Feedback of 10–20-day intraseasonal oscillations on seasonal mean SST in the tropical Western North Pacific during boreal spring through fall
- 256 Downloads
The present study documents the factors for year-to-year changes in the intensity of 10–20-day intraseasonal oscillations (ISOs) and investigates the feedback of the 10–20-day ISO intensity on seasonal mean sea surface temperature (SST) change in the tropical western North Pacific during boreal spring through fall. An analysis of local correlation reveals a significant negative correlation of the 10–20-day ISO intensity and the seasonal mean SST tendency in the tropical western North Pacific during spring, summer, and fall, suggesting a plausible feedback of the ISO intensity on seasonal mean SST anomaly. The 10–20-day ISO intensity change over the tropical western North Pacific is influenced by El Niño-Southern Oscillation (ENSO) through modulation of vertical shear of zonal winds, lower-level moisture, and upward motion. Due to the phase dependence of location of these ENSO-induced background field changes, the ISO intensity is subject to ENSO influence in different regions during the three seasons. The feedback of the 10–20-day ISO intensity on local seasonal mean SST change in the tropical western North Pacific is demonstrated by separating latent heat flux anomalies into components on different time scales. The ISO-induced latent heat flux anomalies may accumulate in a season and overcome interannual anomalies due to seasonal mean changes. Thus, the ISO-induced surface heat flux change may play an important role in the seasonal mean SST anomaly in the tropical western North Pacific.
KeywordsISO feedback Seasonal mean SST Latent heat flux decomposition Tropical western North Pacific
The two anonymous reviewers’ comments help to improve the paper. This study is supported by the National Key Basic Research Program of China grant (2014CB953902), the National Key Research and Development Program grant (2016YFA0600603), and the National Natural Science Foundation of China grants (41475081, 41275081, and 41530425). The NCEP-DOE reanalysis 2 data and the NOAA OLR data were obtained from ftp://ftp.cdc.noaa.gov/. The NOAA OI version 2 SST data are obtained from http://www.esrl.noaa.gov/psd/.
- Griffies SM, Harrison MJ, Pacanowski RC, Rosati A (2004) A technical guide to MOM4. GFDL ocean group technical report no. 5. NOAA/Geophysical Fluid Dynamics Laboratory, Princeton, p 342Google Scholar
- Liu F, Li T, Wang H, Deng L, and Zhang YW (2016b) Modulation of boreal summer intraseasonal oscillations over the western North Pacific by ENSO. J Clim acceptedGoogle Scholar
- Wu R, Hu ZZ, Kirtman BP (2003) Evolution of ENSO-related rainfall anomalies in East Asia. J Clim 16:3741–3757Google Scholar
- Wu R, Cao X, Chen SF (2015) Co-variations of SST and surface heat flux on 10–20-day and 30–60-day time scales over the South China Sea and western North Pacific. J Geophys Res 120(24):12486–12499Google Scholar
- Zhang C (2013) Madden–Julian Oscillation: bridging weather and climate. J Clim 94:1849–1870Google Scholar