Spatio-temporal dynamics of global precipitation and terrestrial vegetation inferred from satellite and climate records

A key challenge to climate change research is understanding how different components in the Earth system influence one another. For example, it is well known that the Earth's climate system exhibits variability at a wide range of time scales. However, the effect of such variability on terrestrial ecosystems is less well understood. In this dissertation, satellite observations of vegetation activity are used in conjunction with climate records to investigate seasonal-scale interactions between the Earth's terrestrial biosphere, atmosphere, and oceans. The results from this research show that interannual variation in the ocean-atmosphere system result in significant and geographically extensive ecosystem responses.; To characterize spatio-temporal patterns of biospheric activity, multi-decadal (1981--2003) global satellite observations of plant growth were used. Non-linear variance decomposition methods were employed to remove artifacts unrelated to vegetation dynamics and to identify climate-related signatures in the data.; Vegetation growth in arid and semi-arid regions exhibits strong correlation with interannual fluctuations in precipitation, and responds most strongly to time-integrated precipitation anomalies. The climate mechanisms that give rise to observed patterns of precipitation-vegetation covariability are associated with perturbations in ocean-atmosphere circulations. Generally, these perturbations are caused by low frequency fluctuations in global sea surface temperatures, which are propagated to remote locations via changes in atmospheric circulation. The analysis shows that distinct patterns of coupled climate-vegetation activity are linked to well-defined circulation features and illustrates the global extent and sensitivity of ecosystems susceptible to perturbations in precipitation regimes.; Observations of ecosystem dynamics derived from recent satellite data reveal unprecedented reductions in vegetation growth for large areas of the Northern Hemisphere during the boreal summer from 1998--2002. These patterns arise from a geographically extensive and intense drought that persisted in much of the Northern Hemisphere during this period, and are linked to a unique confluence of ocean circulation in the Pacific, Atlantic, and Indo-Pacific ocean basins. This condition resulted in rainfall deficits persisting multiple years in much of North America and Eurasia, with 95% of the continental land area showing below-normal precipitation and vegetation greenness. This episode provides evidence of the nature and magnitude of global vegetation responses to future perturbations in the climate system.