Modeling and mapping aboveground biomass of the restored mangroves using ALOS-2 PALSAR-2 in East Kalimantan,Indonesia     

《International Journal of Applied Earth Observation and Geoinformation》2020

Accurate estimation of forest aboveground biomass (AGB) using remote sensing is a requisite for monitoring, reporting and verification (MRV) system of the United Nations Programme on Reducing Emissions from Deforestation and Forest Degradation. However, attaining high accuracy remains a great challenge in the diverse tropical forests. Among available technologies, l-band Synthetic Aperture Radar (SAR) estimates AGB with reasonably high accuracy in the terrestrial tropical forests. Nevertheless, the accuracy is relatively low in the mangrove forests. In this context, the study was carried out to model and map AGB using backscatter coefficients of Advanced Land Observing Satellite-2 (ALOS-2) Phased Array l-band SAR-2 (PALSAR-2) in part of the restored mangrove forest at Mahakam Delta, Indonesia. PALSAR-2 data was acquired with image scene observation during the peak low tide on 30 July 2018 from Japan Aerospace Exploration Agency. The forest parameters namely tree height and diameter at breast height were measured from 71 field plots in September-October 2018. The parameters were used in mangrove allometry to calculate the field AGB. Finally, HV polarized backscatter coefficients of PALSAR-2 were used to model AGB using linear regression. The model demonstrated a comparatively high performance using three distinct methods viz. independent validation (R² of 0.89 and RMSE of 23.16 tons ha⁻¹), random k-fold cross validation (R² of 0.89 and RMSE of 24.59 tons ha⁻¹) and leave location out cross validation (LLO CV) (R² of 0.88 and RMSE of 24.05 tons ha⁻¹). The high accuracy of the LLO CV indicates no spatial overfitting in the model. Thus, the model based on LLO CV was used to map AGB in the study area. This is the first study that successfully obtains high accuracy in modeling AGB in the mangrove forest. Therefore, it offers a significant contribution to the MRV mechanism for monitoring mangrove forests in the tropics and sub-tropics.  相似文献   

Laboratory light-scattering measurements with Titan's aerosols analogues produced by a dusty plasma     

E. Hadamcik  J.-B. Renard  G. Cernogora  C. Szopa 《Planetary and Space Science》2009,57(13):1631-1641

The chemistry leading to the formation of solid aerosols (tholins) in Titan's atmosphere is simulated by a capacitively coupled plasma in a N₂-CH₄ gas mixture. The solid grains are produced in volume directly in the gas phase and studied ex-situ by SEM imaging and by light scattering on clouds of particles. The scattered light properties depend on the physical properties of the particles (morphologies, size distribution), as well as on the phase angle and the wavelength of the light. The particles may be aggregated or agglomerated grains. The grains size distribution is studied as a function of plasma parameters such as initial methane concentration introduced into the discharge, gas flow, absorbed RF power and plasma duration. The average grain size increases when the amount of CH₄ increases, when the gas flow decreases, and when the plasma duration increases up to a limit for each production condition.For all the samples, the absorption decreases with increasing wavelength in the visible domain. As usually found for irregular particles, the polarization phase curves have a bell-shaped positive branch and a shallow negative branch. The maximum of polarization (P_max) increases when the average grain size decreases (sub-μm-sized grains). To obtain P_max values within the range of those measured in Titan's atmosphere; the average grains diameter has to be smaller than 100 nm, in agreement with the space observations results. In the light-scattering experiment, the size of the agglomerates in the clouds is in the 40-80 μm range in equivalent diameter. As a consequence P_max increases with decreasing wavelength due to the increasing absorption, in agreement with observations of Titan from outside the atmosphere.  相似文献   

线性回归在滑坡监测数据粗差判别中的应用   总被引：1，自引：0，他引：1  

周宗华  王翔俊  余和园  杨传贵 《中国地质灾害与防治学报》2009,20(3):118-121

滑坡监测数据预处理中,须剔出含有粗差的数据,本文以马家沟滑坡相邻形变监测点多期监测数据相关性分析,从而建立一元线性回归方程,采用估算值中误差判定实测变形值是否存在粗差,并为滑坡稳定性分析提供了可靠的变形依据。  相似文献   

遥感信息技术在德钦佛山找矿实践中的应用     

王亚萍  高建国  覃荣高  高星刚 《云南地质》2009,28(2):206-212

基于成矿地质背景分析基础,采用遥感信息技术中图像处理增强、解译等方法,提取与成矿相关的线性、环形构造遥感信息,通过遥感影像上色彩的异常,指导该区地质找矿。  相似文献   

Trends in chronic marine oil pollution in Danish waters assessed using 22 years of beached bird surveys     

Larsen JL  Durinck J  Skov H 《Marine pollution bulletin》2007,54(9):1333-1340

Beached bird surveys provide an important tool for monitoring the level of oil pollution at sea, which is the most significant observable cause of death for a large number of waterbird species and pose a serious threat to wintering seabird populations. Linear regression analyses of oil rates from the Danish 22 year dataset show a decline in the oil pollution level in offshore areas of the eastern North Sea and Skagerrak and in near-shore parts of the Kattegat; but a worsening in the offshore areas of the Kattegat. These results raise concern for species such as common scoter, velvet scoter, eider and razorbill, for which the Kattegat serves as a globally important wintering area. It is recommended that surveillance for oil spills is intensified in inner Danish waters, and that action is taken to make responses towards offenders faster, and penalties for oil seepage higher.  相似文献   

夏季中国中东部不同历时降水时空分布特征   总被引：7，自引：2，他引：5  

金炜昕  李维京  孙丞虎  左金清 《气候与环境研究》2015,20(4):465-476

利用1961~2012年台站逐时降水资料,分析了夏季中国中东部不同历时降水的主要气候分布和长期变化特征,为深入认识其时空变化规律和形成机理奠定基础。分析结果表明,降水事件的平均历时由南向北呈"短—长—短"分布型,华南和北方地区以6 h以下的短历时降水为主;而中部地区(28°N~37°N)6 h以上长历时降水占总降水量60%以上。随着降水历时的增加,小雨事件(0.1~1.0 mm/h)的发生概率降低,中雨事件(1.1~10.0 mm/h)的发生概率升高;大雨、暴雨事件(10.0 mm/h)更易出现在35°N以南历时偏短的降水事件中。1961~2012年,中国中东部总降水量呈"南升北降"的趋势分布,夏季南方大部分地区降水强度、时数和事件数均呈上升趋势;而北方地区降水时数和事件数显著减少,不过降水强度呈增强趋势。中东部降水历时总体呈上升趋势,尤其以我国长江与黄河之间的中部地区变化最为显著。同时,该地区短历时(1~6 h)降水无显著的年代际转折,长历时(6 h)降水的年代际增加是20世纪70年代末至20世纪90年代初降水增多的主要原因。20世纪90年代初期以来,南方地区降水的年代际增多则是长、短降水共同作用的结果,但超过6 h降水的影响范围更广,且影响中心较短历时降水偏北。  相似文献   

1961—2017年广西区域性暴雨过程变化特征     

李艳兰  黄卓  何洁琳  覃卫坚 《气象与环境学报》2020,36(1):51-57

利用1961—2017年广西91个气象观测站逐日降水量资料,通过定义广西区域性暴雨,采用线性趋势计算、低通滤波等方法,统计分析了广西区域性暴雨过程的变化特征。结果表明：广西区域性暴雨过程发生频率较高,全年各月均可有区域性暴雨过程出现,5—8月为多发期,出现次数占全年总数的74.2%;持续天数在5 d以上的区域性暴雨过程主要出现在6—8月,以6月最多。近57 a,广西年及秋季区域性暴雨过程频次呈显著增加趋势,20世纪90年代以来区域性暴雨过程总体偏多、强度偏强,暴雨范围在30站以上的过程明显增多;近10 a秋季过程频次偏多、强度偏强特征尤为明显。  相似文献   

一种改进的线性预测滤波算法     

张靖  张晓君  江万寿  王建超  郭大海 《国土资源遥感》2011,22(1):52-56

对传统的线性预测算法进行改进,通过粗差剔除、初始点选取、特殊地形分析及光滑度检验等步骤提高了滤波精度.利用ISPRS发布的6组标准测试数据与原方法进行实验比较,结果证明,改进后的算法提高了滤波总精度以及地面点分类精度.  相似文献   

线性准地转模型中基本流和辐射冷却对感热加热强迫的副热带高压形态的影响     

张亚妮  张恒德  刘屹岷 《气象学报》2020,78(5):816-825

通过求取定常线性准地转位涡模式的数值解,研究了感热型垂直非均匀分布的冷、热源强迫所激发的副热带环流的结构特征,讨论了副热带背景风场和洋面辐射冷却对洋面副热带高压“三角形偏心”结构形成的重要作用。结果表明,基本流对感热加热强迫的副热带环流有重要影响,当基本流为常数时,感热加热强迫的气旋和反气旋主要集中在对流层中下层,且地面系统远强于中高层。当基本流为非常数时,其经向切变能改变气旋和反气旋中心的经向位置,使它移至0风速所在纬度附近;其垂直变化加强了中高层气旋和反气旋,中心位于对流层上层,与南亚高压的位置基本一致。研究结果还表明,在大洋东部洋面辐射冷却与副热带地区背景风场的共同作用下,形成了洋面副热带高压特有的“三角形偏心”结构。副热带高纬度的西风使感热强迫的洋面副热带高压东移,低纬度的东风使其西移,形成东北—西南走向的“平行四边形”结构,且中心位于大洋西部。大洋东部强洋面辐射冷却激发的洋面反气旋加强了大洋东部的副热带高压,使其中心东移至大洋东部,从而表现出东北—西南走向的“三角形偏心”结构。   相似文献   

New optically stimulated luminescence ages provide evidence of MIS3 and MIS2 eolian activity on Black Mesa, northeastern Arizona, USA     

Amy L. Ellwein  Shannon A. Mahan  Leslie D. McFadden 《Quaternary Research》2011,75(3):395-398

Eolian deposition on the semiarid southern Colorado Plateau has been attributed to episodic aridity during the Quaternary Period. However, OSL ages from three topographically controlled (e.g. falling) dunes on Black Mesa in northeastern Arizona indicate that eolian sediments there were deposited in deep tributary valleys as early as 35–30 ka, with most sand deposited before 20 ka. In contrast, the oldest OSL ages for sand sheets fall within the Pleistocene-Holocene climatic transition (~ 12–8 ka). Thus most eolian sediment accumulated on Black Mesa under climatic conditions that were in general cooler, moister, and more variable than today, not more arid, pointing to a considerable increase in sediment supply.  相似文献