Abstract:
AVHRR HRPT level 0 raw telemetry data are acquired at the Arctic and
Antarctic Research Center (AARC) on selective passes by satellite
receivers located at McMurdo Station, Antarctica (77 degrees, 51
minutes S, 166 degrees, 40 minutes E.) and Palmer Station, Antarctic
Peninsula (64 degrees, 46 minutes S, 64 degrees, 4 minutes
... W.)
Generally, most of the Antarctic continent and its coastline are
covered daily. Swaths are 2250 kilometers long and generally start or
end over the extreme South Pacific Ocean adjacent to the Ross Sea.
Data collection from Palmer Station covers the land areas of West
Antarctica, Southern South America, the South Atlantic including the
Falkland Islands and the South Orkney Islands, and the Drake Passage
and portions of the South Pacific Ocean. Continuous data collection at
the McMurdo Station began on 26 October 1987. Data are also archived
for 30 October 1985 - 2 December 1985 and for 30 October 1986 - 30
January 1987. Continuous data collection began at the Palmer Station 3
August 1989.
The data resolution is 1100 meters at subtrack, 4000 - 6000 meters at
limb; 360 scans per minute. Satellite revisit time is twice daily,
however, due to the proximity to the South Pole, 14 passes a day are
received at McMurdo and 10 passes a day are received at Palmer from
each spacecraft.
Data are acquired, archived, processed for requesters, and distributed
by the Arctic & Antarctic Research Center (AARC). Processing of the
raw data will depend on the requirements of the requester, but a
typical sequence might be as follows:
+ Reformat raw data for extraction; up to 10 missing scan lines can be
interpolated by the software.
+ Calibrate the reformatted data to convert from brightness values to
temperature values.
+ Apply the moisture/atmospheric correction.
+ Register selected data to the user-specified grid.
+ Transfer to user-specified medium. Some examples are tape, diskette,
photographic product, or file format for electronic transfer.
About 95 percent of the presently archived data have been cataloged on
our online directory. Data dropouts, caused by transmission
interference due to solar flare activity, occur in some images; the
processing software can smooth the data if fewer than 10 scan lines
are missing. All archived images contain usable data.
Processed data are binary byte arrays of user-defined size. Full
spacecraft attitude correction and earth correction routines are
applied to the raw data to create the products. Orbital elements,
equator crossings, altitude and period of the spacecraft are generated
for the raw data using the AARC scientific workstation. Data products
can be gridded to a user-specified grid.
Data are also available in raw form (10 bits of information stored in
a 16 bit word) on 4mm DDS2 or DDS3 DAT cassettes or DLT7000 tapes.
Users would need access to an 4mm DAT or DLT7000 reader. An
alternative method to access the digital archive is to use the Sun
Workstations located at the AARC, Scripps Institution of Oceanography.
AARC personnel can be contacted for access information. 
