Sectoral approaches to improve regional carbon budgets

Humans utilise about 40% of the earth’s net primary production (NPP) but the products of this NPP are often managed by different sectors, with timber and forest products managed by the forestry sector and food and fibre products from croplands and grasslands managed by the agricultural sector. Other significant anthropogenic impacts on the global carbon cycle include human utilization of fossil fuels and impacts on less intensively managed systems such as peatlands, wetlands and permafrost. A great deal of knowledge, expertise and data is available within each sector. We describe the contribution of sectoral carbon budgets to our understanding of the global carbon cycle. Whilst many sectors exhibit similarities for carbon budgeting, some key differences arise due to differences in goods and services provided, ecology, management practices used, land-management personnel responsible, policies affecting land management, data types and availability, and the drivers of change. We review the methods and data sources available for assessing sectoral carbon budgets, and describe some of key data limitations and uncertainties for each sector in different regions of the world. We identify the main gaps in our knowledge/data, show that coverage is better for the developed world for most sectors, and suggest how sectoral carbon budgets could be improved in the future. Research priorities include the development of shared protocols through site networks, a move to full carbon accounting within sectors, and the assessment of full greenhouse gas budgets.     

应用EOS-MODIS卫星资料反演西北干旱绿洲的地表反照率

地表反照率是一个广泛应用于地表能量平衡、中长期天气预测和全球变化研究的重要参数, 作者应用EOS-MODIS卫星数据和目前发展的推算反照率比较完善的一种二向反射(BRDF)模型Ross Thick-Li Sparse R核算法(AMBRALS算法), 对西北干旱绿洲区非均匀分布的地表反照率进行反演与分析, 结果表明, 应用该方法反演的地表参数与实际观测值基本接近.敦煌戈壁站的反演值与观测值的春、夏、秋季绝对误差最大为0.019, 冬季为0.051, 黑河绿洲实验站的反演值较观测值低0.019; 绿洲、绿洲     

基于GPS观测资料反演庄浪河断裂带、马衔山北缘断裂带的滑动速率

根据地质资料,首先建立庄浪河断裂带、马衔山北缘断裂带空间展布的三维几何模型和分段模型,并把地质方法大致推测或估计的各段滑动速率和滑动方式作为先验初值,通过三维深断裂位错模型对GPS观测站点速度场的最佳拟合,反演获得各断裂段的现今滑动速率。结果表明,马衔山北缘断裂有1.4～3.0mm/a的逆倾滑,且中部断层段有约3mm/a的左旋走滑;庄浪河断裂有0.6～1.2mm/a的逆倾滑,走滑分量不明显。这些滑动速率值均在地质方法的推测范围内,且模型预测的GPS站点速度与实际观测值在整体上取得了较好的吻合。本研究表明,对于庄浪河断裂带、马衔山北缘断裂带这样一些滑动速率相对较低且传统地质调查方法较难实施的断裂,基于GPS观测结果的滑动速率反演是一种有效的补充手段     

电离层舒曼共振的空间观测

通过功率谱分析和波阻抗函数计算,本文证实了Aureol 3卫星在电离层高度上(>600km)观测到的极低频(ELF)波场扰动是和舒曼共振相关的电磁振荡.与舒曼共振地面观测相比较,Aureol 3观测到的舒曼共振电场分量具有很好的谐振谱结构,峰值频率和各阶舒曼共振本征频率对应;磁场分量的高阶峰值频率偏离14, 20, 26Hz等舒曼共振本征频率;随着卫星高度的改变,电场与磁场谐振的一阶最大能量峰值并不会发生在同一频率,结合本文分析的数据,分别位于78Hz和10Hz;水平方向的磁场分量更接近南北方向的线极化而不是地球－电离层空腔中的椭圆极化;波阻抗随频率表现出不太规则的准正弦振荡,它会随着频率增加和飞行高度上升呈现减小的趋势.虽然舒曼共振信号和电离层密度梯度间的非线性作用可以解释舒曼共振空间观测的部分特征,但需加入其他机制,如电离层不稳定性,传播模式的耦合,进一步了解电离层高度上舒曼共振各种特征产生的原因.     

A 2D hydrodynamic model for shallow water flows with significant infiltration losses

Infiltration losses may be significant and warrant proper incorporation into mathematical models for river floods in arid and semi-arid areas, rainfall-induced surface runoffs in watersheds and swashes on beaches. Here, a depth-averaged two-dimensional hydrodynamic model is presented for such processes based on the cell-centred finite volume method on unstructured meshes, with the full Green-Ampt equation evaluating the infiltration rate. A local time stepping strategy is employed along with thread parallelization with Open Multi-processing and high-performance computing to reduce model run time and therefore facilitate applications for large-scale processes. The numerical solutions generally agree with the experimental and field-measured data for typical cases with significant infiltration losses. The case study shows that neglecting infiltration leads to an overestimated discharge hydrograph, which cannot be compensated by means of varied bed resistance as estimated by Manning roughness, and the infiltration parameters play disparate roles in modifying shallow flows compared with Manning roughness. In addition, infiltration affects bed shear stress, which in turn modifies the critical bed sediment size that could be initiated for incipient motion by the flow and therefore needs to be properly accounted for when sediment transport and morphological evolution are to be resolved.     

基于NDVI时序数据的水稻种植面积遥感监测分析——以江苏省为例

MODIS植被指数时间序列产品能够连续反映植被的覆盖情况,是农作物遥感测量的重要数据源.本文选取江苏省为研究区,利用2008年23个时相的MODIS NDVI数据,采用S-G滤波法进行时间序列的重构,提高NDVI时间序列信息的真实性.另结合农作物物候历、种植结构、地面调查样本等辅助资料,将水稻植被指数时间序列曲线参量化...     

The sedimentary record of a Mesoproterozoic tsunami from the North China Craton

A layer of Mesoproterozoic tsunami deposits from the North China Craton was recently discovered and investigated in the Xingcheng area, Liaoning Province, China. They occur at the bottom of the Dahongyu Formation of the Changcheng Group (1.8–1.6 Ga). The tsunami deposits are identified based on the analysis of the sedimentary facies. They are markedly different from the normal deposits of shore‐shallow sea siliciclastics, and are characterized by rip‐up clasts, poorly sorted gravels, fining‐upward sequences, redeposited underlying materials, complex sources of underlying strata and erosional bases at the bottom of beds. They are compelling features of tsunamiites when they occur together. During the Mesoproterozoic, the Xingcheng area was in an active tectonic belt, the Yanshan Taphrogenic Trough. The origin of the tsunami was probably triggered by the earthquake, which resulted from the the activities of the Luanxian–Jianchang Fault in early Mesoproterozoic times. The deposition of tsunamiites occurred in a coastal environment and involved several stages, from the origin, propagation, inundation, and deposition to the backwash flow. The geodynamic backgrounds of the tsunami event in the North China Craton are consistent with the breakup event of the Columbia supercontinent in the Mesoproterozoic. Some events, such as tsunamis and volcanism, are all controlled by extensional rift systems and should be recognized as effects of the breakup of the Columbia supercontinent in the North China Craton. Copyright © 2013 John Wiley & Sons, Ltd.     

冬季北极海冰与中国同期气温的关系

采用Hadley中心的海冰密集度资料和中国160站气温资料,对冬季北极海冰变化的主要模态进行了分析,定义了5个关键海区,重点讨论了冬季北极海冰异常与中国冬季气温的关系.结果表明,冬季北极海冰变化主要表现为第一模态,即太平洋、大西洋的海冰反位相分布.海冰变化的关键区域为区域Ⅰ巴伦支海、区域Ⅱ格陵兰海、区域Ⅲ戴维斯海峡、区...     

利用多个震源机制解求东大别地区平均应力场

利用地震的震源机制解资料,得到应力张量在地理坐标系下的表达式,进而可计算平均应力张量.通过求平均应力张量的本征向量,即可得到其主轴方向,并由此推断区域应力场方向.利用东大别地区219次地震的震源机制解资料,比较了不同相似程度和不同起算震级资料得到的主轴方向,认为该方法计算结果非常稳定,主轴方位角的误差小于5°,倾角的误...     

A Case Study on the Effect of Post-critical SmS on Ground Motion in Yingjiang,Yunnan Province,China

There are controversies on ground motion attenuation relations at the epicentral distance of about 100km. Some models predict that the seismic energy remains almost constant or becomes even stronger with increasing distance at this distance,while other models hold that it decreases with increased distance. The divergence lies mainly in whether SmS is stronger than direct S and surface waves at this distance. With the MS5. 9 earthquake sequence in the Yingjiang region of Yunnan Province as an example,we demonstrate that SmS is always 2 ～ 5 times stronger than direct S waves around the epicentral distance of 100km ( which is the post-critical distance for S in this region ). Study of synthetic seismograms suggest that crustal structure has an important effect on the amplitude of post-critical SmS, with simple crust producing strong SmS. This preliminary study confirms that in China,SmS also plays an important role on ground motion at distances around 100km,which demands more studies of post-critical SmS.