In it’s original implementation, NEXRAD could only detect horizontal measurements of objects in the atmosphere. The dual-polarization upgrades implemented several years ago enable NEXRAD radars to receive both horizontal and vertical data. These data are beneficial in determining precipitation type, filtering non-meteorological clutter, and detecting tornado debris.
Digital Accumulation Array
The Digital Accumulation Array (DAA) is a one-hour dual-pol based Quantitative Precipitation Estimation. Digital Accumulation Array has no bias applied meaning you are seeing raw estimates. The product is updated once per volume scan and is an 8-bit, 256 data level product available at 0.25 kilometer by 1 degree resolution.
Digital Storm Total Accumulation
Digital Storm Total Accumulation (DSA) is an estimate showing total accumulation for an event and may have bias applied. Digital Storm Total Accumulation is an 8-bit, 256 data level product available at 0.25 kilometer by 1 degree resolution.
Digital One-Hour Difference
Digital One-Hour Difference (DOD) shows the difference between the dual-pol product and legacy product with no bias applied. The equation used is dual-pol minus legacy. Positive values indicate the dual-pol estimate is more than the legacy estimate while negative values indicate the legacy estimate is more than the dual-pol estimate.
Digital Storm Total Difference
Digital Storm Total Difference (DSD) shows the difference between the dual-pol product and legacy product with no bias applied. The equation used is dual-pol minus legacy. Positive values indicate the dual-pol estimate is more than the legacy estimate while negative values indicate the legacy estimate is more than the dual-pol estimate.
Storm Total Accumulation
The storm total accumulation product estimates how much rain has fallen over an arbitrary period of time specified by the radar operator, usually corresponding to the beginning of a rainfall event. Since this product is based on the relationship of reflectivity (Z) to rainfall rate (R), it is important to note that it is not an indicator of snowfall accumulation.