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Impact of using a new ultraviolet ozone absorption cross-section dataset on OMI ozone profile retrievalsBak, JuseonLiu, XiongBirk, ManfredWagner, GeorgGordon, Iouli E.Chance, KellyDOI: info:10.5194/amt-13-5845-2020v. 13No. 115845–5854
Bak, Juseon, Liu, Xiong, Birk, Manfred, Wagner, Georg, Gordon, Iouli E., and Chance, Kelly. 2020. "Impact of using a new ultraviolet ozone absorption cross-section dataset on OMI ozone profile retrievals." Atmospheric Measurement Techniques 13 (11):5845– 5854.
ID: 157568
Type: article
Authors: Bak, Juseon; Liu, Xiong; Birk, Manfred; Wagner, Georg; Gordon, Iouli E.; Chance, Kelly
Abstract: We evaluate different sets of high-resolution ozone absorption cross-section data for use in atmospheric ozone profile measurements in the Hartley and Huggins bands with a particular focus on BDM 1995 (Daumont et al. 1992; Brion et al., 1993; Malicet et al., 1995), currently used in our retrievals, and a new laboratory dataset by Birk and Wagner (2018) (BW). The BDM cross-section data have been recommended to use for retrieval of ozone profiles using spaceborne nadir-viewing backscattered ultraviolet (BUV) measurements since its improved performance was demonstrated against other cross-sections including Bass and Paur (1985) (BP) and those of Serdyuchenko et al. (2014) and Gorshelev et al. (2014) (SER) by the "Absorption Cross-Sections of Ozone" (ACSO) activity. The BW laboratory data were recently measured within the framework of the European Space Agency (ESA) project SEOM-IAS (Scientific Exploitation of Operational Missions - Improved Atmospheric Spectroscopy Databases) to provide an advanced absorption cross-section database. The BW cross-sections are made from measurements at more temperatures and in a wider temperature range than BDM, especially for low temperatures. Relative differences of cross-sections between BW and BDM range from similar to 2% at shorter UV wavelengths to similar to 5% at longer UV wavelengths at warm temperatures. Furthermore, these differences dynamically increase by up to +/- 40% at cold temperatures due to no BDM measurements having been made below 218 K. We evaluate the impact of using different cross-sections on ozone profile retrievals from Ozone Monitoring Instrument (OMI) measurements. Correspondingly, this impact leads to significant differences in individual ozone retrievals by up to 50% in the tropopause where the coldest atmospheric temperatures are observed. Bottom atmospheric layers illustrate the significant change of the retrieved ozone values, with differences of 20% in low latitudes, which is not the case in high latitudes because the ozone retrievals are mainly controlled by a priori ozone information in high latitudes due to less photon penetration down to the lower troposphere. Validation with ozonesonde observations demonstrates that BW and BDM retrievals show altitude-dependent bias oscillations of similar magnitude relative to ozonesonde measurements, much smaller than those of both BP and SER retrievals. However, compared to BDM, BW retrievals show significant reduction in standard deviation, by up to 15 %, especially at the coldest atmospheric temperatures. Such improvement is achieved mainly by the better characterization of the temperature dependence of ozone absorption.
New Era of Air Quality Monitoring from Space: Geostationary Environment Monitoring Spectrometer (GEMS)Kim, JhoonJeong, UkkyoAhn, Myoung-HwanKim, Jae H.Park, Rokjin J.Lee, HanlimSong, Chul HanChoi, Yong-SangLee, Kwon-HoYoo, Jung-MoonJeong, Myeong-JaePark, Seon KiLee, Kwang-MogSong, Chang-KeunKim, Sang-WooKim, Young JoonKim, Si-WanKim, MijinGo, SujungLiu, XiongChance, KellyChan Miller, ChristopherAl-Saadi, JayVeihelmann, BenBhartia, Pawan K.Torres, OmarGonzález-Abad, GonzaloHaffner, David P.Ko, Dai HoLee, Seung HoonWoo, Jung-HunChong, HeesungPark, Sang SeoNicks, DennisChoi, Won JunMoon, Kyung-JungCho, AraYoon, JongminKim, Sang-kyunHong, HyunkeeLee, KyunghwaLee, HanaLee, SeoyoungChoi, MyungjeVeefkind, PepijnLevelt, Pieternel F.Edwards, David P.Kang, MinaEo, MijinBak, JuseonBaek, KanghyunKwon, Hyeong-AhnYang, JiwonPark, JunsungHan, Kyung ManKim, Bo-RamShin, Hee-WooChoi, HaklimLee, EbonyChong, JihyoCha, YesolKoo, Ja-HoIrie, HitoshiHayashida, SachikoKasai, YaskoKanaya, YugoLiu, ChengLin, JintaiCrawford, James H.Carmichael, Gregory R.Newchurch, Michael J.Lefer, Barry L.Herman, Jay R.Swap, Robert J.Lau, Alexis K. H.Kurosu, Thomas P.Jaross, GlenAhlers, BeritDobber, MarcelMcElroy, C. ThomasChoi, YunsooDOI: info:10.1175/BAMS-D-18-0013.1v. 101E1–E22
Kim, Jhoon, Jeong, Ukkyo, Ahn, Myoung-Hwan, Kim, Jae H., Park, Rokjin J., Lee, Hanlim, Song, Chul Han, Choi, Yong-Sang, Lee, Kwon-Ho, Yoo, Jung-Moon, Jeong, Myeong-Jae, Park, Seon Ki, Lee, Kwang-Mog, Song, Chang-Keun, Kim, Sang-Woo, Kim, Young Joon, Kim, Si-Wan, Kim, Mijin, Go, Sujung, Liu, Xiong, Chance, Kelly, Chan Miller, Christopher, Al-Saadi, Jay, Veihelmann, Ben, Bhartia, Pawan K. et al. 2020. "New Era of Air Quality Monitoring from Space: Geostationary Environment Monitoring Spectrometer (GEMS)." Bulletin of the American Meteorological Society 101:E1– E22.
ID: 155672
Type: article
Authors: Kim, Jhoon; Jeong, Ukkyo; Ahn, Myoung-Hwan; Kim, Jae H.; Park, Rokjin J.; Lee, Hanlim; Song, Chul Han; Choi, Yong-Sang; Lee, Kwon-Ho; Yoo, Jung-Moon; Jeong, Myeong-Jae; Park, Seon Ki; Lee, Kwang-Mog; Song, Chang-Keun; Kim, Sang-Woo; Kim, Young Joon; Kim, Si-Wan; Kim, Mijin; Go, Sujung; Liu, Xiong; Chance, Kelly; Chan Miller, Christopher; Al-Saadi, Jay; Veihelmann, Ben; Bhartia, Pawan K.; Torres, Omar; González-Abad, Gonzalo; Haffner, David P.; Ko, Dai Ho; Lee, Seung Hoon; Woo, Jung-Hun; Chong, Heesung; Park, Sang Seo; Nicks, Dennis; Choi, Won Jun; Moon, Kyung-Jung; Cho, Ara; Yoon, Jongmin; Kim, Sang-kyun; Hong, Hyunkee; Lee, Kyunghwa; Lee, Hana; Lee, Seoyoung; Choi, Myungje; Veefkind, Pepijn; Levelt, Pieternel F.; Edwards, David P.; Kang, Mina; Eo, Mijin; Bak, Juseon; Baek, Kanghyun; Kwon, Hyeong-Ahn; Yang, Jiwon; Park, Junsung; Han, Kyung Man; Kim, Bo-Ram; Shin, Hee-Woo; Choi, Haklim; Lee, Ebony; Chong, Jihyo; Cha, Yesol; Koo, Ja-Ho; Irie, Hitoshi; Hayashida, Sachiko; Kasai, Yasko; Kanaya, Yugo; Liu, Cheng; Lin, Jintai; Crawford, James H.; Carmichael, Gregory R.; Newchurch, Michael J.; Lefer, Barry L.; Herman, Jay R.; Swap, Robert J.; Lau, Alexis K. H.; Kurosu, Thomas P.; Jaross, Glen; Ahlers, Berit; Dobber, Marcel; McElroy, C. Thomas; Choi, Yunsoo
Abstract: The Geostationary Environment Monitoring Spectrometer (GEMS) is scheduled for launch in February 2020 to monitor air quality (AQ) at an unprecedented spatial and temporal resolution from a geostationary Earth orbit (GEO) for the first time. With the development of UV-visible spectrometers at sub-nm spectral resolution and sophisticated retrieval algorithms, estimates of the column amounts of atmospheric pollutants (O3, NO2, SO2, HCHO, CHOCHO, and aerosols) can be obtained. To date, all the UV-visible satellite missions monitoring air quality have been in low Earth orbit (LEO), allowing one to two observations per day. With UV-visible instruments on GEO platforms, the diurnal variations of these pollutants can now be determined. Details of the GEMS mission are presented, including instrumentation, scientific algorithms, predicted performance, and applications for air quality forecasts through data assimilation. GEMS will be on board the Geostationary Korea Multi-Purpose Satellite 2 (GEO- KOMPSAT-2) satellite series, which also hosts the Advanced Meteorological Imager (AMI) and Geostationary Ocean Color Imager 2 (GOCI-2). These three instruments will provide synergistic science products to better understand air quality, meteorology, the long-range transport of air pollutants, emission source distributions, and chemical processes. Faster sampling rates at higher spatial resolution will increase the probability of finding cloud-free pixels, leading to more observations of aerosols and trace gases than is possible from LEO. GEMS will be joined by NASA's Tropospheric Emissions: Monitoring of Pollution (TEMPO) and ESA's Sentinel-4 to form a GEO AQ satellite constellation in early 2020s, coordinated by the Committee on Earth Observation Satellites (CEOS).
Cross-evaluation of GEMS tropospheric ozone retrieval performance using OMI data and the use of an ozonesonde dataset over East Asia for validationBak, JuseonBaek, Kang-HyeonKim, Jae-HwanLiu, XiongKim, JhoonChance, KellyDOI: info:10.5194/amt-12-5201-2019v. 125201–5215
Bak, Juseon, Baek, Kang-Hyeon, Kim, Jae-Hwan, Liu, Xiong, Kim, Jhoon, and Chance, Kelly. 2019. "Cross-evaluation of GEMS tropospheric ozone retrieval performance using OMI data and the use of an ozonesonde dataset over East Asia for validation." Atmospheric Measurement Techniques 12:5201– 5215.
ID: 154401
Type: article
Authors: Bak, Juseon; Baek, Kang-Hyeon; Kim, Jae-Hwan; Liu, Xiong; Kim, Jhoon; Chance, Kelly
Abstract: The Geostationary Environment Monitoring Spectrometer (GEMS) is scheduled to be launched in 2019-2020 on board the GEO-KOMPSAT (GEOstationary KOrea Multi-Purpose SATellite)-2B, contributing as the Asian partner of the global geostationary constellation of air quality monitoring. To support this air quality satellite mission, we perform a cross-evaluation of simulated GEMS ozone profile retrievals from OMI (Ozone Monitoring Instrument) data based on the optimal estimation and ozonesonde measurements within the GEMS domain, covering from 5 S (Indonesia) to 45 N (south of the Russian border) and from 75 to 145 E. The comparison between ozonesonde and GEMS shows a significant dependence on ozonesonde types. Ozonesonde data measured by modified Brewer-Mast (MBM) at Trivandrum and New Delhi show inconsistent seasonal variabilities in tropospheric ozone compared to carbon-iodine (CI) and electrochemical condensation cell (ECC) ozonesondes at other stations in a similar latitude regime. CI ozonesonde measurements are negatively biased relative to ECC measurements by 2-4 DU; better agreement is achieved when simulated GEMS ozone retrievals are compared to ECC measurements. ECC ozone data at Hanoi, Kuala Lumpur, and Singapore show abnormally worse agreements with simulated GEMS retrievals than other ECC measurements. Therefore, ECC ozonesonde measurements at Hong Kong, Pohang, Naha, Sapporo, and Tsukuba are finally identified as an optimal reference dataset. The accuracy of simulated GEMS retrievals is estimated to be ̃5.0 % for both tropospheric and stratospheric column ozone with the precision of 15 %and 5 %, which meets the GEMS ozone requirements.
Linearization of the effect of slit function changes for improving Ozone Monitoring Instrument ozone profile retrievalsBak, JuseonLiu, XiongSun, KangChance, KellyKim, Jae-HwanDOI: info:10.5194/amt-12-3777-2019v. 123777–3788
Bak, Juseon, Liu, Xiong, Sun, Kang, Chance, Kelly, and Kim, Jae-Hwan. 2019. "Linearization of the effect of slit function changes for improving Ozone Monitoring Instrument ozone profile retrievals." Atmospheric Measurement Techniques 12:3777– 3788.
ID: 154165
Type: article
Authors: Bak, Juseon; Liu, Xiong; Sun, Kang; Chance, Kelly; Kim, Jae-Hwan
Abstract: We introduce a method that accounts for errors caused by the slit function in an optimal-estimation-based spectral fitting process to improve ozone profile retrievals from the Ozone Monitoring Instrument (OMI) ultraviolet measurements (270-330 nm). Previously, a slit function was parameterized as a standard Gaussian by fitting the full width at half maximum (FWHM) of the slit function from climatological OMI solar irradiances. This cannot account for the temporal variation in slit function in irradiance, the intra-orbit changes due to thermally induced change and scene inhomogeneity, and potential differences in the slit functions of irradiance and radiance measurements. As a result, radiance simulation errors may be induced due to convolving reference spectra with incorrect slit functions. To better represent the shape of the slit functions, we implement a more generic super Gaussian slit function with two free parameters (slit width and shape factor); it becomes standard Gaussian when the shape factor is fixed to be 2. The effects of errors in slit function parameters on radiance spectra, referred to as pseudo absorbers (PAs), are linearized by convolving high-resolution cross sections or simulated radiances with the partial derivatives of the slit function with respect to the slit parameters. The PAs are included in the spectral fitting scaled by fitting coefficients that are iteratively adjusted as elements of the state vector along with ozone and other fitting parameters. The fitting coefficients vary with cross-track and along-track pixels and show sensitivity to heterogeneous scenes. The PA spectrum is quite similar in the Hartley band below 310 nm for both standard and super Gaussians, but is more distinctly structured in the Huggins band above 310 nm with the use of super Gaussian slit functions. Finally, we demonstrate that some spikes of fitting residuals are slightly smoothed by accounting for the slit function errors. Comparisons with ozonesondes demonstrate noticeable improvements when using PAs for both standard and super Gaussians, especially for reducing the systematic biases in the tropics and midlatitudes (mean biases of tropospheric column ozone reduced from -1.4̃0.7 to 0.0̃0.4 DU) and reducing the standard deviations of tropospheric ozone column differences at high latitudes (by 1 DU for the super Gaussian). Including PAs also makes the retrievals consistent between standard and super Gaussians. This study corroborates the slit function differences between radiance and irradiance, demonstrating that it is important to account for such differences in the ozone profile retrievals.
Five decades observing Earth's atmospheric trace gases using ultraviolet and visible backscatter solar radiation from spaceGonzalez Abad, GonzaloSouri, Amir HosseinBak, JuseonChance, KellyFlynn, Lawrence E.Krotkov, Nickolay A.Lamsal, LokLi, CanLiu, XiongChan Miller, ChristopherNowlan, Caroline R.Suleiman, RaidWang, HuiqunDOI: info:10.1016/j.jqsrt.2019.04.030v. 238106478
Gonzalez Abad, Gonzalo, Souri, Amir Hossein, Bak, Juseon, Chance, Kelly, Flynn, Lawrence E., Krotkov, Nickolay A., Lamsal, Lok, Li, Can, Liu, Xiong, Chan Miller, Christopher, Nowlan, Caroline R., Suleiman, Raid, and Wang, Huiqun. 2019. "Five decades observing Earth's atmospheric trace gases using ultraviolet and visible backscatter solar radiation from space." Journal of Quantitative Spectroscopy and Radiative Transfer 238:106478.
ID: 154602
Type: article
Authors: Gonzalez Abad, Gonzalo; Souri, Amir Hossein; Bak, Juseon; Chance, Kelly; Flynn, Lawrence E.; Krotkov, Nickolay A.; Lamsal, Lok; Li, Can; Liu, Xiong; Chan Miller, Christopher; Nowlan, Caroline R.; Suleiman, Raid; Wang, Huiqun
Abstract: Over the last five decades, Earth's atmosphere has been extensively monitored from space using different spectral ranges. Early efforts were directed at improving weather forecasts with the first meteorological satellites launched in the 1960s. Soon thereafter, the intersection between weather, climate and atmospheric chemistry led to the observation of atmospheric composition from space. During the 1970s the Nimbus satellite program started regular monitoring of ozone integrated columns and water vapor profiles using the Backscatter Ultraviolet Spectrometer, the Infrared Interferometer Spectrometer and the Satellite Infrared Spectrometer instruments. Five decades after these pioneer efforts, continuous progress in instrument design, and retrieval techniques allow researchers to monitor tropospheric concentrations of a wide range of species with implications for air quality, climate and weather. The time line of historic, present and future space-borne instruments measuring ultraviolet and visible backscattered solar radiation designed to quantify atmospheric trace gases is presented. We describe the instruments technological evolution and the basic concepts of retrieval theory. We include a review of algorithms developed for ozone, nitrogen dioxide, sulfur dioxide, formaldehyde, bromine monoxide, water vapor and glyoxal, a selection of studies using these algorithms, the challenges they face and how these challenges can be addressed. The paper ends by providing insights on the opportunities that new instruments will bring to the atmospheric chemistry, weather and air quality communities and how to address the pressing need for long-term, inter-calibrated data records necessary to monitor the response of the atmosphere to rapidly changing ecosystems.
Improvement of OMI ozone profile retrievals by simultaneously fitting polar mesospheric cloudsBak, JuseonLiu, XiongKim, Jae H.Deland, Matthew T.Chance, Kelly V.DOI: info:10.5194/amt-9-4521-2016v. 94521–4531
Bak, Juseon, Liu, Xiong, Kim, Jae H., Deland, Matthew T., and Chance, Kelly V. 2016. "Improvement of OMI ozone profile retrievals by simultaneously fitting polar mesospheric clouds." Atmospheric Measurement Techniques 9:4521– 4531.
ID: 140791
Type: article
Authors: Bak, Juseon; Liu, Xiong; Kim, Jae H.; Deland, Matthew T.; Chance, Kelly V.
Abstract: The presence of polar mesospheric clouds (PMCs) at summer high latitudes could affect the retrieval of ozone profiles using backscattered ultraviolet (UV) measurements. PMC-induced errors in ozone profile retrievals from Ozone Monitoring Instrument (OMI) backscattered UV measurements are investigated through comparisons with Microwave Limb Sounder (MLS) ozone measurements. This comparison demonstrates that the presence of PMCs leads to systematic biases for pressures smaller than 6 hPa; the biases increase from ~ -2 % at 2 hPa to ~ -20 % at 0.5 hPa on average and are significantly correlated with brightness of PMCs. Sensitivity studies show that the radiance sensitivity to PMCs strongly depends on wavelength, increasing by a factor of ~ 4 from 300 to 265 nm. It also strongly depends on the PMC scattering, thus depending on viewing geometry. The optimal estimation-based retrieval sensitivity analysis shows that PMCs located at 80-85 km have the greatest effect on ozone retrievals at ~ 0.2 hPa ( ~ 60 km), where the retrieval errors range from -2.5 % with PMC vertical optical depth (POD) of 10-4 to -20 % with 10-3 POD at backscattering angles. The impacts increase by a factor of ~ 5 at forward-scattering angles due to stronger PMC sensitivities. To reduce the interference of PMCs on ozone retrievals, we perform simultaneous retrievals of POD and ozone with a loose constraint of 10-3 for POD, which results in retrieval errors of 1-4 × 10-4. It is demonstrated that the negative bias of OMI ozone retrievals relative to MLS can be improved by including the PMC in the forward-model calculation and retrieval.