METR 2413
Homework Assignment #3
Date assigned:  28 January 2004
Due date:  4 February 2004

1.     What is the name of the first weather satellite ever launched, what country launched it, and when was it launched?

TIROS-1, launched by the US in April, 1960

2.     Name one advantage and one disadvantage of polar orbiting satellites

Advantages may include:

Complete global coverage

Polar regions aren't distorted (as they are with geosynchronous satellites)

Can often get higher resolution images

Disadvantages may include:

Only see a particular location once or twice a day

Don't get the "big picture" view of the movement of weather systems

Not as useful for real-time forecasting

Often need more fuel because of lower orbits

3.     Name one advantage and one disadvantage of geosynchronous satellites

Advantages may include:

Can get a whole-disc view of the planet

By looking at the same location at all times, you can watch the development and movement of large-scale weather systems

Can be used for real-time forecasting

Disadvantages may include:

Often don't get high enough spatial resolution to distinguish individual storms

Polar regions are distorted

High orbit limits spatial resolution (this is similar to #1, but stated a little differently)

4.     What is the difference between the water vapor channel and the IR channel on the GOES satellites?

The water vapor channel is a special IR channel, specifically designed to sense energy in the 6 to 7 micron region where water vapor is a strong emitter of radiation.

Other IR channels do not specifically target wavelengths of water vapor emission.  That is, there are many other gases that contribute to the energy sensed in other IR channels.  The IR channel used for IR images on the GOES satellites typically senses in the 10 micron (atmospheric window) region, where there is little atmospheric emission and emission from cloud dominates.

5.     How is wind speed and direction determined by satellite?

Most often by tracking cloud features between sequential geostationary satellite images.  Sounding data can be used to determine winds from height gradients.  (Other, more detailed answers are acceptable)