• Title, Summary, Keyword: Precipitation

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Recent Changes in Summer Precipitation Characteristics over South Korea (최근 한반도 여름철 강수특성의 변화)

  • Park, Chang-Yong;Moon, Ja-Yeon;Cha, Eun-Jeong;Yun, Won-Tae;Choi, Young-Eun
    • Journal of the Korean Geographical Society
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    • v.43 no.3
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    • pp.324-336
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    • 2008
  • This paper examines the recent changes of summer precipitation in the aspect of temporal and spatial features using long-term($1958{\sim}2007$) observed station data over South Korea. tong-term mean summer precipitation has revealed two precipitation peaks during summer(June to September); one is the Changma as the first peak, and the other is the post-Changma as the second peak. During the Changma period, the spatial distribution of the maximum precipitation areas is determined by the prevailing southwesterlies and the quasi-stationary front, which results in large amount of precipitation at the windward side of mountain regions over South Korea. However during the post-Changma period, the spatial distribution of the maximum precipitation areas is determined by the lower tropospheric circulation flows from the west and the southeast around the Korean peninsula, and the weather phenomena such as Typhoons, convective instability, and cyclones which are originated from the Yangtze river. The larger amount of precipitation is founded on the southern coastal region and mountain and coastal areas in Korea during the second peak. Time series of total summer precipitation shows a steady increase and the increasing trend is more obvious during the recent 10 years. Decadal variation in summer precipitation indicates a large increase of precipitation, especially in the recent 10 years both in the Changma and the post-Changma period. However, the magnitude of change and the period of the maximum peak presents remarkable contrasts among stations. The most distinct decadal change occurs at Seoul, Busan, and Gangnueng. The precipitation amount is increasing significantly during the post-Changma period at Gangnueng, while the precipitation increases in the period between two maximum precipitation peaks during summer at Seoul and Busan.

Application of High Resolution Multi-satellite Precipitation Products and a Distributed Hydrological Modeling for Daily Runoff Simulation (고해상도 다중위성 강수자료와 분포형 수문모형의 유출모의 적용)

  • Kim, Jong Pil;Park, Kyung-Won;Jung, Il-Won;Han, Kyung-Soo;Kim, Gwangseob
    • Korean Journal of Remote Sensing
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    • v.29 no.2
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    • pp.263-274
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    • 2013
  • In this study we evaluated the hydrological applicability of multi-satellite precipitation estimates. Three high-resolution global multi-satellite precipitation products, the Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA), the Global Satellite Mapping of Precipitation (GSMaP), and the Climate Precipitation Center (CPC) Morphing technique (CMORPH), were applied to the Coupled Routing and Excess Storage (CREST) model for the evaluation of their hydrological utility. The CREST model was calibrated from 2002 to 2005 and validated from 2006 to 2009 in the Chungju Dam watershed, including two years of warm-up periods (2002-2003 and 2006-2007). Areal-averaged precipitation time series of the multi-satellite data were compared with those of the ground records. The results indicate that the multi-satellite precipitation can reflect the seasonal variation of precipitation in the Chungju Dam watershed. However, TMPA overestimates the amount of annual and monthly precipitation while GSMaP and CMORPH underestimate the precipitation during the period from 2002 to 2009. These biases of multi-satellite precipitation products induce poor performances in hydrological simulation, although TMPA is better than both of GSMaP and CMORPH. Our results indicate that advanced rainfall algorithms may be required to improve its hydrological applicability in South Korea.

Estimating the Monthly Precipitation Distribution of North Korea Using the PRISM Model and Enhanced Detailed Terrain Information (PRISM과 개선된 상세 지형정보를 이용한 월별 북한지역 강수량 분포 추정)

  • Kim, Dae-jun;Kim, Jin-Hee
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.21 no.4
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    • pp.366-372
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    • 2019
  • The PRISM model has been used to estimate precipitation in South Korea where observation data are readily available at a large number of weather station. However, it is likely that the PRISM model would result in relatively low reliability of precipitation estimates in North Korea where weather data are available at a relatively small number of weather stations. Alternatively, a hybrid method has been developed to estimate the precipitation distribution in area where availability of climate data is relatively low. In the hybrid method, Regression coefficients between the precipitation-terrain relationships are applied to a low-resolution precipitation map produced using the PRISM. In the present study, a hybrid approach was applied to North Korea for estimation of precipitation distribution at a high spatial resolution. At first, the precipitation distribution map was produced at a low-resolution (2,430m) using the PRISM model. Secondly, a deviation map was prepared calculating difference between altitudes of synoptic stations and virtual terrains produced using 270m-resolution digital elevation map (DEM). Lastly, another deviation map of precipitation was obtained from the maps of virtual precipitation produced using observation data from the synoptic weather stations and both synoptic and automated weather station (AWS), respectively. The regression equation between precipitation and terrain was determined using these deviation maps. The high resolution map of precipitation distribution was obtained applying the regression equation to the low-resolution map. It was found that the hybrid approach resulted in better representation of the effects of the terrain. The precipitation distribution map for the hybrid approach had similar spatial pattern to that for the existing method. It was estimated that the mean annual cumulative precipitation of entire territory of North Korea was 1,195mm with a standard deviation of 253mm.

A Simulation Model for the Intermittent Hydrologic Process (II) - Markov Chain and Continuous Probability Distribution - (간헐(間歇) 수문과정(水文過程)의 모의발생(模擬發生) 모형(模型)(II) - Markov 연쇄와 연속확률분포(連續確率分布) -)

  • Lee, Jae Joon;Lee, Jung Sik
    • Journal of The Korean Society of Civil Engineers
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    • v.14 no.3
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    • pp.523-534
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    • 1994
  • The purpose of this study is to develop computer simulation model that produce precipitation patterns from stochastic model. In the paper(I) of this study, the alternate renewal process(ARP) is used for the daily precipitation series. In this paper(Il), stochastic simulation models for the daily precipitation series are developed by combining Markov chain for the precipitation occurrence process and continuous probability distribution for the precipitation amounts on the wet days. The precipitation occurrence is determined by first order Markov chain with two states(dry and wet). The amounts of precipitation, given that precipitation has occurred, are described by a Gamma, Pearson Type-III, Extremal Type-III, and 3 parameter Weibull distribution. Since the daily precipitation series shows seasonal variation, models are identified for each month of the year separately. To illustrate the application of the simulation models, daily precipitation data were taken from records at the seven locations of the Nakdong and Seomjin river basin. Simulated data were similar to actual data in terms of distribution for wet and dry spells, seasonal variability, and precipitation amounts.

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Development of a Stochastic Precipitation Generation Model for Generating Multi-site Daily Precipitation (다지점 일강수 모의를 위한 추계학적 강수모의모형의 구축)

  • Jeong, Dae-Il
    • Journal of The Korean Society of Civil Engineers
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    • v.29 no.5B
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    • pp.397-408
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    • 2009
  • In this study, a stochastic precipitation generation framework for simultaneous simulation of daily precipitation at multiple sites is presented. The precipitation occurrence at individual sites is generated using hybrid-order Markov chain model which allows higher-order dependence for dry sequences. The precipitation amounts are reproduced using Anscombe residuals and gamma distributions. Multisite spatial correlations in the precipitation occurrence and amount series are represented with spatially correlated random numbers. The proposed model is applied for a network of 17 locations in the middle of Korean peninsular. Evaluation statistics are reported by generating 50 realizations of the precipitation of length equal to the observed record. The analysis of results show that the model reproduces wet day number, wet and dry day spell, and mean and standard deviation of wet day amount fairly well. However, mean values of 50 realizations of generated precipitation series yield around 23% Root Mean Square Errors (RMSE) of the average value of observed maximum numbers of consecutive wet and dry days and 17% RMSE of the average value of observed annual maximum precipitations for return periods of 100 and 200 years. The provided model also reproduces spatial correlations in observed precipitation occurrence and amount series accurately.

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The Climatological Characteristics of Monthly Precipitation over Han- and Nakdong-river Basins: Part I. Variability of Area Averaged Time Series (한강과 낙동강 유역평균 월강수량의 기후 특성: I. 유역평균 시계열의 변동)

  • Baek, Hee-Jeong;Kwon, Won-Tae
    • Journal of Korea Water Resources Association
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    • v.38 no.2
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    • pp.111-119
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    • 2005
  • The climatological characteristics of the area averaged monthly precipitation over the Han- and Nakdong-river basins were investigated. The data used for this study is monthly precipitation data from 51 meteorological stations for the period of 1954 to 2002. The magnitude of area averaged precipitation in the Han-river basin was about 10% larger than that in the Nakdong-river basin. However, the variability of two monthly precipitation time series exhibited similar characteristics: April precipitation tends to decrease and August precipitation increase significantly, while there was no significant trend for the other months. There were some indications of abrupt change around the 1970's in the periodicity of precipitation and relationship with El Nino index. September precipitation showed negative correlation with NINO3 index but November precipitation, positive correlation with NINO3 index, indicating a possible connection with the global-scale phenomena.

The Regional Characteristics of Daily Precipitation Intensity in Korea for Recent 30 Years (최근 30년간 한반도 일 강수강도의 지역적 특성)

  • Kim Eun-Hee;Kim Maeng-Ki;Lee Woo-Seop
    • Journal of the Korean earth science society
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    • v.26 no.5
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    • pp.404-416
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    • 2005
  • The seasonal and regional distribution of precipitation in Korea, terms of the amount of precipitation per day, number of days, and intensity was analyzed using precipitation data from 1971 to 2000. The significance level of the linear trend of these data was also investigated using the analysis of variance of each variable. The amount of precipitation per day less than 80 mm per day appeared in the Honam area which also shows a large number of precipitation day value during the fall and winter. However, the lowest amuont of precipitation per day was shown in the Youngnam area. The positive trend of the annual precipitation amount has also been detected in all stations except for a few station in Honam, and the positive trend of precipitation intensity is statistically significant in most of the stations at the Chungcheong and Gyeonggi area. The linear trend of precipitation intensity in these area is found to be significant at the $5\%$ level.

Effects of Continental Evaporation for Precipitation Over East Asia in the Past and the Future of HadGEM2-AO Climate Model (HadGEM2-AO 기후모델에 따른 과거와 미래의 동아시아 강수량에 대한 육지 증발량의 영향)

  • Kim, Jin-Uk;Lee, Johan;Boo, Kyung-On;Shim, Sungbo;Kim, Jee-Eun;Byun, Young-Hwa
    • Atmosphere
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    • v.26 no.4
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    • pp.553-563
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    • 2016
  • Land evaporation contribution to precipitation over East Asia is studied to understand terrestrial moisture source of continental precipitation. Moisture recycling of precipitation relying on terrestrial evaporation is estimated based on the analysis method of Van der Ent et al. (2010). We utilize HadGEM2-AO simulations for the period of 1970~1999 and 2070~2099 from RCP8.5. Globally, 46% of terrestrial precipitation is depending from continental evaporation. 58% of terrestrial evaporation returns as continental precipitation. Over East Asia, precipitation has been affected by local evaporation and transported moisture. The advection of upwind continental evaporation results from the prevailing westerlies from the midwestern of Eurasian continent. For the present-day period, about 66% of the precipitation over the land of East Asia originates from land evaporation. Regionally, the ratios change and the ratios of precipitation terrestrial origin over the Northern inland and Southern coast of East Asia are 82% and 48%, respectively. Seasonally, the continental moisture recycling ratio is larger during summer (JJA) than winter (DJF). According to RCP8.5, moisture recycling ratio is expected to change. At the end of the 21st century, the impact of continental moisture sources for precipitation over East Asia is projected to be reduced by about 5% compared to at the end of 20th century. To understand the future changes, moisture residence time change is investigated using depletion and replenishment time.

Precipitation Behaviors of Rapidly Solidified and Hot Worked Al-Zr Base Alloys (급냉응고 및 열간가공된 Al-Zr계 합금의 석출거동)

  • Park, Won-Wook
    • Journal of Korea Foundry Society
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    • v.15 no.2
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    • pp.194-200
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    • 1995
  • Rapidly Solidified (RS) Al-Zr base splats with various alloy contents were prepared by atomization-splat quenching method to understand the continuous and discontinuous precipitation in the aged alloys. And the RS alloys were consolidated by hot extrusion and swaging to analyze the effect of plastic deformation on the precipitation behavior. Discontinuous precipitation dominated at relatively low temperature in the Al-Zr alloy, whereas both V additions to Al-Zr alloys and hot metal working appeared to suppress the discontinuous precipitation. As continuous precipitation is favored in the grain interiors, the driving force for discontinuous precipitation become to disappear with a further process.

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Precipitation Change in Korea due to Atmospheric $ Increase

  • Oh, Jai-Ho;Hong, Sung-Gil
    • Korean Journal of Hydrosciences
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    • v.7
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    • pp.87-106
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    • 1996
  • A precipitation change scenario in Korea due to atmospheric $ doubling has been provided with a mixed method (Rebinson and Finkelstein, 1991) based on the simulated precipitation data by three GCM(CCC, UI, and GFDL GCM) experiments. Through the analysis the precipitation change by atmospheric $ doubing can be summarized as follows : Korea may have more precipitation as much as 25mm/yr during spring season and more less 50 mm/yr during summer and autumn, respectively. In the contrary Korea may have less rainfall as much as 13 mm/yr during winter. In terms of percentage with respect to current climatological value of precipitation Korea may have more rain as much as 10%, 13% and 24%, respectively, for spring, summer and autumn than current climate. However, Korea may have less precipitation during winter than current climatological average.

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