PS07: Radar et al.

CEE 6100 / CSS 6600 1PS 07 Due Wed, 21 Nov 20121. Thermala. The temperature of a glowing tungsten filament in an incandescent light bulb is ~3000K.i. [1] What is the wavelength of peak emission of the filament?ii. [1] What is the total emission for a blackbody at this wavelength?iii. [1] Estimate the exitance over the visible (0.4-0.7) using =0.55 as an average value,i.e., compute M = M . Note: All distance units in Planck's formula are in meters.Be careful to express the wavelength units to meters.iv. [1] What portion of the total exitance is emitted in the visible?b. [2] The ASTER images below show the region around Saline Valley, California as a threebandcolor TIR composite (Figure 1a) and an average brightness (Figure 1b), along with agraph of the spectral reflectance of several types of material in the 8-14 m range (Figure 2)and a graph of the spectral radiance at the detector for the three bands making up the colorimage (Figure 3). Assuming that the brightness of the exposed rocks and minerals in thethermal image is related to temperature and that color of the exposed rocks is related toemissivity, make a preliminary identification of the five surface materials whose location isindicated by the plus signs (aragonite, basalt, dolomite, quartzite and forest) based on thespectral reflectivity and corresponding spectral radiance. Each location is representative ofa relatively pure example of the material.[2] Please explain the rationale for your choices.3 +2 +5 +1 +4 +a) color TIR image b) TIR Grayscale image (Bands 10+12+13)Band 13: 10.25-10.95 m RedBand 12: 8.925-9.275 m GreenBand 10: 8.125-8.475 m BlueFigure 1: ASTER images of Saline Valley, CA.(Courtesy of NASA/GSFC/METI/Japan Space Systems, and U.S./Japan ASTER Science Team

CEE 6100 / CSS 6600 2PS 07 Due Wed, 21 Nov 2012% Reflectance (Qurtzite)706050403020100Band10(blue)AragoniteBand12(grn)BasaltQuartziteTreesDolomiteBand 13(Red)8 9 10 11 12wavelength (microns)Figure 2: TIR Reflectance spectra of selected materials.121086420% Reflectance(Basalt, Aragonite,Dolomite & Trees)Figure 3: Scaled radiance at the detector (proportional to the apparent temperature).TIR imageColor1 Red2 Green3 Cyan4 Purple5 Black ridgeLand coverRationale

CEE 6100 / CSS 6600 3PS 07 Due Wed, 21 Nov 20122. Scatterometer[2]A simplified model of the radar backscattering coefficient of a sea surface is: o = A + B cos (2 )where is the angle between the wind direction and the radar look azimuth, and A and B are:A = 0.8 v – 30B = 3.5 – 0.1 vwhere v is the wind speed in m/s. A scatterometer observation measures o values of -22.9 dB and-21.1 dB looking north and east respectively. Find the wind velocity. Is there any ambiguity inyour answer? If so, could it be removed by a third observation.You may need the trigonometric identities: cos 2 = cos 2 - sin 2 cos ( ± ) = cos cos ± sin sin cos (90-) = sin sin (90-) = - cos 3.Radar - Real vs. Synthetic aperturea. [2] The Seasat SAR was an L-band system (1.275 GHz) that flew at an altitude of ~800 km andprovided a nominal 25 m (azimuth) x 25 m (range) resolution. Its antenna dimensions were10.74 m x 2.16 m and the depression angle was 70. What physical aperture size would havebeen required for a real aperture system with the same azimuthal resolution?b. [1] What would the equivalent real aperture have been for the SIR-C, X-band radar, a 10 GHzradar flying at 225 km with a nominal depression angle of 50 and a nominal resolution of 30 mx 30 m. (The actual size of the X-band antenna was 12.0 x 0.4 meters).c. [1] Finally, what would the azimuthal resolution be for an aircraft flying the SIR-C system as areal aperture radar at an altitude of 20 km.4. Radar: roughnessa. [2] Determine roughness categories for a radar system using the following wavelengths at adepression angle γ of 30 degrees and complete the table below.Roughness Category Ka Band (0.86 cm) X Band (3.0 cm) L Band (25.0 cm)SmoothRoughb. [1] A geologist needs to distinguish talus (h = 12.0 cm) from gravel deposits ( h = 1.5 cm ).According to the above table, what wavelength radar image would be most effective formaking this distinction?

CEE 6100 / CSS 6600 4PS 07 Due Wed, 21 Nov 20125. The image below shows the North shore of Lake Superior, July 1991, imaged by Radarsat in wideswath mode.a. [2] From what direction is the incoming radar illumination coming? Give at least 2 detailsto justify your choice.b. [3] There are several linear features in the image, three of which are indicated by arrows.One is a fault line, one is a road and one is a flaw in the processing (effectively a bad scanline). Specify which is which and justify your choices.