• Atmosphere
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• v.23 no.2
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• pp.171-186
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• 2013

Recently, the number of observations used in a data assimilation system is increasing due to the enormous amount of observations, including satellite data. However, it is not clear that all of these observations are always beneficial to the performance of the numerical weather prediction (NWP). Therefore, it is important to evaluate the effect of observations on these forecasts so that the observations can be used more usefully in NWP process. In this study, the adjoint-based Forecast Sensitivity to Observation (FSO) method with the KMA Unified Model (UM) is applied to two high-impact weather events which occurred in summer and winter in Korea in an effort to investigate the effects of observations on the forecasts of these events. The total dry energy norm is used as a response function to calculate the adjoint sensitivity. For the summer case, TEMP observations have the greatest total impact while BOGUS shows the greatest impact per observation for all of the 24-, 36-, and 48-hour forecasts. For the winter case, aircraft, ATOVS, and ESA have the greatest total impact for the 24-, 36-, and 48-hour forecasts respectively, while ESA has the greatest impact per observation. Most of the observation effects are horizontally located upwind or in the vicinity of the Korean peninsula. The fraction of beneficial observations is less than 50%, which is less than the results in previous studies. As an additional experiment, the total moist energy norm is used as a response function to measure the sensitivity of 24-hour forecast error to observations. The characteristics of the observation impact with the moist energy response function are generally similar to those with the dry energy response function. However, the ATOVS observations were found to be sensitive to the response function, showing a positive (a negative) effect on the forecast when using the dry (moist) norm for the summer case. For the winter case, the dry and moist energy norm experiments show very similar results because the adjoint of KMA UM does not calculate the specific humidity of ice properly such that the dry and moist energy norms are very similar except for the humidity in air that is very low in winter.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.37-42
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• 2005

This paper presents an autonomous system for reconstruction of three-dimensional indoor environments using a mobile robot. The system is composed of a mobile robot, a three-dimensional scanning system, and a notebook computer for registration, observation planning and real-time three-dimensional data transferring. Three-dimensional scanning system obtains three-dimensional environmental data and performs filtering of dynamic objects. Then, it registers multiple three-dimensional scans into one coordinate system and performs observation planning which finds the next scanning position by using the layered hexahedral-map and topological-map. Then, the mobile robot moves to the next scanning position, and repeats all procedures until there is no scanning tree in topological-map. In concurrence with data scanning, three-dimensional data can be transferred through wireless-LAN in real-time. This system is experimented successfully by using a mobile robot named KARA.

• Journal of Wind Energy
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• v.14 no.3
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• pp.5-13
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• 2023

Floating LiDAR systems (FLSs) are used in many countries because they are easier to install than stationary weather towers, have low maintenance costs, and can be installed in deep sea areas. However, FLSs are rarely used in Korea due to a lack of clear evaluation criteria to verify the reliability and uncertainty of their measurements. This study is the first to verify the reliability of FLSs in Korea with one-year simultaneous observation of six lidar systems - two fixed and four floating systems - in sea areas of Gunsan and Yeonggwang. The reliability of FLSs measurement data was verified by comparison between fixed and floating systems. Moreover, differences between existing wind resource maps and the data observed from the six points were analyzed and wind resource maps were calibrated. The results show a return rate of more than 95 % of the observed data and strong correlations between fixed and floating systems (average R2 of 0.977). Additionally, errors in wind speed predictions to produce a wind resource map could be significantly reduced from 5.7 % to 0.6 % after calibrations with the observation data.

• Journal of the Korean Society of Earth Science Education
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• v.4 no.1
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• pp.12-19
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• 2011

This study aimed to analyze the teachers' cognitions about the primary science textbooks(experiment and observation) used in elementary schools. This study surveyed 211 teachers in Seoul and Gyeonggi province. The data were statistically analyzed by SPSS WIN 10.0. The results of this study are as follows : Most of the teachers showed positive opinions on the directions of the compilation of experiment and observation textbook. Teachers used experiment and observation textbook as summary notes, experiment reports and evaluating methods. The experiment and observation textbooks should be compiled and reorganized in order as follows : Lesson introduction, inquiry activities, and intensive and supplementary activities which are followed by space of description in experiment and observation textbook.

• Journal of Environmental Health Sciences
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• v.30 no.2
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• pp.108-114
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• 2004

Observation of microorganisms collected from contaminated soils has been mainly conducted by using microscopy. Microscopic measurement is occupied an important part of the microorganism experiment, and is used as an important tool to count microorganisms as well as to observe cellular form and mode of life in the field of soil microbe observation. In general, observation equipments for soil microbes consist of electron microscope, camera, frame grabber (image acquisition baud), and image analysis software. Because image analysis software should be linked with frame grabber most equipments have to be imported as the package form. Therefore, the observation system is very expensive and difficult to be operated. In this study, soil microbes＇ observation equipment with the vision system which is easy operated and cheaper than imported one was developed and tested. The efficiency of image capturing and data aquisition with developed frame grabber and software in this experiment was good enough to analyze the image of soil microorganism.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.5
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• pp.585-595
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• 2007

Representative impacts and effectiveness of surface meteorological observation data assimilation were examined in order to use wind resources estimation around southern coastal area of the Korean Peninsula. The data used in study are observational wind and temperature data at 5 and 41 sites of Regional Meteorological Offices and Automatical Weather Systems, respectively. Observation wind speed data tends to show small effective radius with limited area. Especially assimilation impacts of data observed at peninsula type sites like Yeosu play only around the inside of the peninsula. This limited effective radius for wind speed is caused by the strong correlation between topography and wind speed. And the efficient radius for surface air temperature is larger than that of wind. Data assimilation for observational air temperature is useful to increase the accuracy of wind energy estimation. However assimilation of wind data requires special care in its application due to high sensitivity of topographical complexity.

• Atmosphere
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• v.28 no.4
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• pp.369-382
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• 2018

Planetary boundary layer height (PBLH), produced by the Local Data Assimilation and Prediction System (LDAPS), was verified using RawinSonde (RS) data obtained from observation at Daegwallyeong (DGW) and Sokcho (SCW) during the International Collaborative Experiments for Pyeongchang 2018 Olympic and Paralympic winter games (ICE-POP 2018). The PBLH was calculated using RS data by applying the bulk Richardson number and the parcel method. This calculated PBLH was then compared to the values produced by LDAPS. The PBLH simulations for DGW and SCW were generally underestimation. However, the PBLH was an overestimation from surface to 200 m and 450 m at DGW and SCW, respectively; this result of model's failure to correctly simulate the Surface Boundary Layer (SBL) and the Mixing Layer (ML) as the PBLH. When the accuracy of the PBLH simulation is low, large errors are seen in the mid- and low-level humidity. The highest frequencies of Planetary boundary layer (PBL) types, calculated by the LDAPS at DGW and SCW, were presented as types Ι and II, respectively. Analysis of meteorological factors according to the PBL types indicate that the PBLH of the existing stratocumulus were overestimated when the mid- and low-level humidity errors were large. If the instabilities of the surface and vertical mixing into clouds are considered important factors affecting the estimation of PBLH into model, then mid- and low-level humidity should also be considered important factors influencing PBLH simulation performance.

• Atmosphere
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• v.27 no.3
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• pp.359-370
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• 2017

In this study, the oceanic Total Precipitable Water (TPW) retrieval algorithm at 16 km altitude of High Altitude Long Endurance Unmanned Aerial Vehicle (HALE UAV) is described. Empirical equation based on Wentz method (1995) that uses the 18.7 and 22.235 GHz channels is developed using the simulated brightness temperature and SeeBor training dataset. To do radiative simulation, Satellite Data Simulator Unit (SDSU) Radiative Transfer Model (RTM) is used. The data of 60% (523) and 40% (349) in the SeeBor training dataset are used to develop and validate the TPW retrieval algorithm, respectively. The range of coefficients for the TPW retrieval at the altitude of 3~18 km with 3 km interval were 153.69~199.87 (${\alpha}$), 54.330~58.468 (${\beta}$), and 84.519~93.484 (${\gamma}$). The bias and RMSE at each altitude were found to be about $-0.81kg\;m^{-2}$ and $2.17kg\;m^{-2}$, respectively. Correlation coefficients were more than 0.9. Radiosonde observation has been generally operated over land. To validate the accuracy of the oceanic TPW retrieval algorithm, observation data from the Korea Meteorological Administration (KMA) Gisang 1 research vessel about six clear sky cases representing spring, autumn, and summer season is used. Difference between retrieved and observed TPW at 16 km altitude were in the range of $0.53{\sim}1.87kg\;m^{-2}$, which is reasonable for most applications. Difference in TPW between retrieval and observation at each altitude (3~15 km) is also presented. Differences of TPW at altitudes more than 6 km were $0.3{\sim}1.9kg\;m^{-2}$. Retrieved TPW at 3 km altitude was smaller than upper level with a difference of $-0.25{\sim}0.75kg\;m^{-2}$ compared to the observed TPW.

• KIEAE Journal
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• v.16 no.6
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• pp.69-75
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• 2016

Climate change has resulted in the urban heat island (UHI) effect throughout the globe, contributing to heat-related illness and fatalities. In order to reduce such damage, it is necessary to improve the climate observation network for precise observation of the urban thermal environment and quick UHI forecasting system. Purpose: This study analyzed the effective range of the climate observation network and the distribution of the existing Automatic Weather Stations (AWS) in Seoul to propose optimal locations for additional installment of AWS. Method: First, we performed quality analysis to pinpoint missing values and outliers within the high-density temperature data measured. With the result from the analysis, a spatial autocorrelation structure in the temperature data was tested to draw the effective range and correlation distance for each major time period. Result: As a result, it turned out that the optimal effective range for the climate observation network in Seoul in July was a radius of 2.8 kilometers. Based on this result, population density, and temperature data, we selected the locations for additional installment of AWS. This study is expected to be used to generate urban temperature maps, select and move measurement locations since it is able to suggest valid, specific spatial ranges when the data measured in point is converted into surface data.

• Atmosphere
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• v.23 no.4
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• pp.453-470
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• 2013

As a part of the KIAPS Observation Processing System (KOPS), we have developed the modules of satellite radiance data pre-processing and quality control, which include observation operators to interpolate model state variables into radiances in observation space. AMSU-A (Advanced Microwave Sounding Unit-A) level-1d radiance data have been extracted using the BUFR (Binary Universal Form for the Representation of meteorological data) decoder and a first guess has been calculated with RTTOV (Radiative Transfer for TIROS Operational Vertical Sounder) version 10.2. For initial quality checks, the pixels contaminated by large amounts of cloud liquid water, heavy precipitation, and sea ice have been removed. Channels for assimilation, rejection, or monitoring have been respectively selected for different surface types since the errors from the skin temperature are caused by inaccurate surface emissivity. Correcting the bias caused by errors in the instruments and radiative transfer model is crucial in radiance data pre-processing. We have developed bias correction modules in two steps based on 30-day innovation statistics (observed radiance minus background; O-B). The scan bias correction has been calculated individually for each channel, satellite, and scan position. Then a multiple linear regression of the scan-bias-corrected innovations with several predictors has been employed to correct the airmass bias.