论测绘地理信息工作的标准化

地理信息数据在各行各业中有着广泛的应用,本文从高效率、高质量地生产测绘地理信息数据,促进不同行业的测绘地理信息数据共建共享,资质单位测绘生产管理3个方面,阐述测绘地理信息工作标准的作用和方法。     

Comparison of four UAV georeferencing methods for environmental monitoring purposes focusing on the combined use with airborne and satellite remote sensing platforms

This work is aimed at the environmental remote sensing community that uses UAV optical frame imagery in combination with airborne and satellite data. Taking into account the economic costs involved and the time investment, we evaluated the fit-for-purpose accuracy of four positioning methods of UAV-acquired imagery: 1) direct georeferencing using the onboard raw GNSS (GNSSNAV) data, 2) direct georeferencing using Post-Processed Kinematic single-frequency carrier-phase without in situ ground support (PPK1), 3) direct georeferencing using Post-Processed Kinematic double-frequency carrier-phase GNSS data with in situ ground support (PPK2), and 4) indirect georeferencing using Ground Control Points (GCP). We tested a multispectral sensor and an RGB sensor, onboard multicopter platforms. Orthophotomosaics at <0.05 m spatial resolution were generated with photogrammetric software. The UAV image absolute accuracy was evaluated according to the ASPRS standards, wherein we used a set of GCPs as reference coordinates, which we surveyed with a differential GNSS static receiver. The raw onboard GNSSNAV solution yielded horizontal (radial) accuracies of RMSEr≤1.062 m and vertical accuracies of RMSEz≤4.209 m; PPK1 solution gave decimetric accuracies of RMSEr≤0.256 m and RMSEz≤0.238 m; PPK2 solution, gave centimetric accuracies of RMSEr≤0.036 m and RMSEz≤0.036 m. These results were further improved by using the GCP solution, which yielded accuracies of RMSEr≤0.023 m and RMSEz≤0.030 m. GNSSNAV solution is a fast and low-cost option that is useful for UAV imagery in combination with remote sensing products, such as Sentinel-2 satellite data. PPK1, which can register UAV imagery with remote sensing products up to 0.25 m pixel size, as WorldView-like satellite imagery, airborne lidar or orthoimagery, has a higher economic cost than the GNSSNAV solution. PPK2 is an acceptable option for registering remote sensing products of up to 0.05 m pixel size, as with other UAV images. Moreover, PPK2 can obtain accuracies that are approximate to the usual UAV pixel size (e.g. co-register in multitemporal studies), but it is more expensive than PPK1. Although indirect georeferencing can obtain the highest accuracy, it is nevertheless a time-consuming task, particularly if many GCPs have to be placed. The paper also provides the approximate cost of each solution.     

不同UT1周日变化海潮模型结果的比较

比较了基于 TOPEX/ Poseidon卫星测高资料 ,长时期甚长基线干涉测量 (VLBI)观测和人卫激光测距 (SLR)观测所决定的地球自转周日变化。经比较显示 ,不同技术或同一种技术使用不同的方法所获得结果是有差异的 ,同一种技术内部符合较好 ,而不同技术间存在系统差。另外 ,我们根据 93年～ 94年的 VL BI观测资料获得一个结果 ,由于观测资料少 ,所获得结果差异较大 ,但 UT1周日变化的大体趋势一致。     

OGC与我国地理信息产业

通过对开放地理信息系统联合会(OGC)的现有规范介绍，探讨了OGC规范与地理空间数据、服务互操作性的关系，以及对我国地理信息产业发展的意义。     

OpenGIS网络地图分块服务实现标准（WMTS）分析

在充分理解OpenGIS网络地图分块服务实现标准（WMTS）1.0的基础上,通过与目前开源社区和商业应用中具有相同定位的几个规范的对比,分析了WMTS所具有的技术特点。分析表明,该规范除支持常规的分块地图服务,还在多图式、多维度、坐标系统适应性以及URL个性化等方面为一些特殊应用提供了有力支持,相应其实现的难度也相对较大,需要实现人员付出更多时间来理解标准的内容。     

Developing environmental standards for abstractions from UK rivers to implement the EU Water Framework Directive / Développement de standards environnementaux sur les prélèvements d'eau en rivière au Royaume Uni pour la mise en œuvre de la directive cadre sur l'eau de l'Union Européenne

Abstract

Under the European Union Water Framework Directive, Member States must put in place a river basin planning framework to determine what measures are necessary to maintain and improve the ecological status for all surface water bodies. The governmental organisations legally responsible for implementing the Directive in the UK have recognised that an appropriate river flow regime is fundamental to maintain a healthy river and, as a result, they need to regulate abstractions and effluent discharges and ensure sufficient water is released from impoundments. This paper reports on the process of producing environmental standards that define the maximum abstraction allowable from UK rivers, to leave sufficient flow to maintain a healthy river ecosystem. As there are currently insufficient data available to determine the relationships between river flow and ecological status empirically, expert knowledge was captured through a series of workshops at which leading UK freshwater scientists defined maximum levels of river flow regime alteration that would achieve ecological objectives for different river water body types. For the least ecologically sensitive rivers, maximum abstractions in the range 15–35% of the natural flow were proposed, depending on the flow magnitude and time of year. For the most sensitive rivers, the maximum abstraction proposed was in the range 7.5–25%. The knowledge was used by the responsible UK authorities to develop environmental standards. The authorities subsequently used the environmental standards to determine regulatory standards that could be implemented within practical constraints and current licensing policies.     

Distribution of cadmium,mercury, and lead in different body parts of Baltic herring (Clupea harengus) and perch (Perca fluviatilis): Implications for environmental status assessments

For heavy metals, quality standards indicating good environmental status are designed to evaluate concentrations in the whole fish body, whereas monitoring of metals is often conducted using muscle or liver tissue. As most metals accumulate at different rates in different parts of fish, data should be adjusted to reflect whole fish body concentrations; however, this requires knowledge on distribution of metal concentrations within fish. Here, concentrations of cadmium, mercury, and lead were analyzed in the liver, muscle and whole fish of herring and perch to create conversion factors for transformation of heavy metal concentrations between these tissues. Species-specific accumulation of metals between muscle, liver, and whole fish were observed. Relationships between different tissues were used to recalculate data from monitoring programs in the Baltic Sea region. Based on whole fish concentrations, environmental status for cadmium and mercury in herring improved compared to assessments based on muscle or liver concentrations alone.     

PM2.5监测及评价研究进展

综合阐述了近年来国内外PM2.5的监测方法、观测站网建设发展,以及PM2.5对人体健康、大气环境及天气、气候等方面的影响研究,并对国内外PM2.5空气质量标准差异进行了比较分析,提出了加强PM2.5监测及影响评价的建议.     

Spatial characteristics of extreme rainfall over China with hourly through 24-hour accumulation periods based on national-level hourly rain gauge data

Hourly rainfall measurements of 1919 national-level meteorological stations from 1981 through 2012 are used to document,for the first time,the climatology of extreme rainfall in hourly through 24-h accumulation periods in China. Rainfall amounts for 3-,6-,12- and 24-h periods at each station are constructed through running accumulation from hourly rainfall data that have been screened by proper quality control procedures. For each station and for each accumulation period,the historical maximum is found,and the corresponding 50-year return values are estimated using generalized extreme value theory. Based on the percentiles of the two types of extreme rainfall values among all the stations,standard thresholds separating Grade I,Grade II and Grade III extreme rainfall are established,which roughly correspond to the 70th and 90th percentiles for each of the accumulation periods. The spatial characteristics of the two types of extreme rainfall are then examined for different accumulation periods. The spatial distributions of extreme rainfall in hourly through 6-h periods are more similar than those of 12- and 24-h periods. Grade III rainfall is mostly found over South China,the western Sichuan Basin,along the southern and eastern coastlines,and in the large river basins and plains. There are similar numbers of stations with Grade III extreme hourly rainfall north and south of 30°N,but the percentage increases to about 70% south of 30°N as the accumulation period increases to 24 hours,reflecting richer moisture and more prolonged rain events in southern China. Potential applications of the extreme rainfall climatology and classification standards are suggested at the end.     

Regulatory control of vehicle and power plant emissions: how effective and at what cost?

Passenger vehicles and power plants are major sources of GHG emissions. While economic analyses generally indicate that a broader market-based approach to GHG reduction would be less costly and more effective, regulatory approaches have found greater political success. We evaluate a global regulatory regime that replaces coal with natural gas in the electricity sector and imposes technically achievable improvements in the efficiency of personal transport vehicles. Its performance and cost are compared with other scenarios of future policy development including a no-policy world, achievements under the Copenhagen Accord, and a price-based policy to reduce global emissions by 50% by 2050. The assumed regulations applied globally achieve a global emissions reduction larger than projected for the Copenhagen agreements, but they do not prevent global GHG emissions from continuing to grow. The reduction in emissions is achieved at a high cost compared to a price-based policy. Diagnosis of the reasons for the limited yet high-cost performance reveals influences including the partial coverage of emitting sectors, small or no influence on the demand for emissions-intensive products, leakage when a reduction in fossil use in the covered sectors lowers the price to others, and the partial coverage of GHGs. If these regulatory measures are in part correcting other barriers or behavioural limitations consumers face, the benefits of overcoming these could offset at least some of the costs we estimate. The extent of any efficiency gap – the difference between engineering estimates of best practice and what actually happens – is highly contested, and offers an important avenue for future research.

Policy relevance

While analysts concerned with national cost of GHG control have long advocated a GHG pricing policy, by a cap-and-trade system or a tax, covering all emissions sources and gases, governments more often pursue sectoral policies and technology standards. Given these political realities, the regulations represent a more politically practical approach to GHG reductions, focusing on solutions that are within reach and that do not depend on technological breakthroughs. If regulations are imposed as a way to get started on larger emissions reductions, and then combined with a broader GHG pricing policy pursuing a deep global cut in emissions, its requirements will eventually be overtaken by the pricing policy. The remaining higher costs of the regulatory targets become diluted so that in later years the difference in average cost per ton between a least-cost approach and one preceded by a period of regulatory action becomes very small.