ENSO IMPACT ON THE VEGETATION IN MURRAY-DARLING BASIN: A SATELLITE MONITORING FROM 1998-2007 BASED ON SPOT/VEGETATION NDVI TIME SERIES DATA

摘要

The El Niflo Southern Oscillation (ENSO) phenomenon produces an important inter-annual variability of oceanic and atmospheric conditions with irregular periods and amplitudes in many regions of the world. Some research showed that the strongest connections between Southern Oscillation and Australian rainfall occur in northern and eastern Australia, especially in Murray-Darling basin. In the present study, we evaluate the ability of Normalized Difference Vegetation Index (NDVI) to monitor the Murray-Darling Basin vegetation behaviour to ENSO induced precipitation anomalies. 10 year time series of Spot/VEGETATION 1km NDVI imagery product (1998-2007) were collected. We calculate the correlation between NDVI and ENSO quantitative indices like the Southern Oscillation Index (SOI). Although the SOI is only a temporal index, we use it as a general indicator for the water stress probability. In this research, we focus on Murray-Darling Basin, at same time, we choose Murray Irrigation Area as our detail analysis region since where we carry out field experiments every year. According to our results, NDVI presents a good correlation with SOI anomalies at seasonal time scale. On the Murray-Darling Basin scale, we clearly show the geographic patterns of the highest sensitivity to El Nifio or La Nina. We also illustrate the inter-annual variability of these events in term of magnitude and geographic distribution. This variability is clearly explained by precipitation anomalies in relationship with ENSO events.