High%20resolution%20radar%20data%20and%20products%20over%20the%20Continental%20United%20States - PowerPoint PPT Presentation

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High%20resolution%20radar%20data%20and%20products%20over%20the%20Continental%20United%20States

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High resolution radar data and products over the Continental United States ... The 2D radar mosaic is created every 2 minutes at 1km resolution. ... – PowerPoint PPT presentation

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Title: High%20resolution%20radar%20data%20and%20products%20over%20the%20Continental%20United%20States


1
High resolution radar data and products over the
Continental United States
  • Valliappa.Lakshmanan_at_noaa.gov
  • National Severe Storms Laboratory
  • Norman OK, USA
  • http//www.wdssii.org/

2
Evolution of WDSS
1993-1998 Single-radar SCIT, MDA, TDA Now part of RPG
1995-2000 Single-radar with multi-sensor input NSE inputs Scheduled for ORPG-8
2003 Multi-radar multi-sensor over regional domain (1000km x 1000 km) Gridded products Shipped to select WFOs Used in Storm Pred. Center Product gen. for AWIPS?
2005 Multi-radar multi-sensor over CONUS CONUS 1km grids Available on the Internet Used in SPC
3
What products? How often?
  • Products
  • Gridded hail products
  • Reflectivity at constant temperature levels and
    layer averages
  • Low-level and mid-level shear and rotation tracks
  • Short-term forecast fields
  • Lightning Density
  • More
  • Spatial Resolution
  • 0.01 deg x 0.01 deg x 1km resolution
  • Approximately 1km x 1km throughout Continental
    United States.
  • 1km in height
  • Temporal resolution
  • 2D reflectivity mosaics every 2 minutes
  • 3D and derived products every 5 minutes

4
How does it work?
  • The process for creating 2D composites
  • Ingest Level-II radar data tilt by tilt
  • QC reflectivity data (Lak06, JAM, review)
  • Create virtual volume composites
  • Merge composites from all the CONUS radars
    (Lak06, WF, accepted)
  • 2nd level of QC -- using satellite and surface
    temperature data.

5
Virtual volume composite
  • In a traditional composite,
  • Process volume-by-volume.
  • Take maximum of all tilts.
  • Need to wait for end of volume.
  • In a virtual volume composite
  • Process tilt-by-tilt.
  • Keep a running volume.
  • Replace older data each time.
  • Take maximum of most current tilts.
  • No need to wait for end of volume scan.
  • A virtual volume provides more timely data.

at19.5
at0.5
6
Why do QC?
  • On a single-radar product, users may
  • want to see clear-air returns.
  • tolerate more clutter
  • tolerate test patterns, etc.
  • On a multi-radar product, clutter and clear-air
    returns are distracting.

7
Impact of QC
With QCed composites
raw
  • Left What we would get if directly combined raw
    (virtual volume) reflectivity composite data
  • Clear-air return, sun strobes, test patterns
  • Right combining QCed virtual volume reflectivity
    composite
  • The QC is performed radar-by-radar
  • Takes into account terrain, texture and vertical
    structure.

8
Second level of QC
  • The radar QC is conservative
  • Doesnt always remove non-precipitation echo
  • Especially if it is biological i.e. moving.
  • A second level of QC looks at satellite and
    surface temperature and retains echo where there
    is likely to be clouds.

Bad data (bloom)
No clouds
9
What do we do with the composite?
  • The 2D radar mosaic is created every 2 minutes at
    1km resolution.
  • Converted to Grib2 and sent to the SPC.
  • Put on the Internet
  • Snapshots with map background
  • Converted to Geotiff
  • Loadable with Google Earth or any GIS software.
  • Google Earth does real-time loading
  • Talk in IIPS on Tuesday
  • http//wdssii.nssl.noaa.gov
  • Not 24x7
  • The software is licensed by some private
    companies
  • They run it on their own machines.
  • They take care of 24x7 reliability.

10
2D vs 3D
  • The 2D composite is cheap to create
  • 5 dual-Xeon machines with 6 GB RAM
  • But always provides an underestimate of true
    values.
  • Need to compute in 3D
  • Height of dBZ value important!
  • Can incorporate NSE information by height
  • A lot more products!
  • The 3D products need
  • 5 dual-Xeon with 6 GB RAM
  • 2 dual-Xeon with 16 GB RAM
  • 64-bit architecture
  • composite from 2D 45 dBZ
  • composite from 3D 50 dBZ

11
The 3D flow
  • Not just reflectivity.
  • Compute shear (Smith05) and low-level shear.
  • Process lightning

12
3D processing
  • Combine QCed reflectivity in 3D
  • Combine AzShear in 3D
  • Compute hail diagnosis and layer averages.
  • Compute storm motion from composite.
  • Use it to advect storms for short-term forecast.

13
Example products
  • Extracted from the real-time generation on Jan.
    11, 2006
  • The day I created this presentation!
  • We havent run the CONUS system in Spring yet, so
    the severe weather products may be underwhelming.

14
Reflectivity products
Composite from 2D
Composite from 3D
Which radars?
Height of Max Ref
15
Azimuthal shear products
30 minute rotation tracks
Azimuthal shear 0-3km MSL
16
Severe weather diagnosis
  • Also
  • Probability of Severe Hail
  • Maximum Expected Hail Size
  • VIL_Density
  • VIL_of_the_day
  • Other echo top dBZ levels

Reflectivity at temp. levels
VIL
Convection
Echo top (18 dBZ)
17
Short-term forecast
Reflectivity at T0
Clusters
Southward motion
Reflectivity at T30 (forecast)
18
Precipitation estimates
Instantaneous precip rate
Ref closest to ground
  • Just the 88D algorithm on CONUS
  • Uses hybrid scan reflectivity
  • Convective/stratiform segregration based on
    presence of hail
  • 88D Z/R relationships.
  • Not multi-sensor
  • QPESUMS-II under development at NSSL.

2hr precip accum
19
What do we do with these products?
  • The 3D products are created every 5 minutes
  • 1km resolution (0.01deg x 0.01deg x 1km)
  • Converted to Grib2 and sent to the SPC.
  • Put on the Internet (not all of them)
  • Snapshots with map background
  • Converted to Geotiff
  • Loadable with Google Earth or any GIS software.
  • Google Earth does real-time loading
  • Talk in IIPS on Tuesday
  • http//wdssii.nssl.noaa.gov
  • Looking for the NWS to pick this up!
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