Field spectroradiometer and simulated multispectral bands for discriminating invasive species from morphologically similar cohabitant plants     

Solomon G. Tesfamichael  Solomon W. Newete  Elhadi Adam  Bambo Dubula 《地理信息系统科学与遥感》2018,55(3):417-436

One of the challenges in fighting plant invasions is the inefficiency of identifying their distribution using field inventory techniques. Remote sensing has the potential to alleviate this problem effectively using spectral profiling for species discrimination. However, little is known about the capability of remote sensing in discriminating between shrubby invasive plants with narrow leaf structures and other cohabitants with similar ecological niche. The aims of this study were therefore to (1) assess the classification performance of field spectroradiometer data among three bushy and shruby plants (Artemesia afra, Asparagus laricinus, and Seriphium plumosum) from the coexistent plant species largely dominated by acacia and grass species, and (2) explore the performance of simulated spectral bands of five space-borne images (Landsat 8, Sentinel 2A, SPOT 6, Pleiades 1B, and WorldView-3). Two machine-learning classifiers (boosted trees classification and support vector machines) were used to classify raw hyperspectral (n = 688) and simulated multispectral wavelengths. Relatively high classification accuracies were obtained for the invasive species using the original hyperspectral bands for both classifiers (overall accuracy, OA = 83–97%). The simulated data resulted in higher accuracies for Landsat 8, Sentinel 2A, and WorldView-3 compared to those computed for bands simulated to SPOT 6 and Pleiades 1B data. These findings suggest the potential of remote-sensing techniques in the discrimination of different plant species with similar morphological characteristics occupying the same niche.  相似文献   

The effects of land cover change on carbon stock dynamics in a dry Afromontane forest in northern Ethiopia     

Negasi Solomon  Opoku Pabi  Ted Annang  Isaac K. Asante  Emiru Birhane 《Carbon balance and management》2018,13(1):14

  相似文献   

Charles Robert Scrivener. the surveyor who sited Australia's national capital twice     

Robert Solomon 《The Australian geographer》2014,45(2):254-256

  相似文献   

Reconstruction of propagating Kelvin–Helmholtz vortices at Mercury's magnetopause     

Torbjörn Sundberg  Scott A. Boardsen  James A. Slavin  Lars G. Blomberg  Judy A. Cumnock  Sean C. Solomon  Brian J. Anderson  Haje Korth 《Planetary and Space Science》2011,59(15):2051-2057

A series of quasi-periodic magnetopause crossings were recorded by the MESSENGER spacecraft during its third flyby of Mercury on 29 September 2009, likely caused by a train of propagating Kelvin–Helmholtz (KH) vortices. We here revisit the observations to study the internal structure of the waves. Exploiting MESSENGER's rapid traversal of the magnetopause, we show that the observations permit a reconstruction of the structure of a rolled-up KH vortex directly from the spacecraft's magnetic field measurements. The derived geometry is consistent with all large-scale fluctuations in the magnetic field data, establishes the non-linear nature of the waves, and shows their vortex-like structure. In several of the wave passages, a reduction in magnetic field strength is observed in the middle of the wave, which is characteristic of rolled-up vortices and is related to the increase in magnetic pressure required to balance the centrifugal force on the plasma in the outer regions of a vortex, previously reported in computer simulations. As the KH wave starts to roll up, the reconstructed geometry suggests that the vortices develop two gradual transition regions in the magnetic field, possibly related to the mixing of magnetosheath and magnetospheric plasma, situated at the leading edges from the perspectives of both the magnetosphere and the magnetosheath.  相似文献   

Mercury after the MESSENGER flybys: An introduction to the special issue of Planetary and Space Science     

Sean C. Solomon  Ralph L. McNutt Jr.  Louise M. Prockter 《Planetary and Space Science》2011,59(15):1827-1828

  相似文献   

Ionospheric Day-to-Day Variability Around the Whole Heliosphere Interval in 2008     

Wenbin Wang  Jiuhou Lei  Alan G. Burns  Liying Qian  Stanley C. Solomon  Michael Wiltberger  Jiyao Xu 《Solar physics》2011,274(1-2):457-472

Ionospheric F2 peak electron densities (NmF2) measured at ten ionosonde stations have been analyzed to investigate ionospheric day-to-day variability around the Whole Heliosphere Interval (WHI) in 2008 (Day of Year (DOY) 50?–?140). The ionosonde data showed that there was significant global day-to-day variability in NmF2. This variability had 5-, 7-, 9-, 11-, 13.5-, and 16?–?21-day periodicities. At middle latitudes, the ionosphere appeared to respond directly to the solar-wind and interplanetary-magnetic-field (IMF) induced geomagnetic-activity forcing, with the day-to-day variability having the same periods as those in the solar-wind/IMF and geomagnetic activity. At the geomagnetic Equator, the ionosphere had a strong 7-day periodicity, corresponding to the same periodicity in the IMF B _z component. In the equatorial anomaly region, the ionosphere showed more complicated day-to-day variability, dominated by the 9-day periodicity. In addition, there were also periodicities of 11 days and 16?–?21 days in the ionosonde data at some stations. The ionosonde data were compared with the Coupled Magnetosphere Ionosphere Thermosphere (CMIT) simulations that were driven by the observed solar-wind and IMF data during the WHI. The CMIT simulations showed similar ionospheric daily variability seen in the data. They captured the positive and negative responses of the ionosphere at middle latitudes during the first corotating interaction region (CIR) event in the WHI. The response of the model to the second CIR event, however, was relatively weak.  相似文献   

Ownership of Mine-Tunnel Discharge     

W.T. Parry  Craig B. Forster  D. Kip Solomon  Laurence P. James 《Ground water》2000,38(4):487-496

  相似文献   

Interannual Variability of Antarctic Hydrographic Structure and Frontal Zones along Meridional Sections between Syowa Station and Southern Africa     

Harold Solomon  Kaoru Ushida  Takashi Suzuki 《Journal of Oceanography》2000,56(1):1-16

Six years of quasi-meridional crossings of the Antarctic Ocean from Antarctica to southern Africa between 4°W and 16°E longitude are analyzed, with emphasis on temperature and salinity distributions. Data are sparse, but (particularly in the southern part of the sections) adequate to show significant variations in the latitude/depth distributions and T-S characteristics of the principal water masses. In particular, the cross-sectional area occupied by Warm Deep Water (Weddell Deep Water) dropped by about one third in 1968. Positions of major features associated with the Antarctic Divergence varied by up to 5 degrees of latitude. The surface temperature gradient often observed at the Antarctic Divergence appears to be the surface expression of a shallow (possibly seasonal) thermocline which sometimes slopes upward to intersect the sea surface. There is a clear need for more closely spaced and consistently planned data from Antarctic cruises, particularly those on which physical oceanography is an ancillary activity. As a bare minimum, much more closely spaced surface temperature (and if possible also salinity) measurements would be useful.  相似文献   

Seismic response of rotating machines–structure–RFBI systems     

Wen‐Chyi Su  Alan G. Hernried  Solomon C. S. Yim 《地震工程与结构动力学》2000,29(2):213-240

The seismic response of a critical rotating machine either rigidly attached to a floor or independently isolated housed within an initially aseismically designed or uncontrolled structure are investigated. A particular isolation system, the Resilient‐Friction Base Isolator (RFBI), is employed. Finite element formulations of a rotor‐disk‐bearing model on a rigid base are developed. The equations of motion for the combined rotating machine–structure–RFBI systems are presented. Parametric studies are performed to investigate the effects of variations in system physical properties including friction coefficient, mass ratio, shaft flexibility, bearing rigidity, bearing damping and speed of rotation on the response of rotating machines for the combined rotating machine–structure–isolator systems. Comparative studies in the peak response of the rotating machine supported on various isolation systems and the corresponding fixed base system are carried out. The study indicates that the Resilient‐Friction Base Isolator can significantly reduce the seismic response of rotating components to potentially damaging ground excitations. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

Formation Age and Tectonic Setting of the Muli Arc-Ophiolite Complex in the South Qilian Belt, NW China     

YAN Zhen  FU Changlei  Jonathan C. AITCHISON  NIU Manlan  Solomon BUCKMAN  CAO Bo 《《地质学报》英文版》2020,94(Z1):69-69

  相似文献