Locate Dataset and Variable 
 Select the "Datasets by Catagory" link in the blue banner on the Data Library page.
 Click on the "Cloud Characteristics and Radiation Budget" link.
 Select the
CAYAN dataset.
 Click on the "net heat flux" link under the Datasets and Variables subheading.
CHECK

Select Temporal and Spatial Domains 
 Click on the "Data Selection" link in the function bar.
 Enter the text 130E, 20N and Jan 1960 to Mar 1998 in the appropriate text boxes.
 Press the Restrict Ranges button and then the Stop Selecting button.
CHECK

Calculate Number of Classes and Class Interval 
 Select the "Filters" link in the function bar.
 Choose the Maximum over "T" command. CHECK
EXPERT
This operation computes the maximum heat flux over the time grid T. The value is located under the Expert Mode text box in bold: 154.3319 W/m^{2}.
Remember this value.
 Click on the right most link prior to the "T 0.0 maxover" box in the source bar. CHECK
This operation undoes the maxover command.
 Again, select the "Filters" link in the function bar.
 Choose the Minimum over "T" command. CHECK
EXPERT
This operation computes the minimum heat flux value over the time grid T. Again, the value is located under the Expert Mode text box in bold: 401.584 W/m^{2}.
Remember this value.
 Click on the right most link prior to the "T 0.0 maxover" box in the source bar. CHECK
This operation undoes the minover command.
 Calculate the range by subtracting the minimum value from the maximum value.
154.3319  401.584 = 555.91 which may be rounded to 556.
 Scroll down the page and find the month variable under the Grids subheading.
 Note how many data points are contained in the grid by finding N=___.
You should have seen the number 459.
 Use the following formula to estimate the number of classes: K = 1 + 3.3 * log n
K = 1 + 3.3 * log 459. K = 9.7840 which may be rounded to 10.
 Calculate the class width by dividing the range (556) by the number of classes (10).
556 ÷ 10 = 55.6, however the class interval should be rounded to a whole number.
Rounding the class interval to 56, and beginning the first class at 405 will ensure that the ten classes include all values in the dataset. 405 + 56 * 10 = 155.

Generate Histogram 
 Press the OK button. CHECK
The RANGESTEP command defines the range of heat flux values to consider, as well as the spacing to use.
The range 405 to 155 includes the entire set of values. The spacing is 56.
The distrib1D command calculates the frequencies within each class that are used to create the histogram.

View Histogram 
 To view the histogram, choose the viewer marked with colors. CHECK
Heat Flux Frequencies at 130E, 20N for January 1960 to March 1998
The histogram is unimodal and is negatively skewed.

Generate Relative Frequency Histogram 
 Press the OK button. CHECK
The div command divides each frequency by 459, the total number of observations.
This transforms the set of frequencies into relative frequencies. The second command changes the variable name from
Frequency to Relative Frequency

View Relative Frequency Histogram 
 To view the relative frequency histogram, choose the viewer marked with colors. CHECK
Heat Flux Relative Frequencies at 130E, 20N for January 1960 to March 1998
The relative frequency histogram looks similar to the frequency histogram, except that the rectangle heights are represented by different values.

Generate Density Histogram 
 Press the OK button. CHECK
The div command divides each relative frequency by 56, the class width.
This transforms the set of relative frequencies into densities. The second command changes the variable name from
Relative Frequency to Density.

View Density Histogram 
 To view the density histogram, choose the viewer marked with colors. CHECK
Heat Flux Relative Frequencies at 130E, 20N for January 1960 to March 1998
The density histogram looks similar to the frequency and relative frequency histograms, except that the rectangle heights are represented by different values. Recall that in a density histogram, the total area of all rectanges is 1.
