Relationship of the Arctic and Antarctic Oscillations to the Outgoing Longwave Radiation

Abstract

While several mechanisms have been suggested to account for the association of the Arctic and Antarctic Oscillations (AO/AAO) with atmospheric parameters, this paper focuses on the relationship with the atmospheric outgoing longwave radiation (OLR). The main objective of this paper is to demonstrate through AO/AAO composite analysis that the NCEP?NCAR reanalysis OLR agrees with the independent observations of the NASA Earth Radiation Budget Experiment (ERBE) broadband satellite instruments both in zonal averages and in geographically mapped space, and to verify AO/AAO characterized general circulations derived from models and analyses. The results indicate several pronounced areas of storminess that are AO/AAO dependent. One is the well-known variation over the North Atlantic Ocean toward Europe. Also, several major areas are indicated in the tropical region?one in the Indian Ocean and the others in the west and central Pacific Ocean. In addition to demonstrating that the signals are statistically significant, also tested is the relationship of the features to other well-known tropical forcing mechanisms: the Madden?Julian oscillation (MJO) and the El Niño?La Niña sea surface temperature variations. It is shown that the tropical features do, in fact, have a strong relationship to the MJO, which indicates an additional tropical?extratropical interaction. With regard to the sea surface temperature, no correlation associated with the AO/AAO variability is seen. These associations with the cloudiness and atmospheric radiation budget suggest that if there is to be improvement of numerical model forecasts to an extended time period that numerical model radiation physics will have to be taken into consideration and improved.