A comparison of the interannual variability in atmospheric angular momentum and length-of-day using multiple reanalysis data sets

Houk Paek, Huei-Ping Huang

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

This study performs an intercomparison of the interannual variability of atmospheric angular momentum (AAM) in eight reanalysis data sets for the post-1979 era. The AAM data are further cross validated with the independent observation of length-of-day (LOD). The intercomparison reveals a close agreement among almost all reanalysis data sets, except that the AAM computed from the 20th Century Reanalysis (20CR) has a noticeably lower correlation with LOD and with the AAM from other data sets. This reduced correlation is related to the absence of coherent low-frequency variability, notably the Quasi-biennial Oscillation, in the stratospheric zonal wind in 20CR. If the upper-level zonal wind in 20CR is replaced by its counterpart from a different reanalysis data set, a higher value of the correlation is restored. The correlation between the AAM and the Nino3.4 index of tropical Pacific SST is also computed for the reanalysis data sets. In this case, a close agreement is found among all, including 20CR, data sets. This indicates that the upward influence of SST on the tropospheric circulation is well captured by the data assimilation system of 20CR, which only explicitly incorporated the surface observations. This study demonstrates the overall close agreement in the interannual variability of AAM among the reanalysis data sets. This finding also reinforces the view expressed in a recent work by the authors that the most significant discrepancies among the reanalysis data sets are in the long term mean and long-term trend.

Original languageEnglish (US)
Article numberD20102
JournalJournal of Geophysical Research: Atmospheres
Volume117
Issue number20
DOIs
StatePublished - 2012

Fingerprint

Angular momentum
angular momentum
zonal wind
quasi-biennial oscillation
Upper atmosphere
sea surface temperature
assimilation
comparison
data assimilation
low frequencies
trends

ASJC Scopus subject areas

  • Atmospheric Science
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Cite this

@article{17367e0446ea427696a817b209c182a5,
title = "A comparison of the interannual variability in atmospheric angular momentum and length-of-day using multiple reanalysis data sets",
abstract = "This study performs an intercomparison of the interannual variability of atmospheric angular momentum (AAM) in eight reanalysis data sets for the post-1979 era. The AAM data are further cross validated with the independent observation of length-of-day (LOD). The intercomparison reveals a close agreement among almost all reanalysis data sets, except that the AAM computed from the 20th Century Reanalysis (20CR) has a noticeably lower correlation with LOD and with the AAM from other data sets. This reduced correlation is related to the absence of coherent low-frequency variability, notably the Quasi-biennial Oscillation, in the stratospheric zonal wind in 20CR. If the upper-level zonal wind in 20CR is replaced by its counterpart from a different reanalysis data set, a higher value of the correlation is restored. The correlation between the AAM and the Nino3.4 index of tropical Pacific SST is also computed for the reanalysis data sets. In this case, a close agreement is found among all, including 20CR, data sets. This indicates that the upward influence of SST on the tropospheric circulation is well captured by the data assimilation system of 20CR, which only explicitly incorporated the surface observations. This study demonstrates the overall close agreement in the interannual variability of AAM among the reanalysis data sets. This finding also reinforces the view expressed in a recent work by the authors that the most significant discrepancies among the reanalysis data sets are in the long term mean and long-term trend.",
author = "Houk Paek and Huei-Ping Huang",
year = "2012",
doi = "10.1029/2012JD018105",
language = "English (US)",
volume = "117",
journal = "Journal of Geophysical Research: Atmospheres",
issn = "2169-897X",
publisher = "Wiley-Blackwell",
number = "20",

}

TY - JOUR

T1 - A comparison of the interannual variability in atmospheric angular momentum and length-of-day using multiple reanalysis data sets

AU - Paek, Houk

AU - Huang, Huei-Ping

PY - 2012

Y1 - 2012

N2 - This study performs an intercomparison of the interannual variability of atmospheric angular momentum (AAM) in eight reanalysis data sets for the post-1979 era. The AAM data are further cross validated with the independent observation of length-of-day (LOD). The intercomparison reveals a close agreement among almost all reanalysis data sets, except that the AAM computed from the 20th Century Reanalysis (20CR) has a noticeably lower correlation with LOD and with the AAM from other data sets. This reduced correlation is related to the absence of coherent low-frequency variability, notably the Quasi-biennial Oscillation, in the stratospheric zonal wind in 20CR. If the upper-level zonal wind in 20CR is replaced by its counterpart from a different reanalysis data set, a higher value of the correlation is restored. The correlation between the AAM and the Nino3.4 index of tropical Pacific SST is also computed for the reanalysis data sets. In this case, a close agreement is found among all, including 20CR, data sets. This indicates that the upward influence of SST on the tropospheric circulation is well captured by the data assimilation system of 20CR, which only explicitly incorporated the surface observations. This study demonstrates the overall close agreement in the interannual variability of AAM among the reanalysis data sets. This finding also reinforces the view expressed in a recent work by the authors that the most significant discrepancies among the reanalysis data sets are in the long term mean and long-term trend.

AB - This study performs an intercomparison of the interannual variability of atmospheric angular momentum (AAM) in eight reanalysis data sets for the post-1979 era. The AAM data are further cross validated with the independent observation of length-of-day (LOD). The intercomparison reveals a close agreement among almost all reanalysis data sets, except that the AAM computed from the 20th Century Reanalysis (20CR) has a noticeably lower correlation with LOD and with the AAM from other data sets. This reduced correlation is related to the absence of coherent low-frequency variability, notably the Quasi-biennial Oscillation, in the stratospheric zonal wind in 20CR. If the upper-level zonal wind in 20CR is replaced by its counterpart from a different reanalysis data set, a higher value of the correlation is restored. The correlation between the AAM and the Nino3.4 index of tropical Pacific SST is also computed for the reanalysis data sets. In this case, a close agreement is found among all, including 20CR, data sets. This indicates that the upward influence of SST on the tropospheric circulation is well captured by the data assimilation system of 20CR, which only explicitly incorporated the surface observations. This study demonstrates the overall close agreement in the interannual variability of AAM among the reanalysis data sets. This finding also reinforces the view expressed in a recent work by the authors that the most significant discrepancies among the reanalysis data sets are in the long term mean and long-term trend.

UR - http://www.scopus.com/inward/record.url?scp=84867638829&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84867638829&partnerID=8YFLogxK

U2 - 10.1029/2012JD018105

DO - 10.1029/2012JD018105

M3 - Article

VL - 117

JO - Journal of Geophysical Research: Atmospheres

JF - Journal of Geophysical Research: Atmospheres

SN - 2169-897X

IS - 20

M1 - D20102

ER -