WSR‐88D Dynamic Scanning - SAILS and AVSET

Fred H. Glass

• 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

Supplemental Adaptive Intra-VolumeLow-Level Scan (SAILS)

Automated Volume Scan Evaluation andTermination (AVSET)

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

How AVSET Works• Only analyzes data above 5°• To terminate, each condition must be met:

1. ≥18 dBZ over < 80 km²2. ≥ 30 dBZ over < 30 km²3. areal coverage ≥18 dBZ has not increased by 12 km² or more

since the last volume scanIf 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°

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 update

3 min, 30 sec

AVSET with storms at far range– Only relevant elevations above 5° used

AVSET with storms at close range– Entire VCP used

AVSET and Range to Weather

Supplemental Adaptive 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 existing severe weather VCPs 12 and 212

• Z, V, SW and Dual Pol variables will be generated and distributed (Level 2)

• Known as the “Sails Scan”

For VCP12

How Does SAILS Work?

SAILS Implementation

• To collect the supplemental 0.5° scan adds approximately 35 seconds to the volume scan duration

• SAILS 0.5° Update Rate: 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

Benefits of SAILS

• Significantly reduces low l‐ evel scan update interval, especially for more distant storms

• Provides more low l‐ evel “looks” during severe weather operations

VCP 12 Number of 0.5° Product Updates per Hour

Volumetric Product Updates per Hour

Standard Operation 14 14AVSET 14 ‐ 19 14 ‐ 19SAILS 24 12

SAILS and AVSET 24 ‐ 32 12 ‐ 16

VCP 212 Number of 0.5° Product Updates per Hour

Volumetric Product Updates per Hour

Standard Operation 13 13AVSET 13 ‐ 17 13 ‐ 17SAILS 22 11

SAILS and AVSET 22 ‐ 28 11 ‐ 14

Summary• Operating in VCP 12, SAILS will add 10-18

additional 0.5° elevation scans per hour• During severe weather operations, the

frequent low l‐ evel “looks” provided by SAILS will significantly enhance WSR‐88D forecast and warning support, while not impacting WSR‐88D data quality or hardware operations

• 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)

Questions????