ENVISAT

Introduction

An ARIANE 5 rocket launched the ENVISAT satellite on the 1st March, 2002 at 02:07:59 (CET) hrs. The satellite follows in the footsteps of ERS 1 and 2 in its mission to provide support for research into global warming and climate change and in pollution and disaster monitoring. It provides complete coverage of the earth within one to three days. Its nine instruments deliver data about the Earth's land, oceans, atmosphere and ice caps.

For the latest information see http://envisat.esa.int/.

Fig. 1 ENVISAT instruments

Platform Parameters

Instruments

The ENVISAT instruments are as follows:

• AATSR
• ASAR
• DORIS
• GOMOS
• MERIS
• MIPAS
• MWR
• RA-2
• SCIAMACHY

Note: The LRR (Laser Retro-Reflector) is not regarded as an ENVISAT instrument

AATSR

The Advanced Along Track Scanning Radiometer (AATSR) continues the ATSR-1 and ATSR-2 mission data sets of precise sea surface temperature (SST), thereby ensuring the production of a 10 year near-continuous data set from the ERS-1 and ERS-2 missions at the levels of accuracy of 0.3 K or better for climate research. AATSR has the same signal channels and embodies exactly the same viewing principle as ATSR-2. These are: thermal channels at 3.7, 10.8, and 12 microns wavelength; and reflected visible/near infrared channels at 0.555, 0.659, 0.865, and 1.61 microns wavelength.

For more details about AATSR see the AATSR fact sheet and http://envisat.esa.int/instruments/tour-index/aatsr/.

GOMOS

As one of the atmospheric instruments on ENVISAT-1, the Global Ozone Monitoring by Occultation of Stars (GOMOS) will complement information obtained with MIPAS and SCIAMACHY. It provides altitude-resolved global ozone mapping and trend monitoring with very high accuracy for the improved understanding of ozone chemistry and for model validation.

The primary GOMOS mission objectives are the measurement of profiles of ozone, NO2, NO3, OClO, temperature, and water vapour; the day-night-side measurement capability; global coverage with typically over 600 profile measurements per day; altitude measurement capability between the tropopause and 100 km; and altitude resolution of better than 1.7 km.

For more details about GOMOS see the http://envisat.esa.int/instruments/tour-index/gomos/

MERIS

The Medium Resolution Imaging Spectrometer (MERIS) is a 68.5° field-of-view "pushbroom" imaging spectrometer that measures the solar radiation reflected by the Earth, at a ground spatial resolution of 300m, in 15 spectral bands, programmable in width and position, in the visible and near infra-red. MERIS allows global coverage of the Earth in 3 days.

Measurement of sea colour in the oceans and in coastal areas can be converted into a measurement of chlorophyll pigment concentration, suspended sediment concentration and of aerosol loads over the marine domain. This provides information about the ocean carbon cycle, the thermal regime of the upper ocean, the management of fisheries and the management of coastal zones

For more details see the MERIS fact sheet and: http://envisat.esa.int/instruments/tour-index/meris/

MIPAS

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is a Fourier transform spectrometer for the measurement of high-resolution gaseous emission spectra at the Earth's limb. It operates in the near to mid infrared where many of the atmospheric trace gases playing a major role in atmospheric chemistry have important emission features.

The objectives of MIPAS are simultaneous and global measurements of geophysical parameters in the middle atmosphere ; stratospheric chemistry (O3, H2O, CH4, N2O and HNO3) and climatology (temperature, CH4, N2O, O3) ; study of chemical composition, dynamics and radiation budget of the middle atmosphere and monitoring of stratospheric O3 and CFC's.

For further details see the MIPAS fact sheet and: http://envisat.esa.int/instruments/tour-index/mipas/.

SCIAMACHY

The SCanning Imaging Absorption Spectrometer for Atmospheric CHartograpY (SCIAMACHY) is an advanced, expanded version of GOME, which has been flying on ERS-1 since 1995. SCIAMACHY measures transmitted, backscattered and reflected radiances from the atmosphere at high resolution (240 to 1700 nm, 2 microns and 2.4 microns). The instrument makes limb and nadir observations that can be combined.

Its main objective is to provide global measurements of trace gases in the troposphere and the stratosphere.

For further details see the SCIAMACHY fact sheet and: http://envisat.esa.int/instruments/sciamachy/.

MWR

The primary mission of the MicroWave Radiometer (MWR) is the measurement of the integrated atmospheric water vapour column and cloud liquid water content, as correction terms for the radar altimeter signal. In addition, MWR measurement data are useful for the determination of surface emissivness and soil moisture over land, for surface energy budget investigations to support atmospheric studies, and for ice characterization.

For further details see http://envisat.esa.int/instruments/tour-index/mwr/.

ASAR

The Advanced Synthetic Aperture Radar (ASAR), operating at C-band ASAR ensures continuity with the image mode (SAR) and the wave mode of the ERS-1 and ERS- 2 AMI (Active Microwave Instrumentation). It features enhanced capability in terms of coverage, range of incidence angles, polarisation, and modes of operation. This enhanced capability is provided by significant differences in the instrument design: a full active array antenna equipped with distributed transmit/receive modules that provides distinct transmit and receive beams, a digital waveform generation for pulse "chirp" generation, a block adaptive unitisation scheme, and a ScanSAR mode of operation by beam scanning in elevation.

For further information see http://envisat.esa.int/instruments/tour-index/asar/.

DORIS

The Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) instrument is a tracking system providing range-rate measurements of signals from a network of ground-based beacons. The ground processing of these data describe the satellite orbit to an accuracy of a few centimetres and on board processing provides real time satellite positions with an accuracy of tens of centimetres.

This data also helps the understanding of Earth dynamics, the monitoring of glaciers, landslides and volcanoes, and the modelling of the Earth's gravity field and of the ionosphere.

For further details see http://envisat.esa.int/instruments/tour-index/doris/

RA-2

The Radar Altimeter 2 (RA-2) is an instrument for determining the two-way delay of the radar echo from the Earth's surface with the very high precision of less than a nanosecond. It also measures the power and the shape of the reflected radar pulses.

Operating over oceans, its measurements are used to determine the ocean topography, thus supporting the research of ocean circulation, bathymetry and marine geoid characteristics. Furthermore, the RA-2 is able to map and monitor sea ice, polar ice sheets, and most land surfaces. Measurement of the radar echo power and shape enable the determination of winds speed and significant wave height at sea, thus supporting weather and sea state forecasting.

For further details see http://envisat.esa.int/instruments/tour-index/ra2/

Data availability

ESA

For information on ENVISAT data products and availability, see http://envisat.esa.int/dataproducts/.

NEODC/BADC

Data from MERIS, MIPAS, GOMOS and SCIAMACHY are available from the NEODC to registered users

Further Information

ENVISAT on the web

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