above 30 hPa/25 km) as shown by the comparison with ozonesonde data.

  • Seven years of IASI ozone retrievals from FORLI: validation with independent total column and vertical profile measurements
    Atmospheric Measurement Techniques, 2016
    Co-Authors: Anne Boynard, Juliette Hadji-lazaro, Catherine Wespes, Daniel Hurtmans, Florence Goutail, Sarah Safieddine, Mariliza E. Koukouli, Jérôme Bureau, Christophe Lerot, Jeanpierre Pommereau
    Abstract:

    This paper presents an extensive inter-comparison and validation for the ozone (O3) product measured by the two Infrared Atmospheric Sounding Interferometers (IASI) launched onboard the Metop-A and Metop-B satellites in 2006 and in 2012, respectively. IASI O3 total columns and vertical profiles obtained from Fast Optimal Retrievals on Layers for IASI (FORLI-O3) v20140922 software (running up until recently) are validated against independent observations during the period 2008–2014 on a global scale. On average for the period 2013–2014, IASI-A and IASI-B TOCs retrieved using FORLI are consistent, with IASI-B providing slightly lower values with a global difference of only 0.2±0.8 %. The comparison between IASI-A and IASI-B O3 vertical profiles shows differences within ±2 % over the entire altitude range. Global validation results for seven years of IASI TOCs from FORLI against GOME-2/Metop-A, Dobson and Brewer data show that, on average, IASI overestimates the UV data by 5–6 % with the largest differences found in the Southern high latitudes. The comparison with UV-vis SAOZ measurements shows a mean bias between IASI and SAOZ TOCs of 2–4 % in the mid-latitudes and tropics, and 7 % at the polar circle. Part of the discrepancies found at high latitudes can be attributed to the limited information content in the observations, due to low brightness temperatures. The comparison with ozonesonde vertical profiles (limited to 30 km) shows that on average IASI with FORLI processing underestimates O3 by ~5–15 % in the troposphere while it overestimates O3 by ~10–40 % in the stratosphere depending on the latitude. In the Northern middle latitudes, the bias varies within ±20 % for the entire altitude range. The largest relative differences are found in the tropical tropopause region; this can be explained by the low O3 amounts leading to large relative errors. In this study, we also evaluate an updated version of FORLI-O3 retrieval software (v20151001), using look-up tables recalculated to cover a larger spectral range using the latest HITRAN spectroscopic database (HITRAN 2012), and implementing numerical corrections. The assessement of the new O3 product with the same set of observations as that used for the validation exercise shows a correction of ~4 % for the TOC positive bias when compared to the UV ground-based and satellite observations, bringing the overall global comparison to ~1–2 % on average. This improvement is mainly associated with a decrease in the retrieved O3 concentration in the stratosphere (above 30 hPa/25 km) as shown by the comparison with ozonesonde data.

Pierre-françois Coheur - One of the best experts on this subject based on the ideXlab platform.

  • Spatial and temporal variability of stratospheric HNO 3 from IASI global measurements
    2016
    Co-Authors: Gaétane Ronsmans, Catherine Wespes, Cathy Clerbaux, Daniel Hurtmans, Bavo Langerock, Martine De Mazière, Pierre-françois Coheur
    Abstract:

    Nitric acid (HNO 3 ) plays a crucial role in the stratospheric ozone cycles but its spatial distribution was until recently only accessible from limb satellite measurements, with medium coverage and sampling. IASI provides since 2007 HNO 3 concentration distributions with unprecedented spatial and temporal sampling, which have not yet been exploited. In this presentation, we will first briefly review the characteristics of the HNO 3 profiles retrieved from IASI and we will show results from a validation exercise, in which the HNO 3 profiles and total columns from IASI are compared with those retrieved from ground-based measurements at several sites. We will then show and discuss the spatial distributions of HNO 3 IASI total and stratospheric columns and assess the seasonal and inter-annual variability of HNO 3 using the 8 years of IASI observations available. Preliminary results from a simple multivariable regression model applied to these time series will be shown to support the analysis and to identify the principal processes driving the variability of stratospheric HNO 3 . In this discussion focus will be given onto the polar regions, where the relation of HNO 3 to ozone will be investigated in greater details. With these results, the potential of using IASI for studying stratospheric chemistry will be more generally highlighted.

  • Validation of IASI NH3 columns at the single pixel scale from airborneand ground-based measurements
    2016
    Co-Authors: Mark A. Zondlo, Simon Whitburn, Cathy Clerbaux, Lieven Clarisse, Martin Van Damme, Pierre-françois Coheur
    Abstract:

    Ammonia (NH3) is an important gas phase precursor species for aerosols, and ammoniated aerosols are significant components of unhealthy fine particulate matter and also exhibit a net cooling effect on climate. IASI column NH3 measurements provide global coverage at ~ 100 km2 (nadir) and sub daily resolution. However, validation of IASI NH3 measurements has been limited due to a lack of in-situ measurements. Because of the short atmospheric lifetime of NH3 (~ day), large spatiotemporal gradients further complicate NH3 IASI validations. To address these concerns, we have conducted a pixel scale validation of daytime (cloud coverage < 25%) IASI NH3 columns from surface-, vehicle-, radiosonde-, and aircraft-based measurements during the 2014 NASA DISCOVER-AQ and NSF FRAPPE field experiments in northeast Colorado, USA (July-August 2014). This region includes a diverse range of validation environments such as agricultural areas (Platte River Valley), urban emissions (Denver metropolitan area), and relativelyclean mountain and prairie regions. To minimize horizontal gradients, a narrow spatial window of ±15 km from the IASI centroid was used (corresponding to temporal window of ± 1 hour at the mean boundary layer wind speed of 4 m s-1). Due to the spiral flight tracks of the NASA P3-B aircraft, a majority of the vertical profiles extended from near the ground (1.5 km MSL) to 5.5 km above sea level, the typical flight ceiling of the P3-B aircraft in DISCOVER-AQ. NH3 concentrations above the flight ceiling were assumed to be zero, consistent with the IASI a prior profile. A total of 58 IASI/in-situ-derived columns were identified within these constraints. The mean relative error of IASI NH3 columns was 15% lower than those derived from the in-situ measurements. Given the in-situ measurement uncertainties (~25%), mean IASI error (38%) for these cases, and the strong spatial NH3 gradients observed in this area, the agreement between IASI and insitu measurement columns is excellent. No systematic bias is observed over IASI column abundances from 8x1014 to 4.4x1016 molec cm-2. These results present the first pixel scale validation for IASI NH3 and are at column abundances one order of magnitude lower than previous work with the NASA AURA TES NH3 columns. Ongoing efforts will examine validations at higher NH3 column abundances in areas such as the San Joaquin Valley (USA), explore the agreement at different spatiotemporal windows, and quantify the agreement with improved retrieval algorithms.

  • antarctic ozone hole as observed by IASI metop for 2008 2010
    Atmospheric Measurement Techniques, 2012
    Co-Authors: Claire Scannell, Maya George, Anne Boynard, Daniel Hurtmans, Andy Delcloo, Juliette Hadjilazaro, O N E Tuinder, Pierre-françois Coheur
    Abstract:

    In this paper we present a study of the ozone hole as observed by the Infrared Atmospheric Sounding Interferometer (IASI) on-board the MetOp-A European satellite platform from the beginning of data dissemination, August 2008, to the end of December 2010. Here we demonstrate IASI's ability to capture the seasonal characteristics of the ozone hole, in particular during polar night. We compare IASI ozone total columns and vertical profiles with those of the Global Ozone Monitoring Experiment 2 (GOME-2, also on-board MetOp-A) and electrochemical concentration cell (ECC) ozone sonde measurements. Total ozone column from IASI and GOME-2 were found to be in excellent agreement for this region with a correlation coefficient of 0.97, for September, October and November 2009. On average IASI exhibits a positive bias of approximately 7 % compared to the GOME-2 measurements over the entire ozone hole period. Comparisons between IASI and ozone sonde measurements were also found to be in good agreement with the difference between both ozone profile measurements being less than ±30 % over the altitude range of 0-40 km. The vertical structure of the ozone profile inside the ozone hole is captured remarkably well by IASI.

  • Antarctic ozone hole as observed by IASI/MetOp for 2008–2010
    Atmospheric Measurement Techniques, 2012
    Co-Authors: Claire Scannell, Maya George, Juliette Hadji-lazaro, Anne Boynard, Daniel Hurtmans, Andy Delcloo, Pierre-françois Coheur, O N E Tuinder, Cathy Clerbaux
    Abstract:

    In this paper we present a study of the ozone hole as observed by the Infrared Atmospheric Sounding Interferometer (IASI) on-board the MetOp-A European satellite platform from the beginning of data dissemination, August 2008, to the end of December 2010. Here we demonstrate IASI's ability to capture the seasonal characteristics of the ozone hole, in particular during polar night. We compare IASI ozone total columns and vertical profiles with those of the Global Ozone Monitoring Experiment 2 (GOME-2, also on-board MetOp-A) and electrochemical concentration cell (ECC) ozone sonde measurements. Total ozone column from IASI and GOME-2 were found to be in excellent agreement for this region with a correlation coefficient of 0.97, for September, October and November 2009. On average IASI exhibits a positive bias of approximately 7 % compared to the GOME-2 measurements over the entire ozone hole period. Comparisons between IASI and ozone sonde measurements were also found to be in good agreement with the difference between both ozone profile measurements being less than ±30 % over the altitude range of 0-40 km. The vertical structure of the ozone profile inside the ozone hole is captured remarkably well by IASI.

  • Antarctic ozone hole as observed by IASI/MetOp for 2008-2010
    Atmospheric Measurement Techniques, 2012
    Co-Authors: Claire Scannell, Maya George, Juliette Hadji-lazaro, Anne Boynard, Daniel Hurtmans, Andy Delcloo, Pierre-françois Coheur, O N E Tuinder, Cathy Clerbaux
    Abstract:

    In this paper we present a study of the ozone hole as observed by the Infrared Atmospheric Sounding Interferometer (IASI) on-board the MetOp-A European satellite platform from the beginning of data dissemination, August 2008, to the end of December 2010. Here we demonstrate IASI's ability to capture the seasonal characteristics of the ozone hole, in particular during polar night. We compare IASI ozone total columns and vertical profiles with those of the Global Ozone Monitoring Experiment 2 (GOME-2, also on-board MetOp-A) and electrochemical concentration cell (ECC) ozone sonde measurements. Total ozone column from IASI and GOME-2 were found to be in excellent agreement for this region with a correlation coefficient of 0.97, for September, October and November 2009. On average IASI exhibits a positive bias of approximately 7% compared to the GOME-2 measurements over the entire ozone hole period. Comparisons between IASI and ozone sonde measurements were also found to be in good agreement with the difference between both ozone profile measurements being less than ±30% over the altitude range of 0-40 km. The vertical structure of the ozone profile inside the ozone hole is captured remarkably well by IASI.