Name: _______________________Spring Semester 2009Name: _______________________Remote Sensing of the EnvironmentGEOG/GEOL 4093/5093Spring Semester 2009Lab Exercise #8: 03/17/2009Due: 03/31/2009This lab focuses on examining information from SAR interferometry, as well as radar andlidar altimetry. The material you need to complete this lab is posted at http://cires.colorado.edu/esoc/classes/geog5093 under “Lab 8 Material”. Refer to the figures provided at this URL to answer the lab questions. Part I: Interferomtric Synthetic Aperture RadarIn 1992 there was a 7.3 magnitude earthquake near Landers, California in the Mojave Desert. This produced one of the earliest interferograms developed from SAR interferometry using the ERS-1 C-Band SAR. For all of the questions in this section, assume that all displacement of the surface is in the direction of the sensor. Refer to the figures on pages 1 and 2, in particular the interferogram on page 2, of the URL given to answer the following questions.1. What is the wavelenth of C-Band SAR? (1 pt.)2. If we made GPS measurements of point A before and after the earthquake, and wemeasured movement of point A to be 50 cm, what is total movement of point B? How did you determine this? (3 pts.)3. What is the relative displacement between points B and C? It will help if you zoom in on the figure on p. 2 of the attachment. Give the reason for your answer. (3 pts.)4. Where is the displacement greatest, close to the fault line or far from it? What is itabout the interferogram that tells you this? (2 pts.)5. What advantage does InSAR provide over GPS measurements in observing thedeformation associated with this Earthquake? What advantage does GPS offerover InSAR? (1 pt.)Part II: Ocean AltimetryRefer to the figure on page 3 of the URL to answer the questions in this section.6. The Topex satellite passes over a point on the ocean at a height above the ellipsoid(mean surface height) of 700 km (He). The travel time of the pulse from the satellite to the Earth and back (from which we can calculate Hs) is 4.666666 milliseconds. What is the height (h) of the ocean surface? (2 pts.)7. 30 days later the satellite passes over the same location again. This time the traveltime of the pulse is 4.666672 milliseconds. Has the surface gone up or has it gone down? By how much? What might cause the surface to do this? (3 pts.)Part III: Laser AltimetryRefer to the figure on page 4 of the URL to answer the questions in this section.8. Why does figure B have 2 peaks, when figure A only has 1? (2 pts.)9. Why is the peak in figure A stronger than either of the peaks in Figure B? (2 pts.)Part IV: Altimetry Over Vegetated SurfacesRefer to the figure on page 4 of the URL to answer the questions in this section.10. At approximately what two-way travel time value is the ground? By two-way pulse travel time, we mean the time it takes the pulse to travel from the satellite tothe ground and back to the satellite again. Explain your answer. (2 pts.)11. Based on the pulse travel time you identified for the ground, how high above the ground is the satellite? Show your work. (2 pts.)12. Which area (1, 2, or 3) has the highest trees? How do you know? (2 pts.)13. Which area (1, 2, or 3) has the smoothest canopy top (i.e. trees closest to the sameheight)? What is the basis for your answer? (2 pts.)14. The bottom peak in profile #2 is the smallest (i.e. has the lowest energy), and the bottom peak in profile #1 is the most distinct (i.e. has the highest energy). What does that tell you about the density of the vegetation cover? Give reasons for youranswer. (3
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