Hurricane Example: Level-III Data

Hurricane Lili, Oct. 2, 2002
Image courtesy Jacques Descloitres,
MODIS Land Rapid Response Team at NASA GSFC

How can the Java NEXRAD Viewer be used to view or identify a hurricane? What type of data is needed? What does a hurricane look like on radar?

These are some of the things that will be covered in this tutorial.

Jump to a section:: Data; Alphanumeric Properties; Backgrounds; What a Hurricane Looks Like on Radar

Data

The first step in any NEXRAD project is ordering and obtaining data. By default, the NEXRAD Data Selector window opens when the Viewer is first opened. If you already have saved data, you can load it now. If you wish to order data, choose Order NEXRAD from the Data menu.

Hurricane Charley, Florida
August 13, 2004

Useful data for hurricanes:

Level-III: Base Reflectivity: N0R, N1R, N2R, N3R
Level-III: Composite Reflectivity: NCR, NCZ
Level-III: Storm Relative Velocity: N0S, N1S, N2S, N3S
Level-III: Digital Precipitation Array: DPA
Level-III: One Hour Precipitation Total: N1P
Level-III: Storm Total Precipitation: NTP
Level-III: Storm Structure*: NSS

* Alphanumeric Products

For more information on radar products, please visit the NEXRAD Level-III Products page.

Alphanumeric Properties

There are a number of alphanumeric Level-III data products. Some are geographic and some are not. Those recommended above have geographic components and can be plotted on the map.

Storm Structure (NSS)

The display can be enhanced by choosing custom items through Overlay Selector and WMS (see the basics tutorial or the help files for more details).

Alphanumeric Display w/ background

KTBW NSS with Base Reflectivity Background

You can also access more options by choosing Alphanumeric Properties from the View menu. Symbol and color for the markers can be changed, as with other viewer options. The attributes table can be accessed through the Alphanumeric Properites window by choosing Show Attribute Table. Specific information about each point can be found here.

The supplemental data buttons will also bring up windows with additional information, based upon the specific product selected:

NSS Supplemental Data 1

Backgrounds

The Alphanumeric properties window is also where you can add a radar image background and set the transparency (via the WMS options). If you have multiple radar products in the same directory, the viewer will automatically display the possible backgrounds for your image (note that the Alphanumeric Properties window displayed above has eight possible images: N0R, N0S, N0V, NTP, NSW, DPA, NCZ, and N0Z).

KTBW NST with Digital Precip Array background

What a Hurricane Looks Like on Radar

What is the radar signature of a hurricane? The images above and below depict Hurricane Charley, which touched down on the Florida coast Friday, August 13, 2004. Reflectivity data for hurricanes will show the characteristic CCW swirl (northern hemisphere) of moisture. The Digital Precipitation Array (DPA) data (and possibly the 1- and 3-hour precipitation products, N1P and N3P, as well as the Storm Total Precipitation product, NTP) will show clusters of heavy precipitation from storm cells within the feeder bands. The Storm Relative Velocity (N0S) will show strong winds with rotation evident in the contrasting positive and negative velocities in close proximity.

KTBW N0R with annotations
(Click for larger view)

Manually composed (outside the Viewer) composite of N0V and N0S:

KTBW Base Velocity, Storm Relative Velocity Superimposed
(Click to enlarge)

This image illustrates the difference between Storm Relative Velocity (N0S) and Base Velocity (N0V). Base Velocity is shown with N0S superimposed (dashed lines). Storm Relative Velocity subtracts out the translational movement, leaving a more accurate view of the rotational velocity with respect to the radar tower.

More information about this event can be found at: