W SR ‐ 88D Dynamic Scanning - SAILS and AVSET

1. WSR‐88D Dynamic Scanning - SAILS and AVSET Fred H. Glass

2. Supplemental Adaptive Intra-Volume Low-Level Scan (SAILS) Automated Volume Scan Evaluation and Termination (AVSET) • Dynamic scanning techniques designed to: • shorten volume scan times • increase frequency of lowest-level scan • Benefits are more frequent volume scan updates/data and more low-level “looks” • AVSET has been in operation since Spring 2010 • SAILS will be implemented in late April-May 2014, and is intended only to support severe weather operations

3. Automated Volume Scan Evaluation and Termination (AVSET) • Operator selectable method to make each volume scan “dynamic” • The number of angles/elevations scanned is dependent on the sampled meteorological return • Terminates volume scan once returns fall below thresholds of dBZ and areal coverage • Shortens time between product updates when no significant data exists on higher elevation tilts • VCP31/32 not impacted by AVSET

6. How AVSET Works • Only analyzes data above5° • To terminate, each condition must be met: • ≥18 dBZ over < 80 km² • ≥ 30 dBZ over <30 km² • areal coverage ≥18 dBZ has not increased by 12 km² or more since the last volume scan • If all three conditions are met… • AVSET terminates the volume scan after completion of the next higher elevation • VCP 212 Example: • Below thresholds at 5.1°? Will terminate after 6.4°

7. How Short Can We Go? • VCP 12 full volume scan time 4 min, 18 sec • AVSET shortest update3 min, 10 sec • VCP 212 full volume scan time 4 min, 36 sec • AVSET shortest update3 min, 30 sec

8. AVSET and Range to Weather • AVSET with storms at far range • Only relevant elevations above 5° used • AVSET with storms at close range • Entire VCP used

9. SupplementalAdaptive Intra‐Volume Low‐Level Scan(SAILS) • A new dynamic scanning method which is operator selectable • Inserts a new low-level scan (0.5°) into the “middle” of the volume scan (wrt time) • The goal is to evenly space, as close as possible, the time interval between low-level data updates • Only functional in the existingsevereweatherVCPs12and 212 • Z, V, SW and Dual Pol variables will be generated and distributed (Level 2) • Known as the “Sails Scan”

10. HowDoesSAILSWork? For VCP12

11. SAILS Implementation • To collect the supplemental 0.5° scan adds approximately 35 seconds to the volume scan duration • SAILS0.5° UpdateRate: Every ~140 seconds (~105 seconds w/ AVSET) • shortens low-level scan update to < 3 minutes; < 2 minutes with AVSET • In VCP 12, volume scan completion times range from as short as 225 sec with AVSET (termination after 6.4°) to 285 sec for a full volume scan

12. Benefitsof SAILS • Significantlyreduces low‐levelscanupdateinterval, especially for more distant storms • Providesmorelow‐level“looks”duringsevereweatheroperations

13. Summary • OperatinginVCP12,SAILSwill add 10-18 additional 0.5° elevation scans per hour • Duringsevereweatheroperations,the frequentlow‐level“looks”providedbySAILS willsignificantlyenhanceWSR‐88Dforecastandwarningsupport,whilenotimpactingWSR‐88Ddataqualityor hardwareoperations • AVSET will be enabled by default with the arrival of SAILS • Extend SAILS to result in 2-4 low-elevation scans per volume in Build 16 (April 2015)

14. Questions ????