• Journal of the Korea Institute of Military Science and Technology
• /
• v.22 no.5
• /
• pp.716-723
• /
• 2019

It is crucial to understand the characteristics of cloud occurrence frequency for development of high precision guided missile using infrared imaging sensor. In this paper, we investigated the vertical structure of cloud for altitude using upper-air observation data. We find that cloud occurrence frequency is high at altitudes of 1.3 km and 9.5 km. Theses features have seasonal and temporal dependency. In the summer, cloud often occur more than average regardless of altitude. In the winter, low clouds occur frequently, and high clouds do not occur well. In temporal characteristics, clouds occur more frequently in daytime than in nighttime regardless of altitude. Many of clouds exist in single layer or double layers in the air. We also find that the 40 % of cloud occurrence frequency at high altitude when low clouds under altitude of 2 km cover entire sky.

• Atmosphere
• /
• v.30 no.1
• /
• pp.17-30
• /
• 2020

KMA performed the special observation program to provide information about severe weather and to monitor typhoon PRAPIROON using the ship which called the Gisang 1 from 29 June 2018 to 4 July 2018 (UTC). For this period, upper-air was observed 21 times with 6 hour intervals using rawinsonde in the Gisang 1. We investigated the impact of upper-air observation data from the Gisang 1 on the performance of the operational convective scale model (we called LDAPS). We conducted two experiments that used all observation data including upper-air observation data from the Gisang 1 (OPER) and without it (EXPR). For a typhoon PRAPIROON case, track forecast error of OPER was lower than EXPR until forecast 24 hours. The intensity forecast error of OPER for minimum sea level pressure was lower than EXPR until forecast 12 hours. The intensity forecast error of OPER for maximum wind speed was mostly lower than EXPR until forecast 30 hours. OPER showed good performance for typhoon forecast compared with EXPR at the early lead time. Two precipitation cases occurred in the south of the Korean peninsula due to the impact of Changma on 1 July and typhoon on 3 July. The location of main precipitation band predicted from OPER was closer to observations. As assimilating upper-air data observed in the Gisang 1 to model, it showed positive results in typhoon and precipitation cases.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.12 no.3
• /
• pp.183-196
• /
• 2010

Increasing human activity due to rapid economic growth and land use change alters the patterns of the Asian monsoon, which is key to crop yields in Asia. In this study, we tested the performance of regional climate model (RegCM3) by simulating important components of Indian summer monsoon, including land-ocean contrast, low level jet (LLJ), Tibetan high and upper level Easterly Jet. Three contrasting rain years (1994: excess year, 2001: normal year, 2002: deficient year) were selected and RegCM3 was integrated at 60 km horizontal resolution from April 1 to October 1 each year. The simulated fields of circulations and precipitation were validated against the observation from the NCEP/NCAR reanalysis products and Global Precipitation Climatology Centre (GPCC), respectively. The important results of RegCM3 simulations are (a) LLJ was slightly stronger and split into two branches during excess rain year over the Arabian Sea while there was no splitting during normal and deficient rain years, (b) huge anticyclone with single cell was noted during excess rain year while weak and broken into two cells in deficient rain year, (c) the simulated spatial distribution of precipitation was comparable to the corresponding observed precipitation of GPCC over large parts of India, and (d) the sensitivity experiment using NIMBUS-7 SMMR snow data indicated that precipitation was reduced mainly over the northeast and south Peninsular India with the introduction of 0.1 m of snow over the Tibetan region in April.

• Korean Journal of Environment and Ecology
• /
• v.35 no.6
• /
• pp.659-668
• /
• 2021

The purpose of this study is to propose a ventilation corridor management plan to improve the thermal environment for Busan Metropolitan City. To this end, the characteristics of hot and cool spots in Busan were identified by conducting spatial statistical analysis, and thermal image data from Landsat-7 satellites and major ventilation corridors were analyzed through WRF meteorological simulation. The results showed the areas requiring thermal environment improvement among hot spot areas were Busanjin-gu, Dongnae-gu, industrial areas in Yeonje-gu and Sasang-gu, and Busan Port piers in large-scale facilities. The main ventilation corridor was identified as Geumjeongsan Mountain-Baekyangsan Mountain-Gudeoksan Mountain Valley. Based on the results, the ventilation corridor management strategy is suggested as follows. Industrial facilities and the Busan Port area are factors that increase the air temperature and worsen the thermal environment of the surrounding area. Therefore, urban and architectural plans are required to reduce the facility's temperature and consider the ventilation corridor. Areas requiring ventilation corridor management were Mandeok-dong and Sajik-dong, and they should be managed to prevent further damage to the forests. Since large-scale, high-rise apartment complexes in areas adjacent to forests interfere with the flow of cold and fresh air generated by forests, the construction of high-rise apartment complexes near Geumjeongsan Mountain with the new redevelopment of Type 3 general residential area should be avoided. It is expected that the results of this study can be used as basic data for urban planning and environmental planning in response to climate change in Busan Metropolitan City.

• Journal of the Korean earth science society
• /
• v.42 no.5
• /
• pp.496-503
• /
• 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 Korean Society of Transportation
• /
• v.28 no.3
• /
• pp.157-167
• /
• 2010

Density is the most important congestion indicator among the three fundamental flow variables, flow, speed and density. Measuring density in the field has two different ways, direct and indirect. Taking photos with wide views is one of direct ways, which is not widely used because of its cost and lacking of proper positions. Another direct density measuring method using two point detectors has been introduced with the concept of instantaneous density, average density and measurement interval. The relationship between accuracy and measurement interval has been investigated using the SIMULATION data produced by Paramics Application Programming Interface function. We analyze the affect of segment density accuracy by sensing gap each road condition such as sensing segment length, lane and LOS after gathering data by Paramics Application Programming Interface.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.8 no.1
• /
• pp.37-44
• /
• 2009

Density is the most important congestion indicator among the three fundamental flow variables, flow, speed and density. Measuring density in the field has two different ways, direct and indirect. Taking photos with wide views is one of direct ways, which is not widely used because of its cost and lacking of proper positions. Another direct density measuring method using two spot detectors has been introduced with the concept of instantaneous density, average density and measurement interval. The relationship between accuracy and measurement interval has been investigated using the simulation data produced by Paramics API function. Finally, density measurement algorithm has been suggested including exponential smoothing for device development.

• Journal of Wetlands Research
• /
• v.21 no.spc
• /
• pp.117-122
• /
• 2019

City parks play an important role in reducing the air pollution and mitigating the city heat island effect caused by global warming. However, from July 2020, restricted parks over 20-year will be partially lifted due to sunset regulation on parks. As a result, the government and local governments have been making efforts to revitalize parks, such as creating ecological parks and securing park sites. However, building winds generated by high-rise buildings constructed around ecological parks in the city may cause discomfort to pedestrians and threaten the ecosystems of plants and animal that live in ecological parks. There are no clearly proposed as standards for wind environment assessment in Korea, but also it has been rarely studied on pedestrian wind environment. In this study, wind environment studies have been reviewed to find the important parameters related to wind environment assessment. Further, wind climate analysis using wind data obtained by Seoul meterological station was performed to examine the possibility of applicability of the wind environment assessment on the city ecological parks.

• Journal of the Korean earth science society
• /
• v.36 no.4
• /
• pp.315-329
• /
• 2015

We investigated the characteristics of meteorological conditions related to the strong downslope wind over the leeward side of the Taebaek Mountains during the period 2005~2010. The days showing the strong wind exceeding $14ms^{-1}$ in Gangwon province were selected as study cases. A total of 15 days of strong wind were observed at Sokcho, Gangneung, Donghae, and Taebaek located over the Yeongdong region. Seven cases related to tropical cyclone (3 cases) and heavy snowfall (2 cases) and heavy rainfall (2 cases) over the Yeongdong region were excluded. To investigate the characteristics of the remaining 8 cases, we used synoptic weather chart, Sokcho radiosonde, Gangneung wind profiler and numerical model. The cases showed no precipitation (or ${\leq}1mm\;day^{-1}$). From the surface and upper level weather chart, we found the pressure distribution of southern high and northern low pattern over the Korean peninsula and warm ridge over the Yeongdong region. Inversion layer (or stable layer) and warm ridge with strong wind were located in about 1~3 km (925~700 hPa) over mountains. The Regional Data Assimilation and Prediction System (RDAPS) indicated that warm core and temperature ridge with horizontal temperature gradient were $0.10{\sim}0.23^{\circ}C\;km^{-1}$ which were located on 850 hPa pressure level above mountaintop. These results were summarized as a forecasting guidance of downslope windstorm in the Yeongdong region.

• Journal of Satellite, Information and Communications
• /
• v.8 no.4
• /
• pp.150-158
• /
• 2013

In Korea, the official monitoring of the atmospheric re-entry of satellites or space debris was initiated by the first operation of a re-entry situation analysis team for the 'Cosmos 1402' of the Soviet Union, which main body re-entered on January 23, 1983 and radio active core re-entered on February 7, 1983. After this incident, a task force team consisting Korea Astronomy and Space Science Institute (KASI), Korea Aerospace Research Institute (KARI) and other related institutes operated a situation monitoring group under the supervision of the Ministry of Science and technology (MOST) for the controlled re-entry of the Russian 'Mir' space station in 2001. The re-entry of the upper atmospheric weather satellite 'UARS' of United States had been monitored and analyzed by KASI on September 24, 2011. As the re-entry of the space object has been frequently occurred, the government officials and the experts from MEST (Ministry of Education, Science and Technology), KASI, KARI had an urgent official meeting to establish a satellite re-entry monitoring room in KASI and to give an operational authority to KASI in September 14, 2011. Under this decision, the satellite re-entry monitoring room in KASI has successfully executed the monitoring, data analyzing, official reporting, media contacting, and public announcing for the German satellite 'Roentgen' in October 2011, Russian space explorer 'Phobos-Grunt' in January 2012, Russian satellite 'Cosmos 1484' in January 2013, and European geodetic satellite 'GOCE' in November 2013 with the support from the Korean Air Force and KARI.