• 대기
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• 제18권2호
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• pp.111-120
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• 2008

This study presents a change-point in the 30 years (1976-2005) time series of the annual and the heavy precipitation characteristics (amount, days and intensity) averaged over South Korea using Bayesian approach. The criterion for the heavy precipitation used in this study is 80 mm/day. Using non-informative priors, the exact Bayes estimators of parameters and unknown change-point are obtained. Also, the posterior probability and 90% highest posterior density credible intervals for the mean differences between before and after the change-point are examined. The results show that a single change-point in the precipitation intensity and the heavy precipitation characteristics has occurred around 1996. As the results, the precipitation intensity and heavy precipitation characteristics have clearly increased after the change-point. However, the annual precipitation amount and days show a statistically insignificant single change-point model. These results are consistent with earlier works based on a simple linear regression model.

• 대기
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• 제19권2호
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• pp.199-211
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• 2009

In this paper, we examine the multiple change-point and change pattern in the 54 years (1954-2007) time series of the annual and the heavy precipitation characteristics (amount, days and intensity) averaged over South Korea. A Bayesian approach is used for detecting of mean and/or variance changes in a sequence of independent univariate normal observations. Using non-informative priors for the parameters, the Bayesian model selection is performed by the posterior probability through the intrinsic Bayes factor of Berger and Pericchi (1996). To investigate the significance of the changes in the precipitation characteristics between before and after the change-point, the posterior probability and 90% highest posterior density credible intervals are examined. The results showed that no significant changes have occurred in the annual precipitation characteristics (amount, days and intensity) and the heavy precipitation intensity. On the other hand, a statistically significant single change has occurred around 1996 or 1997 in the heavy precipitation days and amount. The heavy precipitation amount and days have increased after the change-point but no changes in the variances.

• 한국지역지리학회지
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• 제17권5호
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• pp.505-520
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• 2011

본 연구에서는 호우의 변화경향을 유역별로 분석하였다. 이를 위해 한국을 6개의 유역으로 나누고 호우와 관련된 7개의 극한강수지수를 분석하여 변화지속성을 파악하였다. 호우량은 호우일수보다 증가경향이 더 지속적이다. 일강수량이 50mm 이상 강수일수와 95 퍼센타일 이상 강수량의 증가경향이 가장 지속적이다. 호우관련지수는 분석기간 동안 대부분 증가경향이지만 한강 유역, 낙동강 상류지역, 동해안 지역이 다른 유역에 비해 증가경향이 뚜렷하다. 금강 유역과 섬진강 유역은 호우의 증가경향이 통계적으로 유의하지 않고 변동성이 크다. 호우의 증가경향은 1970년대 중반 이후 한강과 낙동강 유역에서 지속적이지만 2000년대 중반 이후 증가경향이 지속적으로 나타나는 지점들이 감소한다. 이는 최근 호우의 빈도와 강도가 더욱 불규칙해지고 있음을 의미한다.

• 대기
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• 제22권3호
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• pp.287-298
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• 2012

The predictability of heavy precipitation over the Korean Peninsula is studied using THORPEX Interactive Grand Global Ensemble (TIGGE) data. The performance of the six ensemble models is compared through the inconsistency (or jumpiness) and Root Mean Square Error (RMSE) for MSLP, T850 and H500. Grand Ensemble (GE) of the three best ensemble models (ECMWF, UKMO and CMA) with equal weight and without bias correction is consisted. The jumpiness calculated in this study indicates that the GE is more consistent than each single ensemble model. Brier Score (BS) of precipitation also shows that the GE outperforms. The GE is used for a case study of a heavy rainfall event in Korean Peninsula on 9 July 2009. The probability forecast of precipitation using 90 members of the GE and the percentage of 90 members exceeding 90 percentile in climatological Probability Density Function (PDF) of observed precipitation are calculated. As the GE is excellent in possibility of potential detection of heavy rainfall, GE is more skillful than the single ensemble model and can lead to a heavy rainfall warning in medium-range. If the performance of each single ensemble model is also improved, GE can provide better performance.

• 대기
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• 제22권4호
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• pp.387-400
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• 2012

This study aims at examining the sensitivity of numerical simulations to the resolution of initial and boundary data, and to an application of WRF (Weather Research and Forecasting) 3DVAR (Three Dimension Variational data Assimilation). To do this, we ran the WRF model by using GDAS (Global Data Assimilation System) FNL (Final analyses) and the KLAPS (Korea Local Analysis and Prediction System) analyses as the WRF's initial and boundary data, and by using an initial field made by assimilating the radar data to the KLAPS analyses. For the sensitivity experiment, we selected a heavy rainfall case of 21 September 2010, where there was localized torrential rain, which was recorded as 259.5 mm precipitation in a day at Seoul. The result of the simulation using the FNL as initial and boundary data (FNL exp) showed that the localized heavy rainfall area was not accurately simulated and that the simulated amount of precipitation was about 4% of the observed accumulated precipitation. That of the simulation using KLAPS analyses as initial and boundary data (KLAPC exp) showed that the localized heavy rainfall area was simulated on the northern area of Seoul-Gyeonggi area, which renders rather difference in location, and that the simulated amount was underestimated as about 6.4% of the precipitation. Finally, that of the simulation using an initial field made by assimilating the radar data to the KLAPS using 3DVAR system (KLAP3D exp) showed that the localized heavy rainfall area was located properly on Seoul-Gyeonggi area, but still the amount itself was underestimated as about 29% of the precipitation. Even though KLAP3D exp still showed an underestimation in the precipitation, it showed the best result among them. Even if it is difficult to generalize the effect of data assimilation by one case, this study showed that the radar data assimilation can somewhat improve the accuracy of the simulated precipitation.

• 대기
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• 제32권2호
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• pp.135-148
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• 2022

This study investigates the influence of atmospheric river (AR) on precipitation over South Korea with a focus on regional characteristics. The 42-year-long catalog of ARs, which is obtained by applying the automatic AR detection algorithm to ERA5 reanalysis data and the insitu precipitation data recorded at 56 weather stations across the country are used to quantify their relationship. Approximately 51% of the climatological annual precipitation is associated with AR. The AR-related precipitation is most pronounced in summer by approximately 58%, while only limited fraction of precipitation (26%) is AR-related in winter. The heavy precipitation (> 30 mm day^-1) is more prone to AR activity (59%) than weak precipitation (5~30 mm day^-1; 33%) in all seasons. By grouping weather stations into the four sub-regions based on orography, it is found that the contribution of AR precipitation to the total is largest in the southern coast (57%) and smallest in the eastern coast (36%). Similar regional variations in AR precipitation fractions also occur in weak precipitation events. The regional contrast between the northern and southern stations is related to the seasonal variation of AR-frequency. In addition, the regional contrast between the western and eastern stations is partly modulated by the orographic forcing. The fractional contribution of AR to heavy precipitation exceeds 50% in all seasons, but this is true only in summer along the eastern coast. This result indicates that ARs play a critical role in heavy precipitation in South Korea, thus routine monitoring of ARs is needed for improving operational hydrometeorological forecasting.

• 유기물자원화
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• 제22권2호
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• pp.50-56
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• 2014

일반적으로 도금 폐수를 비롯한 산업 폐수 내 중금속 처리에 적용되는 응집-침전은 응집제의 비용과 침전 효율의 불안정성이라는 한계가 존재한다. 본 연구에서는 수산화물 생성-분리막 공정을 전제로 하여, pH와 교반조건에 따른 수용액 상의 중금속 제거 효율과 생성된 수산화물의 입도 분포를 고찰하였다. pH별 실험 결과, pH 9-10에서 최적의 중금속 제거 효율이 확인되었으며, 무기응집제인 $FeCl_3$의 투입은 오히려 제거 효율을 저하시켰다. 완속교반 시간 및 강도는 70 rpm, 20 min 조건이 최대 효율을 보였으며 Cu, Ni, Zn 모두 청정 지역 기준 폐수 배출 기준을 만족하였다. 나타났다. 생성된 중금속 수산화물의 입도 분석을 수행한 결과, 입자의 99.9 %가 $2{\mu}m$ 이상이었다.

• 통합자연과학논문집
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• 제8권3호
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• pp.221-232
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• 2015

In this study, the vertical characteristics of wind were analyzed using the horizontal wind, vertical wind, and vertical wind shear, which are generated from a wind profiler during concentrated heavy rain, and the quantitative characteristics of concentrated heavy rain were analyzed using CAPE, SWEAT, and SRH, among the stability indexes. The analysis of the horizontal wind showed that 9 cases out of 10 had a low level jet of 25 kts at altitudes lower than 1.5 km, and that the precipitation varied according to the altitude and distribution of the low-level jet. The analysis of the vertical wind showed that it ascended up to about 3 km before precipitation. The analysis of the vertical wind shear showed that it increased up to a 1 km altitude before precipitation and had a strong value near 3 km during heavy rains. In the stability index analysis, CAPE, which represents thermal buoyancy, and SRH, which represents dynamic vorticity, were used for the interpretation of the period of heavy rain. As SWEAT contains dynamic upper level wind and thermal energy, it had a high correlation coefficient with concentrated-heavy-rain analysis. Through the case studies conducted on August 12-13, 2012, it was confirmed that the interpretation of the prediction of the period of heavy rain was possible when using the intensive observation data from a wind profiler and the stability index.

• 대기
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• 제25권4호
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• pp.577-589
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• 2015

An unusual long-period and heavy snowfall occurred in the Yeongdong region from 6 to 14 February 2014. This event produced snowfall total of 194.8 cm and the recordbreaking 9-day snowfall duration in the 103-year local record at Gangneung. In this study, satellite-derived cloud-top brightness temperatures from the infrared channel in the atmospheric window ($10{\mu}m{\sim}11{\mu}m$) are examined to find out the characteristics of clouds related with this heavy snowfall event. The analysis results reveal that a majority of precipitation is related with the low-level stratiform clouds whose cloud-top brightness temperatures are distributed from -15 to $-20^{\circ}C$ and their standard deviations over the analysis domain (${\sim}1,000km^2$, 37 satellite pixels) are less than $2^{\circ}C$. It is also found that in the above temperature range precipitation intensity tends to increase with colder temperature. When the temperatures are warmer than $-15^{\circ}C$, there is no precipitation or light precipitation. Furthermore this relation is confirmed from the examination of some other heavy snowfall events and light precipitation events which are related with the low-level stratiform clouds. This precipitation-brightness temperature relation may be explained by the combined effect of ice crystal growth processes: the maximum in dendritic ice-crystal growth occurs at about $-15^{\circ}C$ and the activation of ice nuclei begins below temperatures from approximately -7 to $-16^{\circ}C$, depending on the composition of the ice nuclei.

• 통합자연과학논문집
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• 제14권4호
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• pp.162-175
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• 2021

Recently, due to global warming, the average temperature of the earth has risen, and the glaciers in the Antarctic and Arctic melt, leading to a rise in sea level, which is accompanied by powerful natural disasters such as strong typhoons and tsunamis around the world. Accordingly, a precipitation in summer in Korea also increased, and changes in the form of precipitation were showed with the increase. Compared to the past, the frequency of localized heavy rain is increasing, and the damage from flooding and flooding is increasing day by day. In this study, based on the precipitation data measured in hours from May to September from 2016 to 2021 according to the change in the precipitation form, according to the nature of the torrential rain investigated the change in the summer precipitation form. In addition, the trend of localized heavy rain from 2016 to 2021 was confirmed by classifying them into two types: localized heavy rains caused by cyclones and weather front, and by typhoons and large-scale cyclones. Through this, the change in precipitation due to the climate crisis should not be viewed as a single phenomenon, it should be reflected and discussed on our life focused on scientific and technological development, and it should be used as a stepping stone for realizing a humanistic.