# Presentation: 316943

## Estimated Actual Velocity (EAV)

**Bill Parker**
**NWS Shreveport La**

## What is EAV?EAV is a new AWIPS radar tool that was included in the AWIPS 8.2 software in January 2008.

## What does EAV do?EAV will provide the radar meteorologist with an estimated actual wind from the Base Velocity WSR-88D data.

## How does EAV work?EAV uses the solution of a right triangle to provide an estimate of actual wind speed.EAV = Doppler wind / COS @where @ is angle of wind direction off Doppler radial

## Determination of Doppler Estimated Winds Based on Degrees off Radar Beam

## Black arrow – Doppler wind

- Blue arrow - 2nd component of wind
- Red arrow – Actual wind

- EAV = Doppler wind / COS @

- EAV

- @

## Slide 7

## Slide 8

## Base velocity was 50 kts at point where EAV = 90 kts

## Slide 10

## Base velocity was 38 kts at point where EAV = 60 kts

## Uses of EAV?1. Estimate actual wind speeds in a squall line.2. Estimate winds in a hurricane.3. Estimate winds in a blizzard.Cautions – The estimated wind direction by the radar meteorologist must be accurate or bad EAV data will result. If the input wind direction is greater than ~80 degrees off radial, no EAV will be calculated.

## Four-dimensional Stormcell Investigator (FSI):

**NWS Shreveport La**

- Four-dimensional Stormcell Investigator (FSI):

## To increase warning skill and lead time, and therefore improve public service, 3D/4D visualization will allow forecasters to 

better analyze the signatures which are useful in diagnosis of severe and tornadic storms.

discover new clues and signatures not easily observed using traditional 2D analysis methods.

- better analyze the signatures which are useful in diagnosis of severe and tornadic storms.
- discover new clues and signatures not easily observed using traditional 2D analysis methods.

- Four-Dimensional Stormcell Investigator (FSI)

## Why three (and four) dimensions?

- Because the _atmosphere_ is four-dimensional!
- Storm researchers have used 3D/4D displays for years to facilitate their understanding of signatures related to severe weather.

## The Lemon Technique (1977)

- Original storm structure analysis methods infer vertical structure from horizontal slices at different elevation angles

## Requirements

- Provide for quick and easy access to the data (15-30 seconds per storm)
- Provide linkages between 2D representations and 3D data
- Still difficult for users to overcome tendency to view in traditional 2D manner
- Radar data must be “native” 8-bit resolution polar grids
- Z, V, SRM, SW
- 4D:  Animation while slicing and dicing
- Learn Keyboard shortcuts
- Processes must be stable and cause minimal impact to AWIPS system resources

## FSI Configuration

- PPI
- Plan
- Position
- Indicator
- VDX
- Vertical
- Dynamic
- X-Section

- CAPPI
- Constant
- Altitude
- PPI
- 3D Flier
- Three-
- Dimensional
- Flier

## Summary of Benefits of FSI

**Improved vertical cross-sections**
- Dynamic placement and re-position of a cross-section reference line showing real-time updates to the cross-section data. Cross-sections are **no longer a one-time requested** RPG product, and are instead generated on-the-fly using 8-bit data.
**Constant Altitude cross-sections (CAPPIs)**
- 8-bit radar data plotted at **constant altitude eliminates the need to sample elevation scan data** for altitude or reset elevation angle choices in four-panel displays. Cross-section control is also dynamic, showing real-time updates to the cross-section data.
**3D visualization**
- 8-bit radar data from elevation scans, vertical cross-sections, and CAPPIs are plotted as 2D textures in 3D space. A forecaster can then zoom, pan, pitch, yaw, and fly about the data in 3D.
**Virtual Volumes**
- No volume scan is incomplete. As new elevation scans are updated, they replace the old elevation scans in the virtual volume one-by-one. This means that there are **full volumes of data available at all times for cross-sections** and data perusal.
**Access to a much larger data inventory**
- An “All-Tilts” product only allows the forecaster to peruse a sequential order of elevation scan frames. For a 64 frame limit in VCP12, that only comprises 5 volume scans. **The FSI allows the user to access any elevation scan in the radar data inventory RPS list, for up 2 hours of 8-bit data for all elevation scans.**** **

## FSI Operational Considerations

- Training on the understanding of storm signatures in 3D is important
- Workload management/human factors
- 3D visualization is reaching WFOs via other applications
- 3D experience is gaining in the field.