EECS 823
MACHARIA
 Four-frequency, linearly-polarized, passive microwave
radiometric system which measures atmospheric, ocean
and terrain microwave brightness temperatures at 19.35,
22.235, 37.0, and 85.5 GHz. [1]
• The four frequencies are sampled in both horizontal and
vertical polarizations, except the 22.235 GHz which is
sampled in the vertical only.
• It was first commissioned in June 1987 aboard Defense
Meteorological Satellite Program (DMSP) F-8 satellite and
latter flown aboard the following DMSP satellites F-10, F11, F-12, F-13 and F-15.[2]
The scanning multichannel microwave radiometer (SMMR)-the NASA Nimbus -7
satellite for around nine years (1978-1987),the SMMR was a ten channel instrument
and dual polarized
The Special Sensor Microwave Imager / Sounder (SSMIS), is an enhanced elevenchannel, eight-frequency system. launched on Oct 18 2003 aboard the DMSP F-16
satellite and recently flown aboard DMSP F-17 and F-18 satellites.
Its main objective is to support the Department of Defence (DoD) activities but
the data can be released to the scientific community to extract information on
some
global hydrological parameters like water vapour, cloud water and precipitation
It measures ;
•
Atmospheric, ocean, and terrain microwave brightness temperatures
(similar to NIMBUS-7 SMMR) which are converted into environmental
parameters such as: sea surface winds, rain rates, cloud water, precipitation,
soil moisture, ice edge, and ice age.
• Used to obtain synoptic maps of critical atmospheric, oceanographic and
selected land parameters on a global scale
The SSM/I sensor executes a 45º conical scan of the Earth's surface from
nadir. This gives a nominal incidence (zenith) angle of 53.1º to the Earth's
surface from the nominal orbit. Only part of the possible 360º scan in
azimuth is used to collect data. The active azimuth scan angle is 102.4º is
ahead of the S/C for an afternoon ascending orbit and behind the S/C for a
morning ascending orbit.
It rotates continuously about an axis parallel to the local spacecraft vertical at 31.6 rpm
and measures the upwelling scene brightness temperatures over an angular sector of
102.4 deg about the sub-satellite track.
This results in a swath width of approximately 1400 km. The spin rate provides a
period of 1.9 sec during which the spacecraft sub-satellite point travels 12.5 km. Each
scan 128 discrete uniformly spaced radiometric samples are taken at the two 85 GHz
channels and, on alternate scans, 64 discrete samples are taken at the remaining 5
lower frequency channels.
The antenna beam intersects the Earth's surface at an incidence angle of 53.1 deg (as
measured from the local Earth normal
MAIN
REFLECTOR
HOT LOAD
REFERENCE
COLD SKY
REFLECTION
S
COMMANDS
AND TIMING
ANTENNA
FEED
RADIOMETE
R RECEIVER
STRUCTURE
AND
THERMAL
CONTROL
MOMENTUM
COMPENSATIO
N
OLS
DIGITAL
DATA
SUBSYSTEM
DATA
POWER
SUBSYSTEM
POWER
SPACECRAFT
BAPTA
CONTROL
ELECTRONIC
S
BAPTA
TELEMETRY
OFFSET
FEED
MIXER
BP
FILTER
IF
AMP
VIDEO
AMP
ISOLAT
OR
SQUARE
LAW
DETECTOR
INTEGRAT
E
HOLD
DUMP
GAIN
COMMAND
GUNN LOCAL OSC
GAIN SET DECISION
AND REGISTER
SENSITIVITY
-
CALIBRATION
 Hot load target
 Two microwave reference target.
Tb = Tc + (Th – Tc )* (Vb – Vc/Vh – Vc)
Inst Err = Tb - Tvar
APPLICATIONS
 SDR- EDR
REFERENCES
 J. P. Hollinger, J. L. Peirce, G. A. Poe, “SSM/I USER’S
GUIDE “ 14 SEPTEMBER 1987
 Chris Allen “EECS 823 CLASS NOTES” 10 DECEMBER
2014
 https://directory.eoportal.org/web/eoportal/satellitemissions/d/dmsp-block-5d#references