Long-Term Stability Of Geoidal Geopotential FromTopex/Poseidon Satellite Altimetry 1993–1999     

Burša  Milan  Kenyon  Steve  Kouba  Jan  Müller  Achim  Raděj  Karel  Vatrt  Viliam  Vojtíšková  Marie  Vítek  Vojtěch 《Earth, Moon, and Planets》1999,84(3):163-176

The TOPEX/POSEIDON (T/P) satellite altimeter data from January 1, 1993to October 24, 1999 (cycles 11–261) was used for investigating thelong-term variations in the geoidal geopotential W₀ and/orin the geopotential scale factor R₀ = GM/W₀ (GM is theadopted geocentric gravitational constant). The mean valuesdetermined for the whole period covered are: W₀ =(62 636 856.161 ± 0.002) m² s^-2, R₀ =(6 363 672.5448 ± 0.0002) m. The actual accuracy is limited bythe altimeter calibration error (2–3 cm) and it isestimated to be about ± 0.5 m² s^-2 (± 5 cm).The yearly variations of the above mean values are at the formalerror level. No long-term trend in W₀, representing the oceanvolume change, was found for the seven years period 1993–9 on thebasis of T/P altimeter (AVISO) data. No sea surface topography modelwas used in the solution. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Himawari-8气溶胶光学厚度产品的验证分析     

赵垒  辛金元  杨磊库  司瑞瑞  刘光静 《大气科学》2020,44(3):455-471

Himawari-8是由日本气象局发射的新一代静止气象卫星，其搭载的传感器AHI（Advanced Himawari Imager）可实现10 min/次的高时间分辨率对地观测。本文将2015年9月至2017年12月Himawari-8卫星Level-2气溶胶光学厚度（AOD）产品与AERONET（AErosol RObotic NETwork）70个站点的地基观测数据进行对比验证分析，结果表明Himawari-8卫星反演的气溶胶光学厚度产品的精度存在很大的空间上的差异性，其中有48个站点Himawari-8 AOD与AERONET AOD之间存在较好的相关性（R>0.5），有22个站点Himawari-8卫星反演气溶胶光学厚度产品存在明显的低估现象。在American_Samoa、Bandung、Birdsville、Bukit_Kototabang、Canberra、Fowlers_Gap、Jabiru以及QOMS_CAS等站点出现地基观测值很小而卫星反演的气溶胶光学厚度较大的情况。对绝对误差（Himawari-8 AOD与AERONET AOD的差）进行分析发现Himawari-8 AOD存在低估现象时绝对误差与AERONET AOD之间存在较好的相关性；在地基观测值很小而Himawari-8卫星反演AOD较大的地区绝对误差与Himawari-8 AOD之间存在较好的线性关系，这为Himawari-8 AOD反演算法的改进与完善提供了有用的研究发现。  相似文献   

FORSAT: a 3D forest monitoring system for cover mapping and volumetric 3D change detection     

Efstratios Stylianidis  Daniela Poli  Martin Hofer  Armin Gruen  Victor Sanchez Martin 《International Journal of Digital Earth》2020,13(8):854-885

ABSTRACT

A 3D forest monitoring system, called FORSAT (a satellite very high resolution image processing platform for forest assessment), was developed for the extraction of 3D geometric forest information from very high resolution (VHR) satellite imagery and the automatic 3D change detection. FORSAT is composed of two complementary tasks: (1) the geometric and radiometric processing of satellite optical imagery and digital surface model (DSM) reconstruction by using a precise and robust image matching approach specially designed for VHR satellite imagery, (2) 3D surface comparison for change detection. It allows the users to import DSMs, align them using an advanced 3D surface matching approach and calculate the 3D differences and volume changes (together with precision values) between epochs. FORSAT is a single source and flexible forest information solution, allowing expert and non-expert remote sensing users to monitor forests in three and four (time) dimensions. The geometric resolution and thematic content of VHR optical imagery are sufficient for many forest information needs such as deforestation, clear-cut and fire severity mapping. The capacity and benefits of FORSAT, as a forest information system contributing to the sustainable forest management, have been tested and validated in case studies located in Austria, Switzerland and Spain.  相似文献   

沙漠蝗群对印巴边境植被的影响及其未来可能发展趋势     

房世波  韩威  裴志方 《遥感学报》2020,24(3):326-332

2020年初非洲东北和印巴边境沙漠蝗群席卷多个国家,大面积农田及自然植被被啃食,是什么气候条件促成了此次沙漠蝗灾?距离中国最近的印巴边境蝗群成为研究以及社会关注的热点,蝗灾对当地植被的影响如何?其发展趋势如何?从气候学上分析,蝗灾历史上是否曾经或者未来是否向印度东边迁飞而进入中国呢?本研究利用长时间序列的卫星遥感数据和气象气候观测数据,对沙漠蝗群可能扩展趋势进行了分析。研究结果表明:(1)由于沙漠蝗群的啃食,2020年1月和2月,在蝗群分布区大面积植被区的归一化植被指数较常年大幅度下降,2月(2月3日数据)的啃食面积较1月明显扩大;(2)发生在2018年5月和10月两次印度洋飓风和2019年12月强热带风暴等几个罕见气旋给非洲和阿拉伯半岛带来的强降水,是本次非洲-西亚蝗灾的形成重要原因;(3)从影响沙漠蝗群起飞的气温和沙漠蝗虫适合的降水条件来看,历史上或未来沙漠蝗群迁徙到印度东边的机会很少,进入中国的可能性非常小。  相似文献   

用卫星资料估计降水方法的评述   总被引：2，自引：3，他引：2  

王健康 《气象》1993,19(5):3-8

  相似文献   

与地震预报有关的电磁现象国际讨论会概况   总被引：3，自引：0，他引：3  

钱书清  郝锦绮 《国际地震动态》1994,(2):11-16

与地震预报有关的电磁现象国际学术讨论会已于１９９３年９月６－８日在东京召开。这次学术讨论会的宗旨是，为世界各国学者提供一个公开讲坛以讨论与地震有关的电磁现象，并通过交叉学科与多科学相关领域相结合的方式探讨地震预报等问题。本文较详细地介绍了各国学者在这一领域中的最新成果。  相似文献   

数据同化/卫星反演/数值预报相互循环作用系统   总被引：1，自引：0，他引：1  

王宗皓  张凤英  王子厚  朱宗申  张跃堂  万丰 《气象》1994,20(10):3-11

介绍数据同化／卫星反演／数值预报相互作用的一种方案，将原来相互独立进行的操作组成为相互作用的循环系统。国家卫星气象中心（ＮＳＭＣ）和国家气象中心（ＮＭＣ）联合开发这个项目，其目的是改善我国卫星探测反演及其在业务数值预报中应用的情况。该文首先介绍相互作用循环流物基本原理，以及的分析／预报模式和卫星反演的方案，然后给出国家卫星气象中心和国家气象中心联合试验的阶段性成果。研究试验表明，相互循环作用方案有  相似文献   

Some characteristics of typhoons as revealed by the recent SSM/I microwave radiometry     

Gandikota V. Rao 《Natural Hazards》1994,9(1-2):17-35

Tropical cyclones are notorious for their destruction. Because they occur mostly over oceans their structures are revealed only through aerial reconnaissance, radar or through satellites. The recently launched DMSP satellite (F8) has provided polarized microwave Brightness Temperatures, TB's. Using certain algorithms, rainrates and wind speeds were derived for a few typhoons.The 85 GHz TB's available at nearly 15 km intervals, disclosed that low values such as 230 K are registered within 2° of the advancing side of the center. These low TB's moved centerward as the typhoon developed further. They propagated rearwards as the storm weakened.Convective rainrates, defined as those equalling or exceeding 3 mm h^–1, within the core, seem to set trends for the intensification. On the other hand convective rain outside the core had a negative effect on the storm. Similarly convective rainrates within the core of developing storms were significantly different from those of the weakening typhoons while the corresponding stratiform rainrates were not markedly different between intensifying and deintensifying ones. Some typhoons developed strong winds exceeding 30 m s^–1 even as far from the center as 440 km. The derived speeds decreased in accuracy in rain situations.These preliminary results are to be interpreted with caution in view of the recency of the algorithms and the smallness of the sample. However, the hazards scientist would find the SSM/I data to be valuable in forewarning the public and in using these data for purposes such as surge forecasting.  相似文献   

卫星遥感反演降水研究进展简述     

刘少军  蔡大鑫  韩静  甘业星 《气象科学进展》2021,(1)

高质量的降水数据是开展天气、气候、水文、生态等研究的重要基础。由于传统地面雨量计站观测和地基雷达观测受站点数量和地形条件的限制,很难实现大范围降水的均匀观测,而卫星反演降水能有效弥补传统观测站网的缺点。根据卫星反演降水的原理,简要概述了可见光、红外、微波、多种传感器组合的卫星降水反演算法、总结了5种不同卫星数据反演产品的优点和适用性。改进降水反演算法和加强多种传感器反演降水产品的融合,才能获得更高精度和更大覆盖范围的降水产品,这也是未来一段时间内卫星遥感反演降水的趋势。  相似文献   

基于遥感空间信息的洪水风险识别与动态模拟研究进展          下载免费PDF全文

曾子悦  许继军  王永强 《水科学进展》2020,31(3):463-472

对地观测卫星遥感能够提供广泛可靠的空间信息,是洪水风险识别与动态模拟的重要支撑技术之一。为阐明卫星遥感技术对洪水研究的推动作用,回顾了洪水风险识别与动态模拟研究的发展历程及技术需求,以对地观测卫星遥感三大阶段的发展轨迹为主线,分析了遥感空间信息在洪水研究中的历史性贡献和阶段性效用,讨论总结了危险分区法、水文模型和微波遥感监测等3种洪水研究典型方法的应用进展。提出未来洪水风险识别与动态模拟研究的重点:遥感空间信息与模型算法的深度结合,遥感反演算法与系统的开发及应用,典型洪水研究方法集成系统的开发与应用,大数据方法与手段的应用。以期为提升洪水应急响应能力与灾害风险管理水平提供有效参考。  相似文献