Glossary of Remote Sensing Terminology and Acronyms

Also, check out the University of Nebraska's Glossary

albedo

Same as reflectivity. Expressed as the percent of visible radiation reflected from a surface.

apogee

The point in a satellite's orbit farthest from the Earth.

argument of perigee

Number of degrees from the ascending node where perigee occurs.

ascending node

Intersection of a satellite's orbital plane with the Earth's equatorial plane.

AVHRR

Advanced Very High Resolution Radiometer. Device on board NOAA polar orbiters (part of the TIROS series of satellites) which senses passive radiation emitted from Earth and its atmosphere.

Ground coverage	2700 km
Maximum scan angle	+-55.4 degrees
IFOV	1.39 - 1.51 mrad
Ground resolution (nadir)	1.1 km
Ground resolution	2.4 km along track
(Maximum off-nadir)	6.9 km across track
Channels	(um)
1	0.58 - 0.68
2	0.725 - 1.1
3	3.55 - 3.93
4	10.3 - 11.3
5	11.5 - 12.5
Data precision	10 bits

azimuth

Angle measured in the horizontal plane from true north to target.

blackbody

A perfect radiator and absorber of electromagnetic energy. A blackbody has an emissivity of 1, and its NOAA IR channel temperature will be equivalent to its actual temperature.

DMSP

Defense Meteorological Satellite Program
For more information on the DMSP program, click here.
For more information on DMSP data and sensors, click here.

Doppler effect

If an electromagnetic source moves relative to an observer, there is a shift in the observed frequency. Also known as Red Shift, if the source is receding from the observer, the observed frequency will appear to decrease.

dropout

The loss of data from one or more scan lines.

eccentricity

Description of the shape of a satellite's orbit. A circular orbit has an eccentricity of 0.0, the closer to 1.0 the eccentricity, the more elliptical an orbit is. Most artificial satellite orbits have an eccentricity less than 0.01, essentially circular.

ecliptic

The great circle around the sky on which the sun appears to move through the year as the earth rotates around it. The ecliptic plane is the plane of the earth's orbit. The orbit's of the other planets also lie close to this plane.

emissivity

The ratio of energy emitted by a material to that which would be emitted by a blackbody at the same temperature.

epoch

Year, Month, Day of orbital elements.

equatorial plane

An imaginary plane through the center of the Earth and the Earth's equator.

ERS

European Remote Sensing Satellite

Field of View

Essentially the synthesis of the IFOV from the scanning process of the radiometer.

GAC

Recorded HRPT data at low resolution (4 km).

geostationary orbit

An orbit whose period equals the rotation period of the Earth. Artificial satellites are usually placed in geosynchronous at 35,800km altitude.

GMS

Geostationary Meteorological Satellite

GMT

Greenwich Mean Time, also known as Zulu time, UTC (Coordinated Universal Time), it is the local time at Greenwich Observatory, England (0 degrees longitude).

GOES

Geostationary Operational Environmental Satellite
For more information on GOES click here.

HIRS

High Resolution Infrared Radiation Sounder

HRPT

High Resolution Picture Transmission. A telemetry found on board the NOAA TIROS-N satellites.

IFOV

Instantaneous Field of View. The solid angle through which a detector is sensitive to radiation. It forms one limit to the resolution of an imaging system.

inclination

The angle between the orbit plane and the Earth's equatorial plane, measured counter-clockwise. A zero inclination orbit would mean the satellite is orbiting directly over the equator, an inclination of 90 degrees is a perfectly polar orbit.

LAC

Local Area Coverage, recorded HRPT data (1.1 km).

LANDSAT

Land Remote Sensing Satellite

Inclination of Orbit	98.91 - 99.1 degrees
Satellite Height	916.6 km
Orbits per day	14
Orbital period	103.3 min
Latitudal Coverage	82 N - 82 S
Cycle duration	18 day

luminosity

Total power output of a source of radiation, usually measured in units of the sun's luminosity, which is 4X10^26 Watts.

mean anomaly

Represents the angular distance from the perigee point to the satellites mean position. Measured in degrees along the orbital plane in the direction of motion.

mean motion

Number of complete revolutions the satellite makes in one day.

METEOSAT

Meteorology Satellite

MSS

Multispectral Scanner. Device on board the LANDSAT polar orbiters which senses visible portions of the EM spectrum.

Ground coverage	185 km
Maximum scan angle	+-5.78 degrees
IFOV	0.086 mrad
Ground resolution (nadir)	79 m
Ground resolution	79.5 m along track
(Maximum off-nadir)	80 m across track
Channels	(um)
4	0.5 - 0.6
5	0.5 - 0.7
6	0.7 - 0.8
7	0.8 - 1.0
Data precision	6 or 7 bits

MSU

Microwave Sounding Unit

NOAA

National Oceanic and Atmospheric Administration
For more information on NOAA click here.

nadir

The point on the ground vertically beneath the satellite.

OLS

Operational Line Scanner
For more information on OLS click here.

orbital elements

A collection of quantities that, together, describe the size, shape, and orientation of an orbit.

PDUS

Primary Data User Stations consisting of mainly a ground station and an image processing system.

perigee

The point in a satellite's orbit where it is closest to the Earth.

polar orbit

An orbit whose path crosses the poles.

reflectivity

Same as albedo. Expressed as the percent of visible radiation reflected from a surface.

retrograde

Satellite orbit motion which is opposite to the Earth's direction of rotation, also defined as an orbit with an inclination greater than 90 degrees

right ascension of ascending node

The angular distance from the vernal equinox measured eastward in the equatorial plane to the point of intersection of the orbit plane where the satellite crosses the equatorial plane on the ascending node.

SAR

Synthetic Aperature Radar

SeaWiFS

Sea-viewing Wide Field Sensor
For more information on SeaWiFS, click here.

SPOT

Satellite Pour l'Observation de la Terre

SBUV

Solar Backscattered Ultraviolet system/ Version 2

shimmer

An effect produced by the movement of masses of air with differing refractive indices. Shimmer results in the blurring of remote sensed images, and is the ultimate control over the resolution.

SSIES

Icon Scintillation Monitor on board the DMSP satellites For more information on SSIES click here.

SSM

Magnetometer on board the DMSP satellites.
For more information on SSM Click here.

SSMJ/4

Precipitating Electron and Icon Spectrometer on board the DMSP satellites.
For more information on SSMJ/4 click here.

SSM/I

Special Sensor Microwave Imager on board the DMSP satellites.
For more information on SSM/I click here.

SSM/T1

Special Sensor Microwave Temperature sounder on board the DMSP satellites.
For more information on SSM/T click here.

SSMT/2

Special Sensor Microwave water vapor profiler on board the DMSP satellites.
For more information on SSMT/2 click here.

SST

Sea Surface Temperature

SSU

Stratospheric Sounder Unit

TIROS

Television Infrared Operational System. A series of meteorological satellites put up by NOAA.

Inclination of Orbit	99.092 degrees
Satellite Height	833 km
Orbits per day	14.2
Orbital period	102 min
Latitudal Coverage	90 N - 90 S
Cycle duration	1 day

TM

Thematic Mapper

TOVS

TIROS Operational Vertical Sounder. A device found on TIROS series satellites.

vernal equinox

Point where the sun crosses the Earth's equator going south to north in the northern hemisphere spring.

VISSR

Visible Infrared Spin-Scan Radiometer

WEFAX

Weather Facsimile

This glossary is by no means complete and most definitions are verbatim from the following sources, occasionally altered to fit the context of remote sensing.

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