Based on the National Climate Center （NCC） of China operational seasonal prediction model results for the period 1983-2009 and the US National Weather Service Climate Prediction Center merged analysis of precipitati...Based on the National Climate Center （NCC） of China operational seasonal prediction model results for the period 1983-2009 and the US National Weather Service Climate Prediction Center merged analysis of precipitation in the same period, together with the 74 circulation indices of NCC Climate System Diagnostic Division and 40 climate indices of NOAA of US during 1951 2009, an analogue-dynamical technique for objective and quantitative prediction of monsoon precipitation in Northeast China is proposed and implemented. Useful information is extracted from the historical data to estimate the model forecast errors. Dominant predictors and the predictors that exhibit evolving analogues are identified through cross validating the anomaly correlation coefficients （ACC） among single predictors, meanwhile with reference of the results from the dynamic analogue bias correction using four analogue samples. Next, an optimal configuration of multiple predictors is set up and compared with historical optimal multi-predictor configurations and then dynamically adjusted. Finally, the model errors are evaluated and utilized to correct the NCC operational seasonal prediction model results, and the forecast of monsoon precipitation is obtained at last. The independent sample validation shows that this technique has effectively improved the monsoon precipitation prediction skill during 2005 -2009. This study demonstrates that the analogue-dynamical approach is feasible in operational prediction of monsoon precipitation.展开更多
An optimal algorithm for the retrieval of chlorophyll, suspended sediments and gelbstoff of case Ⅱ waters in the Pearl River estuary was established with the optical parameters derived from the in-situ data obtained ...An optimal algorithm for the retrieval of chlorophyll, suspended sediments and gelbstoff of case Ⅱ waters in the Pearl River estuary was established with the optical parameters derived from the in-situ data obtained in Jan. 2003 in the same area. And then, the chlorophyll, suspended sediments and gelbstoff of the SeaWiFS pixels on Jan. 29, 2003 corresponding to the in-situ sites of Jan. 25 and 26, 2003 were synchronously retrieved, with average relative errors of 14.9%, 12.1% and 13.6% for chlorophyll, suspended sediments and gelbstoff, respectively. The research results indicated that the optimal retrieval algorithm established here was relatively fit for the retrieval of the chlorophyll, suspended sediments and gelbstoff of case Ⅱ waters in the Pearl River estuary, and had quite good retrieval accuracy.展开更多
Accurate values of masked detector signal(MDS)is the key to the correction capability of wavefront sensorless(WFSless)model-based adaptive optics(AO)system.However,imaging detectors always carry different kinds of noi...Accurate values of masked detector signal(MDS)is the key to the correction capability of wavefront sensorless(WFSless)model-based adaptive optics(AO)system.However,imaging detectors always carry different kinds of noises in real applications,which make MDS deviate from theoretical results.Calculation errors of MDS suffered from the noise were analyzed through theory and simulation.Additionally,considering the method of threshold is usually used to mitigate the noise,we also discussed the influence of threshold on MDS.Results showed that the simulation is consistent with the theory and there exists an optimal threshold to make the error minimum for different noise.A fi tting formula,which can accurately calculate optimal thresholds,was proposed based on the simulated data.Above results can provide a plausible method and theoretical basis to mitigate imaging noise of detectors in real applications.展开更多
基金Supported by the Special Public Welfare Research Fund for Meteorological Profession of China Meteorological Administration(GYHY200806005)National Natural Science Foundation of China(40875040 and 40930952)National Science and Technology Support Program of China(2007BAC29B01 and 2009BAC51B04)
文摘Based on the National Climate Center （NCC） of China operational seasonal prediction model results for the period 1983-2009 and the US National Weather Service Climate Prediction Center merged analysis of precipitation in the same period, together with the 74 circulation indices of NCC Climate System Diagnostic Division and 40 climate indices of NOAA of US during 1951 2009, an analogue-dynamical technique for objective and quantitative prediction of monsoon precipitation in Northeast China is proposed and implemented. Useful information is extracted from the historical data to estimate the model forecast errors. Dominant predictors and the predictors that exhibit evolving analogues are identified through cross validating the anomaly correlation coefficients （ACC） among single predictors, meanwhile with reference of the results from the dynamic analogue bias correction using four analogue samples. Next, an optimal configuration of multiple predictors is set up and compared with historical optimal multi-predictor configurations and then dynamically adjusted. Finally, the model errors are evaluated and utilized to correct the NCC operational seasonal prediction model results, and the forecast of monsoon precipitation is obtained at last. The independent sample validation shows that this technique has effectively improved the monsoon precipitation prediction skill during 2005 -2009. This study demonstrates that the analogue-dynamical approach is feasible in operational prediction of monsoon precipitation.
文摘An optimal algorithm for the retrieval of chlorophyll, suspended sediments and gelbstoff of case Ⅱ waters in the Pearl River estuary was established with the optical parameters derived from the in-situ data obtained in Jan. 2003 in the same area. And then, the chlorophyll, suspended sediments and gelbstoff of the SeaWiFS pixels on Jan. 29, 2003 corresponding to the in-situ sites of Jan. 25 and 26, 2003 were synchronously retrieved, with average relative errors of 14.9%, 12.1% and 13.6% for chlorophyll, suspended sediments and gelbstoff, respectively. The research results indicated that the optimal retrieval algorithm established here was relatively fit for the retrieval of the chlorophyll, suspended sediments and gelbstoff of case Ⅱ waters in the Pearl River estuary, and had quite good retrieval accuracy.
基金This work has been supported by National Natural Science Foundation of China(No.11573011)the Six Talent Peaks Project of Jiangsu Province(No.KTHY-058)+1 种基金the‘333’Talent’s Project in Jiangsu Province(No.BRA2019244)the Hai Yan Project Project(No.LYG52105-2018025)in Lianyungang,the Research and Practice Innovation for Postgraduate in Jiangsu Province(No.KYCX20_2906).
文摘Accurate values of masked detector signal(MDS)is the key to the correction capability of wavefront sensorless(WFSless)model-based adaptive optics(AO)system.However,imaging detectors always carry different kinds of noises in real applications,which make MDS deviate from theoretical results.Calculation errors of MDS suffered from the noise were analyzed through theory and simulation.Additionally,considering the method of threshold is usually used to mitigate the noise,we also discussed the influence of threshold on MDS.Results showed that the simulation is consistent with the theory and there exists an optimal threshold to make the error minimum for different noise.A fi tting formula,which can accurately calculate optimal thresholds,was proposed based on the simulated data.Above results can provide a plausible method and theoretical basis to mitigate imaging noise of detectors in real applications.
