Archive for the ‘Climate’ Category
Large-scale vegetation-rainfall correlations in Africa
Weather and climatic variability affect vegetation on continental scales. Intuitively, healthy vegetation is greener. A quantitative index of “greenness” called Normalised Difference Vegetation Index (NDVI) was developed by NASA.В The index takes values between 0 and 1. NDVI is related to the fraction of photosynthetically active radiation absorbed by the vegetation canopy. It is a [...]
May 12, 2010
Tags: Africa, Drought, NDVI Posted in: Climate, ecosystem model 
4 Comments
Visualizing Drought
The impacts of drought depend on time-scale. On short time-scales, drought means dry soil. On long time-scales, it means dry rivers and empty reservoirs. A region may simultaneously experience dry conditions on one time-scale and wet conditions on another e.g. wet soil but low streamflow or visa versa. Standardized Precipitation Index (SPI) is a widely [...]
March 6, 2010
Tags: R, time-series, water stress Posted in: Climate 5 Comments
