Ozone Project Research Articles

Launch of an Innovative Air Pollutant Sampler up to 27,000 Metres Using a Stratospheric Balloon

Air pollution, besides being one of the leading causes of death worldwide, remains one of the most controversial topics in environmental monitoring. The current state of the art refers to remote satellite analysis and static ground-level technologies. The O-ZONE project has set itself the objective of bridging this technological gap using dynamic in situ analysis using compact, inexpensive and reusable samplers that can be integrated onboard stratospheric balloons and drones. The prototype, therefore, consists of a pneumatic system, a set of filters and a sampling bag. Thanks to this architecture, it is possible to sample atmospheric air at different altitudes. After the flight, the samples collected are analysed using chromatographic techniques to provide a picture of the various air layers. On 30 September 2021, the fully autonomous payload successfully flew in Kiruna (Swedish Lapland) aboard BEXUS 30, the stratospheric balloon made available by the promoters of the “hands-on” project of the same name, SNSA (Swedish National Space Agency), DLR (Deutsches Zentrum für Luft- und Raumfahrt) and ESA (European Space Agency). In this paper, the technical specifications of the device are described, with a focus on the sampling system; we then highlight the results obtained by the filters that, at different altitudes, collected stratospheric pollutants such as VOCs and, in the first layers of the atmosphere, PM. In conclusion, an interpretation of the results is provided to better understand the possible future uses of the prototype.

Measurement report: regional trends of stratospheric ozone evaluated using the MErged GRIdded Dataset of Ozone Profiles (MEGRIDOP)

Abstract. In this paper, we present the MErged GRIdded Dataset of Ozone Profiles (MEGRIDOP) in the stratosphere with a resolved longitudinal structure, which is derived from data from six limb and occultation satellite instruments: GOMOS, SCIAMACHY and MIPAS on Envisat, OSIRIS on Odin, OMPS on Suomi-NPP, and MLS on Aura. The merged dataset was generated as a contribution to the European Space Agency Climate Change Initiative Ozone project (Ozone_cci). The period of this merged time series of ozone profiles is from late 2001 until the end of 2018. The monthly mean gridded ozone profile dataset is provided in the altitude range from 10 to 50 km in bins of 10∘ latitude × 20∘ longitude. The merging is performed using deseasonalized anomalies. The created MEGRIDOP dataset can be used for analyses that probe our understanding of stratospheric chemistry and dynamics. To illustrate some possible applications, we created a climatology of ozone profiles with resolved longitudinal structure. We found zonal asymmetry in the climatological ozone profiles at middle and high latitudes associated with the polar vortex. At northern high latitudes, the amplitude of the seasonal cycle also has a longitudinal dependence. The MEGRIDOP dataset has also been used to evaluate regional vertically resolved ozone trends in the stratosphere, including the polar regions. It is found that stratospheric ozone trends exhibit longitudinal structures at Northern Hemisphere middle and high latitudes, with enhanced trends over Scandinavia and the Atlantic region. This agrees well with previous analyses and might be due to changes in dynamical processes related to the Brewer–Dobson circulation.

Comparison of GTO-ECV and adjusted MERRA-2 total ozone columns from the last 2 decades and assessment of interannual variability

Abstract. In this study we compare the satellite-based Global Ozone Monitoring Experiment (GOME)-type Total Ozone Essential Climate Variable (GTO-ECV) record, generated as part of the European Space Agency's Climate Change Initiative (ESA-CCI) ozone project, with the adjusted total ozone product from the Modern Era Retrospective Analysis for Research and Applications version 2 (adjusted MERRA-2) reanalysis, produced at the National Aeronautics and Space Administration (NASA) Global Modeling and Assimilation Office (GMAO). Total ozone columns and associated standard deviations show a very good agreement in terms of both spatial and temporal patterns during their 23-year overlap period from July 1995 to December 2018. The mean difference between adjusted MERRA-2 and GTO-ECV 5∘×5∘ monthly mean total ozone columns is -0.9±1.5 %. A small discontinuity in the deviations is detected in October 2004, when data from the Ozone Monitoring Instrument (OMI) were ingested in the GTO-ECV and adjusted MERRA-2 data records. This induces a small overall negative drift in the differences for almost all latitude bands, which, however, does not exceed 1 % per decade. The mean difference for the period prior to October 2004 is -0.5±1.7 %, whereas the difference is -1.0±1.1 % for the period from October 2004 to December 2018. The variability in the differences is considerably reduced in the period after 2004 due to a significant increase in data coverage and sampling. In the tropical region, the differences indicate a slight zonal variability with negative deviations over the Atlantic, Africa, and the Indian Ocean and positive deviations over the Pacific. Ozone anomalies and the distribution of their statistical moments indicate a very high correlation among both data records as to the temporal and spatial structures. Furthermore, we evaluate the consistency of the data sets by means of an empirical orthogonal function (EOF) analysis. The interannual variability is assessed in the tropics, and both GTO-ECV and adjusted MERRA-2 exhibit a remarkable agreement with respect to the derived patterns. The first four EOFs can be attributed to different modes of interannual climate variability, and correlations with the Quasi-Biennial Oscillation (QBO), the El Niño–Southern Oscillation (ENSO) signal, and the solar cycle were found.

Global Ozone (GO3) Project and AQTreks: Use of evolving technologies by students and citizen scientists to monitor air pollutants

Abstract Over the past decade, new and emerging technologies in air pollution instrumentation have made it possible to involve students and citizen scientists in air pollution monitoring. Similarly, advances in data communication and transmission have made it increasingly easy to share and graphically display data. Two educational programs, the Global Ozone (GO3) Project and AQTreks, have used these advances to get air pollution monitors into the hands of thousands of students around the world and to automate data sharing. The pilot project for AQTreks, GO3 Treks, is also discussed. These educational projects began in 2009 with the GO3 Project, a stationary ground-level ozone monitoring project. In the GO3 Project, students and teachers at more than 100 schools from around the world installed ozone and weather monitoring stations at their schools with automatic uploading of their data every 15 min, resulting in more than 12 million ozone measurements along with associated weather data. Over the years, new technologies became available for students to expand their measurements from stationary to mobile platforms. Since 2016, the AQTreks educational program has been developed concurrently with the Personal Air Monitor (PAM), a mobile sensor suite paired with a smartphone app. Complementing the technology are online curricula and other resources for students and citizens to learn about air pollution and climate change. In these projects, a focus on data quality and the careful selection of monitoring technologies have resulted in scientific use of the student-collected data, including their incorporation in several research campaigns that have furthered understanding of ground-level ozone formation. This approach has demonstrated the utility of these types of educational programs both in terms of furthering scientific research and educating the next generation about air quality issues.

Intercomparison of ground-based microwave remote sensing measurements of stratospheric ozone over the Mendoza region, Argentina with HALOE data

The Tropospheric Water Vapour and Stratospheric Ozone (TROPWA) project has measured ground-based stratospheric ozone by means of millimetre wave radiometry tuned at 142 GHz from 1993 to 2000 in Mendoza, Argentina. Additionally, tropospheric water vapour was measured using a 92-GHz radiometer. This paper presents the theoretical error analysis used to characterize the ozone instrument, and a comparative study of the retrieved profiles with the coincident measurements taken with different instruments. To evaluate and validate the retrieved stratospheric ozone profiles, we have used a set of ozone profiles measured with the Halogen Occultation Experiment (HALOE); while the water vapour data was calibrated against a set of 3-year-radiosounding-balloon data taken by the Argentine National Weather Service. This study also includes a comparison of individual ozone profiles measured using a second ground-based millimetre wave radiometer–spectrometer tuned at 276 GHz from the Max-Planck-Institut für Aeronomie (MPAE), Germany. During this particular campaign carried out in November 1994, the ground-based measurements were contrasted with two space-born experiments: the Millimetre Wave Atmospheric Sounder (MAS), flown in the NASA-ATLAS 3 mission and the above-mentioned HALOE. From the error analysis and the comparison tests, it follows that between 20 to 40 km the TROPWA instrument is able to retrieve ozone profiles with absolute errors varying from 10% to 20%, relative errors less than 5%, and with a height resolution, calculated as full width at half maximum (FWHM), varying from 5 to 11 km depending on the altitude. The major discrepancies between the different set of profiles are about +8% to −10% (+0.4 to −0.8 ppmv), mainly due to the coarser height resolution of our instrument.

Ozone depletion observed by the Airborne Submillimeter Radiometer (ASUR) during the Arctic winter 1999/2000

In the winter 1999/2000 the Airborne Submillimeter Radiometer (ASUR) participated in the Stratospheric Aerosol and Gas Experiment III Ozone Loss and Validation Experiment/Third European Stratospheric Experiment on Ozone project on board the NASA research aircraft DC‐8. During three deployments in early December 1999, late January, and early March 2000, the ASUR instrument took various measurements of ozone and key species related to stratospheric ozone chemistry. After the sunlight reached the vortex region in January 2000 peak values of about 1.8 ppb ClO were measured by ASUR. There was nearly no ozone destruction observed during the period between mid December 1999 and late January 2000. As expected from ASUR observation of high chlorine activation and continuously low temperatures until mid March, significant ozone depletion was observed between late January and mid March 2000. In order to determine ozone loss it is important to separate dynamical and chemical effects. Since N2O is a good tracer due to its chemical stability in the lower stratosphere for determining ozone changes due to descent of air, ozone loss can be estimated from simultaneous measurements of ozone and N2O by ASUR. Between mid December 1999 and mid March 2000 a chemical ozone loss of about 30% (eq 1.1 ppm) in the altitude range between 19.0 and 22.2 km and of about 40% (eq 1.15 ppm) between 16.0 and 18.1 km was observed. The air masses subsided 2.1–3.2 km in the lower stratosphere due to diabatic descent in the period from mid December 1999 to mid March 2000 as derived from ASUR N2O measurements. Vortex‐averaged ASUR measurements of ozone are systematical greater than results from the Global Ozone Monitoring Experiment (GOME) which has a similar vertical resolution than ASUR. This, however, has little impact on the determination of delta ozone and chemical loss estimates.

Intercomparison between ground based and TOMS/EP satellite southern hemisphere ozone data. New results

We present new results of the intercomparison between ozone total column data registered at the Southern Hemisphere with the World Meteorological Organization ground stations of the Southern Cone Ozone Project placed in Uruguay, Argentina and the Antarctic continent, with the Total Ozone Mapping Spectrometer (TOMS) instrument on board the Earth Probe satellite and with the Global Ozone Monitoring Experiment (GOME) instrument on board the Earth Remote Sensing (ERS-2) satellite. At least for the region and period considered, GOME/ERS-2 ozone data gives lower mean systematic relative difference (−1.4 3.2) % than TOMS/EP (4.8 2.7) % with respect to groundspectroradiometers. An analysis of possible causes for the large systematic difference in this last case has been considered: differences with respect to a similar instrument placed in another satellite both measuring the same geophysical variable at different orbits; difference with respect to GOME/ERS-2 satellite measurements in the entire region; possible influence on TOMS data of the difference in reflectivity at the high latitude ice (snow)-sea boundary.

Forecast and simulation of stratospheric ozone filaments: A validation of a high‐resolution potential vorticity advection model by airborne ozone lidar measurements in winter 1998/1999

In the framework of the Third European Stratospheric Experiment on Ozone project Meridional Transport of Ozone in the Lower Stratosphere (METRO) an airborne ozone lidar has been flown on the French Falcon (Mystere 20) during winter 1998/1999 to investigate polar and subtropical filaments at midlatitudes. The objective of the METRO project is to quantify the proportion of the transport of polar and subtropical air and their mixing into midlatitude air masses. The dynamical evolution of the northern winter hemisphere was simulated using a high‐resolution advection model for potential vorticity (PV): Modele Isentropique de transport Mesoechelle de l'Ozone Stratospherique par Advection (MIMOSA). To validate the model for further studies, it was first utilized to forecast the appearance of filaments inside the range of the airplane so that each flight of the airborne campaign could be planned precisely. The vertical ozone distribution measured along the flight tracks was then compared to the respective PV distribution simulated by the advection model. Correlation coefficients between 0.5 and 0.7 found over the altitude range where the filaments were observed show a good agreement between PV and ozone filaments. An improvement of the correlation up to 0.8 by horizontal shifting of the ozone profiles against the PV evolution showed that small displacements of less than 1° of the modeled PV filaments can occur. These displacements can be explained by the uncertainties of the input wind velocity data and of the lidar data. Thus we can conclude that the PV advection model MIMOSA reproduces the position, size, and structure of polar filaments and subtropical intrusions well in the range of the expected accuracy. The model is a suitable tool for further studies of the quantification of the global, long‐term transport and mixing of polar and subtropical air into mid‐latitudes.

Measurement of stratospheric chromatic scintillation with the AMON-RA balloonborne spectrometer

The balloonborne instrument AMON (which is a French acronym for Absorption par les Minoritaires Ozone et NO(x)) has been modified to record chromatic scintillation during stellar occultation by the Earth's atmosphere. A 14-channel spectrophotometer with a sampling rate of 10 Hz was added, and the modified instrument, AMON-RA, performed successful measurements of the setting star Alnilam during the third European Stratospheric Experiment on Ozone (THESEO) project. Unambiguous records of the chromatic scintillation were obtained, to our knowledge for the first time from above the atmosphere, and some of its basic properties are reported. The properties of atmospheric structures that are responsible for this chromatic scintillation were found to be consistent with those of previous monochromatic measurements performed from space. A maximum chromatic delay of 2.5 s was observed for widely different wavelengths.

NO signatures from lightning flashes

In situ measurements of cloud properties, NO, and other trace gases were made in active thunderstorms by two research aircraft. Concurrent measurements from a three‐dimensional (3‐D) VHF interferometer and the 2‐D National Lightning Detection Network were used to determine lightning frequency and location. The CHILL Doppler radar and the NOAA‐WP‐3D Orion X band Doppler radar were also used to measure storm characteristics. Two case studies from the (STERAO) Stratosphere‐Troposphere Experiments: Radiation, Aerosols, and Ozone project in northeastern Colorado during the summer of 1996 are presented. Narrow spikes (0.11–0.96 km across), containing up to 19 ppbv of NO, were observed in the storms. Most were located in or downwind of electrically active regions where the NO produced by lightning would be expected. However, it was difficult to correlate individual flashes with NO spikes. A simple model of the plume of NO from lightning is used to estimate NO production from the mean mixing ratio measured in these spikes. The estimates range from 2.0×1020 to 1.0×1022 molecules of NO per meter of flash length.

A comparison of airborne and surface trace gas measurements during the Southern Oxidants Study (SOS)

The NOAA Twin Otter conducted more than a dozen overflights of ground‐level air quality monitoring stations during the 1995 Southern Oxidants Study (SOS) Nashville/Middle Tennessee Ozone Project Field Intensive. Surface and aircraft observations of ozone and ozone precursors were examined to identify systematic sampling errors, and to assess the degree to which surface measurements may be considered representative of the larger planetary boundary layer (PBL). Overall agreement between surface and aircraft trace gas measurements was excellent in the well developed mixed layer, especially in rural‐regional background air and under stagnant conditions, where surface concentrations change only slowly. On July 2, surface level measurements were representative of the larger mixed layer over distances as far as 70 km in background air, and 30 km in the weakly advected urban plume. Vertical variations in trace gas concentrations were often minimal in the well‐mixed PBL, and measurements at the surface always agreed well with aircraft observations up to 460 m above ground level. Under conditions of rapidly varying surface concentrations (e.g., during episodes of power plant plume fumigation and early morning boundary layer development), agreement between surface and aloft is dependent upon the spatial (aircraft) and temporal (ground) averaging intervals used in the comparison. Under these conditions, surface sites may be representative of the PBL only to within a few kilometers. Under clear skies in the well‐mixed PBL, regression of aircraft trace gas data collected within 5 km of the ground sites against 15–20 min average surface concentrations centered on the times of the overflights yielded the following relationships: [O3]aircraft = ([O3]surface × 0.9374) + 4.86 ppbv (r2 = 0.9642); [CO]aircraft = ([CO]surface × 0.8914) + 16.4 ppbv (r2=0.9673); [SO2]aircraft = ([SO2]surface × 0.9414) − 0.069 ppbv (r2 = 0.9945). Although O3, CO, and SO2 measurements at the surface and aloft generally agreed well, isolated examples of unexplained measurement discrepancies emerged, illustrating the need for side‐by‐side instrument comparisons. NOY measurements agreed poorly between surface and aircraft: [NOY]aircraft = ([NOY]surfacex × 0.9184) + 4.56 ppbv (r2 = 0.9188).

The Ntp/Hei Collaborative Ozone Project on the Health Effects of Chronic Ozone Inhalation

AbstractAlthough many people are exposed to ozone, the effects of chronic exposure to this ubiquitous pollutant, especially low-level chronic exposure, are not well understood. The U.S. Environmental Protection Agency (EPA) current national ambient air quality standard for ozone is exceeded in many communities, especially during the summer. The standard is attained when the number of days per calendar year with maximum hourly average concentrations above 0.12 ppm is equal to or less than 1. The U.S. EPA estimates that 67 million people in the United States, or slightly more than a quarter of the residents, live in areas that were out of compliance with the current National Ambient Air Quality Standard (NAAQS) for ozone in 1989. Although there have been some studies of long-term exposure to ozone, many important questions remain about the health effects of chronic ozone exposure. The Health Effects Institute (HEI), in conjunction with the National Toxicology Program (NTP) carcinogenesis studies, has comple...

Wintertime measurements of stratospheric HNO3 as part of the ISY Polar Ozone Project

Atmospheric infrared emission has been recorded with a scanning variable‐filter radiometer on eight stratospheric balloon flights at Alert, inside the arctic vortex, from December 1991 to March 1992. The radiometer and the data analysis for the determination of the altitude distribution of nitric acid vapour are described. The time development of the nitric acid altitude profile at Alert is presented. A sudden change in the profile and vertical column density appears to be associated with the mid‐January stratospheric warming. There is good overall agreement between our results and other arctic winter measurements.