the sector was generated, such as "D" for Washington,
D.C, or "S" for San Francisco. The next letter indicates
the sector resolution in kilometers, that is A= 1 km, B =
2 km, C = 4 km, and D = 8 km (IR only). The last digit
indicates the identification number of the specific
sector.
GOES TEMPERATURE SCALE
The temperature scale appears only on IR and WV
imagery, and it appears below the legend. The
temperature scale is divided into 10°C increments with
a range from +50°C to -100°C. It has 15 temperature
blocks separated by white or black vertical lines. The
temperature scale is very useful in cloud and non-cloud
identification.
Q25.
Q26.
Q27.
Q28.
Q29.
REVIEW QUESTIONS
What is the purpose of enhancing satellite
imagery?
What is a major disadvantage of providing too
much definition to user-defined enhancement
curves?
Which type of user-defined enhancement curve
applies two complete gray-shade and count
value scales for two separate temperature
ranges?
What is indicated in column 6 of the GOES
legend?
The GOES temperature scale is normally
divided into segments of how many degrees?
METHODS OF ACQUIRING IMAGERY
LEARNING OBJECTIVE: Identify the various
methods used to acquire environmental
satellite imagery.
There are several ways to receive satellite
imagery: weather facsimile broadcast; Navy Ocean-
ographic Data Distribution System (NODDS); GOES
Telecommunications Access Program (GOES-TAP);
satellite direct-readout service; weather facsimile ser-
vice (WEFAX); the Internet; and AUTODIN message.
WEATHER FACSIMILE BROADCAST
Some ships may receive a low quality satellite
image as part of the U.S. Coast Guard facsimile
broadcast. Transmitted via high-frequency (HF) radio,
this broadcast transmits National Weather Service
charts and satellite imagery on a fixed schedule.
Schedules and frequencies for facsimile broadcasts
originating from CONUS stations (San Francisco,
New Orleans, Boston, and Kodiak) are available over
the Internet. Several other countries, such as Japan and
India, also transmit weather charts and satellite
imagery via HF. A listing of all maritime weather
broadcast frequencies is available in the latest edition
of Worldwide Marine Radiofacsimile Broadcast
Schedules published by NOAA.
NAVY OCEANOGRAPHIC DATA
DISTRIBUTION SYSTEM
The Navy Oceanographic Data Distribution
System (NODDS) is a dial-up data service available
from FNMOC. Although originally designed to
transmit graphical data fields for portable computer
systems, selected satellite imagery is now available
within a few hours of sensing. Authorized users may
access the system from anywhere in the world via
computer modem through the U.S. Govemment-
owned Internet routing networks or via direct long-
distance telephone connection on commercial or
Defense Switched Network (DSN) lines. Information
on NODDS satellite imagery is available in the Navy
Oceanographic Data Distribution System Products
Manual.
All of the satellite data available on NODDS is
from DMSP satellites. The pictures that actually
appear on your computer monitor may not be quite as
clear as imagery from other sources. The imagery is
considered near real-time in that it is available to the
user usually within a few hours of sensing. The DMSP
satellites collect imagery, store the information as
digital data aboard the satellite, and then dump the
imagery data on command as it comes within range of a
receiver site capable of copying high-resolution
imagery. DMSP imagery for specific, high-interest
areas around the world may be requested from
FNMOC after some coordination.
GOES TELECOMMUNICATIONS ACCESS
PROGRAM (GOES-TAP)
Ashore, Navy and Marine Corps weather stations
receive satellite imagery primarily from the GOES-
TAP service. The GOES-TAP service is operated by
NESDIS, and satellite images are provided via
dedicated telephone circuits. The circuits are leased
from commercial telephone companies and are
maintained by the telephone companies that own them.
Routine satellite images are transmitted at 15-minute
intervals. The imagery is normally displayed on a
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