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Spatiotemporal spectrum and momentum flux of the stratospheric gravity waves generated by a typhoon

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Science China Earth Sciences 2013年第5期56卷 54-62页

作者： CHEN Dan CHEN ZeYu lü daren Key laboratory of Middle Atmosphere and Global Environment Observation Institute of Atmospheric Physics Chinese Academy of Sciences Graduate University of Chinese Academy of Sciences College of Atmospheric Sciences Nanjing University of Information Science & Technology

The simulation results of Typhoon Matsa (2005) by using the Weather Research and Forecasting (WRF) model show that pronounced stratospheric gravity waves (GWs) are generated in the vicinity of the typhoon. Using the model output, we investigate the spatial structures and the temporal variations of the GWs through a three dimensional (3-d) spectral analysis, i.e. the spectrum with respect to two horizontal wavenumbers and frequency. We further derive the momentum flux carried by the GWs. Spectral investigation results show that the power spectral density (PSD) of the GWs exhibits a single-peaked spectrum, which consists primarily of a distinct spectrum at horizontal wavelength of ~1000km, time period of 12-18h, and vertical wavelength of 7-9km. This spectrum is different from the spectra of GWs generated by deep convections disclosed by the previous researches. Both the PSD and momentum flux spectrum are prominent in positive k h portion, which is consistent with the fact that the GWs propagate in the upstream of mean flow. large momentum flux is found to be associated with the GWs, and the net zonal momentum flux is 0.7845×10 3 Pa at 20km height, which can account for ~26% of the momentum flux that is required in driving the QBO phenomenon.

关键词：动量通量平流层台风引力波时空频谱分析模型显示时间变化

An integrative mathematical model of microwave ion thruster for mHz-frequency thrust noise analysis

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Chinese Journal of Aeronautics 2024年第4期37卷 121-136页

作者： Xiang NIU Hui lIU daren YU Plasma Propulsion laboratory Harbin Institute of TechnologyHarbin 150001China

Many high-precision space missions need thrusters to produce thrust with low noise to compensate for disturbances and ensure satellite platform stability. Microwave ion thruster is characterized with a wide thrust range and potential for these missions. A cost-effective and accurate mathematical model is crucial for mHz-frequency thrust noise analysis and feedback controller design. The Particle-In-Cell(PIC) and global models are two common simulation tools. The PIC model is characterized with high accuracy but huge computation cost, which is difficult to analyze long-time performance characteristics. Now, the global model is only used for the discharge chamber with low accuracy and cannot reflect ion extraction properties. In this paper, an integrative mathematical model is built for a 1-cm microwave ion thruster and can reflect ion beamlet divergence and impingement on the Accelerator Grid(AG). Simulation results show good agreement with experiments at 0.06 sccm. However, the model demonstrates worse consistency with experiments when the flux increases to 0.1 sccm, which may be because the influence of neutral gas on the Electron Cyclotron Resonance(ECR) is not considered in the model. A long-time(1000 s) simulation is conducted with this model under 35 μN. It takes 3 hrs, and the thrust noise reaches 1 μN/Hz^(0.5) at 1 mHz.

关键词： Electric propulsion Microwave ion thruster Integrative model Sheath property Ion beamlet divergence Thrust noise Plasma

Ten-Year Climatological Features and Air Origin of Midlatitude Double Tropopauses

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Advances in Atmospheric Sciences 2015年第12期32卷 1592-1602页

作者： WU Xue lü daren Key laboratory for Atmosphere and Global Environment Observation Institute of Atmospheric PhysicsChinese Academy of Sciences

The 10-year climatological features related to midlatitude double tropopause events （DTs） are examined using ERA- Interim data from 2003 to 2012. The analysis is based on tropopauses defined by lapse rate. Results show that DTs are permanent or semi-permanent in the midlatitudes, and high DT frequency bands move poleward in winter and equatorward in summer, which is consistent with the seasonal movement of the subtropical jet. Based on our statistics, the second tropopause is found at about 100 hPa in the subtropics and at slightly lower altitudes in sub-polar regions. The thickness between the first and second tropopause is smaller in the subtropics and increases with latitude. Next, the origin of air sandwiched between the first and second tropopause of DTs is studied with a revised version of the UK Universities Global Atmospheric Modelling Programme Offline Trajectory Code （Version 3） diabatic trajectory model. The results show that, in the lower or middle troposphere, air is transported into the DTs from lower latitudes, mainly in the tropics. The dominant source regions are mainly areas of deep convection and steep orography, e.g., the western Pacific and Himalayan Mountains, and they show strong seasonality following the seasonal shift of these strong upwelling regions.

关键词： double tropopause trajectory model stratosphere-troposphere exchange

A new method for retrieving equivalent cloud base height and equivalent emissivity by using the ground-based Atmospheric Emitted Radiance Interferometer (AERI)

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Science China Earth Sciences 2013年第1期56卷 43-53页

作者： PAN linJun lü daren laboratory for Middle Atmosphere and Global Environment Observation (lAGEO) Institute of Atmospheric Physics Chinese Academy of Sciences Graduate University of Chinese Academy of Sciences

In the paper, we propose a new method of identifying the clear sky based on the Atmospheric Emitted Radiance Interferometer (AERI). Using the Atmospheric Radiation Measurement (ARM) Mobile Facility (AFM) dataset in Shouxian in 2008, we simulate the downwelling radiances on the surface in the 8-12m window region using line-By-line Radiative Transfer Model (lBlRTM), and compare the results with the AERI radiances. The differences larger (smaller) than 3mW (cm2 sr cm1 ) 1 suggest a cloudy (clear) sky. Meanwhile, we develop the new algorithms for retrieving the zenith equivalent cloud base height (CBH e ) and the equivalent emissivity (e), respectively. The retrieval methods are described as follows. (1) An infinitely thin and isothermal blackbody cloud is simulated by the lBlRTM. The cloud base height (H) is adjusted iteratively to satisfy the situation that the contribution of the blackbody to the downwelling radiance is equal to that of realistic cloud. The final H is considered as CBH e . The retrieval results indicate that the differences between the CBH e and observational cloud base height (CBH) are much smaller for thick low cloud, and increase with the increasing CBH. (2) An infinitely thin and isothermal gray body cloud is simulated by the lBlRTM, with the CBH specified as the observed value. The cloud base emissivity (c) is adjusted iteratively until the contribution of the gray body to the downwelling radiance is the same as that of realistic cloud. The corresponding gc is ge . The average ge for the low, middle, and high cloud is 0.967, 0.781, and 0.616 for the 50 cases, respectively. It decreases with the increasing CBH. The retrieval results will be useful for studying the role of cloud in the radiation budget in the window region and cloud parameterizations in the climate model.

关键词：辐射测量大气发射检索方法发射率干涉仪等效地面辐射传输模型

Recent Progress of Earth Science Satellite Missions in China

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空间科学学报 2022年第4期42卷 712-723页

作者： SHI Jiancheng lÜdaren WANG Yu DU Yan PANG Yong YANG Dongxu WANG Xin DONG Xiaolong YANG Xiaofeng National Space Science Center Chinese Academy of SciencesBeijing 100190 Institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029 Aerospace Information Research Institute Chinese Academy of SciencesBeijing 100094 South China Sea Institute of Oceanology Chinese Academy of SciencesGuangzhou 510301 Institute of Forest Resource Information Technique Chinese Academy of ForestryBeijing 100091

Earth Science from Space is an interdisciplinary discipline that studies the interactions,mechanisms,and evolution of the Earth system through space *** China,the national medium-to long-term civilian space infrastructure development plan and the space-science pilot project from the Chinese Academy of Sciences are two programs associated with advancing the Earth science from *** paper reports recent scientific findings,developments and the status of the six *** is organized as the following sections:Introduction,two satellite missions that are already in orbit—the TanSat-1 for atmospheric COand the luTan-1 for global surface deformation,a Terrestrial Ecosystem Carbon Inventory Satellite to be launched in 2022,and three missions that passed the PhaseⅡstudy and planned for near future—the Ocean Surface Current multiscale Observation,the Terrestrial Water Resources *** and Atmospheric Components Exploring Satellites(CACES),followed by the conclusion.

关键词： Earth science from space Earth observation Energy and water cycle Carbon cycle Human activities

Preface to the Special Issue on the Program of “Carbon Budget and Relevant Issues”-A Strategic Scientific Pioneering Program of the Chinese Academy of Sciences

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Advances in Atmospheric Sciences 2017年第8期34卷 939-940页

作者： daren lü Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

Global warming has been one of the biggest issues faced by the world in recent *** is closely related to anthropogenic emissions of greenhouse gases（GHGs）—mainly CO_2,CH_4 and N_2O—and the effects of reducing emis... 详细信息

关键词： emissions greenhouse warming anthropogenic gases Strategic aerosols faced fixation quantitatively

Retrievals of atmospheric boundary layer temperature and moisture profiles by using Atmospheric Emitted Radiance Interferometer(AERI) measurements in Shouxian

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Chinese Science Bulletin 2014年第8期59卷 795-801页

作者： linjun Pan daren l Key laboratory for Middle Atmosphere and Global Environment Observation Institute of Atmospheric Physics Chinese Academy of Sciences

The ground-based Atmospheric Emitted Radiance Interferometer(AERI)was deployed in Shouxian,China in 2008 to measure down-welling infrared radiances with high *** on AERI observations,we propose a new method for retrieving vertical temperature and water vapor profiles in the planetary boundary layer(PBl).The method exclusively uses NCEP-2,a global reanalysis data as a first-guess profile in an iterative recursive *** PBl profiles of temperature and moisture under clear sky conditions in Shouxian have been retrieved using this new *** with coincident radiosonde measurements,we find that AERI is able to obtain more accurate temperature and water vapor profiles in the *** retrieval results with high temporal resolution can be used to monitor the PBl stability and evolution.

关键词：测量数据检索结果大气发射湿度廓线干涉仪大气边界层温度寿县

The Impact of Surface Properties on Downward Surface Shortwave Radiation over the Tibetan Plateau

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Advances in Atmospheric Sciences 2015年第6期32卷 759-771页

作者： WANG leidi l daren HE Qing Key laboratory of Middle Atmosphere and Global Environmental Observation Institute of Atmospheric PhysicsChinese Academy of Sciences University of Chinese Academy of Sciences

The complexity of inhomogeneous surface-atmosphere radiation transfer is one of the foremost problems in the field of atmospheric physics and atmospheric radiation. To date, the influence of surface properties on shortwave radiation has not been well studied. The daily downward surface shortwave radiation of the latest FlASHFlux/CERES （Fast longwave And Shortwave Fluxes_Time Interpolated and Spatially Averaged/Clouds and the Earth＇s Radiant Energy System） satellite data was evaluated against in situ data. The comparison indicated that the differences between the two data sets are unstable and large over rugged terrain compared with relatively flat terrain, and the mean absolute error of the satellite products reaches 31.4 W m-2 （12.3%） over rugged terrain. Based on the SSF （single satellite footprint）/CERES product, the influence of surface properties on the distribution of downward surface shortwave radiation （DSSR） was analyzed. The influence of surface properties on DSSR over the Tibetan Plateau is about twice as large as that in two other regions located at the same latitude （eastern China-western Pacific and subtropical North Pacific）. A simulation was carried out with the help of the I3RC （International Intercomparision of Three-Dimensional Radiation Code） Monte Carlo 3D radiative transfer community model. The results showed that DSSR increases as surface albedo increases. Moreover, the impact of surface albedo on DSSR is larger if the spatial distribution of clouds is more non-uniform. It is hoped that these results will contribute to the development of 3D radiative transfer models and the improvement of satellite inversion algorithms.

关键词： shortwave radiation surface properties Tibetan Plateau satellite remote sensing

The Effect of the Subtropical Jet on the Rainfall over Southern China in January 2008

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Advances in Atmospheric Sciences 2014年第3期31卷 543-550页

作者： ZUO Qunjie GAO Shouting l daren laboratory of Cloud-Precipitation Physics and Severe Storms Institute of Atmospheric Physics Chinese Academy of Sciences Key laboratory of Middle Atmosphere and Global Environment Observation Institute of Atmospheric Physics Chinese Academy of Sciences State Key laboratory of Severe Weather Chinese Academy of Meteorological Sciences

ABSTRACT The third precipitation episode of China＇s great snowstorms of 2008 was analyzed using station observations and ECMWF six-hourly data. The variation of the shape of the upper-level subtropical jet played an important role in the rainfall over south- ern China. With the eastward movement of the trough, the jet shape changed from two straight jets to a tilting jet over China and then it moved southward. With these variations, the south-north movement of ascending flow and precipitation area over southern China occurred.

关键词： upper-level subtropical jet transverse circulation ageostrophic wind snowstorms