nssl :: ondemand


[08/20/2009] Notice: We have discovered that the RotationTracks product has been incomplete from 14 August 2009 until the present time. We should have the data feed corrected shortly. However, we will need to try to backfill the data since 14 August 2009. An update message will be issued when we know more about restoring those data. Again, this affects the RotationTracks product only for the time period 14 August 2009 to 20 August 2009... (klm 1633z)

[04/13/2009] Notice: There appears to be an issue with the interactive preview image on the results page when running under Firefox 3.x. We are looking into this. This does not affect the OnDemand processing, nor the output files. Other web browsers do not appear to have this issue.

Original Notice
This message, posted on 02/24/2009, serves as a notice that we will be restricting access to the OnDemand Severe Weather Verification System (http://ondemand.nssl.noaa.gov) beginning on a transition date of March 31, 2009. Since this experimental site is intended only for non-commercial use, we will be restricting usage of this site to non-commercial users starting on the transition date. Users originating from any .gov, .edu, or .mil domain will have unrestricted access to the system. Users originating from any other domain will be required to register for access, using the registration form: [User Registration], and will be subject to approval by the system administrators.
Registration is now available: User Registration. [Original Notice]

Please feel free to send questions and comments to: ondemandfeedback@noaa.gov.

NSSL On Demand Algorithm Output :: About->Data

Data:

These data are derived from running algorithms developed at NOAA's [noaa.gov] National Severe Storms Laboratory (NSSL) [www.nssl.noaa.gov] on radar from the entire NEXRAD [www.roc.noaa.gov] network. The data from the individual radar sites are first merged to a three-dimensional 'lat/lon/ht' grid and the algorithms are run on this merged data. The resulting output is composited on a 1 km x 1 km lat/lon grid at a height of [x km] above the Earth's surface. The merging of radar data as well as the algorithms run on the data are developed using NSSL's Warning Deceision Support Service - Integrated Information (WDSSII). More information on how these data are collected and processed can be found on the WDSSII [wdssii.nssl.noaa.gov] webpage.

Sample Rotation Tracks Product Sample MESH Product
Rotation Tracks in Central OK from May 3, 1999 MESH Tracks from March 12, 2006
  • velocity data for each radar is run through a Linear Least Squares Derivative (LLSD) filter (Smith and Elmore 2004), creating an azimuthal shear field
  • 0-3 km layer of the azimuthal shear fields from each radar across the CONUS are then combined and the maximum value at each 250 m2 gridpoint accumulated over time and then plotted
  • merging the reflectivity data from all of the CONUS NEXRAD radars to a three dimensional (lat/lon/ht) grid (Lakshmanan et al. 2006b).
  • modified version of the NSSL Hail Detection Algorithm (HDA) (Witt et al. 1998, Stumpf et al. 2004) is then run on this grid producing a MESH grid at 60 second intervals
  • MESH composite grid at 1 km2 horizontal resolution is then accumulated over time in order to create the areal “swaths” of MESH
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