El-Nino and La-Nina
Directions: Using the Internet, look up the monthly sea surface temperature data for the periods of 1) July 1982 - June 1983,  2) July 1988-June 1989, and 3) July 1991 - June 1992.  Your teacher has the web site addresses.
A) Save all global sea surface temperature images as either a TIFF or a PICT.
B) Use image processing software to create three animated movies; one for each group of images.
C) Save the animations as ANIM1982, ANIM1988, and ANIM1991.
C) Answer the questions below.  To answer some of the questions, you will need to use the following formulas:
Temperature conversion from DN Value to degrees Celsius: C = -.176 * DN + 43
Temperature conversion from degrees Celsius to degrees Fahrenheit: F = 1.8 * C + 32

1) Write down some of the similarities and differences in ocean sea surface temperature that you notice between the animations.

There are several possible answers here, but they should write something concerning the Central and South Pacific waters: about how there is more red color (indicating higher temperatures) during the 1982 and 1991 animations, or less red during the 1988 animation.
 
Open the images from December of 1982, 1987, and 1991.  Using the box tool from the Tools menu (it is the first icon in the second column), and starting at an X value of 1, and a Y value of 80, draw a box that is 90 pixels in length and 20 pixels in height.

2) Complete the tables below:

  Note: These are all rounded to the nearest hundredth.
Central Pacific Temp. Means Data Number (Value) Degrees Celsius Degrees Fahrenheit
December 1982 83.78 28.25 82.85
December 1988 101.52 25.13 77.23
December 1991 88.36 27.45 81.41
 
 
 
Central Pacific Low Temps Data Number (Value) Degrees Celsius Degrees Fahrenheit
December 1982 104 24.70 76.46
December 1988 134 19.42 66.96
December 1991 115 22.76 72.97
 

3) Open the images from January of 1983, 1988, and 1992, and perform the same tasks as for the December images.
 
 
Central Pacific Temp. Means Data Number (Value) Degrees Celsius Degrees Fahrenheit
January 1983 82.76 28.43 83.17
January 1989 100.35 25.34 77.61
January 1992 88.04 27.50 81.50
 
 

 
Central Pacific Low Temps Data Number (Value) Degrees Celsius Degrees Fahrenheit
January 1983 102 25.05 77.09
January 1989 122 21.53 70.75
January 1992 108 23.99 75.18
4) The higher the Data Number (Value), the lower the actual temperature.  Why does this occur?

The students will probably explain it in a variety of ways, but they should realize that the negative value in front of the .176 in the formula will cause smaller answers to appear when larger Data Numbers (values) are used.

5) Higher than normal sea surface temperatures in this area of the Pacific indicate an El-Nino.  Lower than normal sea surface temperatures in this area indicate a La-Nina.  Classify each:

1982 - 1983: El-Nino

1988 - 1989: La-Nina

1991 - 1992: El-Nino

6) Using the January images, move the cursor to X=50, Y=90.  Record the Data Number (Value) below, and fill out the table.
 
X = 50, Y = 90 Data Number (Value) Degrees Celsius Degrees Fahrenheit
January 1983 73 30.15 86.27
January 1989 116 22.58 72.64
January 1992 91 26.98 80.56
7) What is the difference (in degrees Celsius and Fahrenheit) in ocean temperature of January 1983 and January 1989?

7.57 degrees Celsius or 13.63 degrees Fahrenheit