Multidecadal signals in the interannual variability of atmospheric angularmomentum

Citation
Rd. Rosen et Da. Salstein, Multidecadal signals in the interannual variability of atmospheric angularmomentum, CLIM DYNAM, 16(9), 2000, pp. 693-700
Citations number
51
Categorie Soggetti
Earth Sciences
Journal title
CLIMATE DYNAMICS
ISSN journal
09307575 → ACNP
Volume
16
Issue
9
Year of publication
2000
Pages
693 - 700
Database
ISI
SICI code
0930-7575(200009)16:9<693:MSITIV>2.0.ZU;2-M
Abstract
To assess whether trends ill the troposphere's circulation have occurred th is century in concert with changes at the surface, we consider the low-freq uency behavior in the global angular momentum of the atmosphere. Values of this index have been computed each month since 1870 from model experiments conducted by the UK Hadley Centre for Climate Prediction and Research, in w hich the model atmosphere is driven by prescribed boundary forcings, most e specially sea surface temperature (SST) fields. The interannual variability of the model's atmospheric angular momentum compares favorably with that d erived from the NCEP/NCAR reanalysis for the period of overlap (the second half of the twentieth century). Evidence is found for a notable increase in interannual variability since around 1970, but this recent high level of v ariability may not be significantly greater than that during 1900-1920. Thi s latter result is strongly dependent on the character of the SST field use d in an experiment, because low-frequency signals in atmospheric momentum a re closely linked to those in the El Nino/Southern Oscillation. Large diffe rences exist, however, among SST estimates in the tropical Pacific for the early part of the century.