The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY (한국해양학회지:바다)

The Korean Society of Oceanography (한국해양학회)
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Estimation of Optimal Weight in Tidal Modeling with the Adjoint Method

조석 모델링에서 adjoint 방법 적용시 적정 가중치 산정

  • Lee, Jae-Hak (Marine Environment and Climate Change Laboratory, Korea Ocean Research and Development Institute) ;
  • Park, Kyeong (Department of Oceanography, Inha University) ;
  • Song, Yong-Sik (Department of Oceanography, Inha University)
  • 이재학 (한국해양연구소 해양환경기후연구본부) ;
  • 박경 (인하대학교 해양학과) ;
  • 송용식 (인하대학교 해양학과)
  • Published : 2000.08.31
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Abstract

The adjoint method is a method of data assimilation to improve the model results by seeking for model parameters that minimize the cost function and satisfy the governing equations of a model simultaneously. An adjoint package was set up for the two-dimensional linear tidal model and was applied to an idealized domain for an optimal estimation of the open boundary conditions. The assimilating data were selected from the results of forward modeling. Attention is paid on the response of the adjoint package to weighting parameters, the importance of initial estimates of model parameters and the applicability of the adjoint package to the case with varying depth. A procedure to determine optimal weight is presented based on the relationships between weights and other factors.

자료동화기법의 하나인 adjoint 방법은 제약조건으로서 모델의 기본방정식을 만족시키는 동시에 모델 결과와 관측자료 차이의 함수인 비용함수의 크기를 최소화시키는 모델변수를 찾아냄으로서 모델 결과를 향상시키는 기법이다. 본 연구에서는 수평방향 2차원 선형 조석모델과 adjoint 모델로 구성된 adjoint 꾸러미를 수립하고, 이를 임의로 설정한 직사각형 모델영역에 적용하였다. 조석모델로부터의 조위 모델 결과를 관측자료로 삼아 개방경계조건인 조위의 진폭을 역 추정하는 수치실험을 실시하여 자료 가중치에 대한 반응, 모델변수 초기 추정치의 중요성 및 지형 변화에 대한 반응 등을 살펴보았다 특히, adjoint꾸러미 적용시 대부분 경험적으로 설정되어왔던 가중치의 선정방법을 제시하였다.

Keywords

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