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The Roles of Spatial Locations and Patterns of Initial Errors in the Uncertainties of Tropical Cyclone Forecasts

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Advances in Atmospheric Sciences 2012年第1期29卷 63-78页

作者： CHEN Boyu mu mu National Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China Graduate University of Chinese Academy of Sciences Qingdao266071China National Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China Key Laboratory of Ocean Circulation and Wave Institute of OceanologyChinese Academy of SciencesQingdao266071China Graduate University of Chinese Academy of Sciences Beijing100049China

In this study, a series of sensitivity experiments were performed for two tropical cyclones （TCs）, TC Longwang （2005） and TC Sinlaku （2008）, to explore the roles of locations and patterns of initial errors in uncertainties of TC forecasts. Specifically, three types of initial errors were generated and three types of sensitive areas were determined using conditional nonlinear optimal perturbation （CNOP）, first singular vector （FSV）, and composite singular vector （CSV） methods. Additionally, random initial errors in randomly selected areas were considered. Based on these four types of initial errors and areas, we designed and performed 16 experiments to investigate the impacts of locations and patterns of initial errors on the nonlinear developments of the errors, and to determine which type of initial errors and areas has the greatest impact on TC forecasts. Overall, results from the experiments indicate the following：（1） The impact of random errors introduced into the sensitive areas was greater than that of errors themselves fixed in the randomly selected areas. From the perspective of statisticul analysis, and by comparison, the impact of random errors introduced into the CNOP target area was greatest. （2） The initial errors with CNOP, CSV, or FSV patterns were likely to grow faster than random errors. （3） The initial errors with CNOP patterns in the CNOP target areas had the greatest impacts on the final verification forecasts.

关键词： sensitive area conditional nonlinear optimal perturbation CNOP uncertainty of initial conditions nonlinear development

Challenges and improvement strategies in the hospitalization of chronic multimorbid patients

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World Journal of Clinical Cases 2025年第3期13卷 35-41页

作者： Andres Fontalba-Navas Francisco Pozo muñoz Rogelio Garcia Cisneros Maria Jose Garcia Larrosa Maria del Mar Callejon Gil Ignacio Garcia Delgado Maria Belen Jimenez Martinez Antequera Hospital Northern Málaga Integrated Healthcare AreaAntequera 29200AndalusiaSpain Department of Public Health and Psychiatry University of MálagaMálaga 29010Spain Antequera Hospital Northern Málaga Antequera Integrated Healthcare AreaAntequera 29200MálagaSpain

BACKGROUND Addressing the growing challenge of hospitalizing chronic multimorbid patients,this study examines the strain these conditions impose on healthcare systems at a local level,focusing on a pilot *** diseases and complex patients require comprehensive management strategies to reduce healthcare burdens and improve patient *** proven effective,this pilot model has the potential to be replicated in other healthcare settings to enhance the management of chronic multimorbid *** To evaluate the effectiveness of the high complexity unit(HCU)in managing chronic multimorbid patients through a multidisciplinary care model and to compare it with standard hospital *** The study employed a descriptive longitudinal approach,analyzing data from the Basic Minimum Data Set(BMDS)to compare hospitalization variables among the HCU,the Internal Medicine Service,and other services at Antequera Hospital throughout *** HCU,designed for patients with complex chronic conditions,integrates a patient-centered model emphasizing multidisciplinary care and continuity *** The study employed a descriptive longitudinal approach,analyzing data from the BMDS to compare hospitalization variables among the HCU,the Internal Medicine Service,and other services at Antequera Hospital throughout *** HCU,designed for patients with complex chronic conditions,integrates a patient-centered model emphasizing multidisciplinary care and continuity *** This study demonstrates the effectiveness of the HCU in managing patients with complex chronic diseases through a multidisciplinary *** coordinated care provided by the HCU results in improved patient outcomes,reduced unnecessary hospitalizations,and better management of patient *** superiority of the HCU compared to standard care is evident in key outcomes such as fewer readmissions and higher patient satisfaction,reinforcing its value as a model of ca

关键词： High complexity unit Chronic multimorbidity Patient-centered care Integrated care Healthcare management

Stability analysis for semi-Markovian switched stochastic systems with asynchronously impulsive jumps

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Science China(Information Sciences) 2021年第1期64卷 162-174页

作者： Xiaowu mu Zenghui HU School of Mathematics and Statistics Zhengzhou University

The almost surely(a.s.) exponential stability is studied for semi-Markovian switched stochastic systems with randomly impulsive jumps. We start from the case that switches and impulses occur synchronously, in which the impulsive switching signal is a semi-Markovian process. For the case that switches and impulses occur asynchronously, the impulsive arrival time sequence and the types of jump maps are driven by a renewal process and a Markov chain, respectively. By applying the multiple Lyapunov function approach, sufficient conditions of exponential stability a.s. are obtained based upon the ergodic property of semi-Markovian process. The validity of the proposed theoretical results is demonstrated by a numerical example.

关键词： stochastic systems multiple Lyapunov function almost surely exponential stability impulsive jumps semi-Markovian switching renewal process

Evaluation of the Forecast Performance for North Atlantic Oscillation Onset

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Advances in Atmospheric Sciences 2019年第7期36卷 753-765页

作者： Guokun DAI mu mu Zhina JIANG Department of Atmospheric and Oceanic Sciences&Institute of Atmospheric Sciences Fudan UniversityShanghai200438China State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing100081China

By utilizing operational forecast products from TIGGE(The International Grand Global Ensemble) during 2006 to 2015,the forecasting performances of the European Centre for Medium-Range Weather Forecasts(ECMWF), National Centers for Environmental Prediction(NCEP), Japan Meteorology Agency(JMA) and China Meteorological Administration(CMA) for the onset of North Atlantic Oscillation(NAO) events are assessed against daily NCEP–NCAR reanalysis data. Twenty-two positive NAO(NAO+) and nine negative NAO(NAO-) events are identified during this time period. For these NAO events,control forecasts, one member of the ensemble that utilizes the currently most proper estimate of the analysis field and the best description of the model physics, are able to predict their onsets three to five days in advance. Moreover, the failure proportion for the prediction of NAO-onset is higher than that for NAO+ onset, which indicates that NAO-onset is harder to forecast. Among these four operational centers, ECMWF has performs best in predicting NAO onset, followed by NCEP,JMA, and then *** forecasting performance of the ensemble mean is also investigated. It is found that, compared with the control forecast, the ensemble mean does not improve the forecasting skill with respect to the onset time of NAO events. Therefore,a confident forecast of NAO onset can only be achieved three to five days in advance.

关键词： NAO onset operational forecast TIGGE dataset

Ensemble prediction experiments using conditional nonlinear optimal perturbation

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Science China Earth Sciences 2009年第4期52卷 511-518页

作者： JIANG ZhiNa mu mu WANG DongHai State Key Laboratory of Severe Weather(LaSW) Chinese Academy of Meteorological SciencesBeijing 100081China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG) Institute of At-mospheric PhysicsChinese Academy of SciencesBeijing 100029China

Two methods for initialization of ensemble forecasts are compared, namely, singular vector (SV) and conditional nonlinear optimal perturbation (CNOP). The comparison is done for forecast lengths of up to 10 days with a three-level quasi-geostrophic (QG) atmospheric model in a perfect model scenario. Ten cases are randomly selected from 1982/1983 winter to 1993/1994 winter (from December to the following February). Anomaly correlation coefficient (ACC) is adopted as a tool to measure the quality of the predicted ensembles on the Northern Hemisphere 500 hPa geopotential height. The results show that the forecast quality of ensemble samples in which the first SV is replaced by CNOP is higher than that of samples composed of only SVs in the medium range, based on the occurrence of weather re-gime transitions in Northern Hemisphere after about four days. Besides, the reliability of ensemble forecasts is evaluated by the Rank Histograms. The above conclusions confirm and extend those reached earlier by the authors, which stated that the introduction of CNOP improves the forecast skill under the condition that the analysis error belongs to a kind of fast-growing error by using a barotropic QG model.

关键词： ensemble prediction medium range singular vector conditional nonlinear optimal perturbation

Optimal Initial Error Growth in the Prediction of the Kuroshio Large Meander Based on a High-resolution Regional Ocean Model

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Advances in Atmospheric Sciences 2018年第11期35卷 1362-1371页

作者： Xia LIU Qiang WANG mu mu CAS Key Laboratory of Ocean Circulation and Waves Institute of OceanologyChinese Academy of SciencesQingdao 266071China University of Chinese Academy of Sciences Beijing 100049China Institute of Atmospheric Sciences Fudan UniversityShanghai 200433China Pilot National Laboratory for Marine Science and Technology(Qingdao) Qingdao 266237China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China

Based on the high-resolution Regional Ocean Modeling System(ROMS) and the conditional nonlinear optimal perturbation(CNOP) method, this study explored the effects of optimal initial errors on the prediction of the Kuroshio large meander(LM) path, and the growth mechanism of optimal initial errors was revealed. For each LM event, two types of initial error(denoted as CNOP1 and CNOP2) were obtained. Their large amplitudes were found located mainly in the upper 2500 m in the upstream region of the LM, i.e., southeast of Kyushu. Furthermore, we analyzed the patterns and nonlinear evolution of the two types of CNOP. We found CNOP1 tends to strengthen the LM path through southwestward extension. Conversely,CNOP2 has almost the opposite pattern to CNOP1, and it tends to weaken the LM path through northeastward *** growth mechanism of optimal initial errors was clarified through eddy-energetics analysis. The results indicated that energy from the background field is transferred to the error field because of barotropic and baroclinic instabilities. Thus, it is inferred that both barotropic and baroclinic processes play important roles in the growth of CNOP-type optimal initial errors.

关键词： Kuroshio large meander predictability ROMS optimal initial error growth

Finite-Time Stochastic Stability of Random Impulsive Positive System

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Journal of Systems Science & Complexity 2021年第3期34卷 912-923页

作者： YOU Lijie mu Xiaowu School of Mathematics and Statistics Zhengzhou UniversityZhengzhou 450001China

The paper focuses on the finite-time stochastic stability(FTSS)problems for positive system with random *** Lyapunov functions with the probability property of the impulsive interval,first,the sufficient conditions of FTSS for the positive systems affected by one type of random impulses are given;second,the criteria of FTSS for positive systems suffered from multiple types of random impulses are ***,two examples are presented to show the validity of results.

关键词： Finite-time stochastic stability positive system random impulses

Inducing Unstable Grassland Equilibrium States Due to Nonlinear Optimal Patterns of Initial and Parameter Perturbations:Theoretical Models

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Advances in Atmospheric Sciences 2012年第1期29卷 79-90页

作者： SUN Guodong mu mu The State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029 Key Laboratory of Ocean Circulation and Wave Institute of OceanologyChinese Academy of SciencesQingdao 266071

Due to uncertainties in initial conditions and parameters, the stability and uncertainty of grassland ecosystem simulations using ecosystem models are issues of concern. Our objective is to determine the types and patterns of initial and parameter perturbations that yield the greatest instability and uncertainty in simulated grassland ecosystems using theoretical models. We used a nonlinear optimization approach, i.e., a conditional nonlinear optimal perturbation related to initial and parameter perturbations （CNOP） approach, in our work. Numerical results indicated that the CNOP showed a special and nonlinear optimal pattern when the initial state variables and multiple parameters were considered simultaneously. A visibly different complex optimal pattern characterizing the CNOPs was obtained by choosing different combinations of initial state variables and multiple parameters in different physical processes. We propose that the grassland modeled ecosystem caused by the CNOP-type perturbation is unstable and exhibits two aspects： abrupt change and the time needed for the abrupt change from a grassland equilibrium state to a desert equilibrium state when the initial state variables and multiple parameters are considered simultaneously. We compared these findings with results affected by the CNOPs obtained by considering only uncertainties in initial state variables and in a single parameter. The numerical results imply that the nonlinear optimal pattern of initial perturbations and parameter perturbations, especially for more parameters or when special parameters are involved, plays a key role in determining stabilities and uncertainties associated with a simulated or predicted grassland ecosystem.

关键词： conditional nonlinear optimal perturbation initial perturbation parameter perturbation grass-land ecosystem

A General Version of the Retract Method for Discrete Equations

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Acta Mathematica Sinica,English Series 2007年第2期23卷 341-348页

作者： Josef DIBLíK Irena RzIkov Miroslava RZIkov Department of Mathematics Faculty of Electrical Engineering and CommunicationBrno University of TechnologyTechnická 8616 00 BrnoCzech Republic Department of Applied Mathematics Faculty of ScienceCilina UniversityHurbanova 15010 26 CilinaSlovak Republic

We study a problem concerning the compulsory behavior of the solutions of systems of discrete equations u（k ＋ 1） = F（k, u（k））, k ∈ N（a） = {a, a ＋ 1, a ＋ 2 }, a ∈ N,N= {0, 1,... } and F ： N（a） × R^n→R^n. A general principle for the existence of at least one solution with graph staying for every k ∈ N（a） in a previously prescribed domain is formulated. Such solutions are defined by means of the corresponding initial data and their existence is proved by means of retract type approach. For the development of this approach a notion of egress type points lying on the defined boundary of a given domain and with respect to the system considered is utilized. Unlike previous investigations, the boundary can contain points which are not points of egress type, too. Examples are inserted to illustrate the obtained result.

关键词： discrete equation consequent point retract