• Journal of Environmental Science International
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• v.18 no.10
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• pp.1089-1101
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• 2009

In this paper, changes in the intensity (e.g., central pressure and maximum sustained wind speed) of Tropical Cyclone (TC) in summer in the regions located at $30^{\circ}N$ in East Asia from 1988 to 1991 were found. The intensity of TC from 1991 to 2007 was much higher than that of TC from 1965 to 1988. The reason for this was that the frequency of TCs passing China from 1991 to 2007 was much lower than that of TCs from 1965-1988 because a northeasterly wind caused by high-pressure circulation in East Asia got severer along the East Asian coast. Instead, TCs moved from the eastern region of the Tropical West Pacific to Korea and Japan mainly after passing the East China Sea due to the low-pressure circulation strengthened in the subtropical waters of East Asia. In addition, low Vertical Wind Shear (VWS) was created along the mid-latitude regions of East Asia and the main path of TCs from 1991 to 2007. Most of the regions in the Northwestern Pacific showed higher Sea Surface Temperature (SST) from 1991 to 2007, and had a good environment where TCs were able to maintain a higher intensity on the mid-latitude. In particular, a low sensible heat flux occurred due to high snow depth in East Asia in the spring of 1991 to 2007. Accordingly, the lower layer of East Asia showed high-pressure circulation, and the sea surrounding East Asia showed low-pressure circulation. Thus, the typical west-high, east-low pattern of winter atmospheric pressure was shown. The possibility of snowfall in East Asia in spring to be used as a factor for predicting the summer intensity of TC in the mid-latitude regions of East Asia was insinuated. The characteristics of TC in a low-latitude region were the same in Korea. The latest intensity of TCs got higher, and the landing location of TCs gradually changed from the west coast to the south coast.

• Ocean and Polar Research
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• v.39 no.3
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• pp.181-194
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• 2017

The long-term linear trend of global sea-to-air dimethyl sulfide (DMS) flux was analyzed over a 16-year time span (2000~2015), based on satellite observation data. The emission rates of DMS (i.e. DMS flux) in the global ocean were estimated from sea surface DMS concentrations, which were constructed with chlorophyll a (Chl-a) concentrations and mixed layer depths (MLD), and transfer velocity from sea to air, which was parameterized with sea surface wind (SSW) and sea surface temperature (SST). In general, the DMS flux in the global ocean exhibited a gradual decreasing pattern from 2000 (a total of 12.1 Tg/yr) to 2015 (10.7 Tg/yr). For the latitude band ($10^{\circ}$ interval between $0^{\circ}$ and $60^{\circ}$), the DMS flux at the low latitude of the Northern (NH) and Southern hemisphere (SH) was significantly higher than that at the middle latitude. The seasonal mean DMS flux was highest in winter followed by in summer in both hemispheres. From the long-term analysis with the Mann-Kendall (MK) statistical test, a clear downward trend of DMS flux was predicted to be broad over the global ocean during the study period (NH: $-0.001{\sim}-0.036{\mu}mol/m^2/day\;per\;year$, SH: $-0.011{\sim}-0.051{\mu}mol/m^2/day\;per\;year$). These trend values were statistically significant (p < 0.05) for most of the latitude bands. The magnitude of the downward trend of DMS flux at the low latitude in the NH was somewhat higher than that at the middle latitude during most seasons, and vice versa for the SH. The spatio-temporal characteristics of DMS flux and its long-term trend were likely to be primarily affected not only by the SSW (high positive correlation of r = 0.687) but also in part by the SST (r = 0.685).

• Journal of Astronomy and Space Sciences
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• v.32 no.1
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• pp.33-38
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• 2015

Forbush Decreases (FD) are transient, sudden reductions of cosmic ray (CR) intensity lasting a few days, to a week. Such events are observed globally using ground neutron monitors (NMs). Most studies of FD events indicate that an FD event is observed simultaneously at NM stations located all over the Earth. However, using statistical analysis, previous researchers verified that while FD events could occur simultaneously, in some cases, FD events could occur non-simultaneously. Previous studies confirmed the statistical reality of non-simultaneous FD events and the mechanism by which they occur, using data from high-latitude and middle-latitude NM stations. In this study, we used long-term data (1971-2006) from middle-latitude NM stations (Irkutsk, Climax, and Jungfraujoch) to enhance statistical reliability. According to the results from this analysis, the variation of cosmic ray intensity during the main phase, is larger (statistically significant) for simultaneous FD events, than for non-simultaneous ones. Moreover, the distribution of main-phase-onset time shows differences that are statistically significant. While the onset times for the simultaneous FDs are distributed evenly over 24-hour intervals (day and night), those of non-simultaneous FDs are mostly distributed over 12-hour intervals, in daytime. Thus, the existence of the two kinds of FD events, according to differences in their statistical properties, were verified based on data from middle-latitude NM stations.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.27 no.3
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• pp.67-74
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• 2024

In the context of rapid temperature rise in mid-to-high latitude regions, cold region wetlands have become a hotspot for current wetland carbon cycle research due to their high sensitivity to climate change. Strengthening the monitoring of CO₂ fluxes in wetland ecosystems is of great practical significance for clarifying the carbon balance of wetlands and maintaining the ecological balance of wetland ecosystems in China's high latitude regions. In this study, the carbon flux (NEE, Net ecosystem exchange; GPP, Gross Primary Production; RECO, Ecosystem response) of Jingxin Wetland was monitored by eddy correlation method from August 2021 to March 2024.2022-2023 shows CO₂ sinks, absorbing 349.4 g C·m^-2·yr^-1 annually. The correlation analysis showed that Ta, VPD and PPFD were the main environmental factors affecting CO₂ flux in Jingxin wetland.

• Korean Journal of Remote Sensing
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• v.34 no.6_2
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• pp.1203-1213
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• 2018

In Arctic and Antarctic ocean, remote sensing is the most effective observation for environmental changes due to the inaccessibility of the regions. Even though satellite, UAV (Unmanned Aerial Vehical) are well known remote sensing platforms, and research vessel also used for automatic measurement on the regions, varied environment of Polar regions require time series and wide coverage of data. Especially, in high latitude, apply an optical satellite remote sensing is not easy due to low sun altitude. In this paper, we introduce an operation of hyper-spectrometer (HyperSAS/Satlantic inc.) which is mounted on Ice Breaker Research Vessel ARAON of Korea Polar Research Institute since 2010, to acquire an above water reflectance atomatically through every research cruise on Arctic and Antarctic ocean and transit both regions. In addition to, auxiliary data for the remotely acquired data, in situ water sampling were also obtained. The above water reflectance and in situ water sampling data are continuously acquired since 2010 will contribute to improve an Ocean Color algorithm in the high latitude and help to understand ocean reflectances over from high latitude through low latitude. Preliminary result from above water reflectance showed characteristics of Arctic ocean and Antarctic Ocean and used to develop algorithms for estimating various ocean factors such as chlorophyll and suspended sediment.

• Journal of Astronomy and Space Sciences
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• v.15 no.1
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• pp.139-150
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• 1998

We measured the terrestrial nightglow of OI $6300{\AA}$ in the thermosphere (~250km) using a ground-based Fabry-Perot interferometer at the King Sejong Station, Antarcticfrom March through September, 1997. The King Sejong Station is located at high latitude geographically ($62.22^{\circ}S,\;301.25^{\circ}E$) but at mid latitude geomagnetically ($50.62^{\circ}S,\;7.51^{\circ}E$). It is therefore the strategic location to measure the temperatures of the thermosphere in the Southern Hemisphere associated with both solar and geomagnetic activities. In this study, we analyzed the observed temperatures inrelation to F10.7 and Kp indices to examine the effect of the solar and the geomagneticactivities on high-latitude neutral thermosphere. During the observing period, the solaractivity was at its minimum. The measured temperatures are usually in the range between about 600~1000 K with some seasonal variation and are higher than those predicted by semi-empirical model, VSH (Vector Spherical Harmonics) and empirical model, MSIS (Mass-Spectrometer-Incoherent-Scatter)-86.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.121.1-121.1
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• 2012

It has been suggested that oscillatory earthward bursty bulk flows (BBFs) in the magnetotail are driving Pi2 oscillations on the ground. However, only a few studies examined the BBF-driven Pi2 model. The goal of this study is to establish the relation between BBFs and Pi2s. In order to examine BBF-drive model, we will conduct the timing analysis between BBFs and Pi2s for the intervals during which both Pi2 and BBF are present. In our study BBFs are identified with earthward flow speeds up to 200 km/s from THEMIS probes with a geocentric distance between 7 and 12 RE in the nightside magnetosphere for the interval from January 2008 to March 2008. Pi2 pulsations are identified at three low/mid-latitude ground stations having different local times; Bohyun (L = 1.35, LT ~ UT +9 hr), Hermanus (L = 1.83, LT ~ UT +2 hr) and Carson city (L = 2.00, LT ~ UT -2 hr). It is found that ~28% of BBFs have onset timing nearly identical to Pi2 onset. To investigate whether there is high similarity in the waveform between BBF and Pi2 oscillations, the coherence analysis is applied to the time series of BBF and Pi2 events. We found that there is no high coherence between BBF and Pi2 oscillations. Thus our observations suggest that low-latitude Pi2 oscillations are not directly driven by earthward flow bursts.

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.24.4-25
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• 2008

Limb scanning measurements of the O2 (0-0) Atmospheric band emission by the TIDI instrument aboard the TIMED satellite during 2003-2005 are analyzed to examine the tidal effects on their vertical emission rate according to the solar and geomagnetic activities. The data are restricted at latitudes $60^{\circ}S-60^{\circ}N$ to avoid the contributions by the auroral emission. The variation of the vertical emission rate in latitude and local time is summarized in the yaw periods. The vertical emission profiles of the O2 (0-0) Atmospheric band nightglow averaged in the $10^{\circ}$ latitude range are investigated. The result shows the inverse relationship between the peak emission height and the integrated brightness.

• Fisheries and Aquatic Sciences
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• v.27 no.3
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• pp.137-144
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• 2024

Exacanthomysis marsailiae and Nipponomysis neolingvura are described as new species based on specimens collected with a light trap off the East Sea coast of Korea. E. marsailiae is closely related to Exacanthomysis alaskensis (Banner, 1954) and Exacanthomysis borealis (Banner, 1954). However, E. marsailiae can be distinguished from these species by having slightly grouped spines on lateral margins near the telson apex, and the exopod of male's fourth pleopod more than twice as long as the endopod. N. neolingvura can be distinguished from its closest relative, Nipponomysis lingvura (Murano, 1977), in that the lateral sides of the telson are all armed with spines without any empty space, and that the second segment of the fourth male pleopod is longer than the third one. The report of E. marsailiae from the East Sea of Korea extends the distribution range of the genus Exacanthomysis from the high-latitude North Pacific southward to the mid-latitude waters of the western Pacific. The morphological characteristics of the two current new species are also compared with those of their congeners.

• Bulletin of the Korean Space Science Society
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• 2007.10a
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• pp.37-37
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• 2007