Characterization of Asian Dust during ACE-Asia   总被引：4，自引：1，他引：3  

R. Arimoto  Y.J. Kim  Y.P. Kim  P.K. Quinn  T.S. Bates  T.L. Anderson  S. Gong  I. Uno  M. Chin  B.J. Huebert  A.D. Clarke  Y. Shinozuka  R.J. Weber  J.R. Anderson  S.A. Guazzotti  R.C. Sullivan  D.A. Sodeman  K.A. Prather  I.N. Sokolik 《Global and Planetary Change》2006,52(1-4):23

ACE-Asia was a multi-national collaboration organized to investigate and understand the chemistry, radiative properties, and climatic effects of mineral dust and other aerosol particles in the East Asia/Northwest Pacific region. Studies conducted at the Gosan and Zhenbeitai surface supersites show striking variations in aerosol concentrations and properties that were affected by the occurrence and origins of the Asian dust storms, air mass pathways, and mixing during the transport. Investigations conducted on the R/V Ronald H. Brown (RHB) showed that dust had a pervasive influence on the chemical composition, size distribution, and optical properties of the aerosol. Analyses using an aerosol time-of-flight mass spectrometer on the RHB showed that most of the coarse-particle nitrate and sulfate in post-frontal air was associated with dust, and more remarkably, that competitive or exclusionary processes evidently are involved in the uptake or production of these substances. Studies conducted onboard the NCAR C-130 aircraft showed that coarse-mode dust was less absorbing and less hygroscopic than pollution aerosol and that there was little correlation in light scattering and absorption by the sub- vs. super-micrometer aerosol. Below 2 km, dust was commonly mixed with pollutants, and this had a stronger influence on the optical properties of the submicrometer particles than the coarse-mode dust; at higher altitudes, the dust was less affected by pollution. Single particle analyses of C-130 samples showed that the mixing of black carbon (BC) with dust was common, but only certain types of BC particles were aggregated. Models were used in the planning, execution and interpretative phases of ACE-Asia; and summaries of modeling results are presented to illustrate the progress being made in identifying new dust sources; in depicting the time-varying, three-dimensional structure of dust plumes; and in quantifying the production, transport, and deposition of Asian dust.  相似文献   

利用极化合成孔径雷达干涉测量技术生成DEM     

易恒  汪长城  胡波  丁伟 《测绘工程》2012,21(2):9-13

极化合成孔径雷达干涉测量(PolInSAR)是目前雷达遥感的前沿领域之一,它综合了极化和雷达干涉技术(InSAR)的特点.文中应用极化干涉相干最优化技术处理了Amazon雨林地区的真实L波段PALSAR全极化数据,得到该地区的数字高程模型(DEM).与常规的单极化InSAR技术进行对比,证明了利用极化干涉技术可以显著提...  相似文献   

CORS—RTK和全站仪在房屋竣工测量中的应用     

王智超  伊晓东  刘兆民 《北京测绘》2012,(3):93-95

随着GPS技术的飞速前进,利用网络RTK技术建立的连续运行卫星定位系统已成为GPS应用的发展热点之一。本文介绍了CORS系统的特点,叙述了CORS-RTK与全站仪在房屋竣工测量中的应用,结合实例通过对比分析,说明了与常规竣工测量方法相比,运用CORS-RTK和全站仪进行测量可以起到事半功倍的作用。  相似文献   

“天绘一号”卫星在轨辐射定标方法   总被引：1，自引：1，他引：0  

黄红莲  易维宁  乔延利  杜丽丽 《遥感学报》2012,16(S1):22-27

在轨辐射定标包括相对辐射定标和绝对辐射定标, 它是提高遥感数据定量化精度的关键步骤和重要方法。本文阐述了基于均匀场地分区综合的相对辐射定标方法、基于反照率的绝对辐射定标方法及其基本原理, 并首次将其应用于“天绘一号”卫星上的高分辨、多光谱和三线阵相机的辐射定标中。研究结果表明, 相对辐射定标过程去除了卫星图像的条带噪声, 且保存了图像细节;然后, 使用反照率基法, 通过在敦煌场地铺设灰阶靶标, 测量卫星过顶时的地物目标反射率光谱和大气信息, 对“天绘一号”卫星传感器进行了绝对辐射定标;最后, 使用辐射定标结果来反演地物反射率, 与实测的地物反射率相比误差小于5%, 验证了在轨辐射定标系数的有效性。  相似文献   

Pseudo-Newtonian models for the equilibrium structures of rotating relativistic stars     

Jinho Kim  Hee Il Kim  Hyung Mok Lee 《Monthly notices of the Royal Astronomical Society》2009,399(1):229-238

We obtain equilibrium solutions for rotating compact stars, including special relativistic effects. The gravity is assumed to be Newtonian, but we use the active mass density, which takes into account all energies such as the motion of the fluid, internal energy and pressure energy in addition to the rest-mass energy, in computing the gravitational potential using Poisson's equation. Such a treatment could be applicable to neutron stars with relativistic motions or a relativistic equation of state. We applied Hachisu's self-consistent field (SCF) method to find spheroidal as well as toroidal sequences of equilibrium solutions. Our solutions show better agreement with general relativistic solutions than the Newtonian relativistic hydrodynamic approach, which does not take into account the active mass. Physical quantities such as the peak density and equatorial radii in our solutions agree with the general relativistic ones to within 5 per cent. Therefore our approach can be used as a simple alternative to the fully relativistic one when a large number of model calculations is necessary, as it requires much fewer computational resources.  相似文献   

Statistical Analysis of the Relationships among Coronal Holes,Corotating Interaction Regions,and Geomagnetic Storms     

Yunhee Choi  Y.-J. Moon  Seonghwan Choi  Ji-Hye Baek  Sungsoo S. Kim  K.-S. Cho  G. S. Choe 《Solar physics》2009,254(2):311-323

We have examined the relationships among coronal holes (CHs), corotating interaction regions (CIRs), and geomagnetic storms in the period 1996?–?2003. We have identified 123 CIRs with forward and reverse shock or wave features in ACE and Wind data and have linked them to coronal holes shown in National Solar Observatory/Kitt Peak (NSO/KP) daily He i 10?830 Å maps considering the Sun?–?Earth transit time of the solar wind with the observed wind speed. A sample of 107 CH?–?CIR pairs is thus identified. We have examined the magnetic polarity, location, and area of the CHs as well as their association with geomagnetic storms (Dst≤?50 nT). For all pairs, the magnetic polarity of the CHs is found to be consistent with the sunward (or earthward) direction of the interplanetary magnetic fields (IMFs), which confirms the linkage between the CHs and the CIRs in the sample. Our statistical analysis shows that (1) the mean longitude of the center of CHs is about 8°E, (2) 74% of the CHs are located between 30°S and 30°N (i.e., mostly in the equatorial regions), (3) 46% of the CIRs are associated with geomagnetic storms, (4) the area of geoeffective coronal holes is found to be larger than 0.12% of the solar hemisphere area, and (5) the maximum convective electric field E _y in the solar wind is much more highly correlated with the Dst index than any other solar or interplanetary parameter. In addition, we found that there is also a semiannual variation of CIR-associated geomagnetic storms and discovered new tendencies as follows: For negative-polarity coronal holes, the percentage (59%; 16 out of 27 events) of CIRs associated with geomagnetic storms in the first half of the year is much larger than that (25%; 6 out of 24 events) in the second half of the year and the occurrence percentage (63%; 15 out of 24 events) of CIR-associated storms in the southern hemisphere is significantly larger than that (26%; 7 out of 27 events) in the northern hemisphere. Positive-polarity coronal holes exhibit an opposite tendency.  相似文献   

The simulation of aerosol transport over East Asia region   总被引：1，自引：0，他引：1  

Youn-Seo Koo  Sung-Tae Kim  Hui-Young Yun  Jin-Seok Han  Jung-Young Lee  Ki-Hyun Kim  Eui-Chan Jeon 《Atmospheric Research》2008,90(2-4):264-ICNAA07

This study was carried out to understand the contribution of PM10 from China emission to Seoul Metropolitan Area (SMA) during high concentration period in January, 2007. The hourly PM10 concentration in Seoul Metropolitan Area had reached up to over 150 μg/m³ on 17th and 23rd of January in 2007. The aerosol transports from China along the Northwestern wind becomes the background concentrations in Korea and the assessment of the amount of contribution from China is very important in managing the air quality improvement plan in SMA.The U.S. EPA's Models-3/CMAQ (Community Multiscale Air Quality) was used to simulate PM10 concentration. The CMAQ performance was evaluated by comparing with the measurements in SMA for the episode period. The predictions were relatively in a good agreement with the measurements.The results show that the PM10 transport from China to Korea is significant and its contribution reaches up to 80% in the episode period. In order to assess more extensively the aerosol transport in East Asia region, the study to run the model in full year with speciated PM component measurements in super site is underway.  相似文献   

Evaluation of wind resource using numerically optimized data in the southwestern Korean Peninsula     

Dong-Hyuk Kim  Hwa-Woon Lee  Soon-Hwan Lee 《Asia-Pacific Journal of Atmospheric Sciences》2010,46(4):393-403

The wind distribution over the Korean Peninsula was analyzed using numerically optimized wind data to reduce the uncertainties in estimating the wind resources. The simulated data were validated by a comparison with surface wind observations and three statistical indexes. According to the simulated surface winds, mesoscale circulation, such as land-sea breeze and mountain-valley winds affect the wind characteristics of the hub height at coastal and inland regions. However, the prevailing winds are strongly associated with the synoptic forcing at the island and mountainous regions, not the regional circulation. On the other hand, the atmospheric stability definitely affects the strength of the daytime and nocturnal wind speed at a hub height. Overall, there was a significant difference between the numerical and logarithmic method to estimate the wind energy at hub height. Moreover, the discrepancy in the wind density estimated using the two methods becomes clear over inland and mountainous areas.  相似文献   

Simulation of snowstorm over the Yellow Sea using a mesoscale coupled model     

Ki-Young Heo  Kyung-Eak Kim  Kyung-Ja Ha  Kwang-Soon Park  Ki-Cheon Jun  Jae-Seol Shim  Young-Sang Suh 《Asia-Pacific Journal of Atmospheric Sciences》2010,46(4):437-452

This study aims to examine the favorable conditions for an ocean effect snowstorm across the Yellow Sea over the southwestern coast of Korea on 21 December 2005, using a coupled model with a Coupled Ocean/Atmosphere Mesoscale Prediction System as the atmospheric component and the Regional Ocean Modeling System as the oceanic component. Simulation of heavy snowfall event, which was 44.3 cm of snow accumulated in 24-hour, was performed to investigate the mesoscale structure, dynamics and development mechanisms in the snowstorm. As a result from 48-hour integration, the results of simulation showed that barotropic instability and turbulent heat fluxes played important roles in the formation of snowstorm. The enhanced surface diabatic heating was dominant in the latent heat flux, and eventually induced convective instability. An additional factor was the favorable condition of synoptic environment, accessing the cold air transport by the approach of the upper-level cold vortex over the warm ocean. Besides these factors, conditional symmetric instability (CSI) is a mechanism which can result in a heavy snowfall with sufficient moisture and upward vertical motion. A slantwise convection from the release of CSI could support a complex snowfall event with heavier than expected amounts. The result comparison between a coupled model and an uncoupled model supports that airsea coupling has an impact of decreasing of about 10% in a snowfall amount on the snowstorm.  相似文献   

Modification of nocturnal drainage flow due to urban surface heat flux     

Soon-Hwan Lee  Hae-Dong Kim 《Asia-Pacific Journal of Atmospheric Sciences》2010,46(4):453-465

Dense observations and numerical experiments were carried out to estimate the modification of mesoscale circulation, particularly cold drainage wind. It was confirmed that nocturnal drainage flow can develop on clear calm summer day and change due to orographical forcing and the heterogeneity of heat flux induced by the discontinuity of land-use. The temperature of nocturnal drainage flow at Sungji Valley, Busan Korea, tended to increase as it passed over the urban surface due to anthropogenic heat. The increase in temperature reached 2.9 K at night. The roughness associated with the exchange of momentum flux alone and the pass of nocturnal drainage flow is important for modifying the characteristics of flow Numerical simulations carried out under various surface conditions showed good agreement with the observations. Urban heat fluxes from the surface during the day are fundamental causes of the changes in the urban mesoscale circulation. In addition, the impact of a discontinuity of surface heat flux on mesoscale flow modification tends to be greater at night than during the day because the direction of urban surface heat fluxes at night is different from that in rural areas. In addition, the criterion to estimate the increase in temperature nocturnal drainage flow was also proposed, and provided results that generally agreed with the numerical results.  相似文献