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variational Reconstruction and Simulation Experiments of Sea Surface Wind Field for Ocean Data Buoy

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Journal of Ocean University of China 2024年第3期23卷 577-582页

作者： LI Yunzhou HUANG Sixun YAN Shen SUN Xuejin QI Suiping WANG Zhongqiu TANG Xiaoyu College of Meteorology and Oceanography National University of Defense TechnologyChangsha 410073China Institute of Oceanographic Instrumentation Qilu University of Technology(Shandong Academy of Sciences)Qingdao 266061China State Key Laboratory of Industrial Control Technology College of Control Science and EngineeringZhejiang UniversityHangzhou 310027China Laoshan Laboratory Qingdao 266237China

The sea surface wind field is an important physical parameter in oceanography and meteorology.With the continuous refinement of numerical weather prediction,air-sea interface materials,energy exchange,and other studies,three-dimensional(3D)wind field distribution at local locations on the sea surface must be measured accurately.The current in-situ observation of sea surface wind parameters is mainly achieved through the installation of wind sensors on ocean data buoys.However,the results obtained from this single-point measurement method cannot reflect wind field distribution in a vertical direction above the sea surface.Thus,the present paper proposes a theoretical framework for the optimal inversion of the 3D wind field structure variation in the area where the buoy is located.The variation analysis method is first used to reconstruct the wind field distribution at different heights of the buoy,after which theoretical analysis verification and numerical simulation experiments are conducted.The results indicate that the use of variational methods to reconstruct 3D wind fields is significantly effective in eliminating disturbance errors in observations,which also verifies the correctness of the theoretical analysis of this method.The findings of this article can provide a reference for the layout optimization design of wind measuring instruments in buoy observation systems and also provide theoretical guidance for the design of new observation buoys in the future.

关键词： moored buoy three-dimensional wind field distribution variational analysis wind field reconstruction

Two-Dimensional variational analysis of Near-Surface Moisture from Simulated Radar Refractivity-Related Phase Change Observations

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Advances in Atmospheric Sciences 2013年第2期30卷 291-305页

作者： Ken-ichi SHIMOSE Ming XUE Robert D.PALMER Jidong GAO Boon Leng CHEONG David J.BODINE Center for analysis and Prediction of Storms University of OklahomaNorman OKUSA Department of Earth and Planetary Sciences Kyushu UniversityFukuokaJapan School of Meteorology University of OklahomaNorman OKUSA Atmospheric Radar Research Center University of OklahomaNorman OKUSA National Severe Storms Laboratory NOAANorman OKUSA

Because they are most sensitive to atmospheric moisture content, radar refractivity observations can provide high-resolution information about the highly variable low-level moisture field. In this study, simulated radar refractivity-related phase-change data were created using a radar simulator from realistic highresolution model simulation data for a dryline case. These data were analyzed using the 2DVAR system developed specifically for the phase-change data. Two sets of experiments with the simulated observations were performed, one assuming a uniform target spacing of 250 m and one assuming nonuniform spacing between 250 m to 4 km. Several sources of observation error were considered, and their impacts were examined. They included errors due to ground target position uncertainty, typical random errors associated with radar measurements, and gross error due to phase wrapping. Without any additional information, the 2DVAR system was incapable of dealing with phase-wrapped data directly. When there was no phase wrapping in the data, the 2DVAR produced ex- cellent analyses, even in the presence of both position uncertainty and random radar measurement errors. When a separate pre-processing step was applied to unwrap the phase-wrapped data, quality moisture anal- yses were again obtained, although the analyses were smoother due to the reduced effective resolution of the observations by interpolation and smoothing involved in the unwrapping procedure. The unwrapping procedure was effective even when significant differences existed between the analyzed state and the state at a reference time. The results affirm the promise of using radar refractivity phase-change measurements for near-surface moisture analysis.

关键词： radar refractivity variational analysis low-level moisture

OPTIMAL CONDITIONS OF GLOBAL EXISTENCE AND BLOW-UP FOR A NONLINEAR PARABOLIC EQUATION

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Acta Mathematica Scientia 2016年第3期36卷 872-880页

作者：蒋毅罗川 VC/VR Lab and Department of Mathematics Sichuan Normal University

According to the variational analysis and the potential well argument, we get the optimal conditions of global existence and blow-up for a type of nonlinear parabolic equations. Furthermore, we give its application in... 详细信息

关键词： nonlinear parabolic equation variational analysis potential well argument global existence blow up

STUDY ON THE ADJOINT METHOD IN DATA ASSIMILATION AND THE RELATED PROBLEMS

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Applied Mathematics and Mechanics(English Edition) 2004年第6期25卷 636-646页

作者：吕咸青吴自库谷艺田纪伟 College of Physical and Environmental Oceanography Ocean University of ChinaQingdao 266003P.R.China Key Laboratory of Physical Oceanography Ministry of EducationQingdao 266003P.R.China College of Information Engineering Qingdao UniversityQingdao 266071P.R.China

It is not reasonable that one can only use the adjoint of model in data assimilation. The simulated numerical experiment shows that for the tidal model, the result of the adjoint of equation is almost the same as that of the adjoint of model: the averaged absolute difference of the amplitude between observations and simulation is less than 5.0 cm and that of the phase-lag is less than 5.0°. The results are both in good agreement with the observed M2 tide in the Bohai Sea and the Yellow Sea. For comparison, the traditional methods also have been used to simulate M2 tide in the Bohai Sea and the Yellow Sea. The initial guess values of the boundary conditions are given first, and then are adjusted to acquire the simulated results that are as close as possible to the observations. As the boundary conditions contain 72 values, which should be adjusted and how to adjust them can only be partially solved by adjusting them many times. The satisfied results are hard to acquire even gigantic efforts are done. Here, the automation of the treatment of the open boundary conditions is realized. The method is unique and superior to the traditional methods. It is emphasized that if the adjoint of equation is used, tedious and complicated mathematical deduction can be avoided. Therefore the adjoint of equation should attract much attention.

关键词： data assimilation variational analysis adjoint method tide open boundary condition

variational Characterization of Multitype Galton-Watson Branching Processes

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Acta Mathematicae Applicatae Sinica 2014年第1期30卷 27-36页

作者： Ying Wang Max-Planck-Institute for Mathematics in the Sciences Academy of Mathematics and Systems Science Chinese Academy of Sciences Warwick Systems Biology Centre University of Warwick

In this paper, we give a variational characterization for the growth rate of a multitype population modelled by a multitype Galton-Watson branching process. In particular, the so-called retrospective process plays an important role in the description of the equilibrium state used in the variational characterization. We define the retrospective process associated with a multitype Galton-Watson branching process and identify it with the mutation process describing the type evolution along typical lineages of the multitype Galton-Watson branching process.

关键词： multitype branching processes retrospective processes variational analysis equilibrium states large deviations

Soliton-like pulse timing jitter in dispersion-managed systems

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Chinese Physics B 2006年第10期15卷 2306-2314页

作者：李齐良李庆山林理彬 School of Communication Hangzhou Dianzi University Hangzhou 310018 China Institute of Physics Sichuan University Chengdu 610064 China

In this paper, the timing jitter in dispersion-managed soliton-like systems with the Caussian pulse is studied by using two methods. Firstly, the derivation of the dynamic equations for the evolution of soliton-like parameters and the timing jitter expressions for the dispersion-managed soliton-like systems are carried out by the perturbed variational method. By analysing and simulating these timing jitter expressions, one can find that the timing jitter is induced by the amplified spontaneous emission noise and the frequency shift, etc. Nonlinear gain can suppress the timing jitter. The chirp sign and the filters action have also effects on the total timing jitter. Secondly, the timing jitter is calculated and analysed by using the moment method. The results of the two methods prove to be consistent with each other.

关键词： timing jitter variational analysis dispersion-managed soliton

Optimal Control of General Functional-Differential Inclusions of Neutral Type

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Optimal Control of General Functional-Differential Inclusion...