• 한국대기환경학회지
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• 제30권6호
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• pp.600-618
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• 2014

The metadata for urban meteorological observation is standardized through comparison with those established at the World Meteorological Organization and the Korea Meteorological Administration to understand the surrounding environment around the sites exactly and maintain the networks and sites efficiently. It categorizes into metadata for an observational network and observational sites. The latter is again divided into the metadata for station general information, local scale information, micro scale information, and visual information in order to explain urban environment in detail. The metadata also contains the static information such as urban structure, surface cover, metabolism, communication, building density, roof type, moisture/heat sources, and traffic as well as the update information on the environment change, maintenance, replacement, and/or calibration of sensors. The standardized metadata for urban meteorological observation is applied to the Weather Information Service Engine (WISE) integrated meteorological sensor network and sites installed at Incheon area. It will be very useful for site manager as well as researchers in fields of urban meteorology, radiation, surface energy balance, anthropogenic heat, turbulence, heat storage, and boundary layer processes.

• 한국태양에너지학회 논문집
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• 제37권6호
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• pp.103-114
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• 2017

Radiation energy budget was analyzed using observation data from the Weather Information Service Engine (WISE) energy flux tower on the Seoul metropolitan area. Among observation data from the 13 energy flux towers, we used meteorological variables, radiation data (upward and downward short wave, upward and downward long wave, net short wave, net long wave and net radiation), albedo and emissivity for 15 months from July 2016 to September 2017. Although Gajwa (205) and Ttuksumm (216) sites located in urban, the albedo was relatively high due to the surround environment by glass wall buildings and the Han river around the sites. And Bucheon (209) site located in the suburb represented generally low emissivity. As a result, the albedo decreased and the emissivity increased in the city center. In the Seoul metropolitan area, the net radiation energy is $73.9W/m^2$ that the radiation budget of the surface is absorbed into the atmosphere. According to WISE observation data, it can be seen that observation at each sites are influenced by the surrounding environment.

• 대기
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• 제25권2호
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• pp.339-351
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• 2015

The purpose of this study is for the fundamental understandings about building morphological parameters and aerodynamic roughness parameters of Seoul, Korea using the detailed urban geographic information datasets. Applied roughness parameter calculations are based on a digital map of buildings with lot area polygons. The quality of the developed roughness length ($z_0$) of Seoul was evaluated with densely installed 107 automatic weather stations. The correlation coefficient results between averaged wind speeds of AWS data and averaged $z_0$ is -0.303 in night and -0.398 in day (200 m radii circles case). Further $z_0$ enhancement should follow by considering other surface features such as high tree and orography of Seoul. However, this study would meet the needs to for local- or meso-scale meteorological modeling applications of Seoul. However, further studies would require for enhancing the $z_0$ applications of Seoul.

• 대기
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• 제26권1호
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• pp.111-126
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• 2016

In the numerical weather model, surface properties can be defined by various parameters such as terrain height, landuse, surface albedo, soil moisture, surface emissivity, roughness length and so on. And these parameters need to be improved in the Seoul metropolitan area that established high-rise and complex buildings by urbanization at a recent time. The surface roughness length map is developed from digital elevation model (DEM) and it is implemented to the high-resolution numerical weather (WISE-WRF) model. Simulated results from WISE-WRF model are analyzed the relationship between meteorological variables to changes in the surface roughness length. Friction speed and wind speed are improved with various surface roughness in urban, these variables affected to temperature and relative humidity and hence the surface roughness length will affect to the precipitation and Planetary Boundary Layer (PBL) height. When surface variables by the WISE-WRF model are validated with Automatic Weather System (AWS) observations, NEW experiment is able to simulate more accurate than ORG experiment in temperature and wind speed. Especially, wind speed is overestimated over $2.5m\;s^{-1}$ on some AWS stations in Seoul and surrounding area but it improved with positive correlation and Root Mean Square Error (RMSE) below $2.5m\;s^{-1}$ in whole area. There are close relationship between surface roughness length and wind speed, and the change of surface variables lead to the change of location and duration of precipitation. As a result, the accuracy of WISE-WRF model is improved with the new surface roughness length retrieved from DEM, and its surface roughness length is important role in the high-resolution WISE-WRF model. By the way, the result in this study need various validation from retrieved the surface roughness length to numerical weather model simulations with observation data.

• 대기
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• 제26권1호
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• pp.85-95
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• 2016

In this study, we investigated the variabilities of wind speed of 850 hPa and precipitable water over the East Asia region using the NCEP Final Analysis data from December 2001 to November 2011. A large variance of wind speed was observed in northern and eastern China during the winter period. During summer, the regions of the East China Sea, the South Sea of Japan and the East Sea show large variances in the wind speed caused by an extended North Pacific High and typhoon activities. The large variances in the wind speed in the regions are shown to be correlated with the inter-annual variability of precipitable water over the inland region of windward side of the Korean Peninsula. Based on the investigation, sensitivity tests to the domain size were performed using the WRF model version 3.6 for heavy precipitation events over the Korean Peninsula for 26 and 27 July 2011. Numerical experiments of different domain sizes were set up with 5 km horizontal and 50 levels vertical resolutions for the control and the first experimental run, and 9 km horizontal for the second experimental run. We found that the major rainfalls correspond to shortwave troughs with baroclinic structure over Northeast China and extended North Pacific High. The correlation analysis between the observation and experiments for 1-h precipitation indicated that the second experiment with the largest domain had the best performance with the correlation coefficient of 0.79 due to the synoptic-scale systems such as short-wave troughs and North Pacific High.

• 대기
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• 제27권4호
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• pp.385-398
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• 2017

Numerical weather prediction experiments were carried out by applying topographic effects to reduce or enhance the solar radiation by terrain. In this study, x and ${\kappa}({\phi}_o,\;{\theta}_o)$ are precalculated for topographic effect on high resolution numerical weather prediction (NWP) with 1 km spatial resolution, and meteorological variables are analyzed through the numerical experiments. For the numerical simulations, cases were selected in winter (CASE 1) and summer (CASE 2). In the CASE 2, topographic effect was observed on the southward surface to enhance the solar energy reaching the surface, and enhance surface temperature and temperature at 2 m. Especially, the surface temperature is changed sensitively due to the change of the solar energy on the surface, but the change of the precipitation is difficult to match of topographic effect. As a result of the verification using Korea Meteorological Administration (KMA) Automated Weather System (AWS) data on Seoul metropolitan area, the topographic effect is very weak in the winter case. In the CASE 1, the improvement of accuracy was numerically confirmed by decreasing the bias and RMSE (Root mean square error) of temperature at 2 m, wind speed at 10 m and relative humidity. However, the accuracy of rainfall prediction (Threat score (TS), BIAS, equitable threat score (ETS)) with topographic effect is decreased compared to without topographic effect. It is analyzed that the topographic effect improves the solar radiation on surface and affect the enhancements of surface temperature, 2 meter temperature, wind speed, and PBL height.

• 대기
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• 제24권3호
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• pp.445-456
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• 2014

A real-time quality control system for meteorological data (air temperature, air pressure, relative humidity, wind speed, wind direction, and precipitation) measured by an integrated meteorological sensor has been developed based on comparison of quality control procedures for meteorological data that were developed by the World Meteorological Organization and the Korea Meteorological Administration (KMA), using time series and statistical analysis of a 12-year meteorological data set observed from 2000 to 2011 at the Incheon site in Korea. The quality control system includes missing value, physical limit, step, internal consistency, persistence, and climate range tests. Flags indicating good, doubtful, erroneous, not checked, or missing values were added to the raw data after the quality control procedure. The climate range test was applied to the monthly data for air temperature and pressure, and its threshold values were modified from ${\pm}2{\sigma}$ and ${\pm}3{\sigma}$ to ${\pm}3{\sigma}$ and ${\pm}6{\sigma}$, respectively, in order to consider extreme phenomena such as heat waves and typhoons. In addition, the threshold values of the step test for air temperature, air pressure, relative humidity, and wind speed were modified to $0.7^{\circ}C$, 0.4 hPa, 5.9%, and $4.6m\;s^{-1}$, respectively, through standard deviation analysis of step difference according to their averaging period. The modified quality control system was applied to the meteorological data observed by the Weather Information Service Engine in March 2014 and exhibited improved performance compared to the KMA procedures.

• 대기
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• 제27권3호
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• pp.317-329
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• 2017

Ocean mixed layer (OML) depth affects diurnal cycle of sea surface temperature (SST) induced by change of solar radiation absorption and heat budget in ocean. The diurnal SST variation can lead to convection over the ocean, which can impact on localized precipitation both over coastal and inland. In this study, we investigate the OML characteristics affecting the diurnal cycle of SST for the Korean Peninsula and surrounding areas. To analyze OML characteristics, HYCOM oceanic mixed layer depth (MLD) and wind field at 10 m from ERA-interim during 2008~2016 are used. In the winter, MLD is deeply formed when the strong wind field is located on perpendicular to continental slope over deep seafloor areas. Besides, cooling SST-induced vertical mixing in OML is reinforced by dry cold air originated from Siberia. The OML in summer is shallowly distributed about 20 m. In order to estimate the impact of OML model in high resolution NWP model, four experimental simulations are performed. At this time, the prognostic scheme of skin SST is applied in NWP to simulate diurnal SST. The simulation results show that CNTL (off-OML) overestimates diurnal cycle of SST, while EXPs (on-OML) indicate similar results to observations. The prediction performance for precipitation of EXPs shows improvement compared with CNTL over coastal as well as inland. This results suggest that the application of the OML model in summer season can contribute to improving the prediction for performance of SST and precipitation over coastal area and inland.

• 한국대기환경학회지
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• 제32권1호
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• pp.46-56
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• 2016

In order to analyze the surface temperature in accordance with the surface material, surface temperatures between Thermal InfraRed Image (TIRI) and Landsat 8 satellite observed at the commercial area (Gwanghwamun) and residential area (Jungnang) are compared. The surface temperature from TIRI had applied atmospheric correction and compared with that from Landsat 8. The surface temperatures from Landsat 8 at Gwanghwamun and Jungnang are underestimated in comparison with that from TIRI. The difference of surface temperature between the two methods is greater in summer than in winter. When the analysis area was divided into detailed regions, depending on the material and the position of the surface, correlation of surface temperature between TIRI with Landsat 8 is as low as 0.29 (Gwanghwamun) and 0.18 (Jungnang), respectively. The results were caused from the resolution difference between the two methods. While the surface temperatures of each zone from Landsat 8 were observed almost constant, high-resolution TIRI observed relatively precise surface temperatures. When the each area was averaged as one space, correlation of surface temperature between TIRIs and Landsat 8 is more than 0.95. The spatially averaged surface temperature is higher at Jungnang, representing residential areas, than at Gwanghwamun, representing commercial areas. As a result, the observation of high resolution is required in order to observe the precise surface temperature. This is because it appears that the spatial distribution of the various surface temperature in the range of micro-scale according to the conditions of the ground surface.

• 대기
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• 제24권2호
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• pp.197-206
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• 2014

The effects of different averaging operators and atmospheric stability on the turbulent fluxes are investigated using the vertical velocity, air temperature, carbon dioxide concentration, and absolute humidity data measured at 10 Hz by a 3-dimensional sonic anemometer and an open-path $CO_2/H_2O$ infrared gas analyzer installed at a height of 18.5 m on the rooftop of the Jungnang KT building located at a typical residential area in Seoul, Korea. For this purpose, 7 different averaging operators including block average, linear regression, and moving averages during 100 s, 300 s, 600 s, 900 s, and 1800 s are considered and the data quality control procedure such as physical limit check and spike removal is also applied. It is found that as the averaging interval becomes shorter, turbulent fluxes computed by the moving average become smaller and the ratios of turbulent fluxes computed by the 100 s moving average to the fluxes by the 1800 s moving average under unstable stability are smaller than those under neutral stability. The turbulent fluxes computed by the linear regression are 85~92% of those computed by the 1800 s moving average and nearly the same as those computed by 900 s moving average, implying that the adequate selection of an averaging operator and its interval will be very important to estimate more accurate turbulent fluxes at urban area.