Verifying the Patterns of the Antarctic Dipole Using Reanalysis Data
Abstract
The Antarctic Dipole (ADP) is a dipole-like pattern seen in various atmospheric and oceanic variables between the Atlantic and Pacific sectors of the Southern Ocean, respectively. It has been used to infer teleconnections between the Eastern Tropical Pacific (specifically to the El Niño-Southern Oscillation) and the Southern Ocean, but so far only one reanalysis has been utilized to study the ADP. Teleconnections have important implications for climate prediction and impacts. The goal of this research is to verify the previous results and conclusions achieved with the original reanalysis by examining two additional reanalyses using similar methods. Specifically, data from the original reanalysis (NCEP-NCAR’s Reanalysis), as well as from the two additional reanalyses (ECMWF’s ERA-Interim and NCEP-DOE’s Reanalysis 2) has been used to investigate the regional Southern Ocean spatial anomaly pattern of five El Niño and five La Niña years, respectively, of four variables (Surface Air Temperature at 1000 millibars, Sea Ice Concentration, Sea Level Pressure, and Sea Surface Temperature). Additionally, regions representative of the Pacific and the Atlantic sector of the Southern Ocean were defined to create time series of the anomalies of each variable during the period 1980 to 2010 for each reanalysis. While the ADP pattern is overall consistent across all three reanalyses, the magnitude and spatial extent of the dipole varies considerably, and the time series reveal that not every year reproduces the dipole pattern and that the sector and years defined for analysis lead to additional differences between the reanalyses. While the ADP is a dominant feature in the three reanalyses studied here, it reveals significant discrepancies among the reanalyses worth investigating in the future. This research suggests using multiple reanalyses to strengthen findings and statements on teleconnections and climate patterns.
Citation
Walker, Amanda Mae (2015). Verifying the Patterns of the Antarctic Dipole Using Reanalysis Data. Honors and Undergraduate Research. Available electronically from https : / /hdl .handle .net /1969 .1 /154498.