• Title/Summary/Keyword: correlograms

Search Result 15, Processing Time 0.018 seconds

Analysis of Rainfall Spatial Correlation Structure Using Minutely Data (분단위 자료를 이용한 강우의 공간상관구조 분석)

  • Yoo, Chul-Sang;Park, Chang-Yeol;Kim, Kyoung-Jun;Jun, Kyung-Soo
    • Journal of the Korean Society of Hazard Mitigation
    • /
    • v.8 no.6
    • /
    • pp.113-120
    • /
    • 2008
  • This study analyzed the spatial correlograms of minutely rainfall data with respect to various accumulation times. A bivariate mixed lognormal distribution was applied for rainfall modelling. A total of 26 minutely rainfall data sets from rain gauge stations in the central part of Korean peninsula were analyzed, also repeated for several storm types like Jang-Ma, typhoon and convective storms for their comparison. The accumulation times 1, 2, 3, 5, 10, 30 and 60 minutes were considered in this study. As results, it was found that the minutely rainfall data available was not good enough for estimating minutely rainfall intensity at ungaged locations. It seems more practical to use the hourly rainfall data with much higher rain gauge density, if proper methods for interpolation and data dis-aggregation are provided.

Analysis of the Statistical and Time-Series Characteristics for Pan Evaporation (증발계 증발량의 시계예 및 통계적 특성 분석)

  • 구자웅
    • Magazine of the Korean Society of Agricultural Engineers
    • /
    • v.19 no.3
    • /
    • pp.4472-4482
    • /
    • 1977
  • In order to estimate furture consumtive use, some statistical characteristics of 22-year pan evaporation data at four selected stations were calculated in this study. Districal distribution, trend analysis and time-series, statistical and periodic analysis for annual, monethly and ten-day values were performed in the statistical analysis. The stations are Seoul, Taeku, Jeonju and Mokpo for monthly data, and Suweon data are compared to the reported Penman values. The results are as followed: 1. Annual evaporation ranged to 990-1,375mm varying with the locations of the stations. The Districal distribution of evaporation in the Republic is shown in Fig. 1. 2. The trend analysis for annual evaporation resulted in detail in Table 2 and Fig. 2, through simple moving average methods. The results show relatively short-period data of about 10 years would be acceptable for field use. 3. The means and dispersions of monthly evaporation at four stations are detailed in Table 3. 4. The monthly evaporation approached to the trend of normal distribution Fig. 3 showed the examples of normal distribution for each typical monthly data. 5. The correlograms detailed in Fig. 4, shows the time-series characteristics of monthly evaporation, whose periodic term should be twelve months. 6. The periodic analysis for monthly evapolation results in Table 4. Fig. 5 shows the comparison of estimated values to actual and the trend approaches Shuster's periodic trend. 7. A periodic description of days after March 1 for irrigation periods was developed to predict ten-day evaporation in Fig. 6. The ten-day etraporation is different in the distribution form and occurence period of maximum values from the reported Penman's man's evapotranspiration.

  • PDF

Drought Analysis of Nakdong River Basin Based on Multivariate Stochastic Models (다변량 추계학적 모형을 이용한 낙동강 유역의 가뭄해석에 관한 연구)

  • Heo, Jun-Haeng;Kim, Gyeong-Deok;Jo, Won-Cheol
    • Journal of Korea Water Resources Association
    • /
    • v.30 no.2
    • /
    • pp.155-163
    • /
    • 1997
  • In this study, drought analysis of annual flows of Jindong, Hyunpoong, and Waekwan stations located at Nakdong River Basins was performed based on multivariate stochastic models. The stochastic models used were multivariate autoregressive model (MAR) and multivariate contemporaneous (MCAR) model. MCAR(1) and MAR(1) models were selected to be a appropriate models for these stations based on skewness test of normality, test of uncorrelated residuals, and correlograms of the residual series of each model. The statistics generated by MCAR(1) model and MAR(1) model resembled very closely those computed from historical series. The drought characteristics such as run len호, run sum, and run intensity were fairly well reproduced for the various lengths of generated annual flows based on the MCAR(1) and MAR(1) models. Thus, these drought characteristics may give the important informations in planning mid or long term water supplying systems.

  • PDF

Influence of Snow Accumulation and Snowmelt Using NWS-PC Model in Rainfall-runoff Simulation (NWS-PC 모형을 이용한 강우-유출 모의에서 적설 및 융설 영향)

  • Kang, Shin Uk;Rieu, Seung Yup
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.28 no.1B
    • /
    • pp.1-9
    • /
    • 2008
  • The impact of snow accumulation and snowmelt in rainfall-runoff modelling was analyzed for the Soyanggang dam basin by comparing the measured and simulated discharges simulated by the NWS-PC model. Sugawara's conceptual model was used to simulate the snow accumulation and snowmelt phenomena and NWS-PC model was employed to simulate rainfall-runoff. Parameters in model calibration were estimated by the Multi-step Automated Calibration Scheme and optimized using SCE-UA algorithm in each step. The results of the model calibration and verification show that the model considering snowmelt process is better than the one without consideration of snowmelt under the performance criteria such as RMSE, PBIAS, NSE, and PME. The measured discharge time series has over 60 days of persistence. Correlograms for each simulation showed that the simulated discharge with snowmelt model reproduce the persistence closely to the measured discharge's while the one without snow accumulation and snowmelt model reproduce only 20 days of persistence. The study result indicates that the inclusion of snow accumulation and snowmelt model is important for the accurate simulation of rainfall-runoff phenomena in the Soyanggang dam basin.

Determining the Orientations of Broadband Stations in South Korea using Ambient Noise Cross-correlation (배경잡음 교차상관을 이용한 국내 광대역 지진계의 방위각 보정값 측정)

  • Lee, Sang-Jun;Rhie, Junkee
    • Geophysics and Geophysical Exploration
    • /
    • v.18 no.2
    • /
    • pp.85-90
    • /
    • 2015
  • Orientation corrections for Korean seismic stations were calculated by using ambient noise cross-correlation. This method uses Rayleigh waves extracted from ambient noise cross-correlation instead of teleseismic waveforms from earthquakes, which have been generally used for previous studies. The theoretical background of the method is that the phase of radial-vertical cross-correlation function should be the same as that of $90^{\circ}$ phase-shifted vertical-vertical cross-correlation function. The results calculated from stacked cross-correlograms from Jan. 2007 to Sep. 2008 are comparable to the previous results obtained from teleseismic waveforms. In addition, overall the standard deviations of orientation corrections are less than $5^{\circ}$. The temporal variation in orientation corrections calculated for every 30 days shows no significant change and also standard deviations of them are mostly less than $5^{\circ}$. This means that the orientations of stations used in this study have been kept constant during the period. The sensitivity test for stacking period of the ambient noise cross-correlation method shows that continuous ambient noise record of at least about 30 days is required for estimating reliable orientation corrections.