Chapter 1
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.