ENSO Effects on Land Surface-Biosphere-Atmosphere Interactions: A Global Study from Satellite Remote Sensing and NCEP/NCAR Reanalysis Data

Two mechanisms are examined to reveal the impact of El Niño-Southern Oscillation (ENSO) on land surface, biosphere, and atmosphere interactions. One mechanism is large-scale dynamics--namely, changes in circulation patterns and the jet stream. Another mechanism is local land cover effects, in particular, vegetation and skin temperature. Non-lag and lag correlation coefficients between Niño 3 indices derived from sea-surface temperature (SST) anomalies and land surface variables from satellite based moderate resolution imaging spectroradiometer (MODIS) data, as well as National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis data are analyzed for 2001-2010. Strong positive correlations between January Niño 3 indices and both air temperature (Tair) skin temperature (Tskin) occur over the northwest United States, western Canada, and southern Alaska, suggesting that an El Niño event is associated with warmer winter temperatures over these regions, consistent with previous studies. In addition, strong negative correlations exist over central and northern Europe in January, meaning colder than normal winters, with positive correlations over central Siberia meaning warmer than normal winters. Despite the different physical meanings between Tair and Tskin, the general response to ENSO is the same. Furthermore, satellite observations of Tskin provide more rich information and higher spatial resolution than NCEP/NCAR Reanalysis data