MERIS User Guide
1.1 How to Choose MERIS Data
The data from the MERIS instrument is capable of retrieving a variety of geophysical information. In order to exploit these effectively, it is necessary to understand exactly:
· what variables MERIS measures,
· why the instrument has been designed to operate in the way it does,
· and how these measurements are made and processed into information.
MERIS data also offer a number of unique properties over data from similar imaging instruments which result in advantages which are highlighted in the following sections.
The result of these properties is data suitable for a wide range of potential applications. A summary of products and applications is provided to assist the user in identifying the most suitable product for his or her particular use.
1.1.1 Geophysical Measurements
Figure 1.1 - The electromagnetic spectrum indicating the data set measured by MERIS.
The MEdium Resolution Imaging Spectrometer Instrument
MERIS is a 68.5° field-of-view push-broom imaging spectrometer that measures the solar radiation reflected by the Earth, at a ground spatial resolution of 300 m, in 15 spectral bands, programmable in width and position, in the visible and near infrared wavelengths. MERIS allows global coverage of the Earth in 3 days.
The MERIS Mission
The primary mission of MERIS is the measurement of sea colour in the oceans and in coastal areas. Knowledge of sea colour can be converted into a measurement of chlorophyll pigment concentration, suspended sediment concentration and of atmospheric aerosol loads over water.
Why Measure Ocean Colour?
Four applications of ocean-colour data are:
· understanding the ocean carbon cycle
· understanding the thermal regime of the upper ocean
· the management of fisheries
· the management of coastal zones
· climate studies
· ocean dynamic
For more details see http://www.ioccg.org/
What Else Can MERIS Measure?
MERIS is also capable of estimating:
· cloud type, top height, and albedo
· top and bottom of atmosphere vegetation indices
· photosynthetically available radiation
· surface pressure
· water vapour total column content for all surfaces
· aerosol load over land
· vegetation indices
· Fractional Absorbed Photosynthetically Active Radiation (FAPAR)
These measurements constitute MERIS' secondary mission.