• 대기
• /
• 제18권4호
• /
• pp.475-483
• /
• 2008

The hourly precipitation data from 1973 to 2007 observed at 60 weather stations over Korea are used to characterize the diurnal and semidiurnal cycles of total precipitation amount, intensity and frequency and examine their spatial patterns and interannual variations. The results show that the diurnal cycle peaks in the morning (03-09LST) and the semidiurnal cycle peaks in the late afternoon (16-20LST). It is found that the spatial variations of the peak phase of diurnal or semidiurnal cycle relative to their corresponding seasonal mean cycle are considerably small (large) for total precipitation amount and intensity (frequency, respectively) in both winter and summer seasons. Also, the diurnal phase variations for individual years relative to the seasonal mean precipitation show the significant interannual variability with dominant periods of 2-5 years for all three elements of precipitation and the slightly decreasing trend in total precipitation amount and intensity. To compare the relative contributions of frequency and intensity to the diurnal and semidiurnal cycles (and their sum) of total precipitation amount, the percentage variance of each cycle of precipitation amount explained by frequency is estimated. The fractional variance accounted for by precipitation intensity is greater than that of frequency for these three cycles. All above analyses suggest that intensity plays a more important role than frequency in the diurnal variations of total precipitation amount.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2004년도 학술발표회
• /
• pp.1247-1250
• /
• 2004

The amount of precipitation during El Nino over Korea increases in Summer and Winter. However, it decreases in Fall, and exhibits not much change in Spring. Especially, the amount of precipitation during September of El Nino year is much less than that of the September of non-El Nino year. The amount of precipitation during El Nino year of October and November shows similar amount of precipitation during non-El Nino year of the same period. The reason for decreasing precipitation in September is related to the weakening of the 2nd rainy season during the development of El Nino over East Asia including Korea. Insufficiency of fall precipitation during El Nino year influences drought in Spring for next year.

• 대기
• /
• 제33권4호
• /
• pp.367-385
• /
• 2023

The variabilities of precipitation and particulate matters (i.e., PM₁₀ and PM_2.5) and the scavenging efficiency of PMs by precipitation were quantified using long-term measurements in Seoul, Korea. The 21 years (2001~2021) measurements of precipitation and PM₁₀ mass concentrations, and the 7 years (2015~2021) of PM_2.5 mass concentrations were used. Statistical analysis was performed for each period (i.e., year, season, and month) to identify the long-term variabilities of PMs and precipitation. PM₁₀ and PM_2.5 decreased annually and the decreasing rate of PM₁₀ was greater than PM_2.5. The precipitation intensity did not show notable variation, whereas the annual precipitation amount showed a decreasing trend. The summer precipitation amount contributed 61.10% to the annual precipitation amount. The scavenging efficiency by precipitation was analyzed based on precipitation events separated by 2-hour time intervals between hourly precipitation data for 7 years. The scavenging efficiencies of PM₁₀ and PM_2.5 were quantified as a function of precipitation characteristics (i.e., precipitation intensity, amount, and duration). The calculated average scavenging efficiency of PM₁₀ (PM_2.5) was 39.59% (35.51%). PM₁₀ and PM_2.5 were not always simultaneously scavenged due to precipitation events. Precipitation events that simultaneously scavenged PM₁₀ and PM_2.5 contributed 42.24% of all events, with average scavenging efficiency of 42.93% and 43.39%. The precipitation characteristics (i.e., precipitation intensity, precipitation amount, and precipitation duration) quantified in these events were 2.42 mm hr^-1, 15.44 mm, and 5.51 hours. This result corresponds to 145% (349%; 224%) of precipitation intensity (amount; duration) for the precipitation events that do not simultaneously scavenge PM₁₀ and PM_2.5.

• 한국수자원학회논문집
• /
• 제52권6호
• /
• pp.421-427
• /
• 2019

우리나라의 지하수 개발가능량은 10년 빈도에 해당하는 갈수시의 강수량에 함양율을 곱한 값으로 정해져 왔다. 하지만 실무에서는 강수량의 빈도 해석을 생략하고 최근 10년 중 최소 강수량에 평균 함양율을 곱한 값을 개발가능량으로 사용하고 있다. 따라서 실제 10년 빈도의 갈수시 강수량이 적용되기 보다는 기간 선택에 따라 적용하는 강수량이 정해지는 모순이 발생한다. 이에 본 연구에서는 이동 10년 최소강수량 평균과 강수량의 규모를 고려한 함양량을 이용하여 개발가능량을 산정하는 방법을 제안하였다. 이 방법을 의왕 과천 성남지역에 적용하여 개발가능량을 산정하고 보편적으로 이용되고 있는 기존 방법에 의한 결과와 비교 검토하였다. 그 결과 극심한 가뭄해를 포함한 기간에서 10년 최소강수량을 선택할 경우 개발가능량이 과소하게 산정되는 문제를 이동 평균 최저 강수량을 사용함으로써 극복할 수 있는 것으로 확인되었다.

• 대기
• /
• 제22권1호
• /
• pp.57-71
• /
• 2012

Influences of orographic and ocean effect, which depend on the detailed geographic characteristics, upon winter time (December-February) precipitation in the Yeongdong region are investigated. Most of precipitation events in the Yeongdong region during the wintertime are associated with moist northeasterly (coming from the northeast direction) winds and also the spatial distribution of precipitation shows a great difference between Mountain area (Daegwallyeong) and Coastal area (Gangneung). The linear correlation coefficient between the meteorological variables obtained from NCEP/NCAR Reanalysis Data and precipitation amount for each precipitation type is calculated. Mountain type precipitation is dominated by northeasterly wind speed of the low level (1000 hPa and 925 hPa) and characterized with more precipitation in mountain area than coastal area. However, Coastal type precipitation is affected by temperature difference between ocean and atmosphere, and characterized with more precipitation in coastal area than mountain area. The results are summarized as follows; In the case of mountain type precipitation, the correlation coefficient between wind speed at 1000 hPa (925 hPa) and precipitation amount at Daegwallyeong is 0.60 (0.61). The correlation is statistical significant at 1% level. In the case of coastal type precipitation, the correlation coefficient of temperature difference between ocean and 925 hPa (850 hPa) over the East sea area and precipitation amount at Gangneung is 0.33 (0.34). As for the mountain type precipitation, a detailed analysis was conducted in order to verify the relationship between precipitation amount at Daegwallyeong and low level wind speed data from wind profiler in Gangneung and Buoy in the East Sea. The results also show the similar behavior. This result indicates that mountain type precipitation in the Yeongdong region is closely related with easterly wind speed. Thus, the statistical analysis of the few selected meteorological variables can be a good indicator to estimate the precipitation totals in the Yeongdong region in winter time.

• 한국환경과학회지
• /
• 제26권3호
• /
• pp.289-302
• /
• 2017

During the research period, error analysis of the amount of daily precipitation was performed with data obtained from 2DVD, Parsivel, and AWS, and from the results, 79 days were selected as research days. According to the results of a synoptic meteorological analysis, these days were classified into 'LP type, CF type, HE type, and TY type'. The dates showing the maximum daily precipitation amount and precipitation intensity were 'HE type and CF type', which were found to be attributed to atmospheric instability causing strong ascending flow, and leading to strong precipitation events. Of the 79 days, most days were found to be of the LP type. On July 27, 2011 the daily precipitation amount in the Korean Peninsula reached over 80 mm (HE type). The leading edge of the Northern Pacific high pressure was located over the Korean Peninsula with unstable atmospheric conditions and inflow of air with high temperature and high humidity caused ascending flow, 120 mm/h with an average precipitation intensity of over 9.57 mm/h. Considering these characteristics, precipitation in these sample dates could be classified into the convective rain type. The results of a precipitation scale distribution analysis showed that most precipitation were between 0.4-5.0 mm, and 'Rain' size precipitation was observed in most areas. On July 9, 2011, the daily precipitation amount was recorded to be over 80 mm (CF type) at the rainy season front (Jangma front) spreading across the middle Korean Peninsular. Inflow of air with high temperature and high humidity created unstable atmospheric conditions under which strong ascending air currents formed and led to convective rain type precipitation.

• 대기
• /
• 제19권2호
• /
• pp.199-211
• /
• 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.

• 한국수자원학회논문집
• /
• 제45권9호
• /
• pp.875-885
• /
• 2012

본 연구에서는 미계측 강수자료를 생성하여 공간 해석함으로써 제주도의 정확한 수문총량을 산정하였다. 미계측 강수자료는 본 연구에서 제시된 수정된 다중회귀선형 모형으로 생성하였으며 공간강수량은 PRISM을 적용하여 구하였다. 수정된 다중선형회귀 모형에 의한 미계측 강수자료의 추정 값들은 기존의 강수 패턴과 유사한 양상을 나타내어 모형의 정확도가 우수한 것으로 나타났으며, 공간강수량의 해석결과는 Case 1(원자료)과 Case 2(미계측 강수자료를 보완한 자료)의 연평균 강수량이 약 1.5%의 미미한 차이를나타내었으나 고도별 연평균 강수량 차이는 최대 37.4%가 증가하는 것으로 산정되었다. 따라서 본 연구에서 제안한 미계측 관측 자료 생성방법은 현재 관측소의 밀도가 낮은 곳과 국지적으로 강수량의 변화가 큰 곳에서의 수문총량의 산정시 유용할 것으로 판단된다.

• 대기
• /
• 제18권2호
• /
• pp.111-120
• /
• 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.

• 한국농공학회논문집
• /
• 제53권3호
• /
• pp.1-11
• /
• 2011

The temporal variability of spring (March, April, May) monthly precipitation, precipitation effectiveness, monthly maximum precipitation, monthly precipitation of different durations, and the precipitation days over several threshold (i.e. 0, 10, 20, 30, 40, and 50 mm/day) of 59 weather stations between 1973 and 2009 were analyzed. Also to analyze the regional characteristics of temporal variability, 59 weather stations were classified by elevations, latitudes, longitudes, river basins, inland or shore (east sea, south sea, west sea) area and the level of urbanization. Results demonstrated that trends of variables increase in April and decrease in May except precipitation day. Overall trend of precipitation amount and precipitation effectiveness is same but precipitation effectiveness of several sites decrease despite the trend of precipitation amount increases which may be caused by the air temperature increase. Therefore more effective water supply strategy is essential for Spring season. Regional characteristics of Spring precipitation variability can be summarized that increase trend during May become stronger with the increase of latitude and elevation which is similar to that of Summer season. The temporal variability of variables showed different behaviors according to river basins, inland or shore (east sea, south sea, west sea) area and the level of urbanization.