Effect of sensor modelling methods on computation of 3-D coordinates from Cartosat-1 stereo data

The orbital and the rational polynomial coefficients (RPC) models are the two most commonly used models to compute a three-dimensional coordinates from an image stereo-pair. But it is still confusing that with the identical user provided inputs, which one of these two models provides more accurate digital elevation model (DEM), especially for mountainous terrain. This study aimed to find out the answer by evaluating the impact of used models on the vertical accuracy of DEM extracted from Cartosat-1 stereo data. We used high-accuracy photogrammetric DEM as the reference DEM. Apart from general variations in statistics, surprisingly in a few instances, both the DEMs provided contrasting results, thus proving the significance of this study. The computed root mean square errors and linear error at 90% (LE90) were lower in case of RPC DEM for various classes of slope, aspect and land cover, thus suggesting its better relative accuracy.     

用化石天长计算地球年龄的方法及意义——如何理解地球年龄

天长（一天时长）是地球自转速度的直接反映。古生代-中生代化石记录的天长数据表明,古生代-中生代期间的天长随时间呈线性增加。根据角动量守恒定律,这意味着同时段地球自转速度呈线性衰减。如果把这个趋势应用于地球历史的全过程,计算结果为4.519～4.495 Ga,与目前公认的地球绝对年龄4.54 Ga一致。这意味着,从这个时间点起,地球有一种自转速度衰减的总趋势。地球自转速度衰减年龄等值于地球年龄说明：1）所测量的陨石样本生成的时间（表征地球年龄）与地球受月球吸引形成自转减速的时间几乎相同。这意味着地-月体系形成之前的地球比该陨石表征的地球年龄更为古老。2）地球、月球、自转速度衰减时长,三者的年龄呈现等值状态,因而此结果与月球起源于大碰撞的假说可以匹配。     

Early growth fault activity: new evidence for extension in the upper Cambrian Owen Group,Proprietary Peak,western Tasmania,Australia

The coarse-grained, upper Cambrian Owen Group of western and northern Tasmania is a prominent feature of the Tasmanian landscape and regional map series. The group has previously been divided into four informal formations (Lower Owen Conglomerate, Middle Owen Sandstone, Middle Owen Conglomerate and Upper Owen Sandstone) that have been correlated across the state over tens to hundreds of kilometres. The deposition of these sediments is largely believed to have occurred during extensional tectonics, but some authors continue to argue a compressional tectonic regime. Detailed mapping and sedimentological work around Proprietary Peak on the Mount Jukes massif, 10 km south of Queenstown, Tasmania, has identified significant depositional variations controlled by early growth faulting and paleotopography. Discontinuity of stratigraphic units (L6–L13) across two growth faults on the north face of Proprietary Peak shows the strong effect on sediment deposition in the area. Paleotopography is also evident with most stratigraphic units (L8–L13 and U1) gradually onlapping basement during their deposition. Significant paleotopography has also been identified on East Jukes Peak, where lower Owen Group sedimentary units onlap basement volcanics, with no evidence for tectonically controlled deposition. Field evidence strongly supports the deposition of the Owen Group during extensional tectonics, after a period of prolonged erosion of the underlying Mount Read Volcanics. The distinct variation in vertical and lateral extent of stratigraphic units within the Owen Group in the Proprietary Peak area suggests that widespread lithostratigraphic correlation of older Owen Group sedimentary units across Tasmania may not be feasible.     

一次攀西地区飑线天气过程形成机制分析

利用地面气象常规观测资料、区域自动站观测资料、雷达及卫星资料和NCEP 1°×1°的逐6h再分析资料,对2018年5月13日攀西地区南部的飑线天气过程的形成机制进行分析。结果表明:飑线发生在高空槽前,高空槽逐渐东移推动冷性气流沿背风坡东移,然后与前方低层暖空气汇合抬升形成对流;露点锋触发了飑线天气过程的形成;产生飑线天气区域的大气具有上干下湿、不稳定能量高、垂直风切变强、高层风速大和形成之前存在逆温层的特点;高空急流和动量下传对飑线的发生和加强具有促进作用;地形对飑线的形成和天气现象的分布有影响。     

一次强飑线过程极端大风的中尺度分析

利用常规气象观测资料、区域自动气象站加密观测资料和GFS 0.25°×0.25°逐6 h的分析场数据以及多普勒雷达、风廓线等资料,通过背景形势场分析、物理量诊断分析和中尺度分析,对2018年3月4日发生在华东地区的强飑线天气过程进行了诊断分析。结果表明,这次过程具有发生时间(季节)早、移速快、范围广、致灾强等特点,是一次比较少见的早春(冬末)十分强烈的飑线天气过程,是在高空急流辐散区、低空西南急流轴前端、低涡南侧的暖区中发展起来的。飑线过程的地面要素变化十分剧烈,地面有强冷池,与飑线前暖空气之间构成了强的水平温度梯度,致使飑线强度更强;飑线经过时气压涌升所形成的雷暴高压、强气压梯度以及飑线的快速移动均有利于地面极端大风的出现。飑线发展过程中观测到弓形回波、超级单体等强天气系统。中高层动量下传和光滑湖面、喇叭口、狭管效应等特殊地形对于大风的增强效应比较显著,这些因素也加剧了地面极端大风的形成。      

Tectonic Movement and Global Climate Change

Glaciation between northern hemisphere and southern hemisphere were synchronous, the ice age occurred not in high but in low value of the eccentricity of the earth's orbit. Such facts went against the precession principle of the astronomical theory of ice age. The inhomogeneous distribution of climate consisted with the inhomogeneous distribution of ocean and continent. The north/south antisymmetry may be attributed to southward deviation of the thermal center and northward deviation of the mass center within the mantle demonstrated by seismic tomography. The core - mantle angular momentum makes rotational energy into thermal energy and mantle plumes erupt in the ocean bottom. The earth's deformation by tidal force makes the eruption of mantle plumes strong. They are the reason that glaciation between the Northern Hemisphere and Southern Hemisphere are synchronous and the ice age occurred in low value of the eccentricity of the earth' s orbit. The tectonic movement is playing a most important part in global climate change.     

深水等深流沉积中记录的米兰科维奇特性——以陕西富平地区上奥陶统赵老峪组为例

陕西富平地区上奥陶统赵老峪组为深水盆地边缘至深水斜坡沉积环境,发育深水原地沉积、等深流沉积及重力流沉积。以野外实测剖面、岩相特征等资料为基础,结合米兰科维奇理论、天文地层学、古海洋学以及古气候学,系统研究该地区等深流强度与古气候、海平面、古盐度的关系。结果表明:Fischer图解可以客观、准确地反映深水沉积地层相对海平面变化;深水沉积及等深流沉积中不同级次旋回垂向组合关系记录了米兰科维奇特性,即小级别旋回在垂向上有序地按照1∶4或者1∶5的形式叠加构成较大级别旋回;等深流强度受米兰科维奇旋回影响,呈多周期弱→强→弱递变;等深流强化周期约为0.1Ma。     

GNSS精密轨道产品不连续性分析及评估

按照目前的国际规范, 高精度GNSS (Global Navigation Satellite System)轨道产品一般以天为周期进行发布, 提供给用户使用. 连续使用多天的产品存在不同天间的跳变问题. 利用德国地学研究中心(GFZ)、欧洲定轨中心(COD)、欧空局(ESA)、美国喷气试验室(JPL)以及上海天文台(SHA)共5个GNSS分析中心2013---2017年的轨道产品, 分析了轨道跳变的特性. 计算结果表明: GFZ、COD、ESA、SHA和JPL的3维轨道跳变平均分别为7.79cm、1.51cm、7.77cm、11.75cm和2.51cm. 轨道跳变序列的周期特性分析表明: 序列存在90d、120d、340d左右的显著周期项, 对应于海潮对地球自转的影响, 其振幅为数毫米至1cm左右. 表明精密轨道确定需要进一步精化该项模型; GPS的跳变序列还存在与卫星星座相关的175d和352d左右的交点年显著周期项. 此外, 针对COD产品外推轨道的分析, 验证了地球反照辐射压和太阳光压模型等动力学模型对轨道的差异.     

两次大风过程的对比分析

文章对两次冷空气结合低气压大风过程进行了对比分析,揭示了海上低压轴向的突然向西北转变而引起的地面气压梯度的迅速加大是造成浙北沿海大风的重要原因之一。同时,揭示了两次过程由于高低层辐合辐散差异而引起的大风区上空两类不同的高低空垂直下沉速度分布特征,指出动量下传作用在地面造成风速的加大主要决定于对流层低层下沉速度(而非中层),这可能是两次大风过程地面气压梯度接近,而实际风力却差一级的原因。     

0515台风"卡努"影响浙江的强风分析

本文对0515台风“卡努”登陆浙江后,强度减弱为强热带风暴,对影响浙江沿海海面及沿海地区的外围风速远强于近风暴中心风速进行了分析,分析结果表明:副热带高压的加强、对流层中下层急流的动量下传、高空较强的下沉气流和台风外围气压梯度力迅猛增大的共同作用,是造成本次风暴外围风速远强于近风暴中心风速的重要原因。