• Atmosphere
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• v.25 no.1
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• pp.185-191
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• 2015

Ambient measurements of aerosol light absorption (${\sigma}_a$) and scattering coefficients (${\sigma}_s$) were done at Gosan climate observatory during summer 2008 using a 3-wavelength photoacoustic soot spectrometer (PASS). PASS was deployed photoacoustic method for light absorption and integrated nephelometry for light scattering measurements. The ${\sigma}_a$ and ${\sigma}_s$ from PASS were compared with those from co-located aethalometer and nephelometer measurements. The aethalometer measurements of ${\sigma}_a$ correlated reasonably well with photoacoustic measurements, but the slope of the linear fitting line indicated the PASS measurement values of ${\sigma}_a$ were larger by a factor of 1.53. The nephelometer measurement values of ${\sigma}_s$ correlated very well with PASS measurements of ${\sigma}_s$, with a slope of 1.12 and a small offset. Comparing to the aethalometer measurements, the photoacoustic measurements of ${\sigma}_a$ didn't exhibit a significant (i.e., the ratio between aethalometer and PASS increased) change with increasing relative humidity (RH). The ratio of ${\sigma}_s$ between nephelometer and PASS increased with increasing RH, especially when the RH increased beyond 80%. This apparent increase in ${\sigma}_s$ with RH may be due to the contribution of hygroscopic growth of aerosols.

• Journal of the Korean earth science society
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• v.42 no.5
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• pp.496-503
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• 2021

By analyzing the characteristics of atmospheric stability in the southern coastal region of the Korean Peninsula in the summer of 2019, a quantitative threshold of atmospheric instability indices was derived for predicting rainfall events in the Korean Peninsula. For this analysis, we used data from all of the 243 radiosonde intensive observations recorded at the Boseong Standard Weather Observatory (BSWO) in the summer of 2019. To analyze the atmospheric stability of rain events and mesoscale atmospheric phenomena, convective available potential energy (CAPE) and storm relative helicity (SRH) were calculated and compared. In particular, SRH analysis was divided into four levels based on the depth of the atmosphere (0-1, 0-3, 0-6, and 0-10 km). The rain events were categorized into three cases: that of no rain, that of 12 h before the rain, and that of rain. The results showed that SRH was more suitable than CAPE for the prediction of the rainfall events in Boseong during the summer of 2019, and that the rainfall events occurred when the 0-6 km SRH was 150 m² s^-2 or more, which is the same standard as that for a possible weak tornado. In addition, the results of the atmospheric stability analysis during the Changma, which is the rainy period in the Korean Peninsula during the summer and typhoon seasons, showed that the 0-6 km SRH was larger than the mean value of the 0-10 km SRH, whereas SRH generally increased as the depth of the atmosphere increased. Therefore, it can be said that the 0-6 km SRH was more effective in determining the rainfall events caused by typhoons in Boseong in the summer of 2019.

• Journal of Space Technology and Applications
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• v.1 no.2
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• pp.160-177
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• 2021

The Solar and Space Environment Division of the Korean Space Science Society investigated the use and possession of ground and satellite observations and models of solar and planetary data operated by domestic research institutes and universities. Based on the findings, we would like to introduce observational instruments, data, and models in solar and interplanetary fields in this paper to improve understanding and use of each data and explore opportunities for interdisciplinary research. The ground and satellite observations, which require a lot of investment, were mainly held by research institutes (National Meteorological Satellite Center, Polar Research Institute, Korean Space Weather, Korea Astronomy and Space Science Institute and KAIST Satellite Research Institute), and model development was overwhelmingly carried out at Kyung Hee University. In solar and interplanetary fields, we introduce Fast Imaging Solar Spectrograph (FISS), neutron monitors, and the analysis models [for the Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) and Hinode/X-Ray Telescope (XRT) observations] in nonequilibrium ionization state as representatives. Survey on solar and interplanetary fields can be downloaded from the website of the Korean Space Science Society (http://ksss.or.kr/). The paper makes know the importance of long-term and continuous management of space science-related materials, and hopes to contribute to enhancing the status of domestic space science data by utilizing locally produced data by various personnel participating in space science research.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.1
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• pp.1-14
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• 2006

Tropospheric aerosols are highly variant in time and space due to non-uniform source distribution and strong influence of meteorological conditions. Backscatter lidar measurement is useful to understand vertical distribution of aerosol. However, the backscatter lidar equation is undetermined due to its dependence on the two unknowns, extinction and backscattering coefficient. This dependence necessitates the exact value of the ratio between two parameters, that is, the lidar ratio. Also, Iidar ratio itself is useful optical parameter to understand properties of aerosols. Tropospheric aerosols were observed to understand variance of lidar ratio at Anmyeon island ($36.32^{/circ}N$, $126.19^{/circ}E$), Korea using a multi-wavelength raman lidar system developed by the Advanced Environmental Monitoring Research Center (ADEMRC), Gwangju Institute Science and Technology (GIST), Korea during measurement periods; March 15$\sim$April $16^{th}$, 2004 and May 24$\sim$ $8^{th}$ 2005. Extinction coefficient, backscattering coefficient, and lidar ratio were measured at 355 and 532 nm by the Raman method. Different types of aerosol layers were distinguished by the differences in the optical properties such as Angstrom exponent, and lidar ratio. The average value of lidar ratio during two observation periods was found to be $50.85\pm4.88$ sr at 355 nm and $52.43\pm15.15$ sr at 532 nm at 2004 and $57.94\pm10.29$ sr at 355 nm and $82.24\pm15.90$ sr at 532 nm at 2005. We conduct hysplit back-trajectory to know the pathway of airmass during the observation periods. We also calculate lidar ratio of different type of aerosol, urban, maritime, dust, continental aerosols using OPAC (Optical Properties of Aerosols and Clouds), Remote sensing of atmospheric aerosol using a multi-wavelengh lidar system with Raman channels is quite and powerful tool to characterize the optical propertises of troposheric aerosols.

• Atmosphere
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• v.34 no.3
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• pp.305-317
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• 2024

The study examines the effects of parameters that define the characteristics of raindrops on the simulated precipitation during the summer season over Korea using the Weather Research and Forecasting (WRF) Double-Moment 6-class (WDM6) cloud microphysics scheme. Prescribed parameters, defining the characteristics of hydrometeors in the WDM6 scheme such as a_R, b_R, and f_R in the fall velocity (V_R) - diameter (D_R) relationship and shape parameter (𝜇_R) in the number concentration (N_R) - D_R relationship, presents different values compared to the observed data from Two-Dimensional Video Disdrometer (2DVD) at Boseong standard meteorological observatory during 2018~2019. Three experiments were designed for the heavy rainfall event on August 8, 2022 using WRF version 4.3. These include the control (CNTL) experiment with original parameters in the WDM6 scheme; the MUR experiment, adopting the 50th percentile observation value for 𝜇_R; and the MEDI experiment, which uses the same 𝜇_R as MUR, but also includes fitted values for a_R, b_R, and f_R from the 50th percentile of the observed V_R - D_R relationship. Both sensitivity experiments show improved precipitation simulation compared to the CNTL by reducing the bias and increasing the probability of detection and equitable threat scores. In these experiments, the raindrop mixing ratio increases and its number concentration decreases in the lower atmosphere. The microphysics budget analysis shows that the increase in the rain mixing ratio is due to enhanced source processes such as graupel melting, vapor condensation, and accretion between cloud water and rain. Our study also emphasizes that applying the solely observed 𝜇_R produces more positive impact in the precipitation simulation.

• Ocean and Polar Research
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• v.27 no.3
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• pp.237-250
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• 2005

To investigate the air mass modification related with Yeongdong Heavy snowfall events, we examined sensible and latent heat fluxes on the East Sea, the energy exchange between atmosphere and ocean in this study. Sensible and latent heats were calculated by a bulk aerodynamic method, in which NCEP/NCAR reanalysis data and NOAA/AVHRR weekly SST data with high resolution were used. Among winter precipitation events in the Yeongdong region, 19 heavy precipitation events $(1995{\sim}2001)$ were selected and classified into three types (mountain, cold-coastal, and warm types). Mountain-type precipitation shows highly positive anomalies of sensible and latent heats over the southwestern part of the East Set When separating them into the two components due to variability of wind and temperature/ specific Humidity, it is shown that the wind components are dominant. Cold-coastal-type precipitation also shows strong positive anomalies of sensible and latent heats over the northern part and over the central-northern part of the East Sea, respectively. It is shown that the sensible heat anomalies are caused mostly by the decrease of surface air temperature. So it can be explained that cold-coastal-type precipitation is closely related with the air mass modification due to cold air advection over warm ocean surface. But in warm-type precipitation, negative anomalies are found in the sensible and latent heat distributions. From this result, it may be postulated that warm-type precipitation is affected by the internal process of the atmosphere rather than the atmosphere-ocean interaction.

• Atmosphere
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• v.17 no.4
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• pp.339-348
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• 2007

Global Environment Laboratory at Yonsei University in Seoul ($37.57^{\circ}N$, $126.95^{\circ}E$) has carried out the ozone layer monitoring program in the framework of the Global Ozone Observing System of the World Meteorlogical Organization (WMO/GAW/GO3OS Station No. 252) since May of 1984. The daily measurements of total ozone and the vertical distribution of ozone amount have been made with the Dobson Spectrophotometer (No.124) on the roof of the Science Building on Yonsei campus. From 2004 through 2006, major parts of the manual operations are automated in measuring total ozone amount and vertical ozone profile through Umkehr method, and calibrating instrument by standard lamp tests with new hardware and software including step motor, rotary encoder, controller, and visual display. This system takes full advantage of Windows interface and information technology to realize adaptability to the latest Windows PC and flexible data processing system. This automatic system also utilizes card slot of desktop personal computer to control various types of boards in the driving unit for operating Dobson spectrophotometer and testing devices. Thus, by automating most of the manual work both in instrument operation and in data processing, subjective human errors and individual differences are eliminated. It is therefore found that the ozone data quality has been distinctly upgraded after automation of the Dobson instrument.

• Journal of Positioning, Navigation, and Timing
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• v.5 no.2
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• pp.75-85
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• 2016

The performance of up-to-date mapping functions and various mean temperature equations were analyzed to derive optimal mapping function and mean temperature equation when GNSS precipitable water vapor (PWV) was investigated in the Korean Peninsula. Bernese GNSS Software 5.2, which can perform high precision GNSS data processing, was used for accurate analysis, and zenith total delay (ZTD) required to calculate PWV was estimated via the Precise Point Positioning (PPP) method. GNSS, radiosonde, and meteorological data from 2009 to 2014 were acquired from Sokcho Observatory and used. ZTDs estimated by applying the global mapping function (GMF) and Vienna mapping function 1 (VMF1) were compared with each other in order to evaluate the performance of the mapping functions. To assess the performance of mean temperature equations, GNSS PWV was calculated by using six mean temperature equations and a difference with radiosonde PWV was investigated. Conclusively, accuracy of data processing was improved more when using VMF1 than using GMF. A mean temperature equation proposed by Wu (2003) had the smallest difference with that in the radiosonde in the analysis including all seasons. In summer, a mean temperature equation proposed by Song & Grejner-Brzezinska (2009) had the closest results with that of radiosonde. In winter, a mean temperature equation proposed by Song (2009) showed the closest results with that of radiosonde.

• Atmosphere
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• v.25 no.3
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• pp.389-405
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• 2015

In this study, the occurrence circumstances of 3 cases (12 Jan 2006, 11 Jan 2008, 22 Feb 2009) when the freezing rain was observed at more than two observatories in a day with more than three times each observatory, were investigated. Following the advanced study about the same cases, we have tried to find more delicate differences in using the Korea Local Analysis and Prediction System (KLAPS; 5 km reanalysis data) that has the smallest grid scale at current situation. As results, three common characteristics are found: (1) Just before the occurrence of the freezing rain, the wind direction was consistently continuous and the wind speed was constant or gradually increased for at least 3 hr more. (2) Surface air temperature (Relative humidity) was respectively $3.08^{\circ}C$ (28.76%), $0.47^{\circ}C$ (50.07%) and $-3.60^{\circ}C$ (71.07%) 3 hr ago to break out the freezing rain. It means the freezing rain occurs in a wide range of atmospheric environments. However, the closer it got to the occurrence time of the freezing rain, the closer the surface air temperature was to $0^{\circ}C$, and the bigger the humidity of the surface air was. (3) The liquid precipitation formed in the upper atmosphere, met a cold advection bellower than 950 hPa level and suspected to be changed to the super-cooled condition.

• Atmosphere
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• v.23 no.4
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• pp.501-511
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• 2013

In this study, we estimate the background concentration of black carbon (BC) mass concentration measured at Gosan Climate Observatory from January 2008 to December 2011 by applying six methods: (1) Mean and Median (2) Trimmed mean method deployed in Interagency Monitoring of Protected Visual Environments (IMPROVE) network program (hereafter, IMPROVE method), (3) Concentration-frequency distribution analysis method, (4) Advanced Global Atmospheric Gases Experiment (AGAGE) method (hereafter, AGAGE method), (5) Kaufman et al. (2001) method (hereafter, Kaufman method), and (6) Airmass sector analysis. The background concentration of BC mass concentrations is estimated to be about 400~900 ng $m^{-3}$, but each method shows a large difference. The estimated background concentration, in general, is arranged in the order of: mean > IMPROVE method > median > Kaufman method > concentration-frequency distribution analysis method > AGAGE method. The background concentration estimated by the airmass sector analysis is found to be about 550 ng $m^{-3}$ which is lower than those estimated by other methods. When we apply the same analytical period (i.e., 4-day and 6-day) to both AGAGE and Kaufman methods, the estimated background concentrations are quite similar. However, further researches on the development of statistical method for estimating background concentration for various gas-phase and particulate pollutants under different environment are needed.