Rule explorer

Fig. 5. Rule Template.

The domain knowledge in ECliPS is presented as a set of rules. Most commonly, the rules are in the IF-THEN form. For example, a rule may look like

IF ENSO event = warm,
AND Aleutian low circulation type = W1,
THEN winter SAT in the Bering Sea = above normal;
CF = 50.

Here CF is the confidence factor for the rule. Despite the simplicity, this type of rules is very powerful and versatile in expressing  relationships between climate variables.

Fig. 6. Rule edit form.

It is important to note that the data and code for each rule are placed in a separate Excel file. This provides substantial  flexibility in preparing a rule for the knowledge base. In most cases it would be suffice to use a provided template (such as the one in Fig. 5), where the user can simply fill in the table. The advanced users, however, who are familiar with Visual Basic for Excel, can write their own code. Another advantage of this rule information storage is that the user can easily experiment with each rule separately and develop a better feeling of confidence in it.

Fig. 7. Rule Explorer.

Common management tasks, such as inserting new rule, editing (Fig. 6), deleting, sorting, etc., are performed using the Rule Explorer (Fig. 7). The number of variables in the IF part of a rule is unlimited.