Metr 415/715 Name ____________________________

### 100 points.

• Answer in complete, coherent sentences on separate sheet of paper. (6 points)
• Answers requiring calculations should have all equations used in computations numbered sequentially and listed neatly on separate sheet as well. (6 points)

Resources to Help:

Kidder and Vonder Haar (Chapter 2 and 4.1)
Questions 2, 3, 5

Class Handout Tutorial on Polar Orbiters
Questions 2, 3

University of Illinois Passive Remote Sensors: Polar Orbiting Satellites (POES) Online Guide Questions 1, 5

NOAA Office of Satellite Operations Spacecraft Summary Page
Questions 4

NASA Polar Orbiting Earth Systems Monitoring (Water Systems, Surface Processes and Oceanography): Aqua and Terra and the MOSDIS Instrumentation System
Questions 6, 7

1. A satellite in sunsynchronous polar orbit has a tangential (orbital) speed of 7.85 X 103 m s-1. The mass of the earth is Mearth = 5.98x1024 kg, the gravitational constant is G = 6.67 x 10-11 N m2/kg2 and the radius of the earth is Rearth = 6.37 x 106 m. Remember that the orbital radius, R = Rearth + h. [Hint: Mathematics of Satellite Motion Review Sheet.] What is the height (h) of the satellite's orbit? (20 points)

(1a,b)

inserting 1b into 1a, inserting values given in constrant of problem and solving for hsatellite gives

h=102.7 km (yes, that's a very low orbit).

2. What is the altitude and orbital period of polar orbiting (NOAA) vs. geostationary (GOES) weather satellites? (10 points)

Polar Orbiting Environmental Satellites (POES) are placed in circular sun-synchronous (see below) orbits and their altitudes usually range from 700 to 800 kilometers, with orbital periods of 98 to 102 minutes. The GOES satellite is in geostationary orbit at 35,800 km with an orbital period of 24 hours.

3. What does the phrase "sun synchronous orbit" mean? (10 points)

A sun synrchronous orbit is a polar orbit that is synchronized with the revolution of the earth around the sun, such that the sub-satellite point crosses the equator at the same local time each day. (Note: some of you told me what a dawn to dusk orbit is...which is a special type of sun-synchronous orbit, but didn't really answer the question.)

4. What geographic coverage do polar orbiters provide that cannot be obtained from geostationary satellites? (5 points)

The polar orbiters provide coverage of the polar regions. The geostationary satellites are not able to image regions north of around 70N and south of 70S.

5. What are the designations, and equator-crossing times (northbound and southbound) of the currently operational (i.e. primary) AM and PM NOAA polar orbiting satellites? Note: LTAN = local time of ascent node (equator crossing time), often given in hh:mm:ss. (10 points)

For METOP-A: Designation-2006-044A LTAN 21:31::00 PRIMARY AM
For NOAA-18: Designation 2005-018A LTAN 13:33:50 PRIMARY PM

6. On the NOAA satellites is an instrument called AVHRR. What does that acronym mean?

The acronym AVHRR means Advanced Very High Resolution Radiometer.

7. What are the TERRA and AQUA satellites? (10 points)

(a) The Terra satellite a part of the NASA-centered international polar orbiting Earth Observing System (EOS). Terra is collecting data and contributing to what will
ultimately become a new, 15-year global data set on which to base scientific investigations about earth systems and global change and its mission is
• to create detailed maps of land surface temperature, emissivity, reflectance, and elevation.
• to measure the Earth Radiation Budget Experiment (ERBE) mission as well as the Tropical Rainfall Measuring Mission (TRMM);
• to estimate the amount and type of atmospheric aerosol particles, including those formed by natural sources and by human activities;
• to estimate the amount, types, and heights of clouds;
• to monitor the distribution of land surface cover, including vegetation canopy structure.

(b) The Aqua satellite is also a part of the NASA-centered international polar orbiting Earth Observing System (EOS). Aqua was formerly named EOS PM, signifying its afternoon equatorial crossing time. The satellite's mission (and sensors) is/are devoted
• to collecting information/data about the Earth's water cycle, including evaporation from the oceans, water vapor in the atmosphere, clouds, precipitation, soil moisture, sea ice, land ice, and snow cover on the land and ice
• Additional variables also being measured by Aqua include radiative energy fluxes, aerosols, vegetation cover on the land, phytoplankton and dissolved organic matter in the oceans, and air, land, and water temperatures.

8. On the TERRA & AQUA satellites is an instrument called MODIS. What does that acronym mean? (5 points)

The acronym MOSDIS means Moderate Resolution Imaging Spectroradiometer.

9. Print a black and white version of the MODIS image of Vancouver (2 MB). However, in doing this question, make sure that you look at the online version of this wonderful image...and clicking on the image will give you its full resolution and will allow you to make good judgments, even without experience.

I realize that you have not yet had any satellite analysis techniques. But this image is so good, that I would like you take a try at locating the following (by putting the appropriate letter, right on the spot on the image in which you think you see evidence) (18 points):

• Stratus (fog) (s)
• Glaciers/snow fields (g)
• Cumulus clouds forming over mountains (c)
• A solitary snow capped peak (p)
• A range/brush fire (f)
• Muddy runoff from prior heavy precipitation (r)