Cross-evaluation of GEMS tropospheric ozone retrieval performance using OMI data and the use of an ozonesonde dataset over East Asia for validation

Bak, Juseon; Baek, Kwan-Hyuck; Kim, Jaehwan; Liu, Xueliang; Kim, Jhoon; Chance, K.

doi:10.5194/amt-12-5201-2019

Cited by 19 publications

(14 citation statements)

References 36 publications

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“…Previous literature focusing on ozonesonde trends has often focused on specific regions or individual sonde launch locations. In many applications, ozonesonde information is used to validate or assess satellite retrievals rather than as a primary source to investigate trends (Boynard et al, 2018;Shi et al, 2017;Hulswar et al, 2020;Huang et al, 2017;Bak et al, 2019). To date, the most extensive look at ozonesonde trends over Europe is provided by Logan et al (2012), where trends up to 2011 were evaluated.…”

Section: Introductionmentioning

confidence: 99%

Multidecadal increases in global tropospheric ozone derived from ozonesonde and surface site observations: can models reproduce ozone trends?

et al. 2022

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Abstract. Despite decades of effort, the drivers of global long-term trends in tropospheric ozone are not well understood, impacting estimates of ozone radiative forcing and the global ozone budget. We analyze tropospheric ozone trends since 1980 using ozonesondes and remote surface measurements around the globe and investigate the ability of two atmospheric chemical transport models, GEOS-Chem and MERRA2-GMI, to reproduce these trends. Global tropospheric ozone trends measured at 25 ozonesonde sites from 1990–2017 (nine sites since 1980s) show increasing trends averaging 1.8 ± 1.3 ppb per decade across sites in the free troposphere (800–400 hPa). Relative trends in sondes are more pronounced closer to the surface (3.5 % per decade above 700 hPa, 4.3 % per decade below 700 hPa on average), suggesting the importance of surface emissions (anthropogenic, soil NOx, impacts on biogenic volatile organic compounds (VOCs) from land use changes, etc.) in observed changes. While most surface sites (148 of 238) in the United States and Europe exhibit decreases in high daytime ozone values due to regulatory efforts, 73 % of global sites outside these regions (24 of 33 sites) show increases from 1990–2014 that average 1.4 ± 0.9 ppb per decade. In all regions, increasing ozone trends both at the surface and aloft are at least partially attributable to increases in 5th percentile ozone, which average 1.8 ± 1.3 ppb per decade and reflect the global increase of baseline ozone in rural areas. Observed ozone percentile distributions at the surface have shifted notably across the globe: all regions show increases in low tails (i.e., below 25th percentile), North America and Europe show decreases in high tails (above 75th percentile), and the Southern Hemisphere and Japan show increases across the entire distribution. Three model simulations comprising different emissions inventories, chemical schemes, and resolutions, sampled at the same locations and times of observations, are not able to replicate long-term ozone trends either at the surface or free troposphere, often underestimating trends. We find that ∼75 % of the average ozone trend from 800–400 hPa across the 25 ozonesonde sites is captured by MERRA2-GMI, and <20 % is captured by GEOS-Chem. MERRA2-GMI performs better than GEOS-Chem in the northern midlatitude free troposphere, reproducing nearly half of increasing trends since 1990 and capturing stratosphere–troposphere exchange (STE) determined via a stratospheric ozone tracer. While all models tend to capture the direction of shifts in the ozone distribution and typically capture changes in high and low tails, they tend to underestimate the magnitude of the shift in medians. However, each model shows an 8 %–12 % (or 23–32 Tg) increase in total tropospheric ozone burden from 1980 to 2017. Sensitivity simulations using GEOS-Chem and the stratospheric ozone tracer in MERRA2-GMI suggest that in the northern midlatitudes and high latitudes, dynamics such as STE are most important for reproducing ozone trends in models in the middle and upper troposphere, while emissions are more important closer to the surface. Our model evaluation for the last 4 decades reveals that the recent version of the GEOS-Chem model underpredicts free tropospheric ozone across this long time period, particularly in winter and spring over midlatitudes to high latitudes. Such widespread model underestimation of tropospheric ozone highlights the need for better understanding of the processes that transport ozone and promote its production.

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Section: Introductionmentioning

confidence: 99%

Multidecadal increases in global tropospheric ozone derived from ozonesonde and surface site observations: can models reproduce ozone trends?

et al. 2022

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“…Ozonesonde measurements are reported in units of partial pressure (mPa) with vertical resolution of about 100 m by the Korea Meteorological Administration (KMA). Bak et al (2019) demonstrated that Pohang ozonesonde measurements are a stable set of reference profiles for validating satellite products, with quality comparable to ECC ozonesonde measurements in Japan and Hong Kong. To improve the data quality, we screened out sounding measurements at balloon burst altitudes higher than 200 hPa and observations of either tropospheric ozone column values above 80 DU or stratospheric ozone column values below 100 DU.…”

Section: Ozonesonde Measurementsmentioning

confidence: 86%

Temporal variability of tropospheric ozone and ozone profiles in the Korean Peninsula during the East Asian summer monsoon: insights from multiple measurements and reanalysis datasets

et al. 2022

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Abstract. We investigate the temporal variations of ground-level ozone and balloon-based ozone profiles at Pohang (36.02∘ N, 129.23∘ E) in the Korean Peninsula. Satellite measurements and chemical reanalysis products are also intercompared to address their capability of providing consistent information on the temporal and vertical variability of atmospheric ozone. Sub-seasonal variations of the summertime lower-tropospheric ozone exhibit a bimodal pattern related to atmospheric weather patterns modulated by the East Asian monsoon circulation. The peak ozone abundances occur during the pre-summer monsoon with enhanced ozone formation due to favorable meteorological conditions (dry and sunny). Ozone concentrations reach their minimum during the summer monsoon and then re-emerge in autumn before the winter monsoon arrives. Profile measurements indicate that ground-level ozone is vertically mixed up to 400 hPa in summer, while the impact of the summer monsoon on ozone dilution is found up to 600 hPa. Compared to satellite measurements, reanalysis products largely overestimate ozone abundances in both the troposphere and stratosphere and give inconsistent features of temporal variations. Nadir-viewing measurements from the Ozone Monitoring Instrument (OMI) slightly underestimate the boundary layer ozone but represent the bimodal peaks of ozone in the lower troposphere and the interannual changes in the lower-tropospheric ozone in August well, with higher ozone concentrations during strong El Niño events and low ozone concentrations during the 2020 La Niña event.

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“…During the IOT, Defect 3 caused spatial discontinuity to the retrieved cloud and AEH distribution, which made the fitting window of the products modified to avoid bad pixel effects. Ozone properties are also affected by Defect 2 (300-400 nm) as the spectral radiances within 300-380 nm are the major information for the retrieval of GEMS (Bak et al, 2019).…”

Section: Bad Pixelmentioning

confidence: 99%

Spectral replacement using machine learning methods for continuous mapping of Geostationary Environment Monitoring Spectrometer (GEMS)

Lee

Ahn

Kang

et al. 2022

Preprint

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Abstract. Earth radiance in the form of hyperspectral data contains useful information on atmospheric constituents and aerosol properties. The Geostationary Environment Monitoring Spectrometer (GEMS) is an environmental sensor measuring such hyperspectral data in the ultraviolet and visible (UV/VIS) spectral range over the Asia-Pacific region. After successful completion of the in orbit test of GEMS in October 2020, bad pixels are found as a remaining calibration issue to be updated with follow-up treatment. Currently, one-dimensional interpolation in the spatial direction is performed in operation to replace the erroneous pixels of GEMS, which causes high interpolation error for a wider defect area on a detector array. To resolve the issue, this study suggests machine learning methods with artificial neural network (ANN) and multivariate linear regression (Linear) to fill in a spectral gap of defective spectra. The machine learning models are trained with normal measurements to emulate spectral relations between input and output radiances in a spectrum. For efficient training, dimensionality reduction for the input radiances is applied with principal component analysis (PCA) prior to the training process. The results show that the defect area at the wavelengths of strong absorption lines is better replaced with PCA-ANN with the error of 5 %, while PCA-Linear is better for reproducing radiances having strong correlation with input radiances. The shorter the spectral range of output radiances is, the smaller the prediction error is with PCA-Linear (0.5–5 %). Spectral and spatial discontinuity caused by real bad pixels can be significantly improved with the trained machine learning models especially for wide defect areas. This study verifies that spectral relations of radiances in the UV/VIS spectrum are successfully reproduced with a simple machine learning model, which has high potential to be investigated further for enhancing measurement quality of environmental satellite measurements.

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Cross-evaluation of GEMS tropospheric ozone retrieval performance using OMI data and the use of an ozonesonde dataset over East Asia for validation

Cited by 19 publications

References 36 publications

Multidecadal increases in global tropospheric ozone derived from ozonesonde and surface site observations: can models reproduce ozone trends?

Multidecadal increases in global tropospheric ozone derived from ozonesonde and surface site observations: can models reproduce ozone trends?

Temporal variability of tropospheric ozone and ozone profiles in the Korean Peninsula during the East Asian summer monsoon: insights from multiple measurements and reanalysis datasets

Spectral replacement using machine learning methods for continuous mapping of Geostationary Environment Monitoring Spectrometer (GEMS)

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