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

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2. Field Spectroscopy An Analytical Spectral Device (ASD) Imaging Spectrometer was also utilized to collect spectra in the California desert areas of the Mono Lake Basin Owens Valley, and Death Valley. Imaging spectrometers, similar to AVIRIS, measure radiance from surface materials in the UV to near infrared (NIR) and shortwave infrared (SWIR) range (350- 2500nm) (Green et al., 1998; Roberts and Herold, 2004). Unlike AVIRIS, an imaging spectrometer, field spectrometers such as the ASD do not portray collections as imagery, but as an individual spectrum or series of spectra (Figure 18) (Roberts and Herold, 2004). Spectra measured consisted of a variety of areas around the Panum Crater Trail and Mazourka Canyon Off Highway Vehicle (OHV) Park. Spectra were taken from areas of zero disturbance, areas of minimal disturbance related to foot paths, areas of light duty dirt roads, areas of heavy duty dirt roads, and areas with both disturbed and non-disturbed vegetation including cryptobiotic soils. Examples of non-atmospherically corrected spectra collected with the ASD imaging spectrometer can be seen in Figure 18. Figure 18. This figure shows a series of non-atmospherically corrected spectra collected with the ASD spectrometer. 38
Specimens were sampled during the time periods of 0930–1130 and 1300–1500, falling within the +/- 2 hours of solar noon described by (Roberts and Herold, 2004). Collected spectra were then converted to reflectance using spectral math. The spectral math equation used was s1/s2 where s2 was the average white reference spectrum and s1 was one of the field collected spectra. This process was conducted on each individual spectrum from each collection site, and utilized the site specific white reference spectrum for a given calculation. One of the results of this process can be seen in Figure 19. Once the spectra were in units of reflectance, they were examined for proof of concept with respect to detecting soil disturbance using reflectance spectroscopy and the continuum removal method. To verify if differences were significant enough to be considered spectrally extreme, band depths were analyzed between both the ASD collected spectra and the imagery derived endmembers using the following equations (5) and (6) described by Kokaly and Clark, (1999) and Kokaly (2001). Equation (5) calculates the continuum removed reflectance required to then calculate the band depth using equation (6) (Kokaly and Clark, 1999; Kokaly (2001). where: is the continuum removed reflectance at the absorption feature, feature. where: is the the reflectance at the base of the absorption feature, and is the reflectance of the fitted continuum line that corresponds to the absorption is the calculated band depth of the continuum removed absorption feature and is the previously calculated continuum removed reflectance from equation (5). 39 (5) (6)
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 and 28: Figure 3. From Green et al. (1998),
Page 29 and 30: analyzing imagery spectra, it is mo
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 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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