scholarly journals Satellite observation of lowermost tropospheric ozone by multispectral synergism of IASI thermal infrared and GOME-2 ultraviolet measurements over Europe

2013 ◽  
Vol 13 (19) ◽  
pp. 9675-9693 ◽  
Author(s):  
J. Cuesta ◽  
M. Eremenko ◽  
X. Liu ◽  
G. Dufour ◽  
Z. Cai ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Tropospheric Ozone ◽  
Degrees Of Freedom ◽  
Transport Model ◽  
Thermal Infrared ◽  
Satellite Observation ◽  
Ozone Pollution ◽  
Pixel Resolution ◽  
Uv Reflectance ◽  
Global Coverage

Abstract. We present a new multispectral approach for observing lowermost tropospheric ozone from space by synergism of atmospheric radiances in the thermal infrared (TIR) observed by IASI (Infrared Atmospheric Sounding Interferometer) and earth reflectances in the ultraviolet (UV) measured by GOME-2 (Global Ozone Monitoring Experiment-2). Both instruments are onboard the series of MetOp satellites (in orbit since 2006 and expected until 2022) and their scanning capabilities offer global coverage every day, with a relatively fine ground pixel resolution (12 km-diameter pixels spaced by 25 km for IASI at nadir). Our technique uses altitude-dependent Tikhonov–Phillips-type constraints, which optimize sensitivity to lower tropospheric ozone. It integrates the VLIDORT (Vector Linearized Discrete Ordinate Radiative Transfer) and KOPRA (Karlsruhe Optimized and Precise Radiative transfer Algorithm) radiative transfer codes for simulating UV reflectance and TIR radiance, respectively. We have used our method to analyse real observations over Europe during an ozone pollution episode in the summer of 2009. The results show that the multispectral synergism of IASI (TIR) and GOME-2 (UV) enables the observation of the spatial distribution of ozone plumes in the lowermost troposphere (LMT, from the surface up to 3 km a.s.l., above sea level), in good agreement with the CHIMERE regional chemistry-transport model. In this case study, when high ozone concentrations extend vertically above 3 km a.s.l., they are similarly observed over land by both the multispectral and IASI retrievals. On the other hand, ozone plumes located below 3 km a.s.l. are only clearly depicted by the multispectral retrieval (both over land and over ocean). This is achieved by a clear enhancement of sensitivity to ozone in the lowest atmospheric layers. The multispectral sensitivity in the LMT peaks at 2 to 2.5 km a.s.l. over land, while sensitivity for IASI or GOME-2 only peaks at 3 to 4 km a.s.l. at lowest (above the LMT). The degrees of freedom for the multispectral retrieval increase by 0.1 (40% in relative terms) with respect to IASI only retrievals for the LMT. Validations with ozonesondes (over Europe during summer 2009) show that our synergetic approach for combining IASI (TIR) and GOME-2 (UV) measurements retrieves lowermost tropospheric ozone with a mean bias of 1% and a precision of 16%, when smoothing by the retrieval vertical sensitivity (1% mean bias and 21% precision for direct comparisons).

scholarly journals Satellite observation of lowermost tropospheric ozone by multispectral synergism of IASI thermal infrared and GOME-2 ultraviolet measurements

2013 ◽  
Vol 13 (1) ◽  
pp. 2955-2995 ◽  
Author(s):  
J. Cuesta ◽  
M. Eremenko ◽  
X. Liu ◽  
G. Dufour ◽  
Z. Cai ◽  
...  
Keyword(s):  
Tropospheric Ozone ◽  
Degrees Of Freedom ◽  
Transport Model ◽  
Thermal Infrared ◽  
Satellite Observation ◽  
Quantitative Agreement ◽  
Ozone Pollution ◽  
Pixel Resolution ◽  
Uv Reflectance ◽  
Global Coverage

Abstract. We present a new multispectral approach for observing lowermost tropospheric ozone from space by synergism of atmospheric radiances in the thermal infrared (TIR) observed by IASI and earth reflectances in the ultraviolet (UV) measured by GOME-2. Both instruments are onboard the series of MetOp satellites (in orbit since 2006 and expected until 2022) and their scanning capabilities offer global coverage every day, with a relatively fine ground pixel resolution (12-km-diameter pixels spaced by 25 km for IASI at nadir). Our technique uses altitude-dependent Tikhonov-Phillips-type constraints, which optimize sensitivity to lower tropospheric ozone. It integrates the VLIDORT and KOPRA radiative transfer codes for simulating UV reflectance and TIR radiance, respectively. We have used our method to analyse real observations over Europe during an ozone pollution episode in the summer of 2009. The results show that the multispectral synergism of IASI (TIR) and GOME-2 (UV) enables the observation of the spatial distribution of ozone plumes in the lowermost troposphere (LMT, from the surface up to 3 km a.s.l., above sea level), in good quantitative agreement with the CHIMERE regional chemistry-transport model. When high ozone concentrations extend vertically above 3 km a.s.l., they are similarly observed over land by both the multispectral and IASI retrievals. On the other hand, ozone plumes located below 3 km a.s.l. are only clearly depicted by the multispectral retrieval (both over land and over ocean). This is achieved by a clear enhancement of sensitivity to ozone in the lowest atmospheric layers. The multispectral sensitivity in the LMT peaks at 2 to 2.5 km a.s.l. over land, while sensitivity for IASI or GOME-2 only peaks at 3 to 4 km a.s.l. at lowest (above the LMT). The degrees of freedom for the multispectral retrieval increase by 40% (21%) with respect to IASI only retrievals for atmospheric partial columns up to 3 km a.s.l. (6 km a.s.l.). Validations with ozonesondes show that our synergetic approach for combining IASI (TIR) and GOME-2 (UV) measurements retrieves lowermost tropospheric ozone with a mean bias of 2% and a precision of 16%, when smoothing by the retrieval vertical sensitivity (1% mean bias and 24% precision for direct comparisons).

scholarly journals Monitoring the lowermost tropospheric ozone with thermal infrared observations from a geostationary platform: performance analyses for a future dedicated instrument

2014 ◽  
Vol 7 (2) ◽  
pp. 391-407 ◽  
Author(s):  
P. Sellitto ◽  
G. Dufour ◽  
M. Eremenko ◽  
J. Cuesta ◽  
G. Forêt ◽  
...  
Keyword(s):  
Tropospheric Ozone ◽  
Degrees Of Freedom ◽  
Transport Model ◽  
Correlation Coefficients ◽  
Thermal Infrared ◽  
Lower Surface ◽  
Maximum Sensitivity ◽  
Performance Analyses ◽  
Mean Square Errors ◽  
Ozone Column

Abstract. In this paper, we present performance analyses for a concept geostationary observing system called MAGEAQ (Monitoring the Atmosphere from Geostationary orbit for European Air Quality). The MAGEAQ mission is designed to include a TIR (thermal infrared) spectrometer and a broadband VIS (visible) radiometer; in this work we study only the TIR component (MAGEAQ-TIR). We have produced about 20 days of MAGEAQ-TIR tropospheric ozone pseudo-observations with a full forward and inverse radiative transfer pseudo-observations simulator. We have studied the expected sensitivity of MAGEAQ-TIR and we have found that it is able to provide a full single piece of information for the ozone column from surface to 6 km (about 1.0 DOF (degrees of freedom) and maximum sensitivity at about 3.0 km, on average), as well as a partially independent surface–3 km ozone column (about 0.6 DOF and maximum sensitivity at about 2.5 km, on average). Then, we have compared the tropospheric ozone profiles and the lower (surface–6 km) and lowermost (surface–3 km) tropospheric ozone column pseudo-observations to the target pseudo-reality, produced with the MOCAGE (MOdèle de Chimie Atmosphérique à Grande Echelle) chemistry and transport model. We have found very small to not significant average biases (< 1% in absolute value, for the surface–6 km TOC (tropospheric ozone column), and about −2 to −3 %, for the surface–3 km TOC) and small RMSEs (root mean square errors; about 1.3 DU (5%), for the surface–6 km TOC, and about 1.5 DU (10%), for the surface–3 km TOC). We have tested the performance of MAGEAQ-TIR at some selected small (0.2° × 0.2°) urban and rural locations. We have found that, while the vertical structures of the lower tropospheric ozone pseudo-reality are sometimes missed, MAGEAQ-TIR's lower and lowermost column pseudo-observations follow stunningly good the MOCAGE column pseudo-reality, with correlation coefficients reaching values of 0.9 or higher. Unprecedented retrieval performance for the lowermost tropospheric ozone column is shown. In any case, our MAGEAQ-TIR pseudo-observations are only partially able to replicate the MOCAGE pseudo-reality variability and temporal cycle at the very lowest layers (surface and 1 km altitude), especially at southern European urban locations, where the photochemistry signal is partially missed or shifted at higher altitudes. Temporal artifacts on the daily cycle are sometimes observed. Stratospheric-to-tropospheric exchanges during short time periods (of the order of 1 day) are detected by the MAGEAQ-TIR pseudo-observations.

scholarly journals The effect of using limited scene-dependent averaging kernels approximations for the implementation of fast Observing System Simulation Experiments targeted on lower tropospheric ozone

2013 ◽  
Vol 6 (2) ◽  
pp. 2413-2448 ◽  
Author(s):  
P. Sellitto ◽  
G. Dufour ◽  
M. Eremenko ◽  
J. Cuesta ◽  
V.-H. Peuch ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Tropospheric Ozone ◽  
System Simulation ◽  
Ozone Pollution ◽  
Simulation Experiments ◽  
Atmospheric Species ◽  
Radiative Transfer Calculation ◽  
Pollution Event ◽  
Pollution Events ◽  
Simulation Exercises

Abstract. Practical implementations of chemical OSSEs (Observing System Simulation Experiments) usually rely on approximations of the pseudo-observations by means of a prior parametrization of the averaging kernels, which describe the sensitivity of the observing systems to the target atmospheric species. This is intended to avoid the need for use of a computationally expensive pseudo-observations simulator that relies on full radiative transfer calculations. Here we present an investigation on how no, or limited, scene dependent averaging kernels parametrizations may misrepresent the sensitivity of an observing system, and thus possibly lead to inaccurate results of OSSEs. We carried out the full radiative transfer calculation for a three-days period over Europe, to produce reference pseudo-observations of lower tropospheric ozone, as they would be observed by a concept geostationary observing system called MAGEAQ (Monitoring the Atmosphere from Geostationary orbit for European Air Quality). The selected spatiotemporal interval is characterized by a peculiar ozone pollution event. We then compared our reference with approximated pseudo-observations, following existing simulation exercises made for both the MAGEAQ and GEOstationary Coastal and Air Pollution Events (GEO-CAPE) missions. We found that approximated averaging kernels may fail to replicate the variability of the full radiative transfer calculations. Then, we compared the full radiative transfer and the approximated pseudo-observations during a pollution event. We found that the approximations substantially overestimate the capability of the MAGEAQ to follow the spatiotemporal variations of the lower tropospheric ozone in selected areas. We conclude that such approximations may lead to false conclusions if used in an OSSE. Thus, we recommend to use comprehensive scene-dependent approximations of the averaging kernels, in cases where the full radiative transfer is computationally too costly for the OSSE being investigated.

scholarly journals A geostationary thermal infrared sensor to monitor the lowermost troposphere: O<sub>3</sub> and CO retrieval studies

2011 ◽  
Vol 4 (2) ◽  
pp. 297-317 ◽  
Author(s):  
M. Claeyman ◽  
J.-L. Attié ◽  
V.-H. Peuch ◽  
L. El Amraoui ◽  
W. A. Lahoz ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Transport Model ◽  
Signal To Noise Ratio ◽  
Weather Prediction ◽  
Thermal Infrared ◽  
Sampling Interval ◽  
Added Value ◽  
Spatial And Temporal Variability ◽  
Statistical Parameters ◽  
Retrieval Scheme

Abstract. This paper describes the capabilities of a nadir thermal infrared (TIR) sensor proposed for deployment onboard a geostationary platform to monitor ozone (O3) and carbon monoxide (CO) for air quality (AQ) purposes. To assess the capabilities of this sensor we perform idealized retrieval studies considering typical atmospheric profiles of O3 and CO over Europe with different instrument configuration (signal to noise ratio, SNR, and spectral sampling interval, SSI) using the KOPRA forward model and the KOPRA-fit retrieval scheme. We then select a configuration, referred to as GEO-TIR, optimized for providing information in the lowermost troposphere (LmT; 0–3 km in height). For the GEO-TIR configuration we obtain ~1.5 degrees of freedom for O3 and ~2 for CO at altitudes between 0 and 15 km. The error budget of GEO-TIR, calculated using the principal contributions to the error (namely, temperature, measurement error, smoothing error) shows that information in the LmT can be achieved by GEO-TIR. We also retrieve analogous profiles from another geostationary infrared instrument with SNR and SSI similar to the Meteosat Third Generation Infrared Sounder (MTG-IRS) which is dedicated to numerical weather prediction, referred to as GEO-TIR2. We quantify the added value of GEO-TIR over GEO-TIR2 for a realistic atmosphere, simulated using the chemistry transport model MOCAGE (MOdèle de Chimie Atmospherique à Grande Echelle). Results show that GEO-TIR is able to capture well the spatial and temporal variability in the LmT for both O3 and CO. These results also provide evidence of the significant added value in the LmT of GEO-TIR compared to GEO-TIR2 by showing GEO-TIR is closer to MOCAGE than GEO-TIR2 for various statistical parameters (correlation, bias, standard deviation).

scholarly journals Potential of multispectral synergism for observing ozone pollution by combining IASI-NG and UVNS measurements from EPS-SG satellite

2016 ◽  
Author(s):  
Lorenzo Costantino ◽  
Juan Cuesta ◽  
Emanuele Emili ◽  
Adriana Coman ◽  
Gilles Foret ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Transport Model ◽  
Lower Troposphere ◽  
Real Data ◽  
Satellite Observations ◽  
Maximum Sensitivity ◽  
Ozone Pollution ◽  
Chemical Transport Model ◽  
Near Surface ◽  
Multispectral Method

Abstract. Present and future satellite observations offer a great potential for monitoring air quality on daily and global basis. However, measurements from currently in orbit satellites do not allow using a single sensor to probe accurately surface concentrations of gaseous pollutants such as tropospheric ozone (Liu et al., 2010). Using single-band approaches based on spaceborne measurements of either thermal infrared radiance (TIR, Eremenko et al., 2008) or ultraviolet reflectance (UV, Liu et al., 2010) only ozone down to the lower troposphere (3 km) may be observed. A recent multispectral method (referred to as IASI+GOME-2) combining the information of IASI and GOME-2 (both onboard MetOp satellites) spectra, respectively from the TIR and UV, has shown enhanced sensitivity for probing ozone at the lowermost troposphere (LMT, below 3 km of altitude) with maximum sensitivity down to 2.20 km a.s.l. over land, while sensitivity for IASI or GOME-2 only peaks at 3 to 4 km at lowest (Cuesta et al., 2013). Future spatial missions will be launched in the upcoming years, such as EPS-SG, carrying new-generation sensors of IASI and GOME-2 (respectively IASI-NG and UVNS) that will enhance the capacity to observe ozone pollution and particularly by synergism of TIR and UV measurements. In this work we develop a pseudo-observation simulator and evaluate the potential of future EPS-SG satellite observations through IASI-NG+UVNS multispectral method to observer near-surface O3. The pseudo-real state of atmosphere (nature run) is provided by the MOCAGE (MOdèle de Chimie Atmosphérique à Grande Échelle) chemical transport model. Simulations are calibrated by careful comparisons with real data, to ensure the best consistency between pseudo-reality and reality, as well as between the pseudo-observation simulator and existing satellite products. We perform full and accurate forward and inverse radiative transfer calculations for a period of 4 days (8–11 July 2010) over Europe. In the LMT, there is a remarkable agreement in the geographical distribution of O3 partial columns, calculated between the surface and 3 km of altitude, between IASI-NG+UVNS pseudo-observations and the corresponding MOCAGE pseudo-reality. With respect to synthetic IASI+GOME-2 products, IASI-NG+UVNS shows a higher correlation between pseudo-observations and pseudo-reality, enhanced by about 11 %. The bias on high ozone retrieval is reduced and the average accuracy increases by 22 %. The sensitivity to LMT ozone is enhanced on average with 154 % (from 0.29 to 0.75, over land) and 208 % (from 0.21 to 0.66, over ocean) higher degrees of freedom. The mean height of maximum sensitivity for the LMT peaks at 1.43 km over land and 2.02 km over ocean, respectively 1.03 km and 1.30 km below that of IASI+GOME-2. IASI-NG+UVNS shows also good retrieval skill in the surface-2 km altitude range with a mean DOF (degree of freedom) of 0.52 (land) and 0.42 (ocean), and an average Hmax (altitude of maximum sensitivity) of 1.29 km (land) and 1.96 km (ocean). Unique of its kind for retrieving ozone layers of 2–3 km thickness, in the first 2–3 km of the atmosphere, IASI-NG+UVNS is expected to largely enhance the capacity to observe ozone pollution from space.

scholarly journals Monitoring the lowermost tropospheric ozone with thermal infrared observations from a geostationary platform: performance analyses for a future dedicated instrument

2013 ◽  
Vol 6 (4) ◽  
pp. 6445-6490 ◽  
Author(s):  
P. Sellitto ◽  
G. Dufour ◽  
M. Eremenko ◽  
J. Cuesta ◽  
G. Forêt ◽  
...  
Keyword(s):  
Tropospheric Ozone ◽  
Degrees Of Freedom ◽  
Transport Model ◽  
Correlation Coefficients ◽  
Lower Surface ◽  
Maximum Sensitivity ◽  
Infrared Observations ◽  
Performance Analyses ◽  
Short Time ◽  
Ozone Column

Abstract. In this paper, we present performance analyses for a concept geostationary observing system called MAGEAQ (Monitoring the Atmosphere from Geostationary orbit for European Air Quality). The MAGEAQ mission is designed to include a TIR spectrometer and a broadband VIS radiometer; in this work we study only the TIR component (MAGEAQ-TIR). We have produced about 20 days of MAGEAQ-TIR tropospheric ozone pseudo-observations with a full forward and inverse radiative transfer pseudo-observations simulator. We have studied the expected sensitivity of MAGEAQ-TIR and we have found that a completely independent surface −6 km ozone column (about 1.0 DOF (degrees of freedom) and maximum sensitivity at about 3.0 km, on average), as well as a partially independent surface −3 km ozone column (about 0.6 DOF and maximum sensitivity at about 2.5 km, on average) can be achieved. Then, we have compared the tropospheric ozone profiles and the lower (surface −6 km) and lowermost (surface −3 km) tropospheric ozone column pseudo-observations to the target pseudo-reality, produced with the MOCAGE (MOdèle de Chimie Atmosphérique à Grande Echelle) chemistry and transport model. We have found very small to not significant average biases (< 1% in absolute value, for the surface −6 km TOC, and about −2 to −3%, for the surface −3 km TOC) and small RMSEs (about 1.3 DU (5%), for the surface −6 km TOC, and about 1.5 DU (10%), for the surface −3 km TOC). We have tested the performances of MAGEAQ-TIR at some selected small (0.2° × 0.2°) urban and rural locations. We have found that, while the vertical structures of the lower tropospheric ozone pseudo-reality are sometimes missed, MAGEAQ-TIR lower and lowermost column pseudo-observations follow stunningly good the MOCAGE column pseudo-reality, with correlation coefficients reaching values of 0.9 or higher. Unprecedented retrieval performances for the lowermost tropospheric ozone column are shown. In any case, our MAGEAQ-TIR pseudo-observations are only partially able to replicate the MOCAGE pseudo-reality variability and temporal cycle at the very lowest layers (surface and 1 km altitude), especially at Southern European urban locations, where the photochemistry signal is partially missed or shifted at higher altitudes. Temporal artifact on the daily cycle are sometimes observed. Stratospheric-to-tropospheric exchanges during short time periods (of the order of 1 day) are detected by the MAGEAQ-TIR pseudo-observations.

scholarly journals Potential of the future thermal infrared space-borne sensor IASI-NG to monitor lower tropospheric ozone

2012 ◽  
Vol 5 (5) ◽  
pp. 7025-7065 ◽  
Author(s):  
P. Sellitto ◽  
G. Dufour ◽  
M. Eremenko ◽  
J. Cuesta ◽  
P. Dauphin ◽  
...  
Keyword(s):  
Ozone Concentration ◽  
Tropospheric Ozone ◽  
Degrees Of Freedom ◽  
Total Error ◽  
Thermal Infrared ◽  
Added Value ◽  
Key Factor ◽  
Low Sensitivity ◽  
New Generation ◽  
Ozone Column

Abstract. The lower tropospheric (LT) ozone concentration is a key factor for air quality (AQ). Observing efficiently LT ozone from space is crucial to monitor and better understand pollution phenomena occurring from inter-continental to local scales, and that have a proven noxious effect on the human health and the biosphere. The Infrared Atmospheric Sounder Interferometer (IASI) flies on MetOp-A spacecraft and is planned to be launched in the next future as part of the other MetOp modules, i.e. MetOp-B and C. IASI has demonstrated to have the capability to single out the LT ozone signal only at favourable conditions, i.e. in presence of high thermal contrast scenarios. New generation satellite instruments are being designed to address several pressing geophysical issues, including a better observation capability of LT ozone. IASI-NG (New Generation), now having reached the accomplishment of design phase-A for launch in the 2020 timeframe as part of the EPS-SG (EUMETSAT Polar System-Second Generation, formerly post-EPS) mission, may render feasible a better observation of AQ in terms of LT ozone. To evaluate the added-value brought by IASI-NG in this context, we developed a pseudo-observation simulator, including a direct simulator of thermal infrared spectra and a full inversion scheme to retrieve ozone concentration profiles. We produced one month (August 2009) of tropospheric ozone pseudo-observations based on both IASI and IASI-NG instrumental configurations. We compared the pseudo-observations and we found a clear improvement of LT ozone (up to 6 km altitude) pseudo-observations quality for IASI-NG. The estimated total error is expected to be more than 35% smaller at 5 km, and 20% smaller for the LT ozone column. The total error on the LT ozone column is, on average, lower than 10% for IASI-NG. IASI-NG is expected to have a significantly better vertical sensitivity (monthly average degrees of freedom surface-6 km of 0.70) and to be sensitive at lower altitudes (more than 0.5 km lower than IASI, reaching values of nearly 3.0 km). Vertical ozone layers of 4 to 5 km thickness are expected to be resolved by IASI-NG, while IASI has a vertical resolution of 6–8 km. According to our analyses, IASI-NG is expected to have the possibility of effectively separate lower from upper tropospheric ozone information even for low sensitivity scenarios. In addition, IASI-NG is expected to be able to better monitor LT ozone patterns at local spatial scale and to monitor abrupt temporal evolutions occurring at time-scales of a few days, thus bringing an expected added-value with respect to IASI for the monitoring of AQ.

scholarly journals The effect of using limited scene-dependent averaging kernels approximations for the implementation of fast observing system simulation experiments targeted on lower tropospheric ozone

2013 ◽  
Vol 6 (8) ◽  
pp. 1869-1881 ◽  
Author(s):  
P. Sellitto ◽  
G. Dufour ◽  
M. Eremenko ◽  
J. Cuesta ◽  
V.-H. Peuch ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Tropospheric Ozone ◽  
System Simulation ◽  
Temporal Variations ◽  
Ozone Pollution ◽  
Simulation Experiments ◽  
Atmospheric Species ◽  
Radiative Transfer Calculation ◽  
Pollution Event ◽  
Spatio Temporal

Abstract. Practical implementations of chemical OSSEs (Observing System Simulation Experiments) usually rely on approximations of the pseudo-observations by means of a predefined parametrization of the averaging kernels, which describe the sensitivity of the observing system to the target atmospheric species. This is intended to avoid the use of a computationally expensive pseudo-observations simulator, that relies on full radiative transfer calculations. Here we present an investigation on how no, or limited, scene dependent averaging kernels parametrizations may misrepresent the sensitivity of an observing system. We carried out the full radiative transfer calculation for a three-days period over Europe, to produce reference pseudo-observations of lower tropospheric ozone, as they would be observed by a concept geostationary observing system called MAGEAQ (Monitoring the Atmosphere from Geostationary orbit for European Air Quality). The selected spatio-temporal interval is characterised by an ozone pollution event. We then compared our reference with approximated pseudo-observations, following existing simulation exercises made for both the MAGEAQ and GEOstationary Coastal and Air Pollution Events (GEO-CAPE) missions. We found that approximated averaging kernels may fail to replicate the variability of the full radiative transfer calculations. In addition, we found that the approximations substantially overestimate the capability of MAGEAQ to follow the spatio-temporal variations of the lower tropospheric ozone in selected areas, during the mentioned pollution event. We conclude that such approximations may lead to false conclusions if used in an OSSE. Thus, we recommend to use comprehensive scene-dependent approximations of the averaging kernels, in cases where the full radiative transfer is computationally too costly for the OSSE being investigated.

scholarly journals Trends in tropospheric ozone concentrations and forest impact metrics in Europe over the time period 2000–2014

2020 ◽  
Author(s):  
Chiara Proietti ◽  
Maria Francesca Fornasier ◽  
Pierre Sicard ◽  
Alessandro Anav ◽  
Elena Paoletti ◽  
...  
Keyword(s):  
Tropospheric Ozone ◽  
Transport Model ◽  
Control Strategies ◽  
Ground Level ◽  
Ozone Pollution ◽  
Ozone Uptake ◽  
Ozone Concentrations ◽  
Quality Issue ◽  
Stomatal Flux ◽  
Stomatal Ozone Uptake

Abstract In Europe, tropospheric ozone pollution appears as a major air quality issue, and ozone concentrations remain potentially harmful to vegetation. In this study we compared the trends of two ozone metrics widely used for forests protection in Europe, the AOT40 (Accumulated Ozone over Threshold of 40 ppb) which only depends on surface air ozone concentrations, and the Phytotoxic Ozone Dose which is the accumulated ozone uptake through stomata over the growing season, and above a threshold Y of uptake (PODY). By using a chemistry transport model, we found that European-averaged ground-level ozone concentrations (− 2%) and AOT40 metric (− 26.5%) significantly declined from 2000 to 2014, due to successful control strategies to reduce the emission of ozone precursors in Europe since the early 1990s. In contrast, the stomatal ozone uptake by forests increased from 17.5 to 26.6 mmol O3 m−2 despite the reduction in ozone concentrations, leading to an increase of potential ozone damage on plants in Europe. In a climate change context, a biologically-sound stomatal flux-based standard (PODY) as new European legislative standard is needed.

scholarly journals A geostationary thermal infrared sensor to monitor the lowermost troposphere: O<sub>3</sub> and CO retrieval studies

2010 ◽  
Vol 3 (4) ◽  
pp. 3489-3534 ◽  
Author(s):  
M. Claeyman ◽  
J.-L. Attié ◽  
V.-H. Peuch ◽  
L. El Amraoui ◽  
W. A. Lahoz ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Transport Model ◽  
Weather Prediction ◽  
High Surface ◽  
Thermal Infrared ◽  
Added Value ◽  
Spatial And Temporal Variability ◽  
Chemical Transport Model ◽  
Statistical Parameters ◽  
Thermal Contrast

Abstract. This paper describes the capabilities of a nadir thermal infrared (TIR) sensor proposed for embarkation onboard a geostationary platform to monitor ozone (O3) and carbon monoxide (CO) for air quality (AQ) purposes. To assess the capabilities of this sensor we perform idealized retrieval studies considering typical atmospheric profiles of O3 and CO over Europe with different instrument configurations (signal to noise ratio and spectral sampling interval) using the KOPRA forward model and the KOPRA-fit retrieval scheme based on the Tikhonov-Phillips regularization. We then select a configuration, referred to as GEO-TIR, optimized for providing information in the lowermost troposphere (LmT; 0–3 km in height). For the GEO-TIR configuration we obtain around 1.5 degrees of freedom for O3 and 2 for CO at altitudes between 0 and 15 km. The error budget of GEO-TIR, calculated taking account of the principal contributions to the error (namely, temperature, measurement error, smoothing error) shows that information in the LmT can be achieved by GEO-TIR. We also retrieve analogous profiles from another geostationary infrared instrument with characteristics similar to the Meteosat Third Generation Infrared Sounder (MTG-IRS) which is dedicated to numerical weather prediction, referred to as GEO-TIR2. Comparison between GEO-TIR and GEO-TIR2 allows us to quantify the added value of GEO-TIR, a mission complementing the AQ observing system. To better characterize the information provided by GEO-TIR and GEO-TIR2 in the LmT, we retrieve two typical profiles of O3 and CO for different thermal contrast ranging from –10 K to 10 K. The shape of the first averaging kernel (corresponding to the surface level) confirms that GEO-TIR has good sensitivity to CO in the LmT and also to O3 for high positive thermal contrast. GEO-TIR2 has very low sensitivity in the LmT to O3 but can have sensitivity to CO with high positive thermal contrast. To quantify these results for a realistic atmosphere, we simulate it using the chemical transport model MOCAGE (MOdèle de Chimie Atmospherique à Grande Echelle) – this is the nature run. We simulate the O3 and CO spatial and temporal distributions from GEO-TIR observations in the LmT in July 2009 over Europe by sampling the nature run. Results show that GEO-TIR is able to capture well the spatial and temporal variability in the LmT for both O3 and CO, particularly during periods with high positive thermal contrast near the ground and high surface temperature, which results in active photochemistry and a raised planetary boundary layer. These results also provide evidence of the significant added value in the LmT of GEO-TIR compared to GEO-TIR2 by showing GEO-TIR is closer to the nature run than GEO-TIR2 for various statistical parameters (correlation, bias, standard deviation).

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