2000: On the teleconnectivity of the Arctic Oscillation
Abstract. The term "Arctic Oscillation " (AO) has recently been introduced to describe the leading structure of SLP variability over the Northern Hemisphere. A key feature of the AO is its zonally symmetric appearance, with a primary center of action over the Arctic and opposing anomalies...
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Text |
| Language: | English |
| Subjects: | |
| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.384.252 http://www.cgd.ucar.edu/cas/cdeser/Docs/deser.arctic_oscillation.grl00.pdf |
| Summary: | Abstract. The term "Arctic Oscillation " (AO) has recently been introduced to describe the leading structure of SLP variability over the Northern Hemisphere. A key feature of the AO is its zonally symmetric appearance, with a primary center of action over the Arctic and opposing anomalies in midlatitudes. Does the AO's annular appearance result from significant temporal correlations between SLP anomalies at distant longitudes? The results presented indicate that the temporal coherence between the Arctic and midlatitudes is strongest over the Atlantic sector, with weak correlations between the Atlantic and Pacific midlatitudes, both on intraseasonal and interannual time scales during the past 50 yrs. Hence, the "annular " character of the AO is more a reflection of the dominance of its Arctic center of action than any coordinated behavior of the Atlantic and Pacific centers of action in the SLP field. The AO is nearly indistinguishable from the leading structure of variability in the Atlantic sector (e.g., the North Atlantic Oscillation): pletion in the lower stratosphere and increasin greenhouse gas concentrations in the troposphere. The purpose of this note is to examine more closely the degree of zonal symmetry present in the AO using teleconnectivity as a metric. Does the AO's annular appearance result from significant temporal coherence between anoma-lies at distant longitudes or is it a consequence of the EOF methodology used to define it? Such scrutiny of the AO was not performed in Thompson and Wallace's studies. 2. Data and Methods To facilitate comparison of our results with those of TW, identical data sets are employed. The primary data set is monthly SLP on a 5 ø latitude by 5 ø longitude grid poleward of 15 ø N for the period 1947-97, obtained from the NCAR Data Library (see Trenberth and Paolino, 1980 for details). Supplementary data sets include monthly tropospheric and their temporal correlation is 0.95 for monthly data. lower stratospheric geopotential heights from the NCEP-NCAR Reanalysis ... |
|---|