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Construction of Vertical Wind Profile from satellite-Derived Winds for Objective Analysis of Wind Field

Advances in Atmospheric Sciences 1992年第2期9卷 237-246页

作者： P.N.Mahajan D.R.Talwalkar S.Nair S.Rajamani Indian institute of Tropical meteorology Pune-411008Indian Institute of Tropical Meteorology Pune-411008Indian Institute of Tropical Meteorology Pune-411008Indian Institute of Tropical Meteorology Pune-411008

During summer Monex-79, a variety of observing systems viz. research ships, research aircrafts, constant pressure balloons and geostationary satellite etc. were deployed, besides the regular conventional observations. The purpose of these additional systems was to make the best possible data for the studies on various aspects of monsoon circulation. The present study is aimed at the construction of vertical wind profile using cloud motion vectors obtained from GOES (I-O) satellite and to examine whether the constructed wind profiles improves the representation of the monsoon system, flow pattern etc. in the objective analysis. For this purpose, climatological normals of the wind field are considered as the initial guess and the objective analyses of the wind field are made with, first using only data from conventional observations over land areas, subsequently including the constructed winds from cloud motion vectors. These analyses are then compared with the standard analyses of wind field obtained from Quick Look Atlas by T. N. Krishnamurti et al. (1979).It is inferred that satellite estimated mean wind profiles show good agreement with the mean wind profiles of the research ships with RMS errors less than 5 mps below 500 hPa and less than 8 mps above 500 hPa. It is further inferred that the inclusion of constructed winds shows a positive impact on the objective analysis and improvement is seen to be more marked in the data-sparse region of the Arabian sea. Analyses which include the constructed winds show better agreement with the standard analysis, than the analyses obtained using only conventional winds. Thus, results of our study suggest that the wind profiles constructed using cloud motion vectors are of potential use in objective analysis to depict the major circulation features over the Indian region.

关键词： Construction of Vertical Wind Profile from satellite-Derived Winds for Objective Analysis of Wind Field Wind

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End-to-end computational design for an EUV solar corona multispectral imager with stray light suppression

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Astronomical Techniques and Instruments 2024年第1期1卷 31-41页

作者： Jinming Gao Yue Sun Yinxu Bian Jilong Peng Qian Yu Cuifang Kuang Xiangzhao Wang Xu Liu Xiangqun Cui State Key Laboratory of Extreme Photonics and Instrumentation College of Optical Science and EngineeringZhejiang UniversityHangzhou 310027China ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang UniversityHangzhou 310027China Nanjing institute of Astronomical Optics&Technology Chinese Academy of SciencesNanjing 210042China Beijing Environmental satellite Engineering institute Beijing 100094China

An extreme ultraviolet solar corona multispectral imager can allow direct observation of high temperature coronal plasma,which is related to solar flares,coronal mass ejections and other significant coronal *** manuscript proposes a novel end-to-end computational design method for an extreme ultraviolet(EUV)solar corona multispectral imager operating at wavelengths near 100 nm,including a stray light suppression design and computational image *** suppress the strong stray light from the solar disk,an outer opto-mechanical structure is designed to protect the imaging component of the *** the low reflectivity(less than 70%)and strong-scattering(roughness)of existing extreme ultraviolet optical elements,the imaging component comprises only a primary mirror and a curved grating.A Lyot aperture is used to further suppress any residual stray ***,a deep learning computational imaging method is used to correct the individual multi-wavelength images from the original recorded multi-slit *** results and data,this can achieve a far-field angular resolution below 7",and spectral resolution below 0.05 *** field of view is±3 R_(☉)along the multi-slit moving direction,where R☉represents the radius of the solar *** ratio of the corona's stray light intensity to the solar center's irradiation intensity is less than 10-6 at the circle of 1.3 R_(☉).

关键词： EUV solar corona imager Curved grating Stray light suppression Computational multispectral imaging

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Super twisting controller for on-orbit servicing to non-cooperative target

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Chinese Journal of Aeronautics 2015年第1期28卷 285-293页

作者： Chen Binglong Geng Yunhai Research Center of satellite Technology Harbin Institute of Technology

A relative position and attitude coupled controller is proposed for rendezvous and docking between two docking ports located in different spacecraft. It is concerned with servicing to a tumbling non-cooperative target spacecraft in arbitrary orbit subjected to external *** considering both kinematic and dynamical coupled effects of relative rotation on relative translation, a coupled dynamic model is established to represent the relative motion of docking port on target spacecraft with respect to another on the service spacecraft. The spacecraft control is based on the second order sliding mode algorithm of super twisting（ST）. It is schemed to manipulate the relative position and attitude synchronously. A formal proof of the finite time convergence property of the closed-loop system is derived theoretically by the second method of Lyapunov. Numerical simulations with the designed ST controller are presented to validate the analytic analysis by contrast with the twisting control algorithm. Simulation results demonstrate that the proposed relative position and attitude integrated controller is characterized by high precision, strong robustness and high reliability.

关键词： spacecraft orbit cooperative attitude robustness kinematic sliding dynamical rotation concerned

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Modified super twisting controller for servicing to uncontrolled spacecraft

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Journal of Systems Engineering and Electronics 2015年第2期26卷 334-345页

作者： Binglong Chen Yunhai Geng Research Center of satellite Technology Harbin Institute of Technology

A relative position and attitude coupled sliding mode controller is proposed by combining the standard super twisting （ST） control and basic linear algorithm for autonomous rendezvous and docking. It is schemed for on-orbit servicing to a tumbling non- cooperative target spacecraft subjected to external disturbances. A coupled dynamic model is established including both kinemati- cal and dynamic coupled effect of relative rotation on relative translation, which illustrates the relative movement between the docking port located in target spacecraft and another in service spacecraft. The modified super twisting （MST） control algorithm containing linear compensation items is schemed to manipulate the relative position and attitude synchronously. The correction provides more robustness and convergence velocity for dealing with linearly growing perturbations than the ST control algorithm. Moreover, the stability characteristic of closed-loop system is ana- lyzed by Lyapunov method. Numerical simulations are adopted to verify the analysis with the comparison between MST and ST control algorithms. Simulation results demonstrate that the pro- posed MST controller is characterized by high precision, strong robustness and fast convergence velocity to attenuate the linearly increasing perturbations.

关键词： autonomous rendezvous and docking coupled dynamic model modified super twisting Lyapunov method

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A performance evaluation of remotely sensed sea surface salinity products in combination with other surface measurements in reconstructing three-dimensional salinity fields

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Acta Oceanologica Sinica 2017年第7期36卷 15-31页

作者： CHEN Jian YOU Xiaobao XIAO Yiguo ZHANG Ren WANG Gongjie BAO Senliang Beijing institute of Applied meteorology Beijing 100029China institute of meteorology and Oceanography PLA University of Science and TechnologyNanjing 211101China

Several remotely sensed sea surface salinity（SSS） retrievals with various resolutions from the soil moisture and ocean salinity（SMOS） and Aquarius/SAC-D missions are applied as inputs for retrieving salinity profiles（S） using multilinear regressions. The performance is evaluated using a total root mean square（RMS） error, different error sources, and the feature resolutions of the retrieved S fields. In the mixed layer of the salinity, the SSS-S regression coefficients are uniformly large. The SSS inputs yield smaller RMS errors in the retrieved S with respect to Argo profiles as their spatial or temporal resolution decreases. The projected SSS errors are dominant, and the retrieved S values are more accurate than those of climatology in the tropics except for the tropical Atlantic, where the regression errors are abnormally large. Below that level, because of the influence of a sea level anomaly, the areas of high-accuracy S values shift to higher latitudes except in the high-latitude southern oceans, where the projected SSS errors are abnormally large. A spectral analysis suggests that the CATDS-0.25° results are much noisier and that the BEC-L4-0.25° results are much smoother than those of the other retrievals. Aquarius-CAP-1° generates the smallest RMS errors, and Aquarius-V2-1° performs well in depicting large-scale phenomena. BEC-L3-0.25°,which has small RMS errors and remarkable mesoscale energy, is the best fit for portraying mesoscale features in the SSS and retrieved S fields. The current priority for retrieving S is to improve the reliability of satellite SSS especially at middle and high latitudes, by developing advanced algorithms, combining both sensors, or weighing between accuracy and resolutions.

关键词： soil moisture and ocean salinity Aquarius sea surface salinity vertical retrieval feature resolution

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DETECTION OF DAYTIME FOG IN SOUTH CHINA SEA USING MODIS DATA

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Journal of Tropical meteorology 2014年第4期20卷 386-390页

作者：邓玉娇王捷纯曹静曹超雄 Guangzhou Meteorological satellite Station Guangzhou institute of Tropical and Marine meteorology/Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction China Meteorological Administration

Based on a current fog detection theory,a multiband threshold method for MODIS data was put forward to detect daytime fog in the South China *** used Bands 1,2,18,20 and 31 of MODIS data to separate fog from the cloud and the sea *** digital detection indexes were as *** RB1RB2,the pixel was identified to be the sea *** RB1>55%,RB2>55% and TB3120,the pixel was classified to be sea *** method was verified with sea fog data observed from the coastal region of Guangdong during January-April *** of the 13 samples of satellite detection,nine were consistent with the surface observations,three were identified to be low-level the cloud according to the satellite detection but fog according to the surface observations,and only one sample was identified to be the ocean surface by the satellite detection but fog by the surface *** the MODIS data cannot penetrate the cloud or fog,the model was designed for a single field of view which had only one layer of cloud or *** can accurately distinguish fog which is not covered by the cloud,but it identifies fog as cloud if the former is covered by a *** speaking,the model is effective and feasible.

关键词： remote sensing daytime fog MODIS threshold South China Sea

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The Contribution of United States Aircraft Reconnaissance Data to the China Meteorological Administration Tropical Cyclone Intensity Data:An Evaluation of Homogeneity

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Advances in Atmospheric Sciences 2024年第4期41卷 639-654页

作者： Ming YING Xiaoqin LU Shanghai Typhoon institute China Meteorological AdministrationShanghai 200030China

This paper investigates the homogeneity of United States aircraft reconnaissance data and the impact of these data on the homogeneity of the tropical cyclone(TC)best track data for the seasons 1949-1987 generated by the China Meteorological Administration(CMA).The evaluation of the reconnaissance data shows that the minimum central sea level pressure(MCP)data are relatively homogeneous,whereas the maximum sustained wind(MSW)data show both overestimations and spurious abrupt *** comparisons suggest that both the reconnaissance MCP and MSW were well incorporated into the CMA TC best track *** no spurious abrupt changes were evident in the reconnaissance-related best track MCP data,two spurious changepoints were identified in the remainder of the best-track MCP ***,the influence of the reconnaissance MSWs seems to extend to the best track MSWs unrelated to reconnaissance,which might reflect the optimistic confidence in making higher estimates due to the overestimated extreme wind“observations”.In addition,the overestimation of either the reconnaissance MSWs or the best track MSWs was greater during the early decades compared to later decades,which reflects the important influence of reconnaissance data on the CMA TC best track *** wind-pressure relationship(WPR)used in the CMA TC best track dataset is also evaluated and is found to overestimate the MSW,which may lead to inhomogeneity within the dataset between the aircraft reconnaissance era and the satellite era.

关键词： tropical cyclone intensity homogeneity best track aircraft reconnaissance

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A New Hybrid Vertical Coordinate Ocean Model and Its Application in the Simulation of the Changjiang Diluted Water

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China Ocean Engineering 2011年第2期25卷 327-338页

作者：张文静朱首贤董礼先张长宽 College of Physical and Environmental Oceanography Ocean University of China institute of meteorology PLA University of Science and Technology State Key Laboratory of satellite Ocean Environment Dynamics Second Institute of Oceanography College of Ocean Engineering Hohai University

Based on the analysis of the advantages and disadvantages of some vertical coordinates applied in the calculation of the Changjiang diluted water （CDW）, a new hybrid vertical coordinate is designed, which uses σ coordinate for current and σ-z coordinate for salinity. To combine the current and salinity, the Eulerian-Lagrangian method is used for the salinity calculation, and the baroclinic pressure gradient （BPG） is calculated on the salinity sited layers. The new hybrid vertical coordinate is introduced to the widely used model of POM （Princeton Ocean Model） to make a new model of POM-σ-z. The BPG calculations of an ideal case show that POM-σ-z model brings smaller error than POM model does. The simulations of CDW also show that POM-σ-z model is better than POM model on simulating the salinity and its front.

关键词： hybrid vertical coordinate baroclinic pressure gradient Eulerian-Lagrangian method the Changjiang diluted water numerical simulation

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Asymmetric Distribution of Convection in Tropical Cyclones over the Western North Pacific Ocean

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Advances in Atmospheric Sciences 2016年第11期33卷 1306-1321页

作者： Lu YANG Jianfang FEI Xiaogang HUANG Xiaoping CHENG Xiangrong YANG Juli DING Wenli SHI institute of meteorology and Oceanography PLA University of Science and Technology

Forecasts of the intensity and quantitative precipitation of tropical cyclones（TCs） are generally inaccurate, because the strength and structure of a TC show a complicated spatiotemporal pattern and are affected by various factors. Among these, asymmetric convection plays an important role. This study investigates the asymmetric distribution of convection in TCs over the western North Pacific during the period 2005–2012, based on data obtained from the Feng Yun 2（FY2）geostationary satellite. The asymmetric distributions of the incidence, intensity and morphology of convections are *** show that the PDFs of the convection occurrence curve to the azimuth are sinusoidal. The rear-left quadrant relative to TC motion shows the highest occurrence rate of convection, while the front-right quadrant has the lowest. In terms of intensity, weak convections are favored in the front-left of a TC at large distances, whereas strong convections are more likely to appear to the rear-right of a TC within a 300 km range. More than 70% of all MCSs examined here are elongated systems, and meso-β enlongated convective systems（MβECSs） are the most dominant type observed in the outer region of a TC. Smaller MCSs tend to be more concentrated near the center of a TC. While semi-circular MCSs [MβCCSs, MCCs（mesoscale convective complexes）] show a high incidence rate to the rear of a TC, elongated MCSs [MβECSs, PECSs（persistent elongated convective systems）] are more likely to appear in the rear-right quadrant of a TC within a range of 400 km.

关键词： convection Tropical convective asymmetric tropical mesoscale elongated typhoon likely storm

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Use of Surface Observations to Estimate Upper Air Humidity for the Objective Analysis of Relative Humidity over Indian Region

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Advances in Atmospheric Sciences 1990年第4期7卷 491-501页

作者： S.K.Sinha D.R.Talwalkar S.G.Narkhedkar P.L.Kulkarni S.Nair S.Rajamani Indian institute of Tropical meteorology Pune-411008 India Indian Institute of Tropical Meteorology Pune-411008 IndiaIndian Institute of Tropical Meteorology Pune-411008 IndiaIndian Institute of Tropical Meteorology Pune-411008 IndiaIndian Institute of Tropical Meteorology Pune-411008 IndiaIndian Institute of Tropical Meteorology Pune-411008 India

In the present study objective analyses of relative humidity (RH) at surface and at the levels of 850, 700 and 500 hPa have been made using Gandin's (1963) optimum interpolation scheme. As the horizontal resolution of the radiosonde stations is rather inadequate for upper air humidity analysis, a scheme has been developed, following Rasmussen (1982) to estimate the upper air RH from the surface observations like surface RH, present weather and cloud cover. The relative humidities at the levels 850, 700 and 500 hPa were related to the surface observations through three separate regression relations. The RH values at 850, 700 and 500 hPa levels were estimated from the surface RH, cloud coverage and present weather using the above regression relations and subsequently the objective analyses at 00 GMT for the period from 4 July to 8 July 1979, were made using these estimated data along with the observed radiosonde data. Objective analyses were also made for the same period using only the radiosonde data for comparison to study the impact of those estimated data. Root mean square errors were computed for all the five days by interpolating RH at the observing stations from the objectively analysed field and comparing them with the actually observed RH to examine how best the analyses (with and without estimated data) fitted the observations. Lastly they were compared with satellite cloud pictures. This study shows that the estimated upper air RH values have positive impact on the analysis of upper air RH and could be used over radiosonde data sparse region and even over oceanic regions.

关键词： In RH over

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