Momentum forcing of the quasi-biennial oscillation by equatorial waves in recent reanalyses

Y. H. Kim, Hye-Yeong Chun

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

The momentum forcing of the QBO (quasi-biennial oscillation) by equatorial waves is estimated using recent reanalyses. Based on the estimation using the conventional pressure-level data sets, the forcing by the Kelvin waves (3-9 m s-1 month-1) dominates the net forcing by all equatorial wave modes (3-11 m s-1 month-1) in the easterly-to-westerly transition phase at 30 hPa. In the opposite phase, the net forcing by equatorial wave modes is small (1-5 m s-1 month-1). By comparing the results with those from the native model-level data set of the ERA-Interim reanalysis, it is suggested that the use of conventional-level data causes the Kelvin wave forcing to be underestimated by 2-4 m s-1 month-1. The momentum forcing by mesoscale gravity waves, which are unresolved in the reanalyses, is deduced from the residual of the zonal wind tendency equation. In the easterly-to-westerly transition phase at 30 hPa, the mesoscale gravity wave forcing is found to be smaller than the resolved wave forcing, whereas the gravity wave forcing dominates over the resolved wave forcing in the opposite phase. Finally, we discuss the uncertainties in the wave forcing estimates using the reanalyses.

Original languageEnglish
Pages (from-to)6577-6587
Number of pages11
JournalAtmospheric Chemistry and Physics
Volume15
Issue number12
DOIs
Publication statusPublished - 2015 Jun 16

Fingerprint

equatorial wave
quasi-biennial oscillation
gravity wave
momentum
Kelvin wave
phase transition
westerly
zonal wind

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

Cite this

@article{94cc0723cad5405dabdcf7fd6684ab1f,
title = "Momentum forcing of the quasi-biennial oscillation by equatorial waves in recent reanalyses",
abstract = "The momentum forcing of the QBO (quasi-biennial oscillation) by equatorial waves is estimated using recent reanalyses. Based on the estimation using the conventional pressure-level data sets, the forcing by the Kelvin waves (3-9 m s-1 month-1) dominates the net forcing by all equatorial wave modes (3-11 m s-1 month-1) in the easterly-to-westerly transition phase at 30 hPa. In the opposite phase, the net forcing by equatorial wave modes is small (1-5 m s-1 month-1). By comparing the results with those from the native model-level data set of the ERA-Interim reanalysis, it is suggested that the use of conventional-level data causes the Kelvin wave forcing to be underestimated by 2-4 m s-1 month-1. The momentum forcing by mesoscale gravity waves, which are unresolved in the reanalyses, is deduced from the residual of the zonal wind tendency equation. In the easterly-to-westerly transition phase at 30 hPa, the mesoscale gravity wave forcing is found to be smaller than the resolved wave forcing, whereas the gravity wave forcing dominates over the resolved wave forcing in the opposite phase. Finally, we discuss the uncertainties in the wave forcing estimates using the reanalyses.",
author = "Kim, {Y. H.} and Hye-Yeong Chun",
year = "2015",
month = "6",
day = "16",
doi = "10.5194/acp-15-6577-2015",
language = "English",
volume = "15",
pages = "6577--6587",
journal = "Atmospheric Chemistry and Physics",
issn = "1680-7316",
publisher = "European Geosciences Union",
number = "12",

}

Momentum forcing of the quasi-biennial oscillation by equatorial waves in recent reanalyses. / Kim, Y. H.; Chun, Hye-Yeong.

In: Atmospheric Chemistry and Physics, Vol. 15, No. 12, 16.06.2015, p. 6577-6587.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Momentum forcing of the quasi-biennial oscillation by equatorial waves in recent reanalyses

AU - Kim, Y. H.

AU - Chun, Hye-Yeong

PY - 2015/6/16

Y1 - 2015/6/16

N2 - The momentum forcing of the QBO (quasi-biennial oscillation) by equatorial waves is estimated using recent reanalyses. Based on the estimation using the conventional pressure-level data sets, the forcing by the Kelvin waves (3-9 m s-1 month-1) dominates the net forcing by all equatorial wave modes (3-11 m s-1 month-1) in the easterly-to-westerly transition phase at 30 hPa. In the opposite phase, the net forcing by equatorial wave modes is small (1-5 m s-1 month-1). By comparing the results with those from the native model-level data set of the ERA-Interim reanalysis, it is suggested that the use of conventional-level data causes the Kelvin wave forcing to be underestimated by 2-4 m s-1 month-1. The momentum forcing by mesoscale gravity waves, which are unresolved in the reanalyses, is deduced from the residual of the zonal wind tendency equation. In the easterly-to-westerly transition phase at 30 hPa, the mesoscale gravity wave forcing is found to be smaller than the resolved wave forcing, whereas the gravity wave forcing dominates over the resolved wave forcing in the opposite phase. Finally, we discuss the uncertainties in the wave forcing estimates using the reanalyses.

AB - The momentum forcing of the QBO (quasi-biennial oscillation) by equatorial waves is estimated using recent reanalyses. Based on the estimation using the conventional pressure-level data sets, the forcing by the Kelvin waves (3-9 m s-1 month-1) dominates the net forcing by all equatorial wave modes (3-11 m s-1 month-1) in the easterly-to-westerly transition phase at 30 hPa. In the opposite phase, the net forcing by equatorial wave modes is small (1-5 m s-1 month-1). By comparing the results with those from the native model-level data set of the ERA-Interim reanalysis, it is suggested that the use of conventional-level data causes the Kelvin wave forcing to be underestimated by 2-4 m s-1 month-1. The momentum forcing by mesoscale gravity waves, which are unresolved in the reanalyses, is deduced from the residual of the zonal wind tendency equation. In the easterly-to-westerly transition phase at 30 hPa, the mesoscale gravity wave forcing is found to be smaller than the resolved wave forcing, whereas the gravity wave forcing dominates over the resolved wave forcing in the opposite phase. Finally, we discuss the uncertainties in the wave forcing estimates using the reanalyses.

UR - http://www.scopus.com/inward/record.url?scp=84935031489&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84935031489&partnerID=8YFLogxK

U2 - 10.5194/acp-15-6577-2015

DO - 10.5194/acp-15-6577-2015

M3 - Article

VL - 15

SP - 6577

EP - 6587

JO - Atmospheric Chemistry and Physics

JF - Atmospheric Chemistry and Physics

SN - 1680-7316

IS - 12

ER -