Archivos de la categoría: Geographic Information Science

Article: Temporal evolution of vegetation activity by multitemporal Landsat imagery

We analyzed the temporal evolution of vegetation activity on various land cover classes in the Spanish Pyrenees for the period 1984 to 2007. Two time series of the normalized difference vegetation index (NDVI) were used, corresponding to March (early spring) and August (end of summer). The series were generated from Landsat TM and Landsat ETM+ images, […]

Article: The extreme winter of 2010 over the Iberian Peninsula

The winter of 2010 registered the most extreme negative value of the North Atlantic Oscillation (NAO) index since the beginning of systematic instrumental records. The anomalous pressure gradient in the North Atlantic region steered a large number of low pressure systems via an unusually southern path, directly influencing Iberia and northern Africa. Large areas of Iberia-especially […]

SPEIbase, among the most downloaded items of digital.CSIC in 2010

The SPEIbase was one of the most downloaded items of digital.CSIC in 2010 in various formats. The raw version of the data base was the second absolute item with 13021 downloads since March 2010, while the plain text version was third with 11626 downloads. The netCDF version ranked 13th with 4012 downloads. Digital.CSIC is the […]

Generating spatially correlated random fields with R

In several occasions I needed to generate synthetic data with a desired level of spatial autocorrelation. Here I will show how to generate as many such fields as we need by using R, an open-source port of the S language for statical analysis. I will concentrate on two alternative ways of generating spatially correlated random fields (commonly known as unconditional […]