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Wave Height Estimation with a Short Return Period

짧은 재현기간의 파고 추정

  • Hong-Yeon Cho (Marine Bigdata.AI Center, Korea Institute of Ocean Science & Technology) ;
  • Min-Ji Che (Dokdo Research Center, East Sea Research Institute, Korea Institute of Ocean Science & Technology) ;
  • Gi-Seop Lee (Marine Bigdata.AI Center, Korea Institute of Ocean Science & Technology, KIOST)
  • 조홍연 (한국해양과학기술원 해양빅데이터.AI센터) ;
  • 제민지 (한국해양과학기술원 독도전문연구센터) ;
  • 이기섭 (한국해양과학기술원 해양빅데이터.AI센터)
  • Received : 2024.08.07
  • Accepted : 2024.09.05
  • Published : 2024.10.31

Abstract

Bisection and grid search methods are proposed as wave height estimation techniques for short return periods (hereafter RP; reference, one year) using long-term wave monitoring data. The proposed method is compared and evaluated with the estimation results using GP (generalized Pareto) and GEV (generalized extreme value) distribution functions, which are widely used as extreme value analysis methods. The wave height data used for the estimation were KMA Ulleungdo Ocean Buoy's wave height data observed for 12 years from 2012 to 2023. The estimation results show that the annual frequency wave height is 4.55 m, the 90% confidence interval (±5%) is [4.18, 4.69] (m), and the confidence interval for the RP is [0.58, 1.42] (years). The difference from the GP and GEV estimation results (4.61 m and 4.53 m, respectively) was statistically 'no significance difference.' The method proposed in this study can estimate design variables for RPs without assumptions on candidate extreme distribution functions or parameter estimation procedures, so it can be used to estimate wave heights for short RPs of one year or less when observation data of approximately ten years or more are available.

파랑 관측자료를 이용하여 짧은 재현기간(기준: 1년)에 대한 파고 추정 기법으로 격자 검색(Grid search), 양분검색(Bi-section search) 방법을 제안한다. 제안한 방법은 극치 해석기법으로 널리 이용되는 GPD, GEV 분포함수를 이용한 추정 결과와 비교/평가하였다. 추정에 사용된 파고 자료는 2012년부터 2023년까지, 12년 동안 관측된 KMA 울릉도 해양기상부이, 파고부이의 파고 자료를 이용하였으며, 추정 결과 1년 빈도 파고는 4.55 m, 5~95% 신뢰구간은 [4.18, 4.69](m), 재현기간에 대한 신뢰구간은 [0.58, 1.42](년)로 추정되었다. 전통적인 극치해석 기법으로 이용되는 GPD, GEV 추정 결과는 각각 4.61 m, 4.53m로, 본 연구에서 제안하는 방법으로 추정한 결과와 통계적으로 유의미한 차이는 보이지 않는 것으로 파악되었다. 본 연구에서 제안한 방법은 특정 극치분포 함수에 대한 가정, 매개변수 추정 절차 없이도 재현기간에 대한 설계 변량 추정을 할 수 있기 때문에, 대략 10년 이상의 관측자료가 가용한 경우에는 1년 또는 그 이하의 짧은 재현기간에 대한 파고 추정에 활용할 수 있다.

Keywords

Acknowledgement

본 연구는 독도의 지속가능한 이용연구 사업(PG54140)의 지원을 받아 수행되었으며, 본 연구에서 사용한 울릉도, 독도지점에서 장기 파랑 관측자료를 제공해 주신 기상청에 감사드린다.

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