In this paper a generalized version of the classical Hardy-Littlewood-Polya inequality is given.Furthermore,the Stechkin's problem for a linear differential operator is solved in L_2(R), and the optimal recovery p...In this paper a generalized version of the classical Hardy-Littlewood-Polya inequality is given.Furthermore,the Stechkin's problem for a linear differential operator is solved in L_2(R), and the optimal recovery problem for such differential operator is considered.展开更多
Since the initial international cooperation in the framework of Collaboratory for the Study of Earthquake Predictability(CSEP)in 2007,a lot of forecast models have been developed and served for the earthquake forecast...Since the initial international cooperation in the framework of Collaboratory for the Study of Earthquake Predictability(CSEP)in 2007,a lot of forecast models have been developed and served for the earthquake forecasting experiment in different CSEP testing centers(Schorlemmer et al.,2018).展开更多
This note illustrates the multidimensional dispersion relations that connect the real and imaginary parts of the matrixwhere z(p)) is the boundary value of the impedance
This paper disccusses the inverse scattering problem for one-dimensional Schrodinger operatorsrelated to the general Stark effect. We provide a ganeral framework which can be applied both to theStark-effect operator a...This paper disccusses the inverse scattering problem for one-dimensional Schrodinger operatorsrelated to the general Stark effect. We provide a ganeral framework which can be applied both to theStark-effect operator and the ordinary Schrodinger operator.展开更多
Identifying the environmental conditions that control tropical cyclone(TC)genesis is a challenging problem.This study examines a new method to evaluate the precursors of TC genesis using high-resolution ensemble forec...Identifying the environmental conditions that control tropical cyclone(TC)genesis is a challenging problem.This study examines a new method to evaluate the precursors of TC genesis using high-resolution ensemble forecasts and relative operating characteristic(ROC)diagrams.With an advanced research version of the Weather Research and Forecasting(WRF)model,high-resolution ensemble forecasts(at 5 km horizontal resolution)are conducted in various configurations using a bred vector method to form a set of 140 ensemble members for predicting Hurricane Ernesto’s genesis.Basic evaluation shows that high-resolution ensemble forecasts are able to predict well-developed TCs,whereas the NCEP Global Ensemble Forecast System(GEFS)fails to do so.This set of 140 ensemble members is employed to study the precursors of Hurricane Ernesto’s genesis by contrasting the genesis and nongenesis cases.Specifically,ROC curves,composite figures for genesis and nongenesis cases,and Kolmogorov-Smirnov tests are applied to characterize the relationship between important environmental parameters near the beginning of the simulation and genesis likelihood 15-18 h later.It is found that moist conditions at 850 hPa,vertical wind shear,the strength of the 850 hPa pre existing wave,and upper-level warming play notable roles in Ernesto’s genesis.展开更多
Assimilation of satellite-derived relative humidity(Satellite-RH)is capable of improving sea fog forecasts by saturating the background in the observed foggy areas.Previous studies have achieved saturation by increasi...Assimilation of satellite-derived relative humidity(Satellite-RH)is capable of improving sea fog forecasts by saturating the background in the observed foggy areas.Previous studies have achieved saturation by increasing the moisture only(Method-q).However,this method can lead to large wetting and warming biases within the marine atmospheric boundary layer(MABL).A new method using an RH observation operator(Method-RH)is designed to alleviate these biases by simultaneously adjusting the moisture and the temperature.For comparison,saturation is also achieved by decreasing the temperature only(Method-t).The three Satellite-RH assimilation methods are implemented within the Gridpoint Statistical Interpolation-based three-dimensional variational system and examined for three sea fog cases over the Yellow Sea.The three cases on 28 April 2007,9 April 2009,and 29 March 2015 fail to be predicted without the Satellite-RH assimilation as their MABLs have both warming and drying,drying,and warming biases,respectively.Intercomparisons and evaluations show that Method-RH has the best overall performance of the three methods in terms of the forecast of sea fog and MABL structures as only Method-RH can fully or partially address all the bias scenarios in forecasting sea fog.Compared with Method-q,Method-RH produces more well-defined sea fog areas by adding a smaller amount of moisture as well as decreasing the temperature.Compared with Methodt,Method-RH enlarges the sea fog areas by increasing the amount of moisture in addition to the cooling.展开更多
基金Supported by the National Fund of Natural Sciences.
文摘In this paper a generalized version of the classical Hardy-Littlewood-Polya inequality is given.Furthermore,the Stechkin's problem for a linear differential operator is solved in L_2(R), and the optimal recovery problem for such differential operator is considered.
基金granted by the National Key Research and Development Program of China(Grant No.2018YFE0109700)National Natural Science Foundation of China(Grant No.42004038)the Special Fund of the Institute of Earthquake Forecasting,China Earthquake Administration(Grant No.2020IEF0501)
文摘Since the initial international cooperation in the framework of Collaboratory for the Study of Earthquake Predictability(CSEP)in 2007,a lot of forecast models have been developed and served for the earthquake forecasting experiment in different CSEP testing centers(Schorlemmer et al.,2018).
文摘This note illustrates the multidimensional dispersion relations that connect the real and imaginary parts of the matrixwhere z(p)) is the boundary value of the impedance
文摘This paper disccusses the inverse scattering problem for one-dimensional Schrodinger operatorsrelated to the general Stark effect. We provide a ganeral framework which can be applied both to theStark-effect operator and the ordinary Schrodinger operator.
基金supported by research grant from the Office of Naval research(ONr)through award numbers N000140810308 and N000141310582.
文摘Identifying the environmental conditions that control tropical cyclone(TC)genesis is a challenging problem.This study examines a new method to evaluate the precursors of TC genesis using high-resolution ensemble forecasts and relative operating characteristic(ROC)diagrams.With an advanced research version of the Weather Research and Forecasting(WRF)model,high-resolution ensemble forecasts(at 5 km horizontal resolution)are conducted in various configurations using a bred vector method to form a set of 140 ensemble members for predicting Hurricane Ernesto’s genesis.Basic evaluation shows that high-resolution ensemble forecasts are able to predict well-developed TCs,whereas the NCEP Global Ensemble Forecast System(GEFS)fails to do so.This set of 140 ensemble members is employed to study the precursors of Hurricane Ernesto’s genesis by contrasting the genesis and nongenesis cases.Specifically,ROC curves,composite figures for genesis and nongenesis cases,and Kolmogorov-Smirnov tests are applied to characterize the relationship between important environmental parameters near the beginning of the simulation and genesis likelihood 15-18 h later.It is found that moist conditions at 850 hPa,vertical wind shear,the strength of the 850 hPa pre existing wave,and upper-level warming play notable roles in Ernesto’s genesis.
基金Supported by the National Natural Science Foundation of China(42075069)Key Research and Development Program of Shandong Province(2019GSF111066)。
文摘Assimilation of satellite-derived relative humidity(Satellite-RH)is capable of improving sea fog forecasts by saturating the background in the observed foggy areas.Previous studies have achieved saturation by increasing the moisture only(Method-q).However,this method can lead to large wetting and warming biases within the marine atmospheric boundary layer(MABL).A new method using an RH observation operator(Method-RH)is designed to alleviate these biases by simultaneously adjusting the moisture and the temperature.For comparison,saturation is also achieved by decreasing the temperature only(Method-t).The three Satellite-RH assimilation methods are implemented within the Gridpoint Statistical Interpolation-based three-dimensional variational system and examined for three sea fog cases over the Yellow Sea.The three cases on 28 April 2007,9 April 2009,and 29 March 2015 fail to be predicted without the Satellite-RH assimilation as their MABLs have both warming and drying,drying,and warming biases,respectively.Intercomparisons and evaluations show that Method-RH has the best overall performance of the three methods in terms of the forecast of sea fog and MABL structures as only Method-RH can fully or partially address all the bias scenarios in forecasting sea fog.Compared with Method-q,Method-RH produces more well-defined sea fog areas by adding a smaller amount of moisture as well as decreasing the temperature.Compared with Methodt,Method-RH enlarges the sea fog areas by increasing the amount of moisture in addition to the cooling.