High-Resolution Observations in B1-IRS: Ammonia, Ccs and Water Masers

We present a study of the structure and dynamics of the star-forming region B1-IRS (IRAS 03301+3057) using the properties of different molecules at high angular resolution (4). We have used VLA observations of NH₃, CCS, and H₂O masers at 1 cm. CCS emission shows three clumps around the central source, with a velocity gradient from red to blue-shifted velocities towards the protostar, probably due to the interaction with outflowing material. Water maser emission is elongated in the same direction as a reflection nebula detected at 2 m by 2MASS, with the maser spots located in a structure of some hundreds of AU from the central source, possibly tracing a jet. We propose a new outflow model to explain all our observations, consisting of a molecular outflow near the plane of the sky. Ammonia emission is extended and anticorrelated with CCS. We have detected for the first time this anticorrelation at small scales (1400 AU) in a star-forming region.     

Polarization-mode separation and the emission geometry of pulsar 0823 + 26: A new pattern of pulsar emission?

We explore the detailed polarization behaviour of pulsar 0823 + 26 using the technique of constructing partial ‘mode-separated’ profiles corresponding to the primary and secondary polarization modes. The characteristics of the two polarization modes in this pulsar are particularly interesting, both because they are anything but orthogonal and because the secondary mode exhibits a structure seen neither in the primary mode nor in the total profile. The new leading and trailing features in the secondary mode, which appear to represent a conal component pair, are interpreted geometrically on the basis of their width and the associated polarization-angle traverse as an outer cone. If the secondary-mode features are, indeed, an outer cone, then questions about the significance of the pulsar’s postcursor component become more pressing. It seems that 0823 + 26 has a very nearly equatorial geometry, in that both magnetic poles and the sightline all fall close to the rotational equator of the star. We thus associate the postcursor component with emission along those bundles of field lines which are also equatorial and which continue to have a tangent in the direction of our sight line for a significant portion of the star’s rotation cycle. It seems that in all pulsars with postcursor components, this emission follows the core component, and all may thus have equatorial emission geometries. No pulsars with precursors in this sense — including the Crab pulsar — are known. The distribution of power between the primary and secondary modes is very similar at both 430 and 1400 MHz. Our analysis shows that in this pulsar considerable depolarization must be occurring on time scales that are short compared to the time resolution of our observations, which is here some 0.5–1.0 milliseconds. One of the most interesting features of the modeseparated partial profiles is a phase offset between the primary and secondary modes. The secondary-mode ‘main pulse’ arrives some 1.5 ± 0.1‡ before the primary-mode one at 430 MHz and some 1.3 +0.1 ‡ at 21 cm. Given that the polar cap has an angular diameter of 3.36‡, we consider whether this is a geometric effect or an effect of differential propagation of the two modes in the inner magnetosphere of the pulsar.     

Effects of the number of stations and time resolution on derivation

For at least 30 years now it has been well known that the Dst index can be modelled using the solar wind as input. Since then, many attempts have been made to improve the predictability of Dst using different approaches. These attempts are useful, for instance, to understand which features of the solar wind–magnetosphere interactions are most important in producing magnetospheric activity and how the Dst index would improve the space weather forecast. The Dst index is by far the most reliable and simple indication that a magnetic storm is in progress. In this work, the effect of using more than four magnetic stations and shorter time intervals than the hourly averages used in Sugiura's procedures is evaluated. The discussion is based on the results presented by Burton in 1975 and Feldstein in 1984 considering 4 or 12 magnetic stations and time averages of 2.5 min for a magnetic disturbed period that occurred from February 7–28, 1967, including two geomagnetic storms. The analysis has shown that the global representation of a magnetic storm by the standard Dst (Sugiura) is well preserved either using 4, 6, 12 magnetic stations or using 1 h, 2.5 min 1 min averages. A brief review of the current understanding of Dst has been included to support the discussions. The analysis performed has shown that a more refined Dst index (time and number of stations>4) would be useful to investigate the intrinsic processes and the different current systems involved in the ring current development during magnetic storms; the standard Dst, as it is conceived, is quite adequate to monitor geomagnetic storms and identify their overall features; concerning the magnetic stations normally considered, the inclusion of higher magnetic latitude stations (>35) may underestimate the observed Dst.     

国产高分辨率卫星数据在黄河防凌监测中应用

自2002～2003年度首次启用遥感技术监测黄河凌情以来,到目前已连续进行了10个年度。10个年度的生产实践表明:国产高分辨率卫星遥感数据能够有效跟踪黄河凌情的发展过程,实现黄河凌情的日动态监测、重点时段的精细监测和突发凌汛灾害时的实时监测。黄河凌情尤其在封开河阶段,日变化非常显著,中巴资源卫星作为国产高分辨率可见光民用遥感卫星的代表,以其大视场、高空间、高时间分辨率的特点,动态监测凌情,基本做到每天实现一次全覆盖监测的能力,配合其他如中国遥感卫星等高分辨率可见光、雷达数据,初步实现了凌情发展预估、开河前的河道槽蓄水量计算、封开河期间冰凌险情监测以及发生凌汛灾害时灾情信息采集与评估,为黄河防凌调度、决策会商提供了有力的技术支持。     

鄱阳湖HJ-1A/B卫星CCD影像大气校正研究

以准同步的Terra/MODIS反演的气溶胶为辅助,采用FLAASH模型对2009-10-24鄱阳湖HJ-1A/B卫星CCD影像进行大气校正处理。结果表明,大气影响可以被有效去除,在水体遥感反射率较高的红、绿波段,大气校正精度较高,平均相对误差分别为13.4%和9.8%;而在水体遥感反射率较低的近红外、蓝波段,大气校正精度较低,这可能与波段不同的信噪比和陆地邻近像元效应有关。     

利用遥感技术建立墨西哥热带地上生物量模型(英文)

Spatially-explicit estimation of aboveground biomass(AGB) plays an important role to generate action policies focused in climate change mitigation,since carbon(C) retained in the biomass is vital for regulating Earth’s temperature.This work estimates AGB using both chlorophyll(red,near infrared) and moisture(middle infrared) based normalized vegetation indices constructed with MCD43A4 MODerate-resolution Imaging Spectroradiometer(MODIS) and MOD44B vegetation continuous fields(VCF) data.The study area is located in San Luis Potosí,Mexico,a region that comprises a part of the upper limit of the intertropical zone.AGB estimations were made using both individual tree data from the National Forest Inventory of Mexico and allometric equations reported in scientific literature.Linear and nonlinear(expo-nential) models were fitted to find their predictive potential when using satellite spectral data as explanatory variables.Highly-significant correlations(p = 0.01) were found between all the explaining variables tested.NDVI62,linked to chlorophyll content and moisture stress,showed the highest correlation.The best model(nonlinear) showed an index of fit(Pseudo-r2) equal to 0.77 and a root mean square error equal to 26.00 Mg/ha using NDVI62 and VCF as explanatory variables.Validation correlation coefficients were similar for both models:lin-ear(r = 0.87**) and nonlinear(r = 0.86**).     

SharpMap在青海省气象信息网络数据库中的应用

在 .NET环境下开发了基于B/S结构的青海省气象信息网络数据库。该数据库系统由气象信息基础数据库、数据库管理网站及一个空间信息平台构成。气象数据能够实时入库,并具有底图制作、基于地图的数据检索、数据统计和图形绘制等功能,将查询结果叠加在电子地图上显示,直观方便。系统于2009年在青海省气象台投入使用,提高了青海省气象台气象数据共享能力和服务水平,并为青海省气象台的各项业务工作提供了有力的支持。系统采用SharpMap技术实现了空间信息平台,并应用Ajax等技术提高了系统效率,本文对其在网络数据库中的应用     

基于CBERS的黄河湿地生物量反演研究

本研究以黄河湿地郑州段为研究区,利用RS与GIS技术,基于2009年5月7日获得的CBERS 2B卫星CCD多光谱遥感影像和地面实测植被生物量信息,采用回归算法构建反演模型,经对比分析得到最优计算模型。结果表明,反演模型计算精度达到86.32%,利用CBERS 2B卫星CCD多光谱遥感影像可满足植被生物量的反演需要。     

CBERS-02B卫星遥感影像的区域网平差

针对中巴资源一号卫星(CBERS-02B)卫星遥感影像姿态角误差较大的特点,提出了利用区域网平差方法提高其对地目标定位精度的策略和具体计算过程。首先对参与平差的每景影像选取4个地面控制点进行影像姿态角常差检校,然后采用与地形无关方案解求各自的RPC参数,最后选取带仿射变换项的有理函数模型(RFM)进行多重覆盖影像的区域网平差。对两个地区的0级CBERS-02B单条CCD立体影像对的区域网平差试验表明,对地目标定位的平面和高程精度均达到了±3个像元的水平,且高程精度明显优于平面精度。相对于常规的卫星遥感影像区域网平差方法,平面和高程精度均有明显提升,几乎达到国外同等高分辨率卫星遥感影像的几何定位精度。这说明中国卫星遥感影像亦具有较好的几何定位潜力,在区域网平差之前进行系统误差预改正是必要和可行的。     

Prediction Research of Climate Change Trends over North China in the Future 30 Years

A simulation of climate change trends over North China in the past 50 years and future 30 years was performed with the actual greenhouse gas concentration and IPCC SRES B2 scenario concentration by IAP/LASG GOALS 4.0 （Global Ocean-Atmosphere-Land system coupled model）, developed by the State Key Laboratory of Numerical Modelling for Atmospheric Sciences and Geophysical Fluid Dynamics （LASG）, Institute of Atmospheric Physics （IAP）, Chinese Academy of Sciences （CAS）. In order to validate the model, the modern climate during 1951-2000 was first simulated by the GOALS model with the actual greenhouse gas concentration, and the simulation results were compared with observed data. The simulation results basically reproduce the lower temperature from the 1960s to mid-1970s and the warming from the 1980s for the globe and Northern Hemisphere, and better the important cold （1950 1976） and warm （1977-2000） periods in the past 50 years over North China. The correlation coefficient is 0.34 between simulations and observations （significant at a more than 0.05 confidence level）. The range of winter temperature departures for North China is between those for the eastern and western China＇s Mainland. Meanwhile, the summer precipitation trend turning around the 1980s is also successfully simulated. The climate change trends in the future 30 years were simulated with the CO2 concentration under IPCC SRES-B2 emission scenario. The results show that, in the future 30 years, winter temperature will keep a warming trend in North China and increase by about 2.5~C relative to climate mean （1960-1990）. Meanwhile, summer precipitation will obviously increase in North China and decrease in South China, displaying a south-deficit-north-excessive pattern of precipitation.