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Jae H. Park

Abstract

Absorption of solar radiation by O2 in the Schumann-Runge band region is important not only for the production of O(3P) in the atmosphere, but also for H2O and NO photodissociations which depend upon the rotational structure of the O2 absorption lines. The equivalent mean absorption cross sections for the O2 Schumann-Runge bands and NO band intensities are computed and presented in a form to be applicable in calculations of the O2, H2O and NO photodissociation rates under varied atmospheric conditions.

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Jae H. Park and Julius London

Abstract

The distributions of minor atmospheric constituents, principally O3 and O(3P), and their contributions to the heat sources and sinks in the earth’s middle atmosphere (30–100 km) are investigated. The latitudinal and seasonal distributions of radiative heating rates for the region 30–100 km are computed considering the absorption of solar UV by O2 and O3 and the chemical heat release by O(3P) recombination. Absorption of solar radiation by O3 is responsible for most of the radiative heating in the region 30–75 km. Between 75 and 90 km the heating rate is relatively small and is contributed to about equally by absorption by O2 and O3. Above 90 km the heating rate due to absorption by O O2 is of major importance, although non-equilibrium production of O(3P) in the summer results in reduced heating rates at these levels. At 100 km the “effective” heating rate is ∼40K day−1 at high latitudes during the summer. Recombination of O(3P) in the winter polar mesosphere and lower thermosphere results in a significant heat source for that region.

Meridional gradients of computed heating rates in the upper atmosphere are found to be generally larger than previous results. The implications of this distribution with regard to the dynamics of this region is discussed.

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Jae H. Park and James M. Russell III

Abstract

Regions of low stratospheric ozone that are anticorrelated with HCl, NO, and NO2 levels have been observed in the Arctic and Antarctic summers of 1992 and 1993 by the Halogen Occultation Experiment on the UARS platform. The low ozone areas are confined to the ∼8–45 mb (∼33–21 km) region and poleward of ∼60° in each hemisphere. While low polar summer ozone has been observed before, this is the first time simultaneous observations of relevant nitrogen and chlorine chemical species have been made. The phenomenon appears to be a recurring geophysical feature, and the satellite data should provide an excellent opportunity to improve our understanding of the chemistry causing these conditions.

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Maarten C. Buijsman, Jody M. Klymak, Sonya Legg, Matthew H. Alford, David Farmer, Jennifer A. MacKinnon, Jonathan D. Nash, Jae-Hun Park, Andy Pickering, and Harper Simmons

Abstract

The three-dimensional (3D) double-ridge internal tide interference in the Luzon Strait in the South China Sea is examined by comparing 3D and two-dimensional (2D) realistic simulations. Both the 3D simulations and observations indicate the presence of 3D first-mode (semi)diurnal standing waves in the 3.6-km-deep trench in the strait. As in an earlier 2D study, barotropic-to-baroclinic energy conversion, flux divergence, and dissipation are greatly enhanced when semidiurnal tides dominate relative to periods dominated by diurnal tides. The resonance in the 3D simulation is several times stronger than in the 2D simulations for the central strait. Idealized experiments indicate that, in addition to ridge height, the resonance is only a function of separation distance and not of the along-ridge length; that is, the enhanced resonance in 3D is not caused by 3D standing waves or basin modes. Instead, the difference in resonance between the 2D and 3D simulations is attributed to the topographic blocking of the barotropic flow by the 3D ridges, affecting wave generation, and a more constructive phasing between the remotely generated internal waves, arriving under oblique angles, and the barotropic tide. Most of the resonance occurs for the first mode. The contribution of the higher modes is reduced because of 3D radiation, multiple generation sites, scattering, and a rapid decay in amplitude away from the ridge.

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Jhoon Kim, Ukkyo Jeong, Myoung-Hwan Ahn, Jae H. Kim, Rokjin J. Park, Hanlim Lee, Chul Han Song, Yong-Sang Choi, Kwon-Ho Lee, Jung-Moon Yoo, Myeong-Jae Jeong, Seon Ki Park, Kwang-Mog Lee, Chang-Keun Song, Sang-Woo Kim, Young Joon Kim, Si-Wan Kim, Mijin Kim, Sujung Go, Xiong Liu, Kelly Chance, Christopher Chan Miller, Jay Al-Saadi, Ben Veihelmann, Pawan K. Bhartia, Omar Torres, Gonzalo González Abad, David P. Haffner, Dai Ho Ko, Seung Hoon Lee, Jung-Hun Woo, Heesung Chong, Sang Seo Park, Dennis Nicks, Won Jun Choi, Kyung-Jung Moon, Ara Cho, Jongmin Yoon, Sang-kyun Kim, Hyunkee Hong, Kyunghwa Lee, Hana Lee, Seoyoung Lee, Myungje Choi, Pepijn Veefkind, Pieternel F. Levelt, David P. Edwards, Mina Kang, Mijin Eo, Juseon Bak, Kanghyun Baek, Hyeong-Ahn Kwon, Jiwon Yang, Junsung Park, Kyung Man Han, Bo-Ram Kim, Hee-Woo Shin, Haklim Choi, Ebony Lee, Jihyo Chong, Yesol Cha, Ja-Ho Koo, Hitoshi Irie, Sachiko Hayashida, Yasko Kasai, Yugo Kanaya, Cheng Liu, Jintai Lin, James H. Crawford, Gregory R. Carmichael, Michael J. Newchurch, Barry L. Lefer, Jay R. Herman, Robert J. Swap, Alexis K. H. Lau, Thomas P. Kurosu, Glen Jaross, Berit Ahlers, Marcel Dobber, C. Thomas McElroy, and Yunsoo Choi

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).

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