• Water Engineering Research
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• v.6 no.2
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• pp.73-89
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• 2005

Two kinds of high resolution GCMs with the same spatial resolutions but with different schemes run by domestic and foreign agencies are used to clarify the usefulness and sensitivity of GCM for water resources applications for Korea. One is AMIP-II (Atmospheric Model Intercomparison Project-II) type GCM simulation results done by ECMWF (European Centre for Medium-Range Weather Forecasts) and the other one is AMIP-I type GCM simulation results done by METRI (Korean Meteorological Research Institute). Observed mean areal precipitation, temperature, and discharge values on 7 major river basins were used for target variables. Monte Carlo simulation was used to establish the significance of the estimator values. Sensitivity analyses were done in accordance with the proposed ways. Through the various tests, discrimination condition is sensitive for the distribution of the data. Window size is sensitive for the data variation and the area of the basins. Discrimination abilities of each nodal value affects on the correct association. In addition to theses sensitivity analyses results, we also noticed some characteristics of each GCM. For Korean water resources, monthly and small window setting analyses are recommended using GCMs.

• Journal of Korean Society on Water Environment
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• v.33 no.3
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• pp.256-272
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• 2017

Extreme rainfall has become more frequent over the Korean peninsula in recent years, causing serious damages. In a changing climate, traditional approaches based on historical records of rainfall and on the stationary assumption can be inadequate and lead to overestimate (or underestimate) the design rainfalls. A main objective of this study is to develop a stochastic disaggregation method of seasonal rainfall to hourly extreme rainfall, and offer a way to derive the nonstationary IDF curves. In this study, we propose a novel approach based on a Four-Parameter Beta (4P-beta) distribution to estimate the nonstationary IDF curves conditioned on the observed (or simulated) seasonal rainfall, which becomes the time-varying upper bound of the 4P beta distribution. Moreover, this study employed a Bayesian framework that provides a better way to take into account the uncertainty in the model parameters. The proposed model showed a comparable design rainfall to that of GEV distribution under the stationary assumption. As a nonstationary rainfall frequency model, the proposed model can effectively translate the seasonal variation into the sub-daily extreme rainfall.

• Atmosphere
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• v.28 no.3
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• pp.273-289
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• 2018

This paper evaluates daily precipitation products from Integrated Multisatellite Retrievals for Global Precipitation Measurement (IMERG), Tropical Rainfall Measuring Mission Multisatellite (TRMM) Precipitation Analysis (TMPA), and the Climate Prediction Center Morphing Method (CMORPH), validated against gauge observation over South Korea and gauge-based analysis data East Asia during one year from June 2014 to May 2015. It is found that the three products effectively capture the seasonal variation of mean precipitation with relatively good correlation from spring to fall. Among them, IMERG and TMPA show quite similar precipitation characteristics but overall underestimation is found from all precipitation products during winter compared with observation. IMERG shows reliably high performance in precipitation for all seasons, showing the most unbiased and accurate precipitation estimation. However, it is also noticed that IMERG reveals overestimated precipitation for heavier precipitation thresholds. This assessment work suggests the validity of the IMERG product for not only seasonal precipitation but also daily precipitation, which has the potential to be used as reference precipitation data.

• 한국지구물리탐사학회:학술대회논문집
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• 2008.10a
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• pp.145-148
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• 2008

ICESat launched in Jan. 2003 has a capability to monitor polar regions with its inclination of 94 degree. ICESat carries GLAS (Geosciences Laser Altimetry System) to measure Earth's topography in unprecedented accuracy, and thus it can be applied for glacier variation due to recent climate changes. Here we present a new method to estimate velocity structure of Amery Ice-Shelf using ICESat altimtery data. ICESat data shows horizontal displacement of Amery Ice-Shelf, which can be directly used for velocity estimation. This method is expected to extend to other ice-shelves in Antarctica.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.807-812
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• 2008

The various attempts is made to solve the energy and environment problems. In addition, people interested in their life quality want the more eco-friendly living space. So we suggested that the earth-sheltered house could be one of the eco-friendly and low energy consuming houses to meet the social interest. And we also made data for design of the earth-sheltered house to be applicable to climate of Korea. In this study, a simulation was performed to estimate a boundary temperature according to earth sheltering thickness at the earth-sheltered part(exterior wall) in the case of earth sheltering on the plane ground not using a sloped site. And we analyzed the reduction of a thermal load by using this boundary temperature. We also compared a case of earth sheltering at the vertical wall with a case of earth sheltering at the roof to know the thermal reduction effect of a case of earth sheltering at the vertical wall.

• Animal cells and systems
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• v.12 no.4
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• pp.287-295
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• 2008

Variations of larval abundance and hatch timing of Dungeness crabs, Cancer magister Dana 1852, were investigated. Dungeness crab larvae were monthly collected at 16 stations arrayed in four transects, Upper Chatham, Icy Strait, Cross Sound, and Icy Point, in southeastern Alaska from May to September 1997-2004. Larval abundance at all transects was the highest in June except in the Icy Point transect. Larval abundance was the highest in the Icy Strait transect, moderate in the Upper Chatham and Cross Sound transects, and the lowest in the Icy Point transect. Zoeae I(ZI) was predominated in May; thereafter ZI decreased and late zoeal stages occurred. In May and June, small numbers of late stage larvae unusually co-occurred with ZI in three transects. These late stage larvae may have been transported from where hatching occurs earlier. The timing of ZI occurrence varied interannually and was related to degreedays during the egg incubation period of Dungeness crabs: later larval hatching in 1997 and 2002 when temperatures were colder, while earlier larval hatching in 1998 when temperatures were warmer. The distribution patterns of Dungeness crab larvae in southeastern Alaska were markedly different from those reported from other areas of the species distribution ranges: larvae occurring much later in the year, and late stage larvae occurring in inland waters.

• Ocean and Polar Research
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• v.23 no.1
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• pp.23-34
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• 2001

Geochemical and Sr-Nd isotopic compositions and K-Ar ages are analyzed in volcanic rocks from Weno Island, Caroline Islands. Seven Weno lava samples of alkali basalt and basaltic trachyandesite are aphyric or sparsely phyric comprising olivine, plagioclase, and clinopyroxene phenocrysts. Whole-rock geochemical variation of Weno lavas reflects main fractional crystallization of olivine and Cr-spinel phenocrysts. Newly determined K-Ar ages of Weno lavas range from 6.7 to 11.3 Ma (late Miocene), indicating their formation during primary volcanic stage of Chuuk Islands. Trace element compositions of Weno lavas are very similar to those of typical ocean island basalts (OIBs), suggesting their formation during intra-plate mantle plume activity. The plume composition is isotopically very similar to that of Hawaiian hot spot. However, the age span of Chuuk volcanism is longer than that of the other individual volcanoes in the Pacific.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.15 no.1
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• pp.63-71
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• 2012

To investigate the air temperature difference between windward and leeward side at high-rise building area, the air temperature and relative humidity data were observed for 10 minute interval from July 9, 2011 to November 30, 2011. The observed data were compared, analyzed and examined to illustrate air temperature between windward side (H Apartment) and Leeward side (W Apartment). The diurnal and seasonal variation of air temperature difference between windward and leeward site were also investigated. After the analysis, the overheat of windward side by $0.4^{\circ}C$ irrespective short distance of two observation positions. It was also lower than those of surrounding air temperature observing stations. It is mainly due to the air temperature decreasing effects of leeward side of high rise buildings.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.6
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• pp.583-588
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• 2008

Swell data observed in the East Sea in February, 2008 were analyzed using wavelet method. The wavelet analyzed results show detailed time series variation of wave group, peak frequency and spectrum. The comparison of time averaged wavelet spectrum with fourier spectrum turn out to be very similar in terms of spectrum shape and peak frequency evolution but the peak frequency wave energy and the significant wave height show discrepancies. Wavelet analysis can detect the change of spectrum in time as well as in frequency and very efficient to study transient and irregular phenomena such as freak waves and abnormal swells in the ocean. More analysis with more wave data are needed for future application.

• Journal of Astronomy and Space Sciences
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• v.33 no.4
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• pp.305-311
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• 2016

The spatial size and variation of Arctic sea ice play an important role in Earth's climate system. These are affected by conditions in the polar atmosphere and Arctic sea temperatures. The Arctic sea ice concentration is calculated from brightness temperature data derived from the Defense Meteorological Satellite program (DMSP) F13 Special Sensor Microwave/Imagers (SSMI) and the DMSP F17 Special Sensor Microwave Imager/Sounder (SSMIS) sensors. Many previous studies point to significant reductions in sea ice and their causes. We investigated the variability of Arctic sea ice using the daily sea ice concentration data from passive microwave observations to identify the sea ice melting regions near the Arctic polar ice cap. We discovered the abnormal melting of the Arctic sea ice near the North Pole during the summer and the winter. This phenomenon is hard to explain only surface air temperature or solar heating as suggested by recent studies. We propose a hypothesis explaining this phenomenon. The heat from the deep sea in Arctic Ocean ridges and/or the hydrothermal vents might be contributing to the melting of Arctic sea ice. This hypothesis could be verified by the observation of warm water column structure below the melting or thinning arctic sea ice through the project such as Coriolis dataset for reanalysis (CORA).