By Diana Torres
Abstract:
Nowadays, Climate Change is a subject that is being extensively studied, not only the average surface temperature has changed, increasing over the 20th century by about 0.6 ± 0.2˚C (Dose et al., 2004); but as Salinger (2005) says, at the same time there will be changes in precipitation, and climate extremes such as hot days, also heavy rainfall and drought are expected to increase in many areas.
Menzel et al. (2003) highlights the importance of monitoring Phenology changes in order to assess climate change. Changes in greenness and phenology over large areas have been detected using remote sensing techniques (Zhou et al., 2003, Botta et al., 2000, Duchemin et al., 1999).
The present study made use of The Global Inventory Modelling and Mapping Studies (GIMMS) normalized difference vegetation index (NDVI) data sets, that were generated to provide a 22-year satellite record of monthly changes in terrestrial vegetation (GIMMS documentation, 2003). The HANTS Algorithm (Harmonic Analysis of NDVI Time Series) was used to study changes in phenology along the available images.
Climate data was also used to validate the results obtained with HANTS.