Estimates of CO2 from fires in the United States: implications for carbon management

Background  

Fires emit significant amounts of CO₂ to the atmosphere. These emissions, however, are highly variable in both space and time. Additionally, CO₂ emissions estimates from fires are very uncertain. The combination of high spatial and temporal variability and substantial uncertainty associated with fire CO₂ emissions can be problematic to efforts to develop remote sensing, monitoring, and inverse modeling techniques to quantify carbon fluxes at the continental scale. Policy and carbon management decisions based on atmospheric sampling/modeling techniques must account for the impact of fire CO₂ emissions; a task that may prove very difficult for the foreseeable future. This paper addresses the variability of CO₂ emissions from fires across the US, how these emissions compare to anthropogenic emissions of CO₂ and Net Primary Productivity, and the potential implications for monitoring programs and policy development.     

Implications of sampling design and sample size for national carbon accounting systems

Background  

Countries willing to adopt a REDD regime need to establish a national Measurement, Reporting and Verification (MRV) system that provides information on forest carbon stocks and carbon stock changes. Due to the extensive areas covered by forests the information is generally obtained by sample based surveys. Most operational sampling approaches utilize a combination of earth-observation data and in-situ field assessments as data sources.     

Implications of land use change on the national terrestrial carbon budget of Georgia

Background  

Globally, the loss of forests now contributes almost 20% of carbon dioxide emissions to the atmosphere. There is an immediate need to reduce the current rates of forest loss, and the associated release of carbon dioxide, but for many areas of the world these rates are largely unknown. The Soviet Union contained a substantial part of the world's forests and the fate of those forests and their effect on carbon dynamics remain unknown for many areas of the former Eastern Bloc. For Georgia, the political and economic transitions following independence in 1991 have been dramatic. In this paper we quantify rates of land use changes and their effect on the terrestrial carbon budget for Georgia. A carbon book-keeping model traces changes in carbon stocks using historical and current rates of land use change. Landsat satellite images acquired circa 1990 and 2000 were analyzed to detect changes in forest cover since 1990.     

Relevance of carbon stocks of marine sediments for national greenhouse gas inventories of maritime nations

Background

Determining national carbon stocks is essential in the framework of ongoing climate change mitigation actions. Presently, assessment of carbon stocks in the context of greenhouse gas (GHG)-reporting on a nation-by-nation basis focuses on the terrestrial realm, i.e., carbon held in living plant biomass and soils, and on potential changes in these stocks in response to anthropogenic activities. However, while the ocean and underlying sediments store substantial quantities of carbon, this pool is presently not considered in the context of national inventories. The ongoing disturbances to both terrestrial and marine ecosystems as a consequence of food production, pollution, climate change and other factors, as well as alteration of linkages and C-exchange between continental and oceanic realms, highlight the need for a better understanding of the quantity and vulnerability of carbon stocks in both systems. We present a preliminary comparison of the stocks of organic carbon held in continental margin sediments within the Exclusive Economic Zone of maritime nations with those in their soils. Our study focuses on Namibia, where there is a wealth of marine sediment data, and draws comparisons with sediment data from two other countries with different characteristics, which are Pakistan and the United Kingdom.

Results

Results indicate that marine sediment carbon stocks in maritime nations can be similar in magnitude to those of soils. Therefore, if human activities in these areas are managed, carbon stocks in the oceanic realm—particularly over continental margins—could be considered as part of national GHG inventories.

Conclusions

This study shows that marine sediment organic carbon stocks can be equal in size or exceed terrestrial carbon stocks of maritime nations. This provides motivation both for improved assessment of sedimentary carbon inventories and for reevaluation of the way that carbon stocks are assessed and valued. The latter carries potential implications for the management of human activities on coastal environments and for their GHG inventories.

     

天宫二号近天底角交轨干涉SAR的海洋涡旋探测

海洋涡旋是海洋科学研究的一个重要分支,在海洋热循环中起着重要的作用。传统的卫星高度计通常能够探测到水平尺度超过100 km的中尺度涡旋,但是由于其分辨率较为粗糙,对于1—100 km的亚中、小尺度涡旋难以探测。天宫二号搭载的三维成像微波高度计（InIRA）是国际上第1个可以用于进行海面高度测量的Ku波段干涉SAR,为观测和研究海洋亚中、小尺度涡旋提供了数据来源。InIRA不仅可以获取海洋涡旋2维SAR图像,同时通过两个天线获取复图像间的干涉相位,能够获取涡旋海表面高度异常,为海洋涡旋的探测研究提供了新的可能。本文基于天宫二号InIRA数据,开展了海洋涡旋探测的研究,提出一种通过计算涡旋海面相对高度变化实现海洋涡旋探测的方法。通过对InIRA涡旋数据的处理与分析,发现该方法能够实现海洋涡旋的探测,并利用MODIS叶绿素浓度数据和海表温度数据对海洋涡旋探测结果进行了验证。     

Theory of oceanic levelling for improving the geoid from satellite altimetry

The problem of improving the geoid from satellite altimetry is formulated and studied within the scope of geophysical fluid dynamics. The oceanic levelling is defined by analogy to the astrogeodetic levelling and it is used to determine the sea surface topography as a function of current velocity, atmospheric pressure and viscosity. Simulating strong currents like the Gulf Stream or the Kuroshio the numerical treatment of the oceanic levelling shows that the sea surface topography can come up to an order of magnitude of1–2 m, whereby the results depend on latitude and slightly on the actual pressure conditions.     

Feasibility of the short ARC adjustment model for precise determinations of the oceanic geoid

A key element in any attempt to achieve a0.1 m precision in geoid representation via satellite altimetry is obtaining an ephemeris of comparable precision, or circumventing this requirement by adjusting the ephemeris in some way, together with the geoid. The first possibility requires extensive satellite tracking and involves an enormous number of adjustable parameters in the long arc approach. The second psssibility allows for a piece-wise treatment of short orbital arcs considered mutually independent, in which slight adjustments of the state vector parameters can compensate for an inherent modeling error. The main question to be answered when pondering the possibility of using the short arc adjustment model in SEASAT-A altimetry reductions is whether or not this method is inherently capable of representing the detailed geoid with0.1 m precision. An analysis of computer simulations provides at least a partial answer to this question by pointing out the necessary conditions in order to achieve the desired precision; under certain favorable circumstances, not described in detail, these conditions could prove to be also sufficient.     

CO2 concentration and its spatiotemporal variation in the troposphere using multi-sensor satellite data,carbon tracker,and aircraft observations

Satellite-based atmospheric CO₂ observations have provided a great opportunity to improve our understanding of the global carbon cycle. However, thermal infrared (TIR)-based satellite observations, which are useful for the investigation of vertical distribution and the transport of CO₂, have not yet been studied as much as the column amount products derived from shortwave infrared data. In this study, TIR-based satellite CO₂ products – from Atmospheric Infrared Sounder, Tropospheric Emission Spectrometer (TES), and Thermal And Near infrared Sensor for carbon Observation – and carbon tracker mole fraction data were compared with in situ Comprehensive Observation Network for Trace gases by AIrLiner (CONTRAIL) data for different locations. The TES CO₂ product showed the best agreement with CONTRAIL CO₂ data resulting in R² ~ 0.87 and root-mean-square error ~0.9. The vertical distribution of CO₂ derived by TES strongly depends on the geophysical characteristics of an area. Two different climate regions (i.e., southeastern Japan and southeastern Australia) were examined in terms of the vertical distribution and transport of CO₂. Results show that while vertical distribution of CO₂ around southeastern Japan was mainly controlled by horizontal and vertical winds, horizontal wind might be a major factor to control the CO₂ transport around southeastern Australia. In addition, the vertical transport of CO₂ also varies by region, which is mainly controlled by anthropogenic CO₂, and horizontal and omega winds. This study improves our understanding of vertical distribution and the transport of CO₂, both of which vary by region, using TIR-based satellite CO₂ observations and meteorological variables.     

Comparison of polar motion with oceanic and atmospheric angular momentum time series for 2-day to Chandler periods

During a 4-year period starting in July 1996 and using intervals ranging from 3 days to 4 years, four precise polar motion (PM) series have been compared to excitation by atmospheric angular momentum (AAM) augmented with oceanic angular momentum (OAM) data. The first three series (C03, C04 and Bulletin A) are multi-technique combinations generated by the International Earth Rotation and Reference Systems Service (IERS) and the fourth combined series (IGS00P02) is produced by the International GPS Service (IGS) using only GPS data. The IGS PM compared the best with the combined excitations of atmosphere and oceans (AAM+OAM) at all intervals, showing high overall correlation of 0.8–0.9. Even for the interval of only three days, the IGS PM gave a significant correlation of about 0.6. Moreover, during the interval of February 1999 – July 2000, which should be representative of the current precision of the IGS PM, a significant correlation (>0.4) extended to periods as short as 2.2 days and 2.5 days for the x_p and y_p PM components, respectively. When using the IERS Bulletin B (C04) PM and an interval of almost 6 years, starting in November 1994, the combined OAM+AAM accounted for practically all the annual, semi-annual and Chandler wobble (CW) PM signals. When only AAM was used, either the US National Centers for Environment Prediction reanalysis data, which were used throughout this study, or the Japanese Meteorological Agency data, two large and well-resolved amplitude peaks of about 0.1 mas/day, remained at the retrograde annual and CW periods.     

An automated method for the selection of complex railway lines that accounts for multiple feature constraints

The automatic selection of railway marshaling lines is an important procedure in the generalization of road network data. The line selection results must be geometrically consistent with the topological features of the external/internal structural and topological connectivity of the railway stations. When current methods are used to process the lines at railway marshaling stations, which exhibit crisscrossing, dense, non‐hierarchical, and complex characteristics, the selected lines tend to be topologically and structurally erroneous. In this article, we propose an automated method for the selection and generalization of complex railway lines that accounts for multiple feature constraints. First, we identify four types of line structures in accordance with the spatial and topological features of railway stations. Then, based on length and spacing thresholds specified for the generalization process, line selection is performed while accounting for constraints regarding structural robustness and topological extensibility. Finally, we report the validation of our method on a dataset relating to Chengdu Railway Station, China. The results indicate that our method successfully preserves the external and internal structural features and connectivity of railway stations.     

第二次全国土地调查成果的多比例尺缩编方法研究

第二次全国土地调查于2009年底基本完成,本文针对其成果比例尺单一、不能满足各类不同使用目的的用图要求的问题,提出二调成果的多比例尺缩编方法,并采用语义融合、多义线一体化综合、改进的2维Douglas-Peucker算法等相结合策略,高效准确地完成了缩编任务,对全国其他地方刚刚开展的同类型工作提供了一种较好的思路和借鉴。     

Controlling CO2 emissions for each area in a region: the case of Japan

Background

Unlike in the developed countries, Ethiopia does not have carbon inventories and databank to monitor and enhance carbon sequestration potential of different forests. Only small efforts have been made so far to assess the biomass and soil carbon sequestration at micro-level. This study was carried out to obtain sufficient information about the carbon stock potential of Gerba-Dima forest in south-western Ethiopia. A total of 90 sample plots were laid by employing stratified random sampling. Nested plots were used to collect data of the four carbon pools. For trees with a diameter range of 5 cm < diameter < 20 cm, the carbon stock was assessed from a plot size of 49 m² (7 m * 7 m). For trees with a diameter range of 20 cm < diameter < 50 cm, the carbon stock was assessed from a plot size of 625 m² (25 m * 25 m). For trees > 50 cm diameter, an additional larger sample of 35 * 35 m² was used. Litter, herb and soil data were collected from 1 m² subplot established at the center of each nested plot. To compute the above ground biomass carbon stock of trees and shrubs with DBH > 5 cm, their DBH and height were measured. The biomass carbon assessment of woody species having DBH < 5 cm, litter and herb were conducted by measuring their fresh weight in the field and dry weight in the laboratory.

Results

The mean total carbon stock density of Gerba-Dima forest was found to be 508.9 tons carbon ha⁻¹, out of which 243.8, 45.97, 0.03 and 219.1 tons carbon ha⁻¹ were stored in the above ground biomass, below ground biomass, litter biomass and soil organic carbon, respectively.

Conclusions

The existence of high carbon stock in the study forest shows the potential of the area for climate change mitigation. Thus, all stakeholders at the local and national level should work together to implement effective conservation measures and get benefit from the biocarbon fund.

     

Atmospheric and oceanic forcing of the rapid polar motion

The rapid polar motion for periods below 20 days is revisited in light of the most recent and accurate geodetic and geophysical data. Although its amplitude is smaller than 2 mas, it is excited mostly by powerful atmospheric processes, as large as the seasonal ones. The residual amplitude, representing about 20% of the total excitation, stems from the oceans. Rapid polar motion has an irregular nature that is well explained by the combined influence of the atmosphere and the oceans. An overall spectrum reveals cycles principally at 20, 13.6 (fortnightly tidal period) and 10 days (corresponding to the normal atmospheric mode Y₃¹{\Psi_3^1}), but this is only an averaged feature hiding its strong variability over seasonal time scales. This explains why it is so delicate to determine an empirical model of the tidal effect on polar motion. The variability in both amplitude and phase of the 13.6-day term is probably caused by a lunar barometric effect, modulated by some sub-seasonal thermal processes. The irregularities of the prominent cycles of the short-term polar motion are well explained by the atmospheric and oceanic excitations. The oceanic variability reinforces the atmospheric one, as they were triggered by the same agent, maybe seasonal and inter-annual thermal variations.     

Capacity assessment of the Qattara Depression: Egypt as a sink for the global sea level rise

One of the most prominent geomorphological features in the Western Desert of Egypt is the occurrence of the Qattara Depression (20,800 km² or 2% of Egypt’s area), which has the deepest point in Africa. Topographic analysis of the depression was carried out using fine resolution digital elevation models acquired from the Advanced Spaceborne Thermal Emission and Reflection Radiometer-Global Digital Elevation Model (ASTER-GDEM) in order to assess the capacity of the depression. Results showed that the lower point in the depression occurs at ?136 m and its capacity at the sea level is 1340 billion m³, which equals 10 times the live storage capacity of the Lake Nasser behind the Aswan High Dam. Although the depression has the aptitude to be a reservoir for any augmentation in the sea level, detailed environmental impact assessment studies should be implemented to address geologic, climatic, biologic as well as socio-economic impacts.     

利用GPS反射信号遥感全球海态

最近几年，迅速发展一种新的空基海洋遥感技术。它在低轨卫星上接收经海面或地面反射的GPS信号，通过分析C／A或P码的相关函数波形及其后沿，荻得全球海面平均高度、浪高、海面风场以及土壤湿度等，提供海洋中尺度涡旋发展、演变信息，监测和分析高纬地区冰层厚度。它采用无源探测方法，具有成本低、荻取数据量多和快速等突出特点，是传统卫星高度计探测的重要补充和发展。该文讨论了这项技术发展现状、反射信号的时间延迟以及海态参数计算等关键技术；也给出作者利用掩星观测资料分析得到的海面反射回波一些重要结果。     

系列比例尺地形数据库信息量比较——以1∶250000和11∶000000居民地为例

合理度量地理信息信息量可为信息的生产者、质量控制者和用户描述、评价、选用相关产品提供相关技术依据。本文在总结了已有地形数据库信息量量测研究现状后,选择一幅国家11∶000000地形数据和对应范围内的16幅1∶250000地形数据中的居民地要素层,全面分析评价了该要素层的统计信息量,几何信息量和专题(属性)信息量及其在不同比例尺之间的关系。实验表明,对地形数据库中的要素层采用全面评价的方法是可行和必要的,在各比例尺的居民地的信息量之间存在一定的数量关系,同时也部分验证了在地图缩编时为保持信息量最大化所要采取的必要措施的理论依据。     

国家体育场“鸟巢”支撑塔架施工测量

国家体育场是2008年北京第29届奥运会的主体育场。其屋盖钢结构跨度大,覆盖面积也大,受力非常复杂。在施工过程中,主桁架搁置在78个临时支撑塔架上,支撑塔架的施工测量就成了整个钢结构施工的关键。     

Effects of national forest inventory plot location error on forest carbon stock estimation using k-nearest neighbor algorithm

This paper suggested simulation approaches for quantifying and reducing the effects of National Forest Inventory (NFI) plot location error on aboveground forest biomass and carbon stock estimation using the k-Nearest Neighbor (kNN) algorithm. Additionally, the effects of plot location error in pre-GPS and GPS NFI plots were compared. Two South Korean cities, Sejong and Daejeon, were chosen to represent the study area, for which four Landsat TM images were collected together with two NFI datasets established in both the pre-GPS and GPS eras. The effects of plot location error were investigated in two ways: systematic error simulation, and random error simulation. Systematic error simulation was conducted to determine the effect of plot location error due to mis-registration. All of the NFI plots were successively moved against the satellite image in 360° directions, and the systematic error patterns were analyzed on the basis of the changes of the Root Mean Square Error (RMSE) of kNN estimation. In the random error simulation, the inherent random location errors in NFI plots were quantified by Monte Carlo simulation. After removal of both the estimated systematic and random location errors from the NFI plots, the RMSE% were reduced by 11.7% and 17.7% for the two pre-GPS-era datasets, and by 5.5% and 8.0% for the two GPS-era datasets. The experimental results showed that the pre-GPS NFI plots were more subject to plot location error than were the GPS NFI plots. This study’s findings demonstrate a potential remedy for reducing NFI plot location errors which may improve the accuracy of carbon stock estimation in a practical manner, particularly in the case of pre-GPS NFI data.     

第三次国土调查的图斑自动综合方法

从第三次国土调查数据库快速缩编派生出多尺度数据库,是地图制图的重要任务。本文针对大量图斑,首先通过研究图斑栅格综合,减少碎图斑数量;然后构建图斑语义邻近度模型、空间几何拓扑模型,分析了顾及拓扑和地区地理特征约束下的地类图斑制图综合方法;最后形成了自动化图斑缩编生产工艺流程。基于上述方法,采用计算机编程技术研发国土三调缩编系统,并应用于四川省某县23万图斑量的三调数据并试验验证。试验结果表明,通过本文方法的成果符合专题制图要求,极大地提高了三调图斑的自动综合效率。     

第三次全国国土调查土地利用矢量数据栅格化方法

第三次全国国土调查县级土地利用图斑层包含利用类型、耕地类型、坡度等级、种植属性等多属性信息,将县级土地利用矢量数据集成栅格化形成全国无缝的多尺度、多专题栅格产品存在一定技术难度。本文针对第三次全国国土调查土地利用栅格产品应用需求,探讨了多属性综合编码、全国基础地理网格框架、栅格化产品数据模型、矢量栅格化等技术方法,建立了全国土地利用栅格产品生产流程,开展了全国多尺度、多专题土地利用栅格产品生产验证。结果表明:本文方法能够实现第三次全国国土调查土地利用矢量图斑多属性信息集成栅格化和全国多尺度、多专题土地利用栅格产品工程化生产,可为今后的国土调查土地利用栅格产品生产和共享应用提供支撑。