SAN FRANCISCO STATE UNIVERSITY NAME DEPARTMENT OF GEOSCIENCES Spring 2013

Transcription

1 SAN FRANCISCO STATE UNIVERSITY NAME DEPARTMENT OF GEOSCIENCES Spring 2013 METR 415/715: MONTEVERDI QUIZ 1 Open Book and Open Notes 200 points, 45 minutes 1. Compute the altitude of a geostationary orbit for Mars. (radius = 3,397 km; mass= X kg; orbital period=~24 h). (50 points) Show all work. Label all equations sequentially with numbers. Problem 1: Equations Needed F c = m sat V2 R (1) F g = Gm sat m m R 2 (2) V = ωr (3) Relations or Constants Needed R = R m + h ω = 7.292X10 5 s 1 R m = 3.397X10 6 m M m = X10 23 kg G = 6.67X10 11 N m2 kg (4)

2 Solution For a geosynchronous orbit, F c = F g (5) Insert (1), (2), (3) and (4 b, d and e) into (5) and solve for R 3 R 3 =8.056 X m 3 (6) R=2.005 X 10 7 m (7) Substitute (4a and b) into (7) and solve for h h=1.66 X 10 7 m = 16,600 km (8) 2

3 2. Examine the satellite images below (55 points): Satellite Image A 3

4 Satellite Image B 4

5 A. State whether the satellite images were from the imagers of a geostationary satellite or a polar orbiter, and why. (10 points) The images are from the GOES-12 satellite. The images are labeled as such at the bottom of the image. Also, the imagery has a much wider east-west extent than imagery from the POES. B. State the size of a cloud element for the two images, and why. (15 points) The images have a resolution of 4 km. The images are so labeled on the bottom. Since a cloud element is the smallest resolvable feature on the imagery, a cloud element would have a diamter of 4 km on these images. C. What is the cloud top temperature at the three way border of Louisiana, Arkansas and Mississippi? (10 points) The color temperature on the infrared image in the area of the Louisiana/Mississippi border is on the boundary of dark greengrey. This corresponds to a temperature between -60 C to -70C. D. Although the Satellite Image B uses a color enhancement curve, that enhancement most closely resembles which of the following grey scale enhancement curves: (a) Standard; (b) ZA; (c) MB. (5 points) ) MB. E. The color enhancement probably is designed to highlight what features of meteorological significance. Explain. (10 points) The color enhancement appears to highlight the coldest tops of cumulonimbus clouds. F. Which Channel was used to obtain the data for Image B? (5 points) The data comes from Channel 4. 5

6 3. Examine the enhancement curve given below. (25 points) A. What is the designation (name) of this enhancement curve? (10 points) This is the MB enhancement curve, designed to highlight convective storms. B. The enhancement curve shown above appears to highlight color changes between -40C and -80C. What is the purpose for highlighting these temperatures? (15 points) 6

7 This enhancement curve designed to highlight convective storms and the clouds at the upper levels of hurricanes. 4. The following image is a GOES-15 Visible 4 km image processed by the US Navy. (28 points) Locate the following by putting the appropriate letter right on the image: (a) Cloud line; (b) Cloud band; (c) Cloud streets; (d) cumulonimbus. 7

8 5. Examine the Sea Surface Temperature field observed by the Aqua on 3/25/11. (20 points) (a) Which instrument on the Aqua and Terra platforms senses the data used to create this plot? (10 points) The instrument is the Moderate Resolution Imaging Spectroradiometer (MODIS)> (b) The orange pattern in the eastern portion of the Gulf of Mexico is associated with a prominent oceanographic current feature. What is the name of that feature? (10 points) This feature is known as the Loop Current. 8

9 6. Examine the DMSP image below: (22 points) 9

10 A. State how you would know that this image was produced from data sensed by a polar orbiting satellite, even without legend information on the image. (2 points) The image shows part of the polar regions. B. The DMSP satellite is in a so-called sun-synchronous orbit. Give one advantage and one disadvantage (for meteorological applications) of a sun-synchronous satellite orbit compared to a geosynchronous satellite orbit, apart from anything you just mentioned in 6A just above. (10 points) Advantages: superior resolution; consistent illumination; Disadvantage: does not return imagery for the same geographic area except the pole so it is not possible to trace evolution of cloud/storm systems. C. The thermal infrared sensors for both the POES and GOES series detects infrared energy emitted by the earth and clouds passing through the so-called INFRARED or ATMOSPHERIC WINDOW. Define the infrared window and give the approximate range of wavelengths to which it corresponds. (10 points) The infrared or atmospheric window is the transparent portion of the water vapor spectrum through which emitted long wave radiation is allowed free passage to space. It corresponds generally to the range of wavelengths 7 to 11 microns. B. The Aqua satellite has an orbit designed to pass different points on the earth s surface at two times (12 hours apart) during the day and at night each 24 hour period. What are those times? 1:30 PM and 1:30 AM. (10 points) 10