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NOUS41 KWBC 211636
PNSWSH
Technical Implementation Notice 12-45
National Weather Service Headquarters Washington DC
1236 PM EDT Fri Sep 21 2012
To: Subscribers:
-Family of Services
-NOAA Weather Wire Service
-Emergency Managers Weather Information Network
-NOAAPORT
Other NWS Partners, Users and Employees
From: Timothy McClung
Chief, Science Plans Branch
Office of Science and Technology
Subject: Addition of Alaska Region NPP VIIRS Imagery to NOAAPORT
Test Channel Effective October 2, 2012
On or about Tuesday, October 2, 2012, beginning approximately
1500 Coordinated Universal Time (UTC), high resolution imagery
from the Suomi National Polar-Orbiting Partnership (NPP)
satellite will be broadcast across the NOAAPORT satellite
broadcast network. This addition will consist of a limited set of
NPP Visible Infrared Imaging Radiometer Suite (VIIRS) imagery
covering the Alaska region. The imagery stream will be provided
by the NOAA National Environmental Satellite, Data, and
Information Service (NESDIS) NPP Data Exploitation (NDE) system,
based on NPP VIIRS imagery Environmental Data Records (EDRs).
The new NPP VIIRS imagery products will be transmitted across a
test channel of the NOAAPORT satellite broadcast network.
-Digital Video Broadcast (DVB) packet identifier: 105
-Multicast address: 224.0.1.5
-Port number: 1205
-SBN Data Stream field setting in their frame-level headers: 7
NWS anticipates this NOAAPORT channel will be populated with
additional polar-orbiting satellite imagery. For clarity, this
channel will be referred to as the POLARSAT.
The Alaska region NPP VIIRS imagery will, in general, be within
the following latitude-longitude box:
Lower/Southern Latitude: 45 degrees North
Upper/Northern Latitude: 75 degrees North Left/Western Longitude: 120 degrees East Right/Eastern Longitude: 120 degrees West This initial set of imagery products will be based on three NPP VIIRS I channels, the horizontal resolution of which, at nadir, is approximately 375 meters. The imagery products will be formatted in netCDF4, but compressed via gzip. Like all NOAAPORT products, each file will have a plain text WMO heading at its start. These headings are listed below. TIPB01 KNES - Imagery Channel 1 (0.64?m) TIPB04 KNES - Imagery Channel 4 (3.74?m) TIPB05 KNES - Imagery Channel 5 (11.45?m) The "P" in the third character place of the WMO Heading distinguishes this NPP-VIIRS imagery from pre-existing NOAAPORT satellite imagery.To access these products, users should take the following steps:
-Read beyond or strip off the WMO heading
-Decompress the resulting product, e.g., via gunzip
-Use a netCDF4 reader, e.g., a decoder that invokes the Unidata
netCDF4 software package
Each product will consist of one granule of VIIRS imagery for a
single channel. The VIIRS granules will cover approximately
86 seconds of data, roughly 5 degrees or 556 kilometers of along-
track geographical extent.
Unlike existing NOAAPORT satellite imagery, formatted on
prescribed maps, each NPP VIIRS imagery granule will be uniquely
located. Geolocation information is contained in each product
file. The geolocation information consists of three
1541-dimension arrays of latitude/longitude pairs that correspond
to the granule edge (first column), granule centerline, and
granule edge (last column), with all three arrays oriented along
the satellite track.
Given the fixed resolution and gridded Ground Track Mercator
representation of the VIIRS imagery, only these three columns of
geographical information (latitudes and longitudes) are required
to map the imagery. This reduced geolocation information can be
interpreted based on the VIIRS Ground Track Mercator imagery
algorithm (fine 375 meter resolution version) for accurate
georeferencing. Related information (though not specific to the
NOAAPORT stream of NPP VIIRS imagery) can be found in the
following document: "Joint Polar Satellite System (JPSS)
Operational Algorithm Description (OAD) Document for VIIRS Ground
Track Mercator (GTM) Imagery Environmental Data Record (EDR)
Software," Revision A, January 18, 2012, (e.g., section 2.0.4).
The NOAAPORT feed of NPP VIIRS imagery is provided across a test
channel of the satellite broadcast network. This NOAAPORT channel
is under test and evaluation. Product availability across this
channel is nonetheless expected to approach or meet that of
operational/baseline data (i.e., greater than 95% data
availability). If the experimental period is successful, NWS
intends to transition this NOAAPORT stream to full operational
posture in early 2013.
For questions regarding the scientific or technical content of
the NOAAPORT NPP VIIRS imagery feed please contact:
ESPC Help Desk
Suitland, Maryland 20746
Phone: 301-817-3880
Email: ESPCOperations@xxxxxxxx
For questions regarding the NOAAPORT activation or distribution
of these data sets please contact:
Brian Gockel
NOAA/NWS Office of Science and Technology
Phone: 301-713-0304 x158
Email: Brian.Gockel@xxxxxxxx
NWS Technical Implementation Notices are online at:
http://www.nws.noaa.gov/om/notif.htm
$$
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