• 대기
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• 제25권2호
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• pp.193-203
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• 2015

A large aperture scintillometer (LAS) was deployed with an optical path length of 2.1 km to estimate turbulent sensible heat flux (${\mathcal{Q}}_H$) over a highly heterogeneous urban area. Scintillation measurements were conducted during cold season in November and December 2013, and the daytime data of 14 days were used in the analysis after quality control processes. The LAS-derived ${\mathcal{Q}}_H$ show reasonable temporal variation ranging $20{\sim}160W\;m^{-2}$ in unstable atmospheric conditions, and well compare with the measured net radiation. The LAS footprint analysis suggests that ${\mathcal{Q}}_H$ can be relatively high when the newly built-up urban area has high source contribution of the turbulent flux in the study area ('northwesterly winds'). Sensitivity tests show that the LAS-derived ${\mathcal{Q}}_H$ are highly sensitive to non-dimensional similarity function for temperature structure function parameter, but relatively less sensitive to surface aerodynamic parameters and meteorological variables (temperature and wind speed). A lower Bowen ratio also has a significant influence on the flux estimation. Overall uncertainty of the estimated daytime ${\mathcal{Q}}_H$ is expected within about 20% at an upper limit for the analysis data. It is also found that stable atmospheric conditions can be poorly determined when the scintillometry technique is applied over the highly heterogeneous urban area.

• 수산해양교육연구
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• 제20권2호
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• pp.156-167
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• 2008

Meorological data have been collected to monitor the wetland area in Goheung bay since 2003 and four intensive observations were conducted to study effects of the atmospheric turbulence on the energy budget and the ecological changes. We improved an algorithm to estimate the sensible heat flux with routine data. The sensible heat flux estimated by gradient method was in good agreement with that measured by precision instruments such as surface layer scintillometer and ultrasonic anemometer. Diurnal variations of sensible heat flux showed analogous tendency to those of temperature gradient. When the vertical wind shear of horizontal wind components was weak, even though temperature gradient was strong, the gradient method underestimated the sensible heat flux. A compensation for the cloud will make this gradient method be a helpful tool to monitor the ecosystem without expensive instruments except for weak wind shear and temperature gradient.

• 자원환경지질
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• 제22권2호
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• pp.151-166
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• 1989

A study of rare-earth mineralization in Kyemyungsan metasedimentary formation of Precambrian Ogcheon Group was carried out in the Mt. Eore Area near Choongju City based on the thorium (Th) and uranium (U) count data of geophysical airborne survey. This rare-earth mineralization was found in the magnetite-bearing banded quartizite which contains diagnostically some amounts of the metamict allanite. The brown colored allanites are distributed as aggregates of fine grains and sometimes banded structures with magnetite (inter growth) along the banding. The ore bed is displaced by the small faults and granite intrusions, and separated 5 ore blocks. The dimensions of the outcrop are 50-80 m in width, 1,500 m in length with the strike of $N70-80^{\circ}E$ and dip of $50-80^{\circ}NW$. In the field, the values of total gamma ray count of GR-101A scintillometer were able to measure more than 400 cps and maximum 1,500 cps, which data are coincided with the values of GR-310 gamma ray spectrometer and the gamma ray count of well logging data. The chemical compositions of the allanites from EPMA data are ranged from$\sum^{TR_2O_3}$ 18.57% to 26.00%, and the cerium oxides ($Ce_2O_3$) of allanite are positive relation with $La_2O_3$, MgO, FeO, MnO and negative relation with $SiO_2$, $Al_2O_3$, $Nd_2O_3$. The result of Neutron Activation Analysis (N.A.A.), Multi-Channel Analysis (M.C.A.) and wet chemistry of 25 outcrop samples for the elements of REE, Zr, U, Th shows strong anomalies. The good correlation elements with the thorium (Th) are the elements of La, Ce, LREE, $TR_2O_3$, Pr, Sm, Yb, Lu by the increasing order.