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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 sim- ulate the downwelling radiances on the surface in the 8-12 μm window region using line-By-line Radiative Transfer Model （lBlRTM）, and compare the results with the AERI radiances, The differences larger （smaller） than 3 mW （cm2 sr cm-1）-1 suggest a cloudy （clear） sky. Meanwhile, we develop the new algorithms for retrieving the zenith equivalent cloud base height （CBHe） and the equivalent emissivity （ee）, 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 CBHe. The retrieval results indicate that the differences between the CBHe 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 （co） is ad- justed iteratively until the contribution of the gray body to the downwelling radiance is the same as that of realistic cloud. The corresponding εc is εe. The average εe for the low, middle, and high cloud is 0.967, 0.781, and 0.616 for the 50 cases, respec- tively. 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： AERI lBlRTM equivalent cloud base height equivalent emissivity

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

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 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

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

Retrieval of Vertical Distribution of Tropospheric Refractivity through Ground-Based GPS Observation

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Advances in Atmospheric Sciences 2014年第1期31卷 37-47页

作者： WU Xue WANG Xin l daren Key laboratory for Atmosphere and Global Environment Observation Institute of Atmospheric Physics Chinese Academy of Sciences University of the Chinese Academy of Sciences

In the present reported study, the vertical distributions of local atmospheric refractivity were retrieved from ground- based GPS observations at low elevation angles. An improved optimization method was implemented at altitudes of 0-10 km to search for a best-fit refractivity profile that resulted in atmospheric delays most similar to the delays calculated from the observations. A ray-tracing model was used to simulate neutral atmospheric delays corresponding to a given refractivity profile. We initially performed a ＂theoretical retrieval＂, in which no observation data were involved, to verify the optimization method. A statistical relative error of this ＂theoretical retrieval＂（-2% to 2%） indicated that such a retrieval is effective. In a practical retrieval, observations were obtained using a dual-frequency GPS receiver, and its initial value was provided by CIRA86aQ_UoG data. The statistical relative errors of the practical retrieval range from -3% to 5% were compared with co-located radiosonde measurements, Results clearly revealed diurnal variations in local refractivity prc,files, The results also suggest that the general vertical distribution of refractivity can be derived with a high temporal resolution. However, further study is needed to describe the vertical refractivity gradient clearly.

关键词： Global Positioning System (GPS) refractivity atmospheric delay ray-tracing exhaustive search

Eddy Kinetic Energy Study of the Snowstorm over Southern China in January 2008

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Advances in Atmospheric Sciences 2014年第4期31卷 972-984页

The energetics of the third stage of a snowstorm over China was analyzed using ECWMF *** analysis of the energy budget for the Middle East trough and the western Pacific trough that developed toward China on 25-28 January 2008 showed the advection of the geopotential by the ageostrophic wind to be both a crucial source and the primary sink of the eddy kinetic energy centers associated with the *** magnitudes of the energy conversion terms,interaction kinetic energy conversion and baroclinic conversion,were too small to explain the development of the energy centers and the jet *** energy centers gained energy at their entrance regions via the convergence of the ageostrophic geopotential fluxes,and then lost energy at their exit regions by the same *** the entrance regions,the fluxes converged,increasing the geopotential gradient,which generated a stronger geostrophic wind and higher kinetic energy,resulting in an ascending motion in this *** the troughs moved to China,the ascending motion caused by the convergence of the fluxes at entrance region intensified the snowstorms over central and southern China.

关键词： eddy kinetic energy ageostrophic geopotential flux snowstorms jet streaks

Cloud Classification and Distribution of Cloud Types in Beijing Using Ka-Band Radar Data

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Advances in Atmospheric Sciences 2019年第8期36卷 793-803页

作者： Juan HUO Yongheng BI daren lü Shu DUAN Key laboratory for Atmosphere and Global Environment Observation Chinese Academy of Sciences

A cloud clustering and classification algorithm is developed for a ground-based Ka-band radar system in the vertically pointing mode. Cloud profiles are grouped based on the combination of a time–height clustering method and the k-means clustering method. The cloud classification algorithm, developed using a fuzzy logic method, uses nine physical parameters to classify clouds into nine types: cirrostratus, cirrocumulus, altocumulus, altostratus, stratus, stratocumulus, nimbostratus,cumulus or cumulonimbus. The performance of the clustering and classification algorithm is presented by comparison with all-sky images taken from January to June 2014. Overall, 92% of the cloud profiles are clustered successfully and the agreement in classification between the radar system and the all-sky imager is 87%. The distribution of cloud types in Beijing from January 2014 to December 2017 is studied based on the clustering and classification algorithm. The statistics show that cirrostratus clouds have the highest occurrence frequency(24%) among the nine cloud types. High-level clouds have the maximum occurrence frequency and low-level clouds the minimum occurrence frequency.

关键词： clouds clustering algorithm classification algorithm radar cloud type