Map Viewer
Data & Products
Missions & Sensors
AATSR
ACE
AIRS
AMSR
AMSU
ATMOS
ATOVS/TOVS
AVHRR
AVHRR3
CALIPSO
CRISTA
GOME
GOME-2
GOMOS
HALOE
HIRDLS
IASI
MAS
MERIS
MHS
MIPAS
MISR
MLS
MODIS
MOPITT
OMI
OSIRIS
POAM
SABER
SAGE
SBUV
SCIAMACHY
SEVIRI
TES
TMI
TOMS
VIRS
WINDII
About WDC
User Account
Contact

NDMC
WDC Home









Local Weather
Oberpfaffenhofen

Introduction

The Medium Resolution Imaging Spectrometer (MERIS) forms part of the core instrument payload of ESA's environmental research satellite ENVISAT-1. MERIS is funded by ESA. The demands of the European scientific community for a global environmental monitoring system, whose technical characteristics enable the extraction of quantitative information from ocean colour data, as well as for documentation of the state and evolution of the atmosphere and land surfaces, led to the conception of MERIS.

Objective

The oceanographic mission is radiometrically the most demanding in terms of low radiance levels and their associated high signal-to noise ratios. Therefore, the instrument must be capable of detecting the low levels of radiation emerging from the ocean (linked to the water constituents by the processes of absorption and scattering). But at the same time, for the acquisition of e.g. cloud and land information, the instrument must have a high dynamic range in order to detect bright objects. The characteristics of MERIS are also of great value for the retrieval of information on land surfaces, in particular that of global biomass.

Instrument

MERIS is a wide field-of-view pushbroom imaging spectrometer with a swath width of 1150km (field-of-view (FOV) = 68.5°) measuring the solar radiation reflected by the Earth in 15 spectral bands from about 412.5nm to 900nm (ESA 1996, http://envisat.esa.int/instruments/meris/). All bands are programmable in width (variable between 1.25 and 30 nm) and position, but are fixed before launch in response to the recommendations of the Science Advisory Group (SAG) for the main period of the mission (see Table 1).

The most crucial requirements for MERIS is the radiometric performance because signals coming from the ocean are weak while signals emanating from clouds or land surfaces are strong. A radiometric resolution of 0.03 mWm-2sr-1nm-1 is required to discriminate a pigment concentration of 1mg/m3 . For ocean applications a total signal of about 50 mWm-2sr-1nm-1 (including the atmosphere) is expected at the sensor at a solar zenith angle of 40° from the sub-satellite point around 450nm assuming low chlorophyll concentrations. This requires a dynamic range of more than 3 magnitudes. Taking into account that MERIS is designed to monitor all targets on Earth a much higher dynamic range is required and realised.
MERIS allows global coverage of the Earth in 3 days. ENVISAT flies on a sun-synchronous orbit with a mean altitude of 799,8km and an inclination of 98,55°. The orbit time is 100,6 minutes with a repeat cycle of 35 days.

Each MERIS pixel has a field of view of 0.019°. Due to the wide instrument field of view (68.5°), spatial sampling varies in the across track direction, between 0.26 km at nadir and 0.39 km at swath extremities. Along-track sampling is close to 0.29 km.

MERIS
Channel Number
Centre Wavelength ±
Bandwidth (nm)
Application
1 412.5 ± 10 Yellow substance and detrial pigments
2 442.5 ± 10 Chlorophyll absorption maximum
3 490 ± 10 Chloropyll and other pigments
4 510 ± 10 Suspended sediment, red tides
5 560 ± 10 Chlorophyll absorption minimum
6 620± 10 Suspended sediment
7 665± 10 Chlorophyll absorption and fluorescence reference
8 681.25 ± 7.5 Chlorophyll fluorescence peak
9 708.75 ± 10 Fluorescence reference, atmospheric corrections
10 753.75 ± 7.5 Vegetation, cloud
11 760.625 ± 3.75 Oxygen absorption R-branch
12 778.75 ± 15 Atmosphere corrections
13 865 ± 20 Vegetation, water vapour reference
14 885 ± 10 Atmosphere corrections
15 900 ± 10 Water vapour, land

Table 1: Specification of the 15 MERIS channels recommended by the Science Advisory Group (SAG)

MERIS has the capability to output data sampled at the Full Resolution (FR) with the spatial sampling described above, and Reduced Resolution (RR) data sub-sampled at 1.2 km.

Data Access

EOWEB

For more information on value-added products, please see the MAPP - Algorithm Theoretical Basis Document (PDF, 16MB) or visit the MERIS Application and Regional Products Project (MAPP) website.

"Quicklook" images of the most recently acquired MERIS images are currently available on-line. Please click here to view them and get more information on the MERIS data received and processed by DLR-DFD.

ENVISAT Platform

ENVIronment SATellite (launched March 2002).

Envisat, an advanced polar-orbiting Earth observation satellite, provides measurements of the atmosphere, ocean, land, and ice. Instruments include MERIS, AATSR, MWR, GOMOS, MIPAS and SCIAMACHY.

The Envisat satellite has an ambitious and innovative payload that will ensure the continuity of the data measurements of the ESA ERS-1 and ERS-2 satellites. Envisat data supports earth science research and allows monitoring of the evolution of environmental and climatic changes. (http://envisat.esa.int/m-s/).

Links

  • MERIS capabilities, spectral properties, and parameters can be found on the ESA MERIS Website.
  • Description and characteristics of other ENVISAT instruments can be found on the ESA ENVISAT Website.
  • The MERIS data sheet.
  • ESA: Meris Algorithm Theoretical Basis Documents data sheet.

Contact

If you would like to know more about the MERIS instrument or especially the MERIS data available now and in the near future at WDC-RSAT, please contact: wdc@dlr.de.