FFT-enhanced IHS transform method for fusing high-resolution satellite images   总被引：4，自引：0，他引：4  

Yangrong Ling  Manfred Ehlers  E. Lynn Usery  Marguerite Madden 《ISPRS Journal of Photogrammetry and Remote Sensing》2007,61(6):381-392

Existing image fusion techniques such as the intensity–hue–saturation (IHS) transform and principal components analysis (PCA) methods may not be optimal for fusing the new generation commercial high-resolution satellite images such as Ikonos and QuickBird. One problem is color distortion in the fused image, which causes visual changes as well as spectral differences between the original and fused images. In this paper, a fast Fourier transform (FFT)-enhanced IHS method is developed for fusing new generation high-resolution satellite images. This method combines a standard IHS transform with FFT filtering of both the panchromatic image and the intensity component of the original multispectral image. Ikonos and QuickBird data are used to assess the FFT-enhanced IHS transform method. Experimental results indicate that the FFT-enhanced IHS transform method may improve upon the standard IHS transform and the PCA methods in preserving spectral and spatial information.  相似文献   

The effects of thin layer sand renourishment on tidal marsh processes: Masonboro Island, North Carolina     

Alex L. Croft  Lynn A. Leonard  Troy D. Alphin  Lawrence B. Cahoon  Martin H. Posey 《Estuaries and Coasts》2006,29(5):737-750

The objective of this study was to determine if the placement of dredged material on sediment-starved back barrier marshes in southeastern North Carolina could offset submergence without negatively affecting function. Clean sediment was placed in thickness from 0 to 10 cm, on deteriorated and non-deteriorated marsh plots. Original stem densities were greater, in non-deteriorated plots (256 stems m⁻²) compared to deteriorated sites (149 stems m⁻²). By the second growing season (after sediment additions), stem densities in the deteriorated plots (308 stems m⁻²) approached levels in the non-deteriorated plots (336 stems m⁻²). Sediment additions to, both nos-deteriorated and deteriorated plots resulted in a higher redox potential with plots receiving the most sediment exhibiting the highest E_h values. In deteriorated plots, placement of dredged material had the greatest effect on plant density, but also affected soil oxidation-reduction potential and sediment deposition (or mobility). Following sediment placement, substrate texture and composition incrementally returned to prefill conditions due to a combination of bioturbation and sedimentation. Where infaunal differences occurred, they were generally less abundant in deteriorated plots, but responses to sediment addition were variable. Sediment addition had little effect on the non-deteriorated plots, suggesting that the disposal of certain types of dredged material in marshes may be useful to mitigate the effects of marsh degradation without adversely affecting non-deteriorating marsh.  相似文献   

A note on the Raman spectra of water-bearing albite glasses     

Paul F. McMillan  Sigurdur Jakobsson  John R. Holloway  Lynn A. Silver 《Geochimica et cosmochimica acta》1983,47(11):1937-1943

The Raman spectra of albite glasses with 4.5 and 6.6 weight percent water have been obtained, and are compared with that of a dry sample. The hydrous glasses show bands near 3600 cm^?1 due to O-H stretching, and a previously unreported weak band near 1600 cm^?1 due to bending of molecular H₂O. Other weak spectral features are discussed, and the effect of dissolved water on the aluminosilicate framework vibrations is considered.  相似文献   

Theory of the seismomagnetic effect: a reassessment     

Jin-Qi Hao  Lynn M. Hastie  Frank D. Stacey 《Physics of the Earth and Planetary Interiors》1982,28(2):129-140

Transient magnetic anomalies accompanying seismic stresses are more elusive than had been anticipated. We have, therefore, undertaken a more rigorous calculation than hitherto of the piezomagnetic effect accompanying representative seismic strain fields. We present a numerical method of treating faults of arbitrary area and orientation with fault displacement graded to zero at the fault boundaries to avoid stress discontinuities. The effect of grading the displacement in a realistic way is to give a more restricted and generally smaller piezomagnetic anomaly field than is indicated by simpler models. Seismomagnetism remains important in the search for earthquake prediction methods, but is more difficult to observe than had been hoped.  相似文献   

Physical constraints for the analysis of the geomagnetic secular variation     

Loren Shure  Kathy Whaler  David Gubbins  Bruce Hobbs 《Physics of the Earth and Planetary Interiors》1983,32(2):114-131

Slow changes in the magnetic field are believed to originate in the core of the Earth. Interpretation of these changes requires knowledge both of the vertical component of the field and of its rate of change at the core-mantle boundary (CMB). While various spherical harmonic models show some agreement for the field at the CMB, those for secular variation (SV) do not. SV models depend heavily on annual means at relatively few and poorly distributed magnetic observatories. In this paper, the SV at the CMB is modelled by fitting 15-year differences in the annual means of the X, Y and Z components (from 1959 to 1974). The model is made unique by imposing the constraint that $\text{?}{}_{\mathrm{CMB}}\text{B}\text{?}{}_{\mathrm{r}}{}^2\text{d}\text{S}$ be a minimum, using the method of Shure et al. (1982). If SV is attributed to motions of core fluid, then this model will yield, in some sense, the slowest core motions. The null space is determined by the distribution of observations, and therefore, to be consistent, only those observatories have been retained which recorded almost continuously throughout the interval 1959–1974.The method allows misfit between the model and the observations. The best value for the misfit can be derived from estimates of errors in the data, or alternatively, because larger misfit leads to smoother models (i.e., smaller $\text{?}\text{B}\text{?}{}_{\mathrm{r}}{}^2\text{d}\text{S}$), the best value can be estimated subjectively from the final appearance of the model. Both procedures have their counterparts in the conventional spherical harmonic expansion approach, when smoothing is achieved by lowering the truncation level. The new proposal made in this paper is to use objective criteria for determining the misfit, based on the assumption that diffusion is negligible, in which event all integrals $\text{∫}\text{B}\text{?}{}_{\mathrm{r}}{}^2\text{d}\text{S}$ will vanish when S_i is a region on the CMB bounded by a contour of zero vertical component of field. For the 1965 definitive model which is adopted here, and for most other contemporary models, there are six such areas, giving five independent integrals (the integrals over the six regions must sum to zero if ? · B = 0). Tabulating these integrals for various choices of the misfit gives minimum values near 2 nT y^?1. It is impossible to achieve this good a fit to the data using a reasonable model derived by truncating the spherical harmonic expansion. The value 2 nT y^?1 corresponds to errors of ～ 20 nT in individual annual means, which is rather larger than expected from the scatter in the data.  相似文献   

PCR‐based techniques to determine diet of the Australian sea lion (Neophoca cinerea): a comparison with morphological analysis          下载免费PDF全文

Kristian J. Peters  Kathy Ophelkeller    Herdina  Nathan J. Bott  Simon D. Goldsworthy 《Marine Ecology》2015,36(4):1428-1439

Comprehensive dietary information for the endangered Australian sea lion (Neophoca cinerea) is currently limited by the deficiency and poor quality of identifiable prey remains recovered from regurgitate and faeces and the difficulty of observing feeding in the wild. In this study, we investigated DNA‐based prey detection methods using conventional (end‐point) and quantitative real‐time PCR (qPCR) on faeces collected from two captive Australian sea lions fed experimental diets of whole teleost fish, squid and shark tissue. PCR prey detection methods using the mitochondrial cytochrome oxidase subunit I (COI) and 16S genes combined with clone sequencing were compared with prey identified using traditional hard part analysis. The molecular results indicated that prey DNA was degraded. However, prey amplification was successful by targeting short (71 bp) DNA fragments. Both conventional PCR and qPCR techniques significantly increased prey detection compared with analysis of hard parts. For both sea lions, the hard part analysis was constrained by sporadic and extremely low recovery of fish otoliths (<2%), and cephalopod beaks were not recovered from the 116 squid fed. Comparisons between PCR techniques indicated comparable prey detection frequencies for all species tested; however, the sensitivity and greater resolution of qPCR improved prey detection by ~25% in one sea lion fed the experimental squid and perch. The detection of squid DNA ≤ 6 day post‐ingestion by qPCR further exhibits the ability and potential of this method to detect low concentrations of infrequent or pulse prey. This study highlights the use of DNA‐based analysis to detect prey taxa in the absence of identifiable hard prey remains.  相似文献   

The impacts of climate change on tribal traditional foods     

Kathy Lynn  John Daigle  Jennie Hoffman  Frank Lake  Natalie Michelle  Darren Ranco  Carson Viles  Garrit Voggesser  Paul Williams 《Climatic change》2013,120(3):545-556

American Indian and Alaska Native tribes are uniquely affected by climate change. Indigenous peoples have depended on a wide variety of native fungi, plant and animal species for food, medicine, ceremonies, community and economic health for countless generations. Climate change stands to impact the species and ecosystems that constitute tribal traditional foods that are vital to tribal culture, economy and traditional ways of life. This paper examines the impacts of climate change on tribal traditional foods by providing cultural context for the importance of traditional foods to tribal culture, recognizing that tribal access to traditional food resources is strongly influenced by the legal and regulatory relationship with the federal government, and examining the multi-faceted relationship that tribes have with places, ecological processes and species. Tribal participation in local, regional and national climate change adaption strategies, with a focus on food-based resources, can inform and strengthen the ability of both tribes and other governmental resource managers to address and adapt to climate change impacts.  相似文献   

Do asymmetries in ENSO predictability arise from different recharged states?     

Larson  Sarah M.  Pegion  Kathy 《Climate Dynamics》2020,54(3):1507-1522

Climate Dynamics - Prospects for El Niño–Southern Oscillation (ENSO) predictability at long lead-times lie in the subsurface oceanic memory along the equatorial Pacific. Long considered...  相似文献   

A modeling study of coastal inundation induced by storm surge,sea-level rise,and subsidence in the Gulf of Mexico   总被引：2，自引：2，他引：0  

Zhaoqing Yang  Taiping Wang  Ruby Leung  Kathy Hibbard  Tony Janetos  Ian Kraucunas  Jennie Rice  Benjamin Preston  Tom Wilbanks 《Natural Hazards》2014,71(3):1771-1794

The northern coasts of the Gulf of Mexico (GoM) are highly vulnerable to the direct threats of climate change, such as hurricane-induced storm surge, and such risks are exacerbated by land subsidence and global sea-level rise. This paper presents an application of a coastal storm surge model to study the coastal inundation process induced by tide and storm surge, and its response to the effects of land subsidence and sea-level rise in the northern Gulf coast. The unstructured-grid finite-volume coastal ocean model was used to simulate tides and hurricane-induced storm surges in the GoM. Simulated distributions of co-amplitude and co-phase lines for semi-diurnal and diurnal tides are in good agreement with previous modeling studies. The storm surges induced by four historical hurricanes (Rita, Katrina, Ivan, and Dolly) were simulated and compared to observed water levels at National Oceanic and Atmospheric Administration tide stations. Effects of coastal subsidence and future global sea-level rise on coastal inundation in the Louisiana coast were evaluated using a “change of inundation depth” parameter through sensitivity simulations that were based on a projected future subsidence scenario and 1-m global sea-level rise by the end of the century. Model results suggested that hurricane-induced storm surge height and coastal inundation could be exacerbated by future global sea-level rise and subsidence, and that responses of storm surge and coastal inundation to the effects of sea-level rise and subsidence are highly nonlinear and vary on temporal and spatial scales.  相似文献   

Geoarchaeological research in the coastal plain portion of the Savannah River valley     

Mark J. Brooks  Peter A. Stone  Donald J. Colquhoun  Janice G. Brown  Kathy B. Steele 《Geoarchaeology》1986,1(3):293-307

Selected archaeological, stratigraphical, sedimentological, hydrological, sea level, and ¹⁴C data are considered in order to ascertain the times and rates of saltmarsh, floodplain, river swamp, and alluvial terrace development in the lower Savannah River valley. Archaeological data are emphasized in the elucidation of these developmental trends and their environmental correlates. It is concluded that the modern environments associated with the categories of archaeological sites examined (estuarine shell middens, river swamp point bar sites, raised terrace/point bar sites) are not representative of local conditions during occupation(s). Accordingly, a mid-Holocene development of lower energy depositional environments is documented, along with a corresponding shift in subsistence-settlement patterning that suggests more diffuse, or broad spectrum, socio-economic strategies. A base level (sea level) dominance on river sedimentation, even far inland from the coast, may also be indicated.  相似文献