• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• v.22 no.1
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• pp.24-32
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• 1994

A special upper-air observation including airsonde and pibal observations was performed to investigate the characteristics features of the vertical distribution of the meteorological elements over Taegu on a selected clear day of each season from October 1991 to August 1992. The diurnal and seasonal variations of the vertical profiles of air temperature and mixing ratio were obtained from airsonde observations and wind speed and direction from pibal observations. The results of these special upper-air observations are as follow : The diurnal variation of the vertical distribution of air temperature reveals the characteristic features associated with the atmospheric boundary layer. All case days, except for the summer season, show upper-level inversion layer which influenced by surface high, and surface inversion layer produced by radiative cooling. The diurnal variation of mixing ratio shows the maximum vale at 1500 LST in both the upper and low levels, and is larger on the lower level than the upper level. The mixing ratio of the lower level is larger than that of the upper level. On the average the mixing ratio decrease with the height, and is the wettest on the summer case day and the driest on the winter case day. The diurnal variation of the wind velocity and direction are variable in the lower level with time and height, while they are steady in the upper level. On the average, the wind direction is southerly or southeasterly for the summer case day, westerly or northwesterly for the spring and fall case days, and northerly or northwesterly for the winter case day.

• Journal of Environmental Science International
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• v.16 no.10
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• pp.1127-1137
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• 2007

We focused on effects on data assimilation of simulated wind fields by using upper-air observations (wind profiler and sonde data). Local Analysis Prediction System (LAPS), a type of data assimilation system, was used for wind field modeling. Five cases of simulation experiments for sensitivity analysis were performed: which are EXP0) non data assimilation, EXP1) surface data, EXP2) surface data and sonde data, EXP3) surface data and wind profiler data, EXP4) surface data, sonde data and wind profiler data. These were compared with observation data. The result showed that the effects of data assimilation with wind profiler data were found to be greater than sonde data. The delicate wind fields in complex coastal area were simulated well in EXP3. EXP3 and EXP4 using wind profiler data with vertically high resolution represented well sophisticated differences of wind speed compared with EXP1 and EXP2, this is because the effects of wind profiler data assimilation were sensitively adjusted to first guess field than those of sonde observations.

• Journal of Environmental Science International
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• v.15 no.8
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• pp.759-774
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• 2006

We employed two data assimilation techniques including MM5 Four Dimensional Data Asssimilation (FDDA) and Local Analysis and Prediction System (LAPS) to find out the effects of the changed inetial conditions on the wind fields simulation according to the objective analysis methods. We designed 5 different modeling cases. EXP B used no data assimilation system. Both EXP Fl using surface observations and EXP F2 with surface and upper-air observations employed MM5 FDDA. EXP Ll using surface observations and EXP L2 with surface and upper-air observations used LAPS. As results of, simulated wind fields using MM5 FDDA showed locally characterized wind features due to objective analysis techniques in FDDA which is forcefully interpolating simulated results into observations. EXP Fl represented a large difference in comparison of wind speed with EXP B. In case of LAPS, simulated horizontal distribution of wind fields showed a good agreement with the patterns of initial condition and EXP Ll showed comparably lesser effects of data assimilation of surface observations than EXP Fl. When upper-air observations are applied to the simulations, while MM5 FDDA could hardly have important effects on the wind fields simulation and showed little differences with simulations with merely surface observations (EXP Fl), LAPS played a key role in simulating wind fields accurately and it could contribute to alleviate the over-estimated winds in EXP Ll simulations.

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

• Journal of Environmental Science International
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• v.7 no.5
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• pp.639-645
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• 1998

A Jump model was evaluated for the calculation of hourly mixing height and mean potential temperature within the height. The Sump model was modified for estimation of downward heat fluxes by mechanical convections and surface heat fluxes. The surface heat fluxes were estimated from routine weather data such as solar radiation and air temperature. Total of 8 upper-air data observed at 0000UTC and 0600UTC in Osan station during April 23 to 26, 1996 were analyzed, and compared to the model results in detail. The calculated mixing heights and potential temperatures within the height were comparable to the observations, but some differences were showed. The calculated mixing heights were generally higher than observations. And, when variations of wind directions were large, the large difference of potential temperature was occurred. From the results, it was important to note that vortical motions and advections of air masses would affect to the growth of the mixing height.

• Atmosphere
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• v.29 no.3
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• pp.283-294
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• 2019

For the upper air observations, a temperature measurement using radiosonde is a common method, and the compensation of solar radiation effects in the radiosonde temperature sensor is an important factor. In this paper, we present various experiments and compensation methods of the radiosonde temperature sensor to overcome the errors caused by the movement of the radiosonde rotation, etc. The methods and procedures of this study are as follows. First, we used the solar simulator to analyze the temperature variation and solar effect of the temperature sensor in the radiosonde according to the insolation. We also analyzed the temperature variation and solar effect of the temperature sensor according to the incident angle between the solar simulator and radiosonde. Second, we measured and analyzed solar radiation absorbed by solar cells attached to radiosonde. Third, we present combined compensate solution of the first and the second experiment results, to overcome errors caused by insolation effects in the radiosonde temperature sensors. Fourth, we compared that the reference temperature in similar environment with the upper air conditions, to verify the new radiated compensation performance of the radiosonde temperature sensor. Finally, the radiosonde fabricated in this study was raised to the atmosphere, and the laser correction algorithm proposed through experiments was reviewed. As a result of the radiosonde SRS-10 produced in this study, the temperature deviation from Vaisala RS92 was $0.057^{\circ}C$ in nighttime observation, $0.17^{\circ}C$ in daytime observation, It is expected that the GRUAN under WMO will be able to obtain a high test rating of 5.0.

• Journal of the Korean earth science society
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• v.41 no.6
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• pp.575-587
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• 2020

Meteorological phenomena are observed by the Korea Meteorological Administration in a variety of ways (e.g., surface, upper-air, marine, ocean, and aviation). However, there are limits to the meteorological observation of the planetary boundary layer (PBL) that greatly affects human life. In particular, observations using a sonde or aircraft require significant observational costs in economic terms. Therefore, the goal of this study was to measure and analyze the meteorological factors of the vertical distribution of the see-land breeze among local meteorological phenomena using meteorological drones. To investigate the spatial distribution of the see-land breeze, a same integrated meteorological sensor was mounted on each drone at three different points (seaside, bottom of mountain, and mountainside), including the Boseong tall tower (BTT) at the Boseong Standard Weather Observatory (BSWO) in the Boseong region. Vertical profile observations for air temperature, relative humidity, wind direction, wind speed, and air pressure were conducted up to 400 m every 30 minutes from 1100 LST to 1800 LST on August 4, 2018. The spatial characteristics of meteorological phenomena for temperature, relative humidity, and atmospheric pressure were not shown at the four points. Strong winds (~8 m s-1) were observed from the midpoint (~100 m) at strong solar radiation hour, and in the afternoon the wind direction changed from the upper layer at the inland area to the west wind. It is expected that the analysis results of the lower atmospheric layer observed using the meteorological drone may help to improve the weather forecast more accurately.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• v.23 no.1
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• pp.34-38
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• 1995

A diagnostic study on the summertime air mass thunderstorms occurring in the middle region of South Korea was made by analyzing the data of surface and upper air observations as well as the surface and upper level weather charts. The key parameters used in the present study are the amount of precipitable water below 850 hPa level, the vertical profiles of water vapor content and wind, and both the temperature difference and the equivalent potential temperature difference between 850 hPa and 700 hPa levels. It is found from this study that the summertime air mass thunderstorms in the middle region of South Korea can be classified into two distinct types, type I and type II. The thunderstorms of type I occur under the atmospheric conditions of high moisture content, low vertical wind shear in low levels, and conditional instability between 850 hPa and 700 hPa levels. On the other hand, the thunderstorms of type II occur under the atmospheric conditions of less moisture content, higher wind shear and conditional instability. Furthermore, our study suggests that atmospheric instability and the amount of water vapor below 850 hPa level are complementary in the development of air mass thunderstorms. The complementary nature between these two parameters may be an explanation for the thunderstorm development in the areas of low atmospheric water vapor content such as the plains of eastern Colorado.

• Journal of Environmental Science International
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• v.7 no.3
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• pp.335-348
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• 1998

The intensive meteorological observations including pibal balloon at Ungcheon, airsonde and 10m meteorological tower observations at Gulup-Do, where are located In the western coastal region, are taken to Investigate the characteristics of the upper and lower atmospheric structure and the local circulation pattern during the period of 17 to 22 September 1996. The diurnal variations of weather elements(i.e. air temperature, humidity, pressure, and Und speeds at Gulup-Do are analyzed and discussed with those at four inland meteorological stations. The vertical profiles of wind vector, ortho- gonality(Ω), and shear obtained from the pibal obsenrations are also presented to examine the change of wand structure according to the synoptic-scale pressure system's movement. The diurnal temperature changes at Gulup-Do are more sensitive than that of Inland meteorological stations In case of the mow of southwesterlies but are not dominant due to the ocean effect under the Influence of relatively cold northerlies. A well defined mixed layer Is developed from the 500m to the maximum 1700m with a significant capping Inversion layer on the top of it. It can be found from the vertical profiles of wind vector that the wind become generally strong at the interface heights between cloud lay- ers and non-cloud layers. The maximum Und shear Is appeared at the bel각t where the varlauon of wand direction Induced by the passage of synoptic-scale pressure system Is accompanied with the In- crease of Und speed. Based on the wind orthogonality, the change of wind direction with height is more complicated In cloudy day than In clear day. In case of a fair weather, the change of wand direction is showed to be at around 2km.

• Journal of Environmental Science International
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• v.10 no.5
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• pp.329-336
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• 2001

Characgcteristics of nocturnal boundary layer(NBL) were analyzed by the upper-air observations data using with the airsonde and pilot balloons from 1994 to 1999 in Kyungpook province. The automate weather boundary layer can become stably stratified when the surface is cooler than the air. Stable nocturnal boundary layer height were estimated from the top of surface stable layer where the vertical gradient of temperature and mixing ratio tend to zero or negative. The depth of the stable nocturnal boundary layer depended largely on the thermal effect rather than the wind effect at nighttime. The NBL was more developed on the land than on the coastal region. The stability index (bulk Richardson number) showed that the NBL was stable when the wind was weak and the vertical gradient of the temperature was strong. The heat budget in the NBL was studied by considering the effect of the radiative and the cooled by both the longwave radiative flux and the divergence of the heat flux, while NBL under the cloudy sky the longwave radiative flux played a role of the warming. It was noted that the heat was not conserved in both cases. To complete the heat budget in the NBL the warming/cooling by advection and subsidence must be considered.