Link Between CERES Radiative Energy Flux and Southern Hemisphere Jet Stream Variability

As the global temperature increases, there are numerous effects on global circulation, including changes in the spatial pattern of clouds, radiative energy flux, and the location of the jet stream. Using 300-hPa zonal wind and Clouds and the Earth’s Radiative Energy System (CERES) observations of top-of-the-atmosphere radiative energy flux data, this study explores the lead-lag relationship between the poleward shift in the jet stream for the austral summers from 2001 through 2014. Composite analysis of daily data indicates that the poleward jet shift leads 2 to 6 days. To determine whether there is a statistically significant relationship this study uses composite analysis with a Monte Carlo significance test. Additionally, this study uses individual layers of clouds, separating high, medium, and low cloud cover to assist in interpreting the short and longwave radiation cloud forcing patterns, therefore supporting the evidence of the jet-radiative energy flux relationship. Latitude-time evolution patterns of low-level clouds correspond to shortwave radiative energy flux anomalies and additionally, high-level clouds correspond to longwave radiative energy flux anomalies. These results suggest that changes of the radiative energy flux patterns arise as a response to the poleward shift in the southern hemisphere jet stream through its influence on cloud forcing.