ACRONYMS AND ABBREVIATIONS

a b c d e f g h i j k l m n o p q r s t u v w x y z

A

AATSR

Advanced Along-Track Scanning Radiometer; this instrument is in fact the same design as the ATSR-2 flying on ERS-2. It has four infrared channels and three visible channels. The swath, centered on the subsatellite ground track, is imaged under two different incidence angles in both spectral bands.

ACF

Auto-Correlation Function

A/D

Analogue / Digital

ADC

Analogue / Digital Converter

ADEOS

Advanced Earth Observation Satellite

ADS

Annotation Data Set

ADSR

Annotation Data Set Record

AMF

Air Mass Factor; a parameter which allows the transformation from slant column densities to cloumn densities along the line of sight.

AMI

Active Microwave Instrument, a part of ERS-1 and ERS-2 payload, incorporating image (SAR), wind (scatterometer), and wave (imagette) modes.

ANC

Ascending Node Crossing, the point in the orbit path of a satellite, where the orbit crosses the equator and the spacecraft moves from South to North.

AO

Announcement of Opportunity; the call for proposals to utilize a satellite mission. Utilization can mean data exploitation but also the opportunity to provide payloads.

AOCS

Attitude and Orbit Control; an important and complex subsystem of the satellite, providing measurement of the attitude in nominal and anomalous situations, and a range of actuators to modify attitude and attitude rates. It also provides the thrusters needed for orbit control and maintenance.

AOI

Announcement of Opportunity Instrument. These instruments are developed independently of ESA, under national funding. They have been selected following an Announcement of Opportunity, one of the selection criteria being the extent to which the AOI would enhance the overall measurement system.

ASAR

Advanced Synthetic Aperture Radar

Astrium

ESA partners for the Envisat satellite, see; http://www.astrium-space.com http://www.astrium-envisat.de

ATBD

Algorithm Theoretical Basis Document

ATSR

Along Track Scanning Radiometer

AVHRR

Advanced Very High Resloution Radiometer

B

BIH

Bureau International de l'Heure

BRDF

Solid State Recorder

C

CCD

Charge Coupled Device, an integrating optical detector in the near infrared, visible and ultraviolet region

CCT

Computer Compatible Tape

CEOS

Committee on Earth Observation Satellites

CFRP

Carbon Fibre Reinforced Plastic, a very stiff, and lightweight material with negligible thermal expansion coefficient

CIS

Conventional Inertial System

CTS

Conventional Terrestrial System

CZCS

Coastal Zone Colour Scanner

D

DBU

Digital Bus Unit, which provides the electrical interface between the signals on the OBDH bus and terminal equipment such as ICU's.

Dobson units

Dobson Units (DU) are used to measure atmospheric trace gases such as ozone. If you took all the molecules of ozone from a column of air, and compressed these molecules to the base of the column itself at STP (0oC and 1 atm), they would form a slab. One DU is defined to be 0.01 mm thickness of this slab. In the case of ozone, 1 DU corresponds to 2.69x1016 molecules per square centimeter of column base. See an example.

DORIS

Envisat Instrument for Doppler Orbitography and Radiopositioning Integrated by Satellite

DSB

DSR

Data Set Record

E

ECMWF

European Centre for Medium-Range Weather Forecasts

EDI

ESA Developed Instrument. Such instruments are part of the Envisat industrial contract and are developed under full ESA responsibility

EM

Engineering Model

EMC

Electro-Magnetic compatibility

ENVISAT

ENVIronment SATellite

ERS

European Remote Sensing Satellite

ESA

European Space Agency

ESL

Expert Support Laboratory. The algorithms for Level 2 data processing comprise the retrieval of geophysical parameters from Level 1b (engineering) products. This step relies strongly on scientific inputs (e.g. methods for determing gas densities for atmospheric measurements) to be provided by scientific experts, i.e. the algorithms used in the operational processors are based on expert investigations. The Expert Support Laboratories are the formal implementation of this philosophy.

F

FD

Fast Delivery

FDGDR

Fast Delivery Geophysical Data Record, the standard RA GDR data product, available in slightly reduced quality within a few hours of measurement.

FFT

Fast Fourier Transform

FM

Frequency Modulated (eo) or Flight Model (envisat) ?????

FOCC

Flight Operations Control Centre, located at ESOC Darmstadt

FOS

Flight Operation Segment, composed of the Flight Operations Control Centre located at ESOC, Darmstadt and the associated command and control stations. It provides control of the satellite through all mission phases.

FR

Full Resolution

G

GCP

Ground Control Points

GDR

Geophysical Data Record; the basic Level 2 product of RA-2.

GEM

Goddard Earth Model

GLI

GOME

Global Ozone Monitoring Experiment

GOMOS

Global Ozone Measurement by the Occultation of Stars

GRS1984

Geodetic Reference System 1984

GSE

Ground Support Equipment

H

HDDT

High Density Digital Tape

HLOP

High Level Operation Plan

HSM

High Speed Multiplexer, which assembles the payload science data into a continuous data stream

I

I

In-phase

ICU

Instrument Control Unit, a part of the distributed command and control function implemented on ESA spacecraft. The unit receives, decodes and executes high-level commands for its instrument, and autonomously performs health-checking and parameter monitoring. In the event of anomalies it takes autonomous recovery actions.

IFOV

Instantaneous Field of View

IGBP

International Geosphere-Biosphere Programme

IGDR

Interim Geophysical Data Record; the basic Level 2 product of RA-2. The term Interim refers to the fact that it is generated very soon after data acquisition so interim values of some parameters, such as the orbit, must be used until the full-precision values become available. Otherwise the product is identical to the GDR.

IJRS

International Journal of Remote Sensing

ILRS

International Laser Ranging Service. A service which collects data from a world-wide network of ground-based laser ranging stations, in order to provide satellite tracking and orbit determination. See LRR.

IRS

ISCCP

International Satellite Cloud Climatology Project

ISLR

Integrated Side Lobe Ratio

L

LBR

Low Bit Rate

LEOP

Launch and Early Orbit Phase, the critical first few orbits where appendage deployments are performed and the satellite is brought into a stable configuration.

LRAC

Low Rate Reference Archive Centre, colocated with the Payload Data Handling Station in Kiruna. Its primary goal is to maintain a Level 0 reference archive for all Low Rate instruments for the lifetime of the mission.

LRR

Laser Retro-Reflector. A passive device which is used as a reflector by ground-based satellite ranging stations.

M

MDS

Measurement Data Set, a defined data entity within a product.

MERIS

Medium Resolution Imaging Spectrometer

MGVI

Meris Global Vegetation Index

MIPAS

Michelson Interferometer for Passive Atmospheric Sounding

MLST

Mean Local Solar Time, which in the context used here refers to the descending node of the sun-synchronous orbit. The true local solar time of the descending node varies by up to 15 minutes around this value due to the eccentricity of the earths orbit around the sun, which induces an uneven angular velocity around the sun, while th eorbital precession rate is constant. This effect is known as the equation of time.

MPH

Main Product Header, the main description record at the start of every product, it follows a generic format.

MPP

Milestone Payment Plan.

MWR

MicroWave Radiometer

MWS

MicroWave Radiometer (sometimes referred to as MicroWave Sounder)

N

NASA

National Aeronautics and Space Administration

NMSF

Net Multiplicative Scaling Factor

NRT

Near Real Time

N/S

North / South

O

OBDH

On-Board Data Handling, this term is used in the context OBDH Bus, which is a synchronous serial data exchange and time-management network used on-board ESA spacecraft.

OBRC

On Board Range Compression

OCI

OCM

OCTS

Ocean Colour and Temperature Scanner

OGRC

On Ground Range Compression

OSMI

P

PAC

Processing and Archiving Centre; a concept which evolved from the PAF's of the ERS era. Their development and implementation is funded on a national basis while the operation for the services defined in the Payload Data Segment concept is provided by ESA.

PAF

Processing and Archiving Facility of the ERS-1/2 mission. Four PAFs are operational. These are the D-PAF (located at the German Remote Sensing Data Centre (DFD) at the DLR premises at Oberpfaffenhofen/Germany), the F-PAF at IFREMER (Brest/France), the I-PAF in Matera/Italy and the UK-PAF in Farnborough/UK.

PAR

Photosynthetically Active Radiation

PCD

Product Confidence Data, a coded set of quality flags generated at various stages of data processing.

PDHS

Payload Data Segment, comprises all those elements which are related to payload data acquisition, processing, archiving and those concerning the user interfaces and services.

PDS

Payload Data Segment, comprises all those elements which are related to payload data acquisition, processing, archiving and those concerning the user interfaces and services.

PEB

Payload Equipment Bay, part of the Payload Module of the Polar Platform.

PLC

Payload Carrier, part of the Payload Module of the Polar Platform.

PLM

Payload Module, the part of the Polar Platform which is mission-specific.

PMC

Payload Management Computer, located in the Payload Module, is responsible for command and control of the payload. It communicates with the on-board computer in the Service Module.

POLDER

Polarization and Directionality of the Earth's Reflectances

PPF

Polar Platform, a multimission spacecraft designed to accomadate large payloads in a sun-synchronous low earth orbit.

PPTL

Processor Point Target Linearity

PRARE

Precise Range and Range-rate Equipment

PRF

Pulse Repetition Frequency, the rate at which (typically) a radar emits transmit pulses.

PRI

Pulse Repetition Interval, the interval between radar pulses.

Q

Q

Quadrature

QA

Quality Assurance

Q/L

Quick-look

R

RA

Radar Altimeter

RA-2

Radar Altimeter-2

RAC

Reflective Acoustic Coupling; a type of surface acoustic wave device in which the acoustic signal undergoes a reflection.

RMS

Root Mean Square

RS

RTU

Remote Terminal Unit, a semi-intelligent device which is linked to the PMC by the OBDH bus and which proveides control and monitoring functions for relatively simple equipment such as power distribution units.

S

SAG

Science Advisary Group

SAGE I/II

Stratospheric Aerosol and Gas Experiment I and II

SAR

Synthetic Aperture Radar

SAW

Surface Acoustic Wave, refers to a device in which acoustic waves propagating on the surface of a piezo-electric crystal transfer a signal between two transducers. Extensively used for delay lines, both dispersive and non-dispersive.

SBUV

Solar Backscatter Ultraviolet, flown on ??

S/C

Spacecraft

SCATT

Scatterometer

SCIAMACHY

Scanning Imaging Absorption Spectrometer for Atmospheric Cartography

SeaWiFS

Sea-Viewing Wide -Field-of-View Sensor

SLR

Satellite Laser Ranging station.

SPH

Secondary Product Header.

SSH

Sea Surface Height

StM

Structural Model

STP

Standart Temperature (0oC) and Pressure (1 atm)

T

TBC

To Be Confirmed

TDT

Terrestrial Dynamic Time

TM

Telemetry

TOA

Top of Atmosphere

TOMS

Total Ozone Mapping Spectrometer, flown on Nimbus-7 and operational in 1978 - 1988.

TT&C

Tracking, Telemetry and Control, a term used to refer to the ground stations used in the day-to-day monitoring and control of a satellite. In the case of Envisat this function is performed by conventional S-band low-rate lnks to a ground station located in Kiruna.

TWT

Travelling Wave Tube, a microwave amplification device, which works by transferring energy from an electron beam to a wave propagating in a helix structure within the tube.

U

UET

User Earth Terminal

UNCFCCC

United Nation Framework Convention on Climate Change

UPS

Universal Polar Stereographic

USO

Ultra Stable Oscillator. an oscillator with a long term frequency stability of the order 10^8.

UTC

Universal Time Coordinate (eo) or Universal Time Corrected. (envisat) ????

UTM

Universe Transverse Mercator

W

WRS

World Reference System

WS

Wind Scatterometer

WSC

Wind Scatterometer

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry