scholarly journals NO<sub>2</sub> climatology in the northern subtropical region: diurnal, seasonal and interannual variability

2008 ◽  
Vol 8 (6) ◽  
pp. 1635-1648 ◽  
Author(s):  
M. Gil ◽  
M. Yela ◽  
L. N. Gunn ◽  
A. Richter ◽  
I. Alonso ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Transport Model ◽  
Atmospheric Composition ◽  
Data Sets ◽  
Chemical Transport Model ◽  
Vertical Column ◽  
Stratospheric Temperature ◽  
The Hours ◽  
Vertical Column Density

Abstract. Daily NO2 vertical column density (VCD) has been routinely measured by zenith sky spectroscopy at the subtropical station of Izaña (28° N, 16° W) since 1993 in the framework of the Network for the Detection of Atmospheric Composition Change (NDACC). Based on 14 years of data the first low latitude NO2 VCD climatology has been established and the main characteristics from short timescales of one day to interannual variability are presented. Instrumental descriptions and different sources of errors are described in detail. The observed diurnal cycle follows that expected by gas-phase NOx chemistry, as can be shown by the good agreement with a vertically integrated chemical box model, and is modulated by solar radiation. The seasonal evolution departs from the phase of the hours of daylight, indicating the signature of upper stratospheric temperature changes. From the data record (1993–2006) no significant long-term trends in NO2 VCD can be inferred. Comparison of the ground-based data sets with nadir-viewing satellite spectrometers shows excellent agreement for SCIAMACHY with differences between both datasets of 1.1%. GOME displays unrealistic features with the largest discrepancies during summer. The ground-based data are compared with long-term output of the SLIMCAT 3-D chemical transport model (CTM). The basic model, forced by ECMWF (ERA-40) analyses, captures the observed NO2 annual cycle but significantly underestimates the spring/summer maximum (by 12% at sunset and up to 25% at sunrise). In a model run which uses assimilation of satellite CH4 profiles to constrain the model long-lived tracers the agreement is significantly improved. This improvement in modelled column NO2 is due to better modelled NOy profiles and points to transport errors in the ECMWF ERA-40 reanalyses.

scholarly journals NO<sub>2</sub> climatology in the northern subtropical region: diurnal, seasonal and interannual variability

2007 ◽  
Vol 7 (5) ◽  
pp. 15067-15103 ◽  
Author(s):  
M. Gil ◽  
M. Yela ◽  
L. N. Gunn ◽  
A. Richter ◽  
I. Alonso ◽  
...  
Keyword(s):  
Transport Model ◽  
Atmospheric Composition ◽  
Data Sets ◽  
Chemical Transport Model ◽  
Vertical Column ◽  
Basic Model ◽  
Stratospheric Temperature ◽  
The Hours ◽  
Vertical Column Density

Abstract. Daily NO2 vertical column density (VCD) has been routinely measured by zenith sky spectroscopy at the subtropical station of Izaña (28° N, 16° W) since 1993 in the framework of the Network for the Detection of Atmospheric Composition Change (NDACC). Based on 14 years of data the first low latitudes NO2 VCD climatology has been established and the main characteristics from short scales of one day to inter-annual variability are presented. Instrumental descriptions and different source of errors are described in detail. The observed diurnal cycle follows that expected by gas-phase NOx chemistry, as can be shown by the good agreement with a vertically integrated chemical box model, and is modulated by solar radiation. The seasonal evolution departs from the phase of the hours of daylight, showing the signature of upper stratospheric temperature changes. From the data record no significant long-term trends in NO2 VCD can be inferred. Comparison of the ground-based data sets with nadir looking satellite spectrometers shows excellent agreement for SCIAMACHY with differences between both datasets of 1.1%. GOME displays unrealistic features with largest discrepancies during summer. The ground-based data are compared with long-term output of the SLIMCAT 3-D chemical transport model (CTM). The basic model, forced by ECMWF (ERA-40) analyses, captures the observed NO2 annual cycle but significantly underestimates the spring/summer maximum. In a model run which uses assimilation of satellite CH4 profiles to constrain the model long-lived tracers the agreement is significantly improved. This improvement in modelled column NO2 is due to better modelled NOy profiles and points to transport errors in the ECMWF ERA-40 reanalyses.

scholarly journals Updated tropospheric chemistry reanalysis and emission estimates, TCR-2, for 2005–2018

2020 ◽  
Vol 12 (3) ◽  
pp. 2223-2259 ◽  
Author(s):  
Kazuyuki Miyazaki ◽  
Kevin Bowman ◽  
Takashi Sekiya ◽  
Henk Eskes ◽  
Folkert Boersma ◽  
...  
Keyword(s):  
Transport Model ◽  
Horizontal Resolution ◽  
Tropospheric Chemistry ◽  
Atmospheric Composition ◽  
Data Sets ◽  
Vertical Profiles ◽  
Chemical Transport Model ◽  
Near Surface ◽  
Key Species

Abstract. This study presents the results from the Tropospheric Chemistry Reanalysis version 2 (TCR-2) for the period 2005–2018 at 1.1∘ horizontal resolution obtained from the assimilation of multiple updated satellite measurements of ozone, CO, NO2, HNO3, and SO2 from the OMI, SCIAMACHY, GOME-2, TES, MLS, and MOPITT satellite instruments. The reanalysis calculation was conducted using a global chemical transport model MIROC-CHASER and an ensemble Kalman filter technique that optimizes both chemical concentrations of various species and emissions of several precursors, which was efficient for the correction of the entire tropospheric profile of various species and its year-to-year variations. Comparisons against independent aircraft, satellite, and ozonesonde observations demonstrate the quality of the reanalysis fields for numerous key species on regional and global scales, as well as for seasonal, yearly, and decadal scales, from the surface to the lower stratosphere. The multi-constituent data assimilation brought the model vertical profiles and interhemispheric gradient of OH closer to observational estimates, which was important in improving the description of the oxidation capacity of the atmosphere and thus vertical profiles of various species. The evaluation results demonstrate the capability of the chemical reanalysis to improve understanding of the processes controlling variations in atmospheric composition, including long-term changes in near-surface air quality and emissions. The estimated emissions can be employed for the elucidation of detailed distributions of the anthropogenic and biomass burning emissions of co-emitted species (NOx, CO, SO2) in all major regions, as well as their seasonal and decadal variabilities. The data sets are available at https://doi.org/10.25966/9qgv-fe81 (Miyazaki et al., 2019a).

scholarly journals NDACC UV-visible total ozone measurements: improved retrieval and comparison with correlative satellite and ground-based observations

2010 ◽  
Vol 10 (8) ◽  
pp. 20405-20460
Author(s):  
F. Hendrick ◽  
J.-P. Pommereau ◽  
F. Goutail ◽  
R. D. Evans ◽  
D. Ionov ◽  
...  
Keyword(s):  
Cross Sections ◽  
Total Ozone ◽  
Complete Removal ◽  
Temperature Correction ◽  
Atmospheric Composition ◽  
Vertical Column ◽  
Stratospheric Temperature ◽  
Uv Visible ◽  
Ozone Column

Abstract. Accurate long-term monitoring of total ozone is one of the most important requirements for identifying possible natural or anthropogenic changes in the composition of the stratosphere. For this purpose, the NDACC (Network for the Detection of Atmospheric Composition Change) UV-visible Working Group has made recommendations for improving and homogenizing the retrieval of total ozone columns from twilight zenith-sky visible spectrometers. These instruments, deployed all over the world in about 35 stations, allow measurements of total ozone twice daily with little sensitivity to stratospheric temperature and cloud cover. The NDACC recommendations address both the DOAS retrieval parameters and the calculation of air mass factors (AMF) needed for the conversion of O3 slant column densities into vertical column amounts. The most important improvement is the use of O3 AMF look-up tables calculated using the TOMS V8 O3 profile climatology, that allows accounting for the dependence of the O3 AMF on the seasonal and latitudinal variations of the O3 vertical distribution. To investigate their impact on the retrieved ozone columns, the recommendations have been applied to measurements from the NDACC/SAOZ (Système d'Analyse par Observation Zénithale) network. The revised SAOZ ozone data from eight stations covering all latitude regions have been compared to TOMS, GOME-GDP4, SCIAMACHY-TOSOMI, OMI-TOMS, and OMI-DOAS satellite overpass observations, as well as to those of collocated Dobson and Brewer instruments. A significant improvement is obtained after applying the new O3 AMFs, although systematic seasonal differences between SAOZ and all other instruments remain. These are shown to mainly originate from i) the temperature dependence of the ozone absorption cross sections in the UV being not or improperly corrected by some retrieval algorithms, and ii) the longitudinal differences in tropospheric ozone column being ignored by zonal climatologies. For those measurements sensitive to stratospheric temperature like TOMS, OMI-TOMS, Dobson and Brewer, the application of a temperature correction results in the almost complete removal of the seasonal difference with SAOZ, improving significantly the consistency between all ground-based and satellite total ozone observations.

scholarly journals ML-TOMCAT: machine-learning-based satellite-corrected global stratospheric ozone profile data set from a chemical transport model

2021 ◽  
Vol 13 (12) ◽  
pp. 5711-5729
Author(s):  
Sandip S. Dhomse ◽  
Carlo Arosio ◽  
Wuhu Feng ◽  
Alexei Rozanov ◽  
Mark Weber ◽  
...  
Keyword(s):  
Transport Model ◽  
Stratospheric Ozone ◽  
Chemical Transport ◽  
Data Sets ◽  
Chemical Transport Model ◽  
Profile Data ◽  
Data Set ◽  
Ozone Profile ◽  
Satellite Instruments

Abstract. High-quality stratospheric ozone profile data sets are a key requirement for accurate quantification and attribution of long-term ozone changes. Satellite instruments provide stratospheric ozone profile measurements over typical mission durations of 5–15 years. Various methodologies have then been applied to merge and homogenise the different satellite data in order to create long-term observation-based ozone profile data sets with minimal data gaps. However, individual satellite instruments use different measurement methods, sampling patterns and retrieval algorithms which complicate the merging of these different data sets. In contrast, atmospheric chemical models can produce chemically consistent long-term ozone simulations based on specified changes in external forcings, but they are subject to the deficiencies associated with incomplete understanding of complex atmospheric processes and uncertain photochemical parameters. Here, we use chemically self-consistent output from the TOMCAT 3-D chemical transport model (CTM) and a random-forest (RF) ensemble learning method to create a merged 42-year (1979–2020) stratospheric ozone profile data set (ML-TOMCAT V1.0). The underlying CTM simulation was forced by meteorological reanalyses, specified trends in long-lived source gases, solar flux and aerosol variations. The RF is trained using the Stratospheric Water and OzOne Satellite Homogenized (SWOOSH) data set over the time periods of the Microwave Limb Sounder (MLS) from the Upper Atmosphere Research Satellite (UARS) (1991–1998) and Aura (2005–2016) missions. We find that ML-TOMCAT shows excellent agreement with available independent satellite-based data sets which use pressure as a vertical coordinate (e.g. GOZCARDS, SWOOSH for non-MLS periods) but weaker agreement with the data sets which are altitude-based (e.g. SAGE-CCI-OMPS, SCIAMACHY-OMPS). We find that at almost all stratospheric levels ML-TOMCAT ozone concentrations are well within uncertainties of the observational data sets. The ML-TOMCAT (V1.0) data set is ideally suited for the evaluation of chemical model ozone profiles from the tropopause to 0.1 hPa and is freely available via https://doi.org/10.5281/zenodo.5651194 (Dhomse et al., 2021).

scholarly journals Intercomparison of vertically resolved merged satellite ozone data sets: interannual variability and long-term trends

2015 ◽  
Vol 15 (6) ◽  
pp. 3021-3043 ◽  
Author(s):  
F. Tummon ◽  
B. Hassler ◽  
N. R. P. Harris ◽  
J. Staehelin ◽  
W. Steinbrecht ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Atmospheric Chemistry ◽  
Lower Stratosphere ◽  
Piecewise Linear ◽  
Atmospheric Composition ◽  
Data Sets ◽  
Ozone Data ◽  
Long Term Trends ◽  
Clear Shift

Abstract. In the framework of the SI2N (SPARC (Stratosphere-troposphere Processes And their Role in Climate)/IO3C (International Ozone Commission)/IGACO-O3 (Integrated Global Atmospheric Chemistry Observations – Ozone)/NDACC (Network for the Detection of Atmospheric Composition Change)) initiative, several long-term vertically resolved merged ozone data sets produced from satellite measurements have been analysed and compared. This paper presents an overview of the methods, assumptions, and challenges involved in constructing such merged data sets, as well as the first thorough intercomparison of seven new long-term satellite data sets. The analysis focuses on the representation of the annual cycle, interannual variability, and long-term trends for the period 1984–2011, which is common to all data sets. Overall, the best agreement amongst data sets is seen in the mid-latitude lower and middle stratosphere, with larger differences in the equatorial lower stratosphere and the upper stratosphere globally. In most cases, differences in the choice of underlying instrument records that were merged produced larger differences between data sets than the use of different merging techniques. Long-term ozone trends were calculated for the period 1984–2011 using a piecewise linear regression with a change in trend prescribed at the end of 1997. For the 1984–1997 period, trends tend to be most similar between data sets (with largest negative trends ranging from −4 to −8% decade−1 in the mid-latitude upper stratosphere), in large part due to the fact that most data sets are predominantly (or only) based on the SAGE-II record. Trends in the middle and lower stratosphere are much smaller, and, particularly for the lower stratosphere, large uncertainties remain. For the later period (1998–2011), trends vary to a greater extent, ranging from approximately −1 to +5% decade−1 in the upper stratosphere. Again, middle and lower stratospheric trends are smaller and for most data sets not significantly different from zero. Overall, however, there is a clear shift from mostly negative to mostly positive trends between the two periods over much of the profile.

scholarly journals Influences of the variation in inflow to East Asia on surface ozone over Japan during 1996–2005

2011 ◽  
Vol 11 (16) ◽  
pp. 8745-8758 ◽  
Author(s):  
S. Chatani ◽  
K. Sudo
Keyword(s):  
East Asia ◽  
Interannual Variability ◽  
Transport Model ◽  
Surface Ozone ◽  
Chemical Transport ◽  
Chemical Transport Model ◽  
Term Trend ◽  
East Asian Region ◽  
Long Term Trend

Abstract. Air quality simulations in which the global chemical transport model CHASER and the regional chemical transport model WRF/chem are coupled have been developed to consider the dynamic transport of chemical species across the boundaries of the domain of the regional chemical transport model. The simulation captures the overall seasonal variations of surface ozone, but overestimates its concentration over Japanese populated areas by approximately 20 ppb from summer to early winter. It is deduced that ozone formation around Northeast China and Japan in summer is overestimated in the simulation. On the other hand, the simulation well reproduces the interannual variability and the long-term trend of observed surface ozone over Japan. Sensitivity experiments have been performed to investigate the influence of the variation in inflow to East Asia on the interannual variability and the long-term trend of surface ozone over Japan during 1996–2005. The inflow defined in this paper includes the recirculation of species with sources within the East Asian region as well as the transport of species with sources out of the East Asian region. Results of sensitivity experiments suggest that inflow to East Asia accounts for approximately 30 % of the increasing trend of surface ozone, whereas it has much less influence on the interannual variability of observed surface ozone compared to meteorological processes within East Asia.

scholarly journals NDACC/SAOZ UV-visible total ozone measurements: improved retrieval and comparison with correlative ground-based and satellite observations

2011 ◽  
Vol 11 (12) ◽  
pp. 5975-5995 ◽  
Author(s):  
F. Hendrick ◽  
J.-P. Pommereau ◽  
F. Goutail ◽  
R. D. Evans ◽  
D. Ionov ◽  
...  
Keyword(s):  
Cross Sections ◽  
Total Ozone ◽  
Stratospheric Ozone ◽  
Complete Removal ◽  
Atmospheric Composition ◽  
Spectral Parameters ◽  
Vertical Column ◽  
Stratospheric Temperature ◽  
Uv Visible

Abstract. Accurate long-term monitoring of total ozone is one of the most important requirements for identifying possible natural or anthropogenic changes in the composition of the stratosphere. For this purpose, the NDACC (Network for the Detection of Atmospheric Composition Change) UV-visible Working Group has made recommendations for improving and homogenizing the retrieval of total ozone columns from twilight zenith-sky visible spectrometers. These instruments, deployed all over the world in about 35 stations, allow measuring total ozone twice daily with limited sensitivity to stratospheric temperature and cloud cover. The NDACC recommendations address both the DOAS spectral parameters and the calculation of air mass factors (AMF) needed for the conversion of O3 slant column densities into vertical column amounts. The most important improvement is the use of O3 AMF look-up tables calculated using the TOMS V8 (TV8) O3 profile climatology, that allows accounting for the dependence of the O3 AMF on the seasonal and latitudinal variations of the O3 vertical distribution. To investigate their impact on the retrieved ozone columns, the recommendations have been applied to measurements from the NDACC/SAOZ (Système d'Analyse par Observation Zénithale) network. The revised SAOZ ozone data from eight stations deployed at all latitudes have been compared to TOMS, GOME-GDP4, SCIAMACHY-TOSOMI, SCIAMACHY-OL3, OMI-TOMS, and OMI-DOAS satellite overpass observations, as well as to those of collocated Dobson and Brewer instruments at Observatoire de Haute Provence (44° N, 5.5° E) and Sodankyla (67° N, 27° E), respectively. A significantly better agreement is obtained between SAOZ and correlative reference ground-based measurements after applying the new O3 AMFs. However, systematic seasonal differences between SAOZ and satellite instruments remain. These are shown to mainly originate from (i) a possible problem in the satellite retrieval algorithms in dealing with the temperature dependence of the ozone cross-sections in the UV and the solar zenith angle (SZA) dependence, (ii) zonal modulations and seasonal variations of tropospheric ozone columns not accounted for in the TV8 profile climatology, and (iii) uncertainty on the stratospheric ozone profiles at high latitude in the winter in the TV8 climatology. For those measurements mostly sensitive to stratospheric temperature like TOMS, OMI-TOMS, Dobson and Brewer, or to SZA like SCIAMACHY-TOSOMI, the application of temperature and SZA corrections results in the almost complete removal of the seasonal difference with SAOZ, improving significantly the consistency between all ground-based and satellite total ozone observations.

scholarly journals An updated tropospheric chemistry reanalysis and emission estimates, TCR-2, for 2005–2018

2020 ◽  
Author(s):  
Kazuyuki Miyazaki ◽  
Kevin Bowman ◽  
Takashi Sekiya ◽  
Henk Eskes ◽  
Folkert Boersma ◽  
...  
Keyword(s):  
Transport Model ◽  
Horizontal Resolution ◽  
Tropospheric Chemistry ◽  
Atmospheric Composition ◽  
Vertical Profiles ◽  
Chemical Transport Model ◽  
Near Surface ◽  
Key Species

Abstract. This study presents the results from the Tropospheric Chemistry Reanalysis version 2 (TCR-2) for the period 2005–2018 at 1.1° horizontal resolution obtained from the assimilation of multiple updated satellite measurements of ozone, CO, NO2, HNO3, and SO2 from the OMI, SCIAMACHY, GOME-2, TES, MLS, and MOPITT satellite instruments. The reanalysis calculation was conducted using a global chemical transport model MIROC-CHASER and an ensemble Kalman filter technique that optimizes both chemical concentrations of various species and emissions of several precursors, which was efficient for the correction of the entire tropospheric profile of various species and its year-to-year variations. Comparisons against independent aircraft, satellite, and ozonesonde observations demonstrate the quality of the reanalysis fields for numerous key species on regional and global scales, as well as for seasonal, yearly, and decadal scales, from the surface to the lower stratosphere. The multi-constituent data assimilation brought the model vertical profiles and inter-hemispheric gradient of OH closer to observational estimates, which played an important role in improving the description of the oxidation capacity of the atmosphere and thus vertical profiles of various species. The evaluation results demonstrate the capability of the reanalysis products to improve understanding of the processes controlling variations in atmospheric composition, including long-term changes in near-surface air quality and emissions. The estimated emissions can be employed for the elucidation of detailed distributions of the anthropogenic and biomass-burning emissions of co-emitted species (NOx, CO, SO2) in all major regions, as well as their seasonal, and decadal variabilities. The datasets are available at: https://doi.org/10.25966/9qgv-fe81 (Miyazaki et al., 2019a).

scholarly journals Smithsonian Astrophysical Observatory Ozone Mapping and Profiler Suite (SAO OMPS) formaldehyde retrieval

2016 ◽  
Vol 9 (7) ◽  
pp. 2797-2812 ◽  
Author(s):  
Gonzalo González Abad ◽  
Alexander Vasilkov ◽  
Colin Seftor ◽  
Xiong Liu ◽  
Kelly Chance
Keyword(s):  
Detection Limit ◽  
Spectral Resolution ◽  
Signal To Noise Ratio ◽  
Data Sets ◽  
Ozone Monitoring Instrument ◽  
Vertical Column ◽  
Vertical Column Density ◽  
High Concentrations ◽  
The One

Abstract. This paper presents our new formaldehyde (H2CO) retrievals, obtained from spectra recorded by the nadir instrument of the Ozone Mapping and Profiler Suite (OMPS) flown on board NASA's Suomi National Polar-orbiting Partnership (SUOMI-NPP) satellite. Our algorithm is similar to the one currently in place for the production of NASA's Ozone Monitoring Instrument (OMI) operational H2CO product. We are now able to produce a set of long-term data from two different instruments that share a similar concept and a similar retrieval approach. The ongoing overlap period between OMI and OMPS offers a perfect opportunity to study the consistency between both data sets. The different spatial and spectral resolution of the instruments is a source of discrepancy in the retrievals despite the similarity of the physic assumptions of the algorithm. We have concluded that the reduced spectral resolution of OMPS in comparison with OMI is not a significant obstacle in obtaining good-quality retrievals. Indeed, the improved signal-to-noise ratio of OMPS with respect to OMI helps to reduce the noise of the retrievals performed using OMPS spectra. However, the size of OMPS spatial pixels imposes a limitation in the capability to distinguish particular features of H2CO that are discernible with OMI. With root mean square (RMS) residuals  ∼ 5 × 10−4 for individual pixels we estimate the detection limit to be about 7.5 × 1015 molecules cm−2. Total vertical column density (VCD) errors for individual pixels range between 40 % for pixels with high concentrations to 100 % or more for pixels with concentrations at or below the detection limit. We compare different OMI products (SAO OMI v3.0.2 and BIRA OMI v14) with our OMPS product using 1 year of data, between September 2012 and September 2013. The seasonality of the retrieved slant columns is captured similarly by all products but there are discrepancies in the values of the VCDs. The mean biases among the two OMI products and our OMPS product are 23 % between OMI SAO and OMPS SAO and 28 % between OMI BIRA and OMPS SAO for eight selected regions.

scholarly journals Air Quality in the Italian Northwestern Alps during Year 2020: Assessment of the COVID-19 «Lockdown Effect» from Multi-Technique Observations and Models

2021 ◽  
Author(s):  
Henri Diémoz ◽  
Tiziana Magri ◽  
Giordano Pession ◽  
Claudia Tarricone ◽  
Ivan Karl Friedrich Tombolato ◽  
...  
Keyword(s):  
Air Quality ◽  
Large Scale ◽  
Transport Model ◽  
Learning Algorithm ◽  
Steel Mill ◽  
Chemical Transport Model ◽  
Vertical Column ◽  
Particle Matter ◽  
Vertical Column Density ◽  
Secondary Aerosols

The effect of COVID-19 confinement regulations on air quality in the northwestern Alps is here assessed based on measurements at five valley sites in different environmental contexts. Surface concentrations of nitrogen oxides, ozone, particle matter, together with size, chemical, and optical (light absorption) aerosol properties, complemented by observations along the vertical column are considered. The 2020 concentration anomalies relative to previous years&rsquo; average are compared with the output of a machine learning algorithm accounting for weather effects and a chemical transport model, their difference being within 10&ndash;20 %. Even in the relatively pristine environment of the Alps, the &laquo;lockdown effect&raquo; is well discernible, both in the early confinement phase and in late 2020, especially in NOx concentrations (NO decreasing by &gt;80 % and NO2 by &gt;50 %). While ozone shows little variation, secondary aerosols increase due to enhanced transport from the neighbouring Po basin and coarse particles decrease due to missing resuspension by traffic and, in the city, to the shutdown of a steel mill. The NO2 vertical column density decreases by &gt;20 %, whereas the aerosol profile is mainly influenced by large-scale dynamics, except a shallow layer about 500 m thick possibly sensitive to curtailed surface emissions.

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