• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.40.3-41
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• 2017

Korea Astronomy and Space Science Institute The observation of particles and waves using a single satellite inherently suffers from space-time ambiguity. Recently, such ambiguity has often been resolved by multi-satellite observations; however, the inter-satellite distances were generally larger than 100 km. Hence, the ambiguity could be resolved only for large-scale (> 100 km) structures while numerous microscale phenomena have been observed at low altitude satellite orbits. In order to resolve those spatial and temporal variations of the microscale plasma structures on the topside ionosphere, SNIPE mission consisted of four (TBD) nanosatellites (~10 kg) will be launched into a polar orbit at an altitude of 700 km (TBD). Two pairs of satellites will be deployed on orbit and the distances between each satellite will be from 10 to 100 km controlled by a formation flying algorithm. The SNIPE mission is equipped with scientific payloads which can measure the following geophysical parameters: density/temperature of cold ionospheric electrons, energetic (~100 keV) electron flux, and magnetic field vectors. All the payloads will have high temporal resolution (~ 16 Hz (TBD)). This mission is planned to launch in 2020. The SNIPE mission aims to elucidate microscale (100 m-10 km) structures in the topside ionosphere (below altitude of 1,000 km), especially the fine-scale morphology of high-energy electron precipitation, cold plasma density/temperature, field-aligned currents, and electromagnetic waves. Hence, the mission will observe microscale structures of the following phenomena in geospace: high-latitude irregularities, such as polar-cap patches; field-aligned currents in the auroral oval; electro-magnetic ion cyclotron (EMIC) waves; hundreds keV electrons' precipitations, such as electron microbursts; subauroral plasma density troughs; and low-latitude plasma irregularities, such as ionospheric blobs and bubbles. We have developed a 6U nanosatellite bus system as the basic platform for the SNIPE mission. Three basic plasma instruments shall be installed on all of each spacecraft, Particle Detector (PD), Langmuir Probe (LP), and Scientific MAGnetometer (SMAG). In addition we now discuss with NASA and JAXA to collaborate with the other payload opportunities into SNIPE mission.

• Journal of the Korean earth science society
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• v.41 no.6
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• pp.599-616
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• 2020

Sea-surface temperature (SST) is one of the most important oceanic variables for understanding air-sea interactions, heat flux variations, and oceanic circulation in the global ocean. Extremely low SSTs from 0℃ down to -2℃ should be more important than other normal temperatures because of their notable roles in inducing and regulating global climate and environmental changes. To understand the temporal and spatial variability of such extremely low SSTs in the global ocean, the long-term SST climatology was calculated using the daily SST database of satellites observed for the period from 1982 to 2018. In addition, the locations of regions with extremely low surface temperatures of less than 0℃ and monthly variations of isothermal lines of 0℃ were investigated using World Ocean Atlas (WOA) climatology based on in-situ oceanic measurements. As a result, extremely low temperatures occupied considerable areas in polar regions such as the Arctic Ocean and Antarctic Ocean, and marginal seas at high latitudes. Six earth science textbooks were analyzed to investigate how these extremely low temperatures were visualized. In most textbooks, illustrations of SSTs began not from extremely low temperatures below 0℃ but from a relatively high temperature of 0℃ or higher, which prevented students from understanding of concepts and roles of the low SSTs. As data visualization is one of the key elements of data literacy, illustrations of the textbooks should be improved to ensure that SST data are adequately visualized in the textbooks. This study emphasized that oceanic literacy and data literacy could be cultivated and strengthened simultaneously through visualizations of oceanic big data by using satellite SST data and oceanic in-situ measurements.

• Journal of Soil and Groundwater Environment
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• v.20 no.5
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• pp.16-25
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• 2015

The City of Boulder is located at an average elevation of 1,655 m (5,430 feet), the foothills of the Rocky Mountains in Colorado. Its daily air temperature is much varying and snow is very frequent and heavy even in spring. This paper examines characteristics of shallow (surface and depth = 10 cm) soil temperatures measured from January to May 2015 in the high elevation city Boulder, Colorado. The surface soil temperature quickly responded to the air temperature with the strongest periodicity of 1 day while the subsurface soil temperatures showed a less correlation and delayed response with that. The short-time Fourier of the soil temperatures uncovered their very low frequencies characteristics in heavy snow days while it revealed high frequencies of their variations in warm spring season. The daily minimum air temperature exhibited high cross-correlations with the soil temperatures without lags unlike the maximum air temperature, which is derived from its higher and longer auto-correlation and stronger spectrums of low frequencies than the maximum air temperature. The snow depth showed an inverse relationship with the soil temperature variations due to snow's low thermal conductivity and high albedo. Multiple regression for the soil temperatures using the air temperature and snow depth presented its predicting possibility of them even though the multiple r² of the regression is not that much satisfactory (r² = 0.35-0.64).

• Ocean and Polar Research
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• v.32 no.1
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• pp.15-22
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• 2010

Calcium carbonate ($CaCO_3$) content was measured from 3 box core (BC060301, BC060303, BC070301) sediments, in addition to pilot core (PC313) sediments, from deep waters within the Western Pacific Ocean. At the two collection sites (BC060301, PC313) located close to the equator, downcore variation exhibited low $CaCO_3$ content during the interglacial period and high $CaCO_3$ content during the glacial period. Variation of coarse fraction (>$63\;{\mu}m$) content also followed changes in $CaCO_3$ content, indicating that dissolution effect of bottom water decreased during the glacial period. Such variation pattern is typical of the Pacific Ocean. However, downcore variation at the two collection sites (BC060303, BC070301) in the Philippine Sea contrasted the trend of the previous two cores (i.e., high $CaCO_3$ content during the interglacial period and low during the glacial period). This pattern is typical of the Atlantic Ocean. Such results may be attributed to the increasing dilution effect, initiated possibly by the increased transportation of terrigenous materials from nearby continent and archipelago during the glacial period when sea level was low. Alternatively, it is possible that the non-carbonate biogenic particles may have been responsible for dilution. Because of these uncertainties, the record of $CaCO_3$ variation in the deep Western Pacific Ocean is not regionally consistent.

• Ocean and Polar Research
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• v.37 no.1
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• pp.37-47
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• 2015

The effects of low salinity (fertilization success and larval survival) on the limpet Cellana grata were studied at early stages of development using the marine bioassay technique. It was shown that, under normal conditions for development from fertilization to the post veliger stage, the salinity must be not less than 20.0~35.0 psu. However, the fertilization rate and larval survival of C. grata was obviously reduced at 5.0 psu and 10.0 psu, respectively. Mass mortality was estimated to occur at <20.0 psu (48-h $EC_{50}=19.54psu$) and the survival rate of normal veliger larvae decreased with experimental time during exposure. No observed effective concentration (NOEC) and lowest observed effect concentration (LOEC) of post veliger were estimated at 30.0 psu and 25.0 psu, respectively, during 48-h exposure. The tolerance limits of the test species to salinity revealed various concentration ranges of salinity, which may reflect the physiology and ecology of the initial development stages of C. grata. These results demonstrate that reduced salinity is detrimental to the reproductive success and larval survival of C. grata, and if salinity is lowered by natural or anthropogenic sources during spawning, this would lead to decreased reproductive success and larval settlement.

• Ocean and Polar Research
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• v.30 no.3
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• pp.215-224
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• 2008

A piston core (MR06-04 PC23A) collected from the northern continental slope in the central Bering Sea has recorded the high-resolution millennial-scale variation of calcium carbonate ($CaCO3$) content during the last 65 kyr. An estimation of the age of the core sediments was carried out by using the lithologic correlation of the deglacial laminated layers with a neighboring core (HLY02023JPC), complementing the last appearance datum of both Lychnocanoma nipponica sakaii (54 kyr) and Amphimelissa setosa (85 kyr). The probable age of core MR06-04 PC23A was approximately younger than 65 kyr. Two distinct events of a significant increase of $CaCO3$ in the deglacial laminated sediments clearly correspond to MWP1A and MWP1B in the Bering Sea (Gorbarenko et al. 2005) and to T1ANP and T1BNP in the North Pacific (Gorbarenko 1996). These pronounced peaks of $CaCO3$ contents result from the elevated carbonate production in the surface water and the subsequent weakened dilution due to terrestrial input, along with an enhanced oxygen minimum zone. The $CaCO3$ contents are low (${\sim}2%$) during the last glacial period mainly because of a low carbonate production caused by an expanded sea-ice cover and an increased dilution by terrigenous particles due to their closer distance to the continent during the sea-level low stand. The occurrence of seven distinct $CaCO3$ peaks in core MR06-04 PC23A is remarkable during MIS 3 and MIS 4, and they most likely correlate to the short-term millennial Dansgaard-Oeschger events.

• Journal of Astronomy and Space Sciences
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• v.25 no.4
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• pp.335-346
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• 2008

Using the global total electron contents (TEC) measured by the TOPEX satellite from Aug. 1992 to Oct. 2005, we investigate the variations of the longitudinal wavenumber-4 (LW-4) structure in the equatorial anomaly (EA) crests with season, local time, and solar activity. Our study shows that the LW-4 structure in the EA crests ($5{\sim}20^{\circ}$ MLAT in both hemispheres) has clear four peaks at fixed longitude sectors during the daytime for both equinoxes and June solstice. In spite of being called a wavelike structure, however, the magnitudes and spatial intervals of the four peaks are far from being the same or regular. After sunset, the four-peak structure begins to move eastward with gradual weakening in its amplitude during equinoxes and this weakening proceeds much faster during June solstice. Interestingly, the longitudinal variations during December solstice do not show clear four-peak structure. All these features of the LW-4 structure are almost the same for both low and high solar activity conditions although the ion densities are greatly enhanced from low to high solar activities. With the irrelevancy of the magnetic activity in the LW-4, this implies that the large changes of the upper atmospheric ion densities, one of the important factors for ion-neutral interactions, have little effect on the formation of the LW-4 structure. On the other hand, we found that the monthly variation of the LW-4 is remarkably similar to that of the zonal component of wavenumber-3 diurnal tides at low latitudes, which implies that the lower atmospheric tidal forcing, transferred to the upper atmosphere, seems to have a dominant role in producing the LW-4 structure in the EA crests via the E-region dynamo.

• Korean Journal of Food Science and Technology
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• v.37 no.1
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• pp.50-54
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• 2005

Antimicrobial activities of ethanol extracts of marta rosemary (Rosemarinus officinalis L.) against Bacillus subtilis and Salmonella typhimurium were investigated under conditions similar to processing of general food materials to develop natural food preservatives. The strongest antimicrobial activities were shown against the tested organisms at pH 7. In B. subtilis, the herbal extract extended the lag phase at low concentrations, and reduced the specific growth rate during logarithmic phase at high concentrations. In S. typhimurium the herbal extract reduced the specific growth rate even at lower concentrations. These trends were obtained at low pHs of culture solution. Antimicrobial substances of herbs were efficiently extracted with low polar solvents. The thermal stability of antimicrobial substances decreased with heating time at $100^{\circ}C$. S. typhimurium was more sensitive to herbal extracts at $100\;and\;121^{\circ}C$ than B. subtilis.

• Korean Journal of Microbiology
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• v.45 no.2
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• pp.119-125
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• 2009

To understand the ecological function of heterotrophic bacterial community in water column of large freshwater lakes in the permafrost zone, we investigated the structure and function of bacterial community in Lake Khuvsgul, Mongolia. Species composition of overall bacterial community was analyzed by denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments, and bacteria that can be cultured at 10oC were isolated and characterized. Based on the depth profile of environmental parameters, thermocline and chemocline were recognized at the 5~10 m zone of the water column. The stratified DGGE profile indicated that the discontinuity of water properties might influence the structure of bacterial community: band profiles in the 0~5 m zone were diverse with large change by depth, but the profile was relatively stable at the $\geq$10 m zone, with predominance of the band identified as Acidovorax facilis. Bacterial cultures were screened for protease, cellulase, amylase and lipase activity, and 23 isolates were selected for high activity of the hydrolytic enzymes. The isolates were identified based on their 16S rRNA gene sequences. In the surface water (zero meter depth), Acidovorax defluvii and Sphingobacterium faecium with high cellulase activity were present. Flavobacterium succinicans, Mycoplana bullata and A. facilis were stably predominant isolates at 2 m, 5 m, and $\geq$10 m depths, respectively. F. succinicans isolates showed high protease activity while M. bullata isolates showed moderate levels of protease and celluase activity. A. facilis isolates showed either cellulase or lipase activity, exclusively to each other. According to the profile of growth rates of the isolates in the temperature range of $0\sim42^{\circ}C$, the surface-zone (0~5 m) isolates were facultative psychrophiles while isolates from $\geq$10 m depth were typical mesophiles. This stratification is believed to be due to stratified availability of organic materials to the bacterial decomposers. In the water column below the chemoline, the environment is extremely oligotrophic so that the trait of rapid growth in low temperature might not be demanded by deep-lake decomposers. The stratified distribution of community composition and decomposer activity in Lake Khuvsgul implies that ecological functions of bacterial community in lakes of cold region are sharply divided by water column stratification.

• Journal of Climate Change Research
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• v.1 no.1
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• pp.31-50
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• 2010

The Arctic climate change for the Last Glacial Maximum(LGM) occurred at 21,000 years ago (21ka) was investigated using simulation results of atmosphere-ocean coupled models from the second phase of the Paleoclimate Modelling Intercomparison Program(PMIP2). In the analysis, we used seven models, the NCAR CCSM of USA, ECHAM3-MPIOM of German Max-Planxk Institute, HadCM3M2 of UK Met Office, IPSL-CM4 of France Laplace Institute, CNRM-CM3 of France Meteorological Institute, MIROC3.2 of Japan CCSR at University of Tokyo, and FGOALS of China Institute of Atmospheric Physics. All the seven models reproduces the Arctic climate features found in the present climate at 0ka(pre-industrial time) in a reasonable degree in comparison to observations. During the LGM, the atmospheric $CO_2$ concentration and other greenhouse gases were reduced, the ice sheets were expanded over North America and northern Europe, the sea level was lowered by about 120m, and orbital parameters were slightly different. These boundary conditions were implemented to simulated LGM climate. With the implemented LGM conditions, the biggest temperature reduction by more than $24^{\circ}C$ is found over North America and northern Europe owing to ice albedo feedback and the change in lapse rate by high elevation. Besides, the expansion of ice sheets leads to the marked temperature reduction by more then $10^{\circ}C$ over the Arctic Ocean. The temperature reduction in northern winter is larger than in summer around the Arctic and the annual mean temperature is reduced by about $14^{\circ}C$. Compared to low mid-latitudes, the temperature reduction is much larger in high northern altitudes in the LGM. This results mirror the larger warming around the Artic in recent century. We could draw some information for the future under global warming from the knowledge of the LGM.