HWT/DTC 2011 Evaluation - Evaluation Techniques

Spatial Verification Techniques

For this collaboration, the DTC will be employing the use of the Model Evaluation Tools. Specifically, for Spatial Verification, we will be using the Method for Object-Based Diagnostic Evaluation (MODE) tool, which provides an object-based verification for comparing gridded forecasts to gridded observations. MODE may be used in a generalized way to compare any two fields containing data from which objects may be well defined. It has most commonly been applied to precipitation fields and radar reflectivity. The steps performed in MODE consist of:

• Define objects in the forecast and observation fields based on user-defined parameters.
• Compute attributes for each of those objects: such as area, centroid, axis angle, and intensity.
• For each forecast/observation object pair, compute differences between their attributes: such as area ratio, centriod distance, angle difference, and intensity ratio.
• Use fuzzy logic to compute a total interest value for each forecast/observation object pair based on user-defined weights.
• Based on the computed interest values, match objects across fields and merge objects within the same field.
• Write output statistics summarizing the characteristics of the single objects, the pairs of objects, and the matched/merged objects.

Learn more about object-based evaluation.

Learn more about MET and MODE.

View Feb 2009 MET Tutorial Presentation on how objects are defined in MODE.

View Feb 2009 MET Tutorial Presentation on how matching and merging of objects is done in MODE.