This thesis reports on the design, evaluation and application of a surrogate REP index for use with spectral data recorded at the standard band settings of the Medium Resolution Imaging Spectrometer (MERIS). This index, termed the MERIS terrestrial chlorophyll index (MTCI) uses data in three red and NIR wavebands centred at 681.25 nm, 708.75 nm and 753.75 nm (bands 8, 9 and 10 in the MERIS standard band setting) to locate the relative position of the red edge. The MTCI is easy to calculate and can be automated. Preliminary indirect evaluation using model, field and MERIS data suggested the sensitivity of MTCI to chlorophyll content, notably at high levels and its insensitivity to spatial resolution and atmospheric effects. As a result this index is now an ESA level-2 product. Two data sets were used for direct evaluation of the MTCI-chlorophyll content relationship. First, spectral reflectance and chlorophyll content data for spinach and poplar grown under controlled condition in a greenhouse and second, field data for a number of crops grown in sites in southern Spain. This suggests a stronger MTCI-chlorophyll content relationship than REP-chlorophyll content relationship. Due to lack of spatial and temporal chlorophyll content data from a suitably sized plot at MERIS spatial resolution it was not possible to validate the performance of the index with ground data. However, comparison with other vegetation indices available space-borne sensor suggested higher sensitive of MTCI to change in canopy chlorophyll content. MTCI was used successfully to (i) infer the salt stress in the coastal and near coastal vegetation affected by the 26th December Indian Ocean Tsunami, (ii) monitor the condition of southern Vietnamese forests that had been contaminated by herbicides during the 1960s and 70s and (iii) map landcover in the state of Wisconsin, USA.