https://repository.kopri.re.kr/handle/201206/9722 Wed, 08 Apr 2026 23:01:07 GMT 2026-04-08T23:01:07Z https://repository.kopri.re.kr/handle/201206/10887 Title: Mosaicking Opportunistically Acquired Very High-Resolution Helicopter-Borne Images over Drifting Sea Ice Using COTS Sensors Authors: Hyun, Chang-Uk; Kim, Joo-Hong; Han, Hyangsun; Kim, Hyun-cheol Abstract: Observing sea ice by very high-resolution (VHR) images not only improves the quality of lower-resolution remote sensing products (e.g., sea ice concentration, distribution of melt ponds and pressure ridges, sea ice surface roughness, etc.) by providing details on the ground truth of sea ice, but also assists sea ice fieldwork. In this study, two fieldwork-based methods are proposed, one for the practical acquisition of VHR images over drifting Arctic sea ice using low-cost commercial off-the-shelf (COTS) sensors equipped on helicopter, and the other for quantifying the compensating effect from continuously drifting sea ice that reduces geolocation uncertainty in the image mosaicking procedure. The drifting trajectory of the target ice was yielded from that recorded by an icebreaker that was tightly anchored to the floe and was then used to reversely compensate the locations of acquired VHR images. After applying the compensation, three-dimensional geolocation errors of the VHR images were decreased by 79.3% and 24.2% for pre-defined two image groups, respectively. The enhanced accuracy of the imaging locations was affected by imaging duration causing variable drifting distances of individual images. Further applicability of the mosaicked VHR image was discussed by comparing it with a TerraSAR-X synthetic aperture radar image containing the target ice, suggesting that the proposed methods can be used for precise comparison with satellite remote sensing products. Fri, 01 Mar 2019 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/10887 2019-03-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/12249 Title: Dimethylsulfide sea-to-air fluxes in Chukchi Sea and East Siberian Sea in the summer of 2016 and 2017 Authors: Choi, Jung-Ok; Park, Keyhong; Jung, Jinyoung; Hahm, Doshik; Kim, In-Tae Abstract: In the global radiation budget estimate, the largest uncertainty is derived by the current understanding of sulfate aerosols. Dimethylsulfide (DMS) is the major biogenic source of sulfate aerosols in the remote marine atmosphere. DMS production in the oceans is closely associated with phytoplankton biomass because it is produced by the phytoplankton activity. Arctic is warming faster than any other region on Earth due to the global warming. The decline in sea ice and the rise in sea surface temperature also affect the production of DMS by changing marine ecosystems. In this study, we measured continuous underway surface DMS and ΔO2/Ar during R/V Araon’s 2016 and 2017 summer Arctic expeditions. The high-resolution DMS concentrations are obtained in Chukchi Sea and East Siberian Sea, using membrane inlet mass spectrometry (MIMS). Surface DMS concentrations varied between ~1 to 31 nM (mean 6 ± 7 nM) in 2016 and between ~1 to 105 nM (mean 7 ± 14 nM) in 2017. Sea-to-air flux estimates of DMS were determined using the empirical dependence of exchange coefficients on wind speed, surface water DMS concentrations. Surface atmospheric DMS concentrations are assumed to zero. Surface water DMS measurements yielded sea-to-air flux estimates of DMS ranged from 0.01 to 82.50 μmol m2d1 (mean 10.96 ± 15.50 μmol m2d1) in 2016 and from 0.00 to 404.43 μmol m2d1 (mean 9.82 ± 27.95 μmol m2d1) in 2017. This study contributes to broadening the spatial coverage of the Arctic DMS dataset and serves as a baseline for future studies. Tue, 01 Jan 2019 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/12249 2019-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/10839 Title: Transmission of Solar Light according the Relative CDOM Concentration of the Sea-ice-covered Pacific Arctic Ocean Authors: Kang, Sung-Ho; Kim, Hyun-cheol; Ha, Sun-Yong Abstract: The transmission of solar light according to the distribution of chromophoric dissolved organic matter (CDOM) was measured in the Pacific Arctic Ocean. The Research Vessel Araon visited the icecovered East Siberian and Chukchi Seas in August 2016. In the Arctic, solar [ultraviolet-A (UV-A), ultraviolet-B (UV-B), and photosynthetically active radiation (PAR)] radiation reaching the surface of the ocean is primarily protected by the distribution of sea ice. The transmission of solar light in the ocean is controlled by sea ice and dissolved organic matter, such as CDOM. The concentration of CDOM is the major factor controlling the penetration depth of UV radiation into the ocean. The relative CDOM concentration of surface sea water was higher in the East Siberian Sea than in the Chukchi Sea. Due to the distribution of CDOM, the penetration depth of solar light in the East Siberian Sea (UV-B, 9 ± 2 m; UV-A,13 ± 2 m; PAR, 36 ± 4 m) was lower than in the Chukchi Sea (UV-B, 15 ± 3 m; UV-A, 22 ± 3 m; PAR, 49 ± 3 m). Accelerated global warming and the rapid decrease of sea ice in the Arctic have resulted in marine organisms being exposed to increased harmful UV radiation. With changes in sea ice covered areas and concentrations of dissolved organic matter in the Arctic Ocean, marine ecosystems that consist of a variety of species from primary producers to high-trophic-level organisms will be directly or indirectly affected by solar UV radiation. Sat, 01 Dec 2018 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/10839 2018-12-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/10854 Title: Algorithm for Flat First-Year Ice Draft Using AMSR2 Data in the Arctic Ocean Authors: E., Yoshizawa; K., Shimada; Cho, Kyoung-Ho Abstract: First-year ice has replaced multiyear ice in the Northern Sea Route area since 2008. In this area, sea ice survival during summer substantially depends on first-year ice thickness at melt onset, and thus monitoring of first-year ice thickness in the freezing period is a key to forecasting sea ice distributions in the following summer. In this paper, we introduce a new algorithm to estimate flat first-year ice draft using brightness temperature data measured by the Advanced Microwave Scanning Radiometer-2 (AMSR2). The algorithm uses a gradient ratio (GR) of 18- and 36-GHz vertically polarized brightness temperatures based on decreases in sea ice emissivity in higher AMSR2 frequency channels with thermodynamic growth associated with increase in volume scattering. Such spectral characteristics of the emissivity are examined by comparing GR values with flat first-year ice draft extracted by mode values of in situ draft data measured by a moored ice profiling sonar. The accuracy of the daily draft estimated from GR values after applying proper noise filters is about 10 cm for a draft range of 0.4-1.2 m. Thu, 01 Nov 2018 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/10854 2018-11-01T00:00:00Z