• Asian-Australasian Journal of Animal Sciences
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• v.4 no.1
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• pp.79-83
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• 1991

Diurnal variation in faecal chromic oxide levels was estimated from 4 hourly faecal sampling of 56 wethers allotted to one of six different feeding patterns. Sampling occurred on days 6 and 7 (Period 1) after a controlled release device was administered, and was repeated on days 14 and 15 (Period 2) following re-randomisation of the wethers to the feeding patterns. Increasing the frequency of feeding tended to be associated with higher faecal chromic oxide levels (p < 0.05), particularly in wethers fed thrice daily at 8 hour intervals. There was no interaction between feeding pattern and period, sampling day or time within-day. There were significant period x time within-day (p < 0.05) and day x time within-day (p < 0.001) interactions, indicating that variation in faecal chromic oxide between sample times was not consistent. This implies that sampling at any time of day is unlikely to result in a biased estimate of pasture intake, providing sufficient samples are collected. Significant period (p < 0.001) and period x day (p < 0.01) effects were associated with slow faecal chromic oxide equilibration in period 1. Equilibration did not occur until after day 7, indicating a need for caution when commencing sampling.

• Journal of Environmental Science International
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• v.5 no.1
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• pp.7-14
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• 1996

Two experiments were conducted to evaluate breathing zone air quality in Taegu, using automatic analyzers for four air quality standards($SO_2$, $NO_2$, CO, and $O_3$). First, air target compounds were measured for 8 to 12 hours in each of two commercial areas and five residential areas. Second, air target compounds were hourly measured for 24 hours in each of two commercial areas, two residential areas, and an industrial complex area. Based on the first experiment the breathing zone air was more polluted in the commercial area as compared to the residential area, while the second experiment showed that the breathing zone air was polluted rather in the residential are3 as compared to the commercial area. The second experiment also indicated that there was some variation of breathing zone air concentration with time and measuring sites. Diurnal variation of breathing zone air concentrations was consistent with previous studies which measured at building height. The highest breathing zone air concentration was shown in Seongseo industrial complex area. An unusual finding of this study was that $SO_2$ concentration in the breathing zone air of Bisandong, a typical residential area of Taegu, was higher than that of other residential areas, even higher than that of Seongseo industrial complex area.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2013.11a
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• pp.23-24
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• 2013

Micrometeorological fluxes measured over a tall forest in a complex terrain are difficult to interpret. $CO_2$ storage often makes significant contributions to net ecosystem exchange of $CO_2$ (NEE) in early morning and during nighttime due to calm and stable conditions. We measured the above-canopy $CO_2$ flux along with its concentration profiles at eight levels within and above the canopy to evaluate $CO_2$ storage term. Our question is whether or not the $CO_2$ storage term can be estimated accurately from a single level measurement of $CO_2$ concentration in a complex terrain. Our objectives are (1) to document vertical profiles of $CO_2$ concentration and (2) to compare the diurnal and seasonal variations of $CO_2$ storages estimated from single and multi-level $CO_2$ concentration data. Seasonally averaged Diurnal variations of $CO_2$ concentration ranged from 398 to 455 ppm near the forest floor at 0.1 m whereas they ranged from 364 to 395 ppm at 40 m in the atmosphere. The diurnal variation of vertical profiles of $CO_2$ concentration shows very interesting features with season. At all eight levels, diurnal variation of $CO_2$ concentration showed little change in winter. In spring, the diurnal variations of $CO_2$ concentration at 8 levels showed three distinct groups of layers with height: the first layer: 0.1m (near surface), second layer: 1.0 m and 4.0m (below canopy) and the third layer: 7.4m to 40.7 m (near canopy and above). In summer, these three groups of layers were further separated with larger variations whereas such distinction became smaller in fall. The diurnal variation of $CO_2$ concentration in the first three layers near surface always showed higher concentration with larger variability. Typically, $CO_2$ concentration showed peaks in early morning and in the evening. After the evening peak, $CO_2$ concentration gradually increased except for those near the surface (i.e., 0.1, 1.0 and 4.0 m) where the concentrations actually decreased. We suspect that this could be attributed to the drainage flow of $CO_2$ along the hill slope from the headwater to downstream, which is not taken into account for net ecosystem $CO_2$ exchange. In comparison to the results of other studies, the distinct and different vertical structures of $CO_2$ concentrations observed at our site may be due to complex terrain and weak turbulent mixing under calm conditions at the site. The annual mean of diurnal variation of $CO_2$ storage flux from single level ranged from -0.6 to $0.9{\mu}mol\;m^{-2}s^{-1}$ and from multi-level from -1.2 to $1.0{\mu}\;{\mu}mol\;m^{-2}s^{-1}$. When compared against the results from the multi-level concentrations, the storage flux estimated from a single-level concentration was generally adequate except for specific hours near sunrise and sunset. Further details and their implication will be discussed in the presentation.

• Journal of Environmental Science International
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• v.17 no.8
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• pp.907-918
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• 2008

In order to monitor the impact of high temperature which is seen frequently with climate change, we investigated the monthly change in globe temperature, air temperature, mean radiant temperature and effective radiant heat flow, because the four well reflect thermal radiation from bio-meteorological aspect. Both globe temperature and air temperature showed an increasing trend every month. Compared to air temperature, globe temperature had a wider range of temperature change and was more influenced by meteorological element such as precipitation. Diurnal trends of air temperature, globe temperature and the difference between their temperature had the lowest value before the sunrise and the highest around $1300{\sim}1500$ LST, showing the typical diurnal trends. Globe temperature and the difference between their temperature had a sharp increase around $1000{\sim}1100$ LST, maintained high value until 1700 LST and then reclined, though varied by month. The difference between globe temperature and air temperature was highly dependent on the amount of precipitation and clouds. The duration in which globe temperature was higher than air temperature was the lowest in July. Therefore the amount of precipitation was the most affecting, followed by the amount of clouds and wind. In order to find out the diurnal trends of temperature in city center and city outskirts, we assumed the roof of a concrete build ing as a city center, and the grass-covered observatory of the Gimhae International Airport as city outskirts. The diurnal trends of temperature in the two sites showed a strong correlation. The highest and lowest temperature also had the same trend.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.04a
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• pp.216-217
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• 1999

• Atmosphere
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• v.21 no.4
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• pp.447-454
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• 2011

As dust storms originated in Neimongu Plateau and Manchuria became more frequent in Korea, there was a growing need for Asian Dust (Hwangsa) monitoring stations in North Korea, which is a pathway of Asian Dust to South Korea. The South Korean and the North Korean Governments agreed to build the Automatic Weather System and the PM10 measurement instruments in the Gaeseong Industrial Zone and the Keumgangsan Tourist Region, North Korea in 2007. PM10 mass concentration data in the Keumgangsan Tourist Region could be collected only during the period from September 2007 to May 2008. In this study, daily, monthly and diurnal variations of PM10 mass concentration of the Keumgangsan are analyzed and compared with those of Sokcho and Gwangdeoksan. Three sites show similar variations in daily and monthly means. Correlation coefficients (r) between Sokcho and Keumgangsan, and between Gwangdeoksan and Keumgangsan are 0.89 and 0.67, respectively. But diurnal variation at Keumgangsan has a distinct feature compared to the other sites. Diurnal PM10 variation shows two peaks around 8 AM and 4-5 PM and very low at night. The difference between the daily maximum and minimum is $20{\sim}60{\mu}g\;m^{-3}$ during September to November 2007. Temperature, relative humidity and wind speed from the Keumgangsan AWS data were compared with those from the Changjon station, and showed good correlation each other except wind speed.

• Atmosphere
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• v.26 no.3
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• pp.401-412
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• 2016

A 3D sonic anemometer has been installed at Yongpyong alpine slope since Oct. 23th 2014 to observe the slope winds and to analyze turbulent characteristics with the change in surface cover (grass and snow) and the synoptic wind strength. Eddy covariance method has been applied to calculate the turbulent quantity after coordinate transformation of a planar-fit rotation. We have carefully selected 3 good episodes in the winter season (23 October 2014 to 28 February 2015) for each category (9 days in total), such as grass and snow covers in case of weak synoptic wind condition, and grass cover of strong synoptic wind. The diurnal variations of the slope winds were well developed like the upslope wind in the daytime and downslope wind in the nighttime for both surface covers (grass and snow) in the weak synoptic forcing, when accordingly both heat and momentum fluxes significantly increased in the daytime and decreased in the nighttime. Meanwhile, diurnal variation of heat flux was not present on the snow cover probably in associated with significant fraction of sunlight reflection due to high albedo especially during the daytime in comparison to those on the grass cover. In the strong synoptic regime, the most dominant feature at Yongpyong, only the southeasterly downslope winds were steadily generated irrespective of day and night with significant increases in momentum flux and turbulent kinetic energy as well, which could suggest that local circulations are suppressed by the synoptic scale forcing. In spite of only one season analysis applied to the limited domain, this kind of an observation-based study will provide the basis for understanding of the local wind circulation in the complex mountain domain such as Gangwon in Korea.

• 한국지구물리탐사학회:학술대회논문집
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• 2009.10a
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• pp.54-59
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• 2009

Seismic station of high noise level has difficulties detecting relatively weak ground motions due to small earthquakes or teleseismic events because earthquake detectability of seismic station depends on seismic noise level. To figure out the capability of earthquake detection of a seismic network, therefore, seismic noise level of each station also needs to be considered, including the distribution of seismic stations. Recently, it has been known that most of broadband seismic stations in South Korea have affected by cultural noise in the frequencies higher than 1 Hz and show diurnal variations of noise level. In order to analyze the effect of diurnal variation of seismic noise level on earthquake detectability, we used the result of background seismic noise level analysis of seismograms of 30 broadband stations of KIGAM and KMA from 2005 to 2007. This study shows that earthquakes greater than magnitude 2.4 occurring within the Korean Peninsula can be detected at night while those greater than magnitude 2.6 can be detected in the daytime.

• Journal of the Korean earth science society
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• v.31 no.4
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• pp.335-347
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• 2010

The statistical characteristics of Cloud-to-Ground (CG) lightning data, observed by the total lightning detection system (TLDS) of KMA during the recent seven years (2002-2008), have been analyzed. Lightning frequency shows a strong interannual, seasonal and diurnal variations without regard to the polarity. The 74% and 0.6% of the total lightning occurred during the summer and winter, respectively. And it has a bimodal diurnal variation with two peaks (dawn: 0500-0700 LST, mid-afternoon: 1500-1600 LST). The ratio of positive flashes to negative ones also has a strong seasonal variation with the maximum and minimum during winter (62.5%) and summer (7.3%), respectively. Unlike the lightning frequency, the lightning intensity of negative flashes shows a weak interannual, seasonal and diurnal variations. However, the lightning intensity of positive flashes exhibits an inverse seasonal variation to that of lightning frequency, with the minimum and maximum during summer and winter, respectively. The lightning density is greatly higher in the western inland areas and the West/South Sea than in the eastern part and the East Sea. In general, the lightning intensity is stronger in the ocean, especially in the East Sea than in the inland area, regardless of the polarity.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.4
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• pp.262-272
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• 2007

Diurnal and tidal variation in the abundance of the macro- and megabenthic assemblages were studied in the macrotidal flat, Incheon, Korea. The samples were collected by modified otter trawl during 8-9, June 2000. The macro- and megabenthic assemblages comprised a total of 60 species, including 6,309 individuals and 67,835.5 gWWt. As a result, the abundance pattern showed two different categories relating to diel and tidal cycles. First, the diel pattern of these assemblages was subdivided into 3 groups. 1) Diurnal species such as Hexagrammos otakii, Thryssa baelama, Loligo beka, Metapenaeus joyneri. 2) Nocturnal species such as Cynoglossus joyneri, Sebastes schlegeli, Charybdis japonica, Crangon affinis, Trachysalambria curvirostris, Metapenaeopsis dalei. 3)Other species showing no obvious pattern with Johnius grypotus, Platycephalus indicus, Repomucenus richardsonii. However, based on the result of Mann-Whitney U-test, diel patterns of macro- and megabenthos did not reveal any significant differences. Second, tidal variation in the macro- and megabenthic assemblages was significant between ebb and flood tides. Total macro- and megafaunal species number, abundance and biomass were higher in ebb tide$(13^h30',\;16^h30',\;1^h30',\;4^h30')$ than in flood tide$(19^h30',\;21^h30',\;10^h30',\;13^h00')$. As a consequence, the macro- and megabenthic assemblages were clearly influenced by tides but their diel variations were not significantly different.