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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Korean Meteorological Society
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Volume & Issues
Volume 25, Issue 4 - Dec 2015
Volume 25, Issue 3 - Sep 2015
Volume 25, Issue 2 - Jun 2015
Volume 25, Issue 1 - Mar 2015
Selecting the target year
Case Studies on Freezing Rain over the Korean Peninsula Using KLAPS
Kwon, Hui-Nae ; Byun, Hi-Ryong ; Park, Chang-Kyun ;
Atmosphere, volume 25, issue 3, 2015, Pages 389~405
DOI : 10.14191/Atmos.2015.25.3.389
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
(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
, 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.
Reconstitution of Meteorological Daily Logs in Choseon Dynasty and Analyzing Weather Records of the Annals of King Gojong
Kim, Il-Gwon ;
Atmosphere, volume 25, issue 3, 2015, Pages 407~433
DOI : 10.14191/Atmos.2015.25.3.407
First half of my article focused on analyzing the current state of historical materials regarding weather and climate, and established a list of weather-related historical literature collection of Korea with which to make a lexical approach to the situations of all kinds of weather literature. It also put emphasis on gathering information and data of weather logs from journal-type historical records which were contained in 48 weather-related journals of Choseon period. The results of this research are expected to be useful for the activation of study in historical meteorology. The latter half of my research focused on analyzing various meteorological states of sunny, cloudy, rainy, snowy and frosty weather which were recorded in the official Annals of King Kojong (1864~1907). And it re-verified historical rainfall data of preceding researches of Wada Yuji (1917), Jung-Lim (1994), Jhun-Moon (1997). In result, different records were found between data of theirs and mine. It means that we have to analyze and reconstruct newly the meteorological data of the Annals of King Gojong and the Daily Records of Royal Sungjungwon (1623~1910) during the late Choseon period.
Synoptic Characteristics of Cold Days over South Korea and Their Relationship with Large-Scale Climate Variability
Yoo, Yeong-Eun ; Son, Seok-Woo ; Kim, Hyeong-Seog ; Jeong, Jee-Hoon ;
Atmosphere, volume 25, issue 3, 2015, Pages 435~447
DOI : 10.14191/Atmos.2015.25.3.435
This study explores the synoptic characteristics of cold days over South Korea and their relationship with large-scale climate variability. The cold day, which is different from cold surge, is defined when daily-mean surface air temperature, averaged over 11 KMA stations, is colder than 1-percentile temperature in each year by considering its long-term trend over 1960~2012. Such event is detected by quantile regression and the related synoptic patterns are identified in reanalysis data. Composite geopotential height anomalies at 500 hPa show that cold days are often preceded by positive anomalies in high latitudes and negative anomalies in midlatitudes on the west of Korea. While the formers are quasi-stationary and quasi-barotropic, and often qualified as blocking highs, the latters are associated with transient cyclones. At cold days, the north-south dipole in geopotential height anomalies becomes west-east dipole in the lower troposphere as high-latitude anticyclone expands equatorward to the Northern China and mid-latitude cyclone moves eastward and rapidly develops over the East Sea. The resulting northerlies cause cold days in Korea. By performing composite analyses of large-scale climate indices, it is further found that the occurrence of these cold days are preferable when the Arctic Oscillation is in its negative phase and/or East Asian monsoon circulation and Siberian high are anomalously strong.
Assessment of Observation Environment for Surface Wind in Urban Areas Using a CFD model
Yang, Ho-Jin ; Kim, Jae-Jin ;
Atmosphere, volume 25, issue 3, 2015, Pages 449~459
DOI : 10.14191/Atmos.2015.25.3.449
Effects of buildings and topography on observation environment of surface wind in central regions of urban areas are investigated using a computational fluid dynamics (CFD) model. In order to reflect the characteristics of buildings and topography in urban areas, geographic information system (GIS) data are used to construct surface boundary input data. For each observation station, 16 cases with different inflow directions are considered to evaluate effects of buildings and topography on wind speed and direction around the observation station. The results show that flow patterns are very complicated due to the buildings and topography. The simulated wind speed and direction at the location of each observation station are compared with those of inflow. As a whole, wind speed at observation stations decreases due to the drag effect of buildings. The decrease rate of wind speed is strongly related with total volume of buildings which are located in the upwind direction. It is concluded that the CFD model is a very useful tool to evaluate location of observation station suitability. And it is expected to help produce wind observation data that represent local scale excluding the effects of buildings and topography in urban areas.
Impact of Sudden Stratospheric Warming on the Surface Air Temperature in East Asia
Song, Kanghyun ; Son, Seok-Woo ; Woo, Sung-Ho ;
Atmosphere, volume 25, issue 3, 2015, Pages 461~472
DOI : 10.14191/Atmos.2015.25.3.461
The sudden stratospheric warming (SSW), which is characterized by an abrupt increase of polar stratospheric temperature by several tens of degrees in a week, has been known to affect tropospheric weather and climate on sub-seasonal time scale in the boreal winter. Such downward coupling has been often examined in North Atlantic and Europe, but rarely examined in East Asia. In this study, by applying the two definitions of SSW to the reanalysis data, the possible impacts of the SSW events on the surface air temperature (SAT) and tropospheric circulation in East Asia are analyzed. It is found that Eurasian continent, including Siberia and the Northeast Asia, tends to experience anomalously cold SAT for up to sixty days after the SSW events. The resulting SAT anomalies largely resemble those associated with negative Artic Oscillation. However, over East Asia, SSW-related SAT change is weak and not statistically significant. Only during the extreme SSW events when the downward coupling between the stratosphere and troposphere is strong, East Asia exhibits significantly cold SAT anomalies. This relationship is presented by grouping SSW events into those followed by cold SAT anomalies over East Asia and those by warm anomalies for varying threshold values of the SSW events.
A Study on the Characteristics of Flow and Reactive Pollutants` Dispersion in Step-up Street Canyons Using a CFD Model
Kim, Eun-Ryoung ; Park, Rokjin J. ; Lee, Dae-Geun ; Kim, Jae-Jin ;
Atmosphere, volume 25, issue 3, 2015, Pages 473~482
DOI : 10.14191/Atmos.2015.25.3.473
In this study, street canyons with a higher downwind building (so called, step-up street canyons) are considered for understanding characteristics of flow and reactive pollutants` dispersion as a basic step to understand the characteristics in wider urban areas. This study used a CFD_NIMR_SNU coupled to a chemistry module just including simple
photochemical reactions. First, flow characteristics are analyzed in step-up street canyons with four aspect ratios (0.33, 0.47, 0.6, 0.73) defined as ratios of upwind building heights to downwind building height. The CFD_NIMR_SNU reproduced very well the main features (that is, vortices in the street canyons) which appeared in the wind-tunnel experiment. Wind speed within the street canyons became weak as the aspect ratio increased, because volume of flow incoming over the upwind building decreased. For each step-up street canyon, chemistry transport model was integrated up to 3600 s with the time step of 0.5 s. The distribution patterns of
were largely dependent on the mean flow patterns, however,
concentrations were partly affected by photochemical reactions.
concentration near the upwind lower region of the street canyons was much lower than background concentration, because there was much reduction in
concentration due to NO titration there. Total amount of
in the street canyons increased with the aspect ratio, resulting from the decrease of mean wind intensity.
Study on Heat Environment Changes in Seoul Metropolitan Area Using WRF-UCM: A Comparison between 2000 and 2009
Lee, Bo-Ra ; Lee, Dae-Geun ; Nam, Kyung-Yeub ; Lee, Yong-Gon ; Kim, Baek-Jo ;
Atmosphere, volume 25, issue 3, 2015, Pages 483~499
DOI : 10.14191/Atmos.2015.25.3.483
This study examined the impact of change of land-use and meteorological condition due to urbanization on heat environment in Seoul metropolitan area over a decade (2000 and 2009) using Weather Research and Forecasting (WRF)-Urban Canopy Model (UCM). The numerical simulations consist of three sets: meteorological conditions of (1) October 2000 with land-use data in 2000 (base simulation), (2) October 2009 with land-use data in 2000 (meteorological condition change effect) and (3) October 2009 with land-use data in 2009 (both the effects of land-use and meteorological condition change). According to the experiment results, the change of land-use and meteorological condition by urbanization over a decade showed different contribution to the change of heat environment in Seoul metropolitan area. There was about
increase in near-surface (2 m) temperature over all of the analyzed stations due to meteorological condition change. In stations where the land-use type changed into urban, large temperature increase at nighttime was observed by combined effects of meteorological condition and land-use changes (maximum
). Urban heat island (UHI) over
(temperature difference between Seoul and Okcheon) increased 5.24% due to the meteorological condition change and 26.61% due to the land-use change. That is, land-use change turned out to be contributing to the strengthening of UHI more than the meteorological condition change. Moreover, the land-use change plays a major role in the increase of sensible heat flux and decrease of latent heat flux.
A Study on the Characteristics of Flows around Building Groups Using a CFD Model
Lee, Hankyung ; Kim, Jae-Jin ; Lee, Young-Gon ;
Atmosphere, volume 25, issue 3, 2015, Pages 501~510
DOI : 10.14191/Atmos.2015.25.3.501
In this study, the characteristics of flows around building groups are investigated using a computational fluid dynamics (CFD) model. For this, building groups with different volumetric ratios in a fixed area are considered. As the volumetric ratio of the building group increases, the region affected by the building group is widened. However, the wind-speed reduced area rather decreases with the volumetric ratio near the ground bottom (z
0.7H, here, H is the height of the building group) and, above 0.7H, it increases. As the volumetric ratio decreases (that is, space between buildings was widened), the size of recirculation region decreases but flow recovery is delayed, resulting in the wider wind-speed reduced area. The increase in the volumetric ratio results in larger drag force on the flow above the roof level, consequently reducing wind speed above the roof level. However, above z
1.7H, wind speed increases with the volumetric ratio for satisfying mass conservation, resultantly increasing turbulent kinetic energy there. Inside the building groups, wind speed decreased with the volumetric ratio and averaged wind speed is parameterized in terms of the volumetric ratio and background flow speed. The parameterization method is applied to producing averaged wind speed for 80 urban areas in 7 cities in Korea, showing relatively good performance.
Uncertainty Analysis of Quantitative Radar Rainfall Estimation Using the Maximum Entropy
Lee, Jae-Kyoung ;
Atmosphere, volume 25, issue 3, 2015, Pages 511~520
DOI : 10.14191/Atmos.2015.25.3.511
Existing studies on radar rainfall uncertainties were performed to reduce the uncertainty for each stage by using bias correction during the quantitative radar rainfall estimation process. However, the studies do not provide quantitative comparison with the uncertainties for all stages. Consequently, this study proposes a suitable approach that can quantify the uncertainties at each stage of the quantitative radar rainfall estimation process. First, the new approach can present initial and final uncertainties, increasing or decreasing the uncertainty, and the uncertainty percentage at each stage. Furthermore, Maximum Entropy (ME) was applied to quantify the uncertainty in the entire process. Second, for the uncertainty quantification of radar rainfall estimation at each stage, this study used two quality control algorithms, two rainfall estimation relations, and two bias correction techniques as post-processing and progressed through all stages of the radar rainfall estimation. For the proposed approach, the final uncertainty (ME
Retrieval of Nighttime Aerosol Optical Thickness from Star Photometry
Oh, Young-Lok ;
Atmosphere, volume 25, issue 3, 2015, Pages 521~528
DOI : 10.14191/Atmos.2015.25.3.521
In this study star photometry was applied to retrieve aerosol optical thickness (AOT) at night. The star photometry system consisted of small refractor, optical filters, CCD camera, and driving mount and was located in Suwon. The calibration constants were retrieved from the astronomical Langley method but standard deviations of these were more than 10% of the mean values. After the calibration the nighttime AOT was retrieved and cloud-screened in clear six days from 25 Nov. 2014 to 17 Jan. 2015. To estimate the quality of the measurements the nighttime AOT was combined with daytime AOT retrieved from sky-radiometer that was located in Seoul and 17 km away from the star photometry system. In spite of the uncertainty of the calibration constants and the spatial difference of two observation systems, the temporal changes of the nighttime AOT coincided with the daytime. The nighttime
exponent was about 20% lower and more variable than the daytime because of the uncertainty of the calibration constants. If the calibration process is more precise, the combination of star and sun or sky photometry system can monitor the air pollution day and night constantly.
Optimization of the Vertical Localization Scale for GPS-RO Data Assimilation within KIAPS-LETKF System
Jo, Youngsoon ; Kang, Ji-Sun ; Kwon, Hataek ;
Atmosphere, volume 25, issue 3, 2015, Pages 529~541
DOI : 10.14191/Atmos.2015.25.3.529
Korea Institute of Atmospheric Prediction System (KIAPS) has been developing a global numerial prediction model and data assimilation system. We has implemented LETKF (Local Ensemble Transform Kalman Filter, Hunt et al., 2007) data assimilation system to NCAR CAM-SE (National Center for Atmospheric Research Community Atmosphere Model with Spectral Element dynamical core, Dennis et al., 2012) that has cubed-sphere grid, known as the same grid system of KIAPS Integrated Model (KIM) now developing. In this study, we have assimilated Global Positioning System Radio Occultation (GPS-RO) bending angle measurements in addition to conventional data within ensemble-based data assimilation system. Before assimilating bending angle data, we performed a vertical unit conversion. The information of vertical localization for GPS-RO data is given by the unit of meter, but the vertical localization method in the LETKF system is based on pressure unit. Therefore, with a clever conversion of the vertical information, we have conducted experiments to search for the best vertical localization scale on GPS-RO data under the Observing System Simulation Experiments (OSSEs). As a result, we found the optimal setting of vertical localization for the GPS-RO bending angle data assimilation. We plan to apply the selected localization strategy to the LETKF system implemented to KIM which is expected to give better analysis of GPS-RO data assimilation due to much higher model top.
Mean Meridional Circulation-Eddy Interaction in Three Reanalysis Data Sets during the Boreal Winter
Moon, Hyejin ; Ha, Kyung-Ja ;
Atmosphere, volume 25, issue 3, 2015, Pages 543~557
DOI : 10.14191/Atmos.2015.25.3.543
The present study examines an interaction between the eddy and mean meridional circulation (MMC) comparing the results in three reanalysis data sets including ERA-Interim, NCEP2, and JRA-55 during the boreal winter in the Northern Hemisphere. It is noteworthy that the JRA-55 tends to produce stronger MMC compared to those of others, which is mainly due to the weak eddy flux. ERA-Interim represents the ensemble averages of MMC. The MMC-eddy interaction equation was adopted to investigate the scale interaction of the eddy momentum flux (EMF), eddy heat flux (EHF), and diabatic heating (DHT) with MMC. The EMF (EHF) shows a significant correlation coefficient with streamfunction under (above) 200 hPa-level. The perturbation (time mean) part of each eddy is dominant compared to another part in the EMF (EHF). The DHT is strongly interacted with streamfunction in the region between the equator and extra-tropical latitude over whole vertical column. Thus, the dominant term in each significant region modulates interannual variability of MMC. The inverse (proportional) relationship between MMC and pressure (meridional) derivative of the momentum (heat) divergence contributions is well represented in the three reanalysis data sets. The region modulated interannual variability of MMC by both EMF and DHT (EHF) is similar in ERA-Interim and JRA-55 (ERA-Interim and NCEP2). JRA-55 shows a lack of significant region of EHF due to the high resolution, compared to other data sets.
The Fine Power Spectra of the Southern Oscillation Index and Its Components and their Implication
Lim, G.-H. ; Suh, Y.-C. ;
Atmosphere, volume 25, issue 3, 2015, Pages 559~568
DOI : 10.14191/Atmos.2015.25.3.559
As is evident from its definition, Southern Oscillation Index variability conformed to a combination of the variations of Darwin and Tahiti pressure. Over the El-
Southern Oscillation spectra, the Darwin pressure shared variations associated with the SSN tendency while the Tahiti had a connection with the stratospheric quasi-biennial oscillation modulating annual cycle. The power peak near the 3.5-year period comprised the third harmonic of the sun and the second of the modulated annual cycle. The derived harmonics came from both sources, so the initiation of El-
could be predicted more successfully when including the effects of the sun and QBO.
An Estimation of the of Tropical Cyclone Size Using COMS Infrared Imagery
Lee, Yoon-Kyoung ; Kwon, MinHo ;
Atmosphere, volume 25, issue 3, 2015, Pages 569~573
DOI : 10.14191/Atmos.2015.25.3.569
An algorithm to symmetric radius of
isotaches of tropical cyclones is suggested using infrared (IR) imagery of geostationary satellite. It is assumed that symmetric tangential winds outside the maximum winds exponentially decrease with the radial distances of the tropical cyclone, which has a clear eye-wall structure. Four parameters for estimation of the tropical cyclone size are center location, maximum sustained wind, radius of the maximum wind, and relaxation coefficient for the decreasing rate with distances of the tropical cyclone. The estimation results are limitedly verified as comparing to surface winds of polar orbiting satellite such as ASCAT data.
Atmosphere, volume 25, issue 3, 2015, Pages 575~575
DOI : 10.14191/Atmos.2015.25.3.575