Spectral Unmixing Applied to Desert Soils for the - Naval ...

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transitions in which electron movement is between ions or ions and ligands and in Fe, for example, are the reason for its red color. When electrons move amongst two different energy levels there is a gap in the band (band gap) represented by the difference in energy levels. These bands often show themselves in the visible range and causes colorations in some minerals. Color centers are a response to impurities and defects in the structure of the material and cause for example, the blue color in fluorite. They show up as absorption features because they use photon energy to gain electrons (Clark, 1999). 2. Vibrational Processes Vibrational Processes are associated with the crystal lattice structure and the bonds within it and can be compared to a spring with a weight attached vibrating with fundamental frequencies and overtones (Clark, 1999; Jensen, 2007). Fundamental frequencies are the normal modes of vibrations; overtones are multiples of the fundamental frequency as well as different combinations of it (Clark, 1999; Jensen, 2007). Natural materials exhibiting these vibrational processes include phosphates, borates, carbonates, water and hydroxyl (Jensen, 2007). Vibration fundamental modes have traditionally been represented as ν1, ν2, ν3 and overtones as 2 ν1, 3 ν1, 2 ν2 with combinations being represented as additions and subtractions of fundamentals (Clark, 1999). 3. Imagery Collection, Processing, and Analysis a. Collection The collection and analysis of these spectra allows one to identify such things as mineral and rock type in a given area remotely based on its unique absorption features. The current Hyperspectral Imagery (HSI) technology utilizes spatial resolution of 2–20 m, spectral resolution of 10–20 nm and a signal-to-noise (SNR) ratio that is greater than 500:1 for data collection (Kruse, 2012) On a mineral or rock surface, incident light (photons) can be absorbed, reflected/refracted, or passed through to other grains of a material. Reflected or refracted light is also called scattered light which can be directed toward a remote sensing sensor capable of measuring abundances and properties of some material within the sensors field of view (FOV) (Figure 4). When 8
analyzing imagery spectra, it is most useful to have the spectra in units of reflectance rather than radiance because radiance energy tends to be dominated by the solar spectrum (Roberts and Herold, 2004). Remote sensing primarily uses two different types of reflectance; directional-hemispherical reflectance and bidirectional reflectance collected commonly in the nadir (normal to the surface) viewing geometry. The differentiating factor between the two types of reflectance is that they are measured in the laboratory and in the field, respectively (Roberts and Herold, 2004). Laboratory Reflectance Wavelength (µm) (1000–2600 nm) Figure 4. This figure from Mustard et al (2008) shows the varying and somewhat unique absorption features for a variety of different minerals at the 1.4 and 2.2 micrometer (1400–2200 nm) wavelengths. These absorption features are related to the electronic and vibrational processes associated with the chemistry of the different materials (Goetz et al., 1985; Clark, 1999). Here, a number of processes and interactions come into play, which determines the amount of energy each type of material will emit, absorb, and scatter (Jensen, 2007) 9
Page 1 and 2: NAVAL POSTGRADUATE SCHOOL MONTEREY,
Page 3 and 4: REPORT DOCUMENTATION PAGE Form Appr
Page 5 and 6: Approved for public release; distri
Page 7 and 8: ABSTRACT Desert areas cover approxi
Page 9 and 10: TABLE OF CONTENTS I. INTRODUCTION..
Page 11 and 12: LIST OF FIGURES Figure 1. The above
Page 13 and 14: spectrum by atmospheric effects. Re
Page 15 and 16: emoved function showing an absorpti
Page 17 and 18: LIST OF TABLES Table 1. This table
Page 19 and 20: LIST OF ACRONYMS AND ABBREVIATIONS
Page 21 and 22: I. INTRODUCTION A study published b
Page 23 and 24: II. THE PHYSICS BEHIND REMOTE SENSI
Page 25 and 26: sensitive a given sensor is to diff
Page 27: Figure 3. From Green et al. (1998),
Page 31 and 32: After data have been converted to r
Page 33 and 34: Collins et al. (1997) was able to s
Page 35 and 36: These purposes include, but are not
Page 37 and 38: III. DESERT ECOSYSTEM CHARACTERISTI
Page 39 and 40: sagebrush of Utah, Montana, and the
Page 41 and 42: in desert regions include argids, o
Page 43 and 44: 2. Biological Soil Crusts (BSCs) Bi
Page 45 and 46: 2004), especially in cases where ma
Page 47 and 48: IV. STUDY SITES The focus area of t
Page 50 and 51: Figure 13. This figure illustrates
Page 52 and 53: Following the uplift that occurred
Page 54 and 55: the Mazourka Canyon OHV park betwee
Page 56 and 57: wavelengths being analyzed to obtai
Page 58 and 59: 2. Field Spectroscopy An Analytical
Page 60 and 61: A spectral library was then built a
Page 62 and 63: after atmospherically correcting th
Page 64 and 65: where: is the mean corrected and no
Page 66 and 67: also be seen in Figure 23. The leve
Page 68 and 69: Figure 24. This figure is a compari
Page 70 and 71: Figure 25. This figure shows ASD co
Page 72 and 73: Looking at Figure 25 it is apparent
Page 74 and 75: A. IMAGERY DERIVED ENDMEMBERS The i
Page 76 and 77: Figure 28. The above shows some of
Page 78 and 79:
spectrometer, reflectance values we
Page 80 and 81:
such an inference can be made (Ben-
Page 82 and 83:
While this is lower than the hoped
Page 84 and 85:
While the lower value would initial
Page 86 and 87:
Figure 33. This figure shows the ad
Page 88 and 89:
Inset C of Figure 35 is the same da
Page 90 and 91:
However, the presences of BSCs are
Page 92 and 93:
A B C Figure 37. Inset A shows the
Page 94 and 95:
A B C Figure 38. Inset A shows a co
Page 96 and 97:
differences in the studies by other
Page 98 and 99:
small concentrations making them un
Page 100 and 101:
area making it possible to tell wha
Page 102 and 103:
Clark, R. N., Swayze, G. A., Livo,
Page 104 and 105:
Kruse, F. A., Boardman, J. W., and
Page 106 and 107:
Sharp, R. P., and Glazner, A. F., (
Page 108:
INITIAL DISTRIBUTION LIST 1. Defens
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