Overview and initial results of the very long baseline interferometry space observatory programme

High angular resolution images of extragalactic radio sources are being made with the Highly Advanced Laboratory for Communications and Astronomy (HALCA) satellite and ground-based radio telescopes as part of the Very Long Baseline Interferometry (VLBI) Space Observatory Programme (VSOP). VSOP observations at 1.6 and 5 gigahertz of the milli-arc-second-scale structure of radio quasars enable the quasar core size and the corresponding brightness temperature to be determined, and they enable the motions of jet components that are close to the core to be studied. Here, VSOP images of the gamma-ray source 1156+295, the quasar 1548+056, the ultraluminous quasar 0014+813, and the superluminal quasar 0212+735 are presented and discussed.     

California current eddy formation: ship, air, and satellite results

Until recently, quantitative measurements of the circulation of the California Current were limited to hydrographic determinations [See figure in the PDF file] of temperature and salinity. This information is now being augmented by satellite data. Clouds permitting, satellite scanner systems can locate major ocean frontal boundaries if they are associated with even quite weak horizontal sea-surface temperature gradients. The satellite data are most usefully interpreted in a region such as that encompassing the California Current, where the surface and main thermocline temperature distributions bear some relation to each other. In such a region, it is possible to make interpretations of circulation based on satellite-derived sea-surface temperature patterns. The correctness of these interpretations depends heavily on the availability of historical and present-day subsurface data, collected by conventional methods from ships and aircraft. Satellite infrared scanners, in addition to providing information on circulation with vastly increased spatial resolution, have the potential (with cooperative weather) for providing increased time resolution. These improvements in resolution have permitted us to see that much of the spatial variation in the California Current takes place along welldefined fronts and to observe the evolution of one particular meander.     

Prediction of protein content in malting barley using proximal and remote sensing

This paper examines the prediction of within-field differences in protein in malting barley at a late growth stage using the Yara N-Sensor and prediction of its regional variation with medium resolution satellite images. Field predictions of protein in the crop at a late growth stage could be useful for harvest planning, whereas regional prediction of barley quality before harvest would be useful for the grain industry. The project was carried out in central Sweden where the variation in protein content of malting barley has been documented both within fields and regionally. Scanning with an N-sensor and crop sampling were carried out in 2007 and 2008 at several fields. The regional data used consisted of weather data, quality analyses of the malting barley delivered to the major farmers’ co-operative, crops grown and field boundaries. Satellite scenes (SPOT 5 and IRS-P6 LISS-III) were acquired from a date as close as possible to the N-sensor scans. Reasonable partial least squares (PLS) models could be constructed based on weather and reflectance data from either the N-sensor or satellite. The models used mainly reflectance data, but the weather data improved them. Better field models could be created with data from the N-sensor than from the satellite image, but a local satellite-based model based on a simple ratio (middle infrared/green) in combination with weather was useful in regional prediction of malting barley protein. A regional prediction model based only on the weather variables explained about half the variation in recorded protein.     

沈阳“8·21”罕见冰雹防雹天气预警再分析

[目的]分析2011年8月21日18:30～19:30期间发生的冰雹天气。[方法]利用NCEP 6 h再分析资料、Micaps资料、FY-2卫星云图资料,对2011年8月21日18:30～19:30期间发生的冰雹天气的天气形势场、冰雹特征气象要素场和卫星云图进行再分析,探讨此次冰雹的天气成因及冰雹云的云图特征,总结如何从实况天气资料及数值预报产品进行防雹天气预警分析。[结果]此次冰雹天气的发生发展过程,高空500 hPa冷涡是背景天气系统,低空850 hPa暖舌和地面风切变是形成强对流冰雹云的必要条件;分析尽早时次的天气图,可以从天气系统的机理方面分析天气的发生原因,并能尽早地发出天气预警;利用数值预报产品分析冰雹特征气象要素场,可以更进一步地分析并精确地预测冰雹发生的概率、时间以及范围;而红外卫星云图对于对流旺盛的冰雹云的监测更准确,特征更明显,可以更直观地预测冰雹天气的发生。[结论]该研究为今后类似的冰雹天气提供防雹预警经验。     

Transcontinental baselines and the rotation of the Earth measured by radio interferometry

Nine separate very-long-baseline interferometry (VLBI) experiments, carried out in 1972 and 1973 with radio telescopes 3900 kilometers apart, yielded values for the baseline length with a root-mean-square deviation about the mean of less than 20 centitneters. The corresponding fractional spread is about five parts in 10(8). Changes in universal time and in polar motion were also detertnined accurately from these data; the root-mean-square scatter of these results with respect to those based on optical methods were 2.9 milliseconds and 1.3 meters, respectively. Solid-earth tides were apparently detected, but no useful estimate of their amplituide was extracted.     

卫星遥感在海洋渔业资源开发、管理与保护中的应用

海洋渔业资源的开发、管理与保护需要大量的海洋环境数据。由于卫星遥感能大面积、长时间、近实时地获取海洋环境数据,其在海洋渔业资源开发、管理与保护中的作用越来越大。本文回顾了卫星遥感数据在海洋渔业资源评估、渔情预报、鱼类栖息地分类与保护、渔船监测、渔业安全、渔具渔法等方面的应用,探讨了在这些应用中可能存在的问题,并对其未来的发展进行了展望,为相关学者了解卫星遥感在海洋渔业资源的开发、管理与保护中的作用提供参考。     

Influence of satellite data uncertainties on the detection of externally forced climate change

Two independent analyses of the same satellite-based radiative emissions data yield tropospheric temperature trends that differ by 0.1 degrees C per decade over 1979 to 2001. The troposphere warms appreciably in one satellite data set, while the other data set shows little overall change. These satellite data uncertainties are important in studies seeking to identify human effects on climate. A model-predicted "fingerprint" of combined anthropogenic and natural effects is statistically detectable only in the satellite data set with a warming troposphere. Our findings show that claimed inconsistencies between model predictions and satellite tropospheric temperature data (and between the latter and surface data) may be an artifact of data uncertainties.     

基于国产GF-1影像的川金丝猴生境评价研究

利用国产高分一号(GF-1)卫星遥感影像,综合神农架川金丝猴已有科考数据和相关研究成果,以地理信息系统为主要分析手段,选取植被类型、海拔、坡度、坡向、水源和人类干扰等作为评价因子,快速进行神农架川金丝猴秋季生境适宜性评价,首次将GF-1卫星影像应用于野生动物生境评价。评价结果表明:在不考虑人类活动影响时,川金丝猴潜在的最适宜生境和适宜生境面积分别为56.876和305.156 km2,分别占保护区面积的7.77%和41.69%;由于居民区和公路等的影响,神农架自然保护区川金丝猴实际适宜生存面积变小,实际最适宜生境和适宜生境面积分别为46.935和214.617 km2,分别占保护区总面积的6.41%和29.32%。将基于GF-1卫星遥感影像得到的川金丝猴生境适宜性评价结果,与基于Landsat8遥感影像得到的生境评价结果对比,二者评价结果符合度达91.7%,表明在野生动物生境研究领域国产GF-1卫星影像可以有效地替代国外Landsat影像,利用GF-1卫星影像进行野生动物生境评价是可行的。GF-1卫星突破了在野生动物研究领域普遍依赖国外数据的局面。GF-1卫星影像具有高空间分辨率、高时间分辨率、低成本和数据来源可靠等特点,无疑是我国野生动物生境遥感应用研究中可供选择的新的数据源。由于GF-1是我国高分辨率对地观测系统的第一颗卫星,开展GF-1数据的应用验证具有十分重要的科学意义。目前,利用GF-1开展此类研究国内外尚未见类似报道,本研究对于在林业实际业务中开展国产高分卫星遥感数据应用同样具有指导作用。      

Crop canopy heterogeneity detected based on MODIS satellite data as an indicator of contrast in soil patterns

Using a test site in the Saratov Near-Volga Region, the paper shows that the crop canopy heterogeneity detected based on MODIS satellite data can serve as an indicator of contrast in soil patterns. The results from the satellite analysis of the crop canopy heterogeneity are proposed to be used as additional data for digital soil mapping.     

Some Doubts about the Earth's Dust Cloud

Considerable doubt is cast on the validity of past satellite measurements of micrometeoroid fluxes in which piezoelectric microphones have been used as detectors. Data have been obtained from satellite and laboratory experiments which show that the microphone crystals emit noise when subject to slowly varying temperatures. The rate of noise is consistent with past flight data which have previously been interpreted on the basis of micrometeoroid impacts. These measurements have given rise to the theory that the earth is surrounded by a cloud of dust, although no satisfactory mechanism has yet been found to explain this apparent phenomenon. On the basis of the results reported here, it now appears that whether or not a concentration of dust exists in the vicinity of the earth, the data from satellite microphone measurements should not be used to support such a hypothesis.     

Determination of area of drought-affected crops based on satellite data (exemplified by crops in Chuvashia in 2010)

A method is developed for determining at the level of a federal subject of Russia the area of drought-affected crops based on using MODIS and Landsat satellite data. Underlying the method is a comparative analysis of the behavior of the vegetation index in the current and other seasons during the past ten years. Evaluation of the method, using the 2010 drought in Chuvashia as an example, showed a good similarity between the results obtained on the basis of satellite data and official information on crop death.     

黑龙江大兴安岭卫星热点预报森林火灾准确性研究

卫星监测是现阶段我国主要森林火灾监测方法,其本质是测报地面的高温热源,利用粗分辨率的遥感数据进行林火监测时不能区分高温热源性质、精确定位火场,对于热点数据的地面核查反馈工作造成一定困难。提升热点数据处置的技术水平是森林防火研究的热点。本文基于2005—2015年黑龙江省大兴安岭林区卫星热点数据和同时期森林火灾历史资料,利用ARCGIS和统计分析,得出结论如下:1)卫星热点初判林火发生次数的准确率79.7%,不同卫星初判热源差异较大,NOAA-16、NOAA-18、NOAA-19和FY-1D的报准率均在80%左右,监测次数综合达到1 928次,占总数的2/3,是监测林火的主力卫星。2)卫星预报初判林火发生位置平均误差为5 787.9 m;不同卫星初判热源差异较大,NOAA-19和Terra预报热点的误差较小,但监测数量偏少;NOAA-15和NOAA-17的监测数量虽然较多,但其误差非常大,NOAA-15有7 064.7 m,NOAA-17达到万米以上。3)在卫星监测到的219次森林火灾和历史资料记录的165次火灾中,有147次森林火灾能够对应,卫星的多报、少报问题主要集中于呼玛县,在连续监测同一场森林火灾时,容易出现多报、少报的现象。建议在无法提高卫星性能的情况下,改进卫星图像的处理技术,完善卫星图像的判读标准,提高判读的准确性,同时完善地面核查反馈的方案,以增加核查效率,降低核查经济成本,同时基于不同卫星的性能差异,建议在进行林火监测时应以预报精确的风云系列极轨卫星为主,以性能稳定的NOAA系列卫星为辅。      

应用线形插值对风云二数据进行图像定位与投影计算

应用VC＋＋语言对风云二卫星数据进行读取、显示,并进行图像定位及投影变换。主要介绍通过线形插值的方法对风云二数据中提供的简化网格数据进行分区近似计算。从计算结果看比较理想,基本实现了风云二数据的图像定位,确定了目标遥感数据,为遥感数据的参数反演和针对性分析做铺垫。     

Comparison of QuickBird Satellite Imagery and Airborne Imagery for Mapping Grain Sorghum Yield Patterns

Timely and accurate information on crop conditions obtained during the growing season is of vital importance for crop management. High spatial resolution satellite imagery has the potential for mapping crop growth variability and identifying problem areas within fields. The objectives of this study were to use QuickBird satellite imagery for mapping plant growth and yield patterns within grain sorghum fields as compared with airborne multispectral image data. A QuickBird 2.8-m four-band image covering a cropping area in south Texas, USA was acquired in the 2003 growing season. Airborne three-band imagery with submeter resolution was also collected from two grain sorghum fields within the satellite scene. Yield monitor data collected from the two fields were resampled to match the resolutions of the airborne imagery and the satellite imagery. The airborne imagery was related to yield at original submeter, 2.8 and 8.4 m resolutions and the QuickBird imagery was related to yield at 2.8 and 8.4 m resolutions. The extracted QuickBird images for the two fields were then classified into multiple zones using unsupervised classification and mean yields among the zones were compared. Results showed that grain yield was significantly related to both types of image data and that the QuickBird imagery had similar correlations with grain yield as compared with the airborne imagery at the 2.8 and 8.4 m resolutions. Moreover, the unsupervised classification maps effectively differentiated grain production levels among the zones. These results indicate that high spatial resolution satellite imagery can be a useful data source for determining plant growth and yield patterns for within-field crop management.     

林火卫星监测技术研究进展

介绍了4种林火卫星监测的技术,包括NOAA/AVHR R卫星监测、EOS/MODIS数据监测、风云(FY)系列卫星监测及环境减灾(HJ)卫星监测,对国内外林火卫星监测发展状况进行了论述,并对林火卫星监测技术研究方向进行了展望。     

Satellite radar interferometry for monitoring ice sheet motion: application to an antarctic ice stream

Satellite radar interferometry (SRI) provides a sensitive means of monitoring the flow velocities and grounding-line positions of ice streams, which are indicators of response of the ice sheets to climatic change or internal instability. The detection limit is about 1.5 millimeters for vertical motions and about 4 millimeters for horizontal motions in the radar beam direction. The grounding line, detected by tidal motions where the ice goes afloat, can be mapped at a resolution of approximately 0.5 kilometer. The SRI velocities and grounding line of the Rutford Ice Stream, Antarctica, agree fairly well with earlier ground-based data. The combined use of SRI and other satellite methods is expected to provide data that will enhance the understanding of ice stream mechanics and help make possible the prediction of ice sheet behavior.     

FY-2C气象卫星延时云图的校正及实现方法

应用非线性插值法对FY-2C静止气象卫星数据中提供的简化网格数据进行近似插值计算.从计算结果看,使用非线性插值法对延时云图的校正效果较为理想,像点定位后扫描列的形状为一条平滑的曲线,基本实现了风云二数据的图像定位,为遥感数据的参数反演和针对性分析做了铺垫.     

基于Google Earth/GPS技术的海上安全救助系统综合应用

采用Orbcomm的低轨数据卫星通信技术,开发了点对点数据、短信双向透明卫星数据通讯机,通过运用.NET技术辅以Google Earth建立了海上安全救助管理信息系统,海上安全救助系统由卫星数据通信模块、GPS定位模块、嵌入式子系统和互联网模块组成,该系统有效提供了远洋船舶指挥调度、应急通信、灾情信息快速上报和共享等服务。     

Using high spatial resolution satellite imagery for mapping powdery mildew at a regional scale

Efficient crop protection management requires timely detection of diseases. The rapid development of remote sensing technology provides a possibility of spatial continuous monitoring of crop diseases over a large area. In this study, to monitor powdery mildew in winter wheat in an area where a severe disease infection occurred, the capability of high resolution (6 m) multi-spectral satellite imagery, SPOT-6, in disease mapping was assessed and validated using field survey data. Based on a rigorous feature selection process, five disease sensitive spectral features: green band, red band, normalized difference vegetation index, triangular vegetation index, and atmospherically-resistant vegetation index were selected from a group of candidate spectral features/variables. A spectral correction was processed on the selected features to eliminate possible baseline effect across different regions. Then, the disease mapping method was developed based on a spectral angle mapping technique. By validating against a set of field survey data, an overall mapping accuracy of 78 % and kappa coefficient of 0.55 were achieved. Such a moderate but practically acceptable accuracy suggests that the high resolution multi-spectral satellite image data would be of great potential in crop disease monitoring.     

Changes in Earth's albedo measured by satellite

NASA global satellite data provide observations of Earth's albedo, i.e., the fraction of incident solar radiation that is reflected back to space. The satellite data show that the last four years are within natural variability and fail to confirm the 6% relative increase in albedo inferred from observations of earthshine from the moon. Longer global satellite records will be required to discern climate trends in Earth's albedo.