Ocean temperature and salinity components of the Madden–Julian oscillation observed by Argo floats
- 1k Downloads
New diagnostics of the Madden–Julian oscillation (MJO) cycle in ocean temperature and, for the first time, salinity are presented. The MJO composites are based on 4 years of gridded Argo float data from 2003 to 2006, and extend from the surface to 1,400 m depth in the tropical Indian and Pacific Oceans. The MJO surface salinity anomalies are consistent with precipitation minus evaporation fluxes in the Indian Ocean, and with anomalous zonal advection in the Pacific. The Argo sea surface temperature and thermocline depth anomalies are consistent with previous studies using other data sets. The near-surface density changes due to salinity are comparable to, and partially offset, those due to temperature, emphasising the importance of including salinity as well as temperature changes in mixed-layer modelling of tropical intraseasonal processes. The MJO-forced equatorial Kelvin wave that propagates along the thermocline in the Pacific extends down into the deep ocean, to at least 1,400 m. Coherent, statistically significant, MJO temperature and salinity anomalies are also present in the deep Indian Ocean.
KeywordsIntraseasonal oscillation MJO Equatorial Kelvin wave Argo Salinity
These data were collected and made freely available by the International Argo Project and the national programs that contribute to it (http://www.argo.ucsd.edu and http://argo.jcommops.org). Argo is a pilot program of the Global Ocean Observing System. The interpolated OLR, NCEP Reanalysis, and NOAA interpolated sea surface temperature data were provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their web site at http://www.cdc.noaa.gov/. The TAO buoy data were provided by the TAO Project Office of NOAA/PMEL from their web site at http://www.pmel.noaa.gov/tao/index.shtml. The Wheeler and Hendon MJO index data were provided by Matt Wheeler, from the Australian Bureau of Meteorology website at http://www.bom.gov.au/bmrc/clfor/cfstaff/matw/maproom/RMM/index.htm. PS studentship was partially funded by the Thai government. We thank two anonymous reviewers whose comments helped to improve the manuscript.
- Antonov JI, Locarnini RA, Boyer TP, Mishonov AV, Garcia HE (2006) World Ocean Atlas 2005, volume 2: salinity. NOAA Atlas NESDIS 62, U.S. Government Printing Office, Washington, DCGoogle Scholar
- Gill AE (1982) Atmosphere-ocean dynamics. Academic Press, LondonGoogle Scholar
- Gould J, Roemmich D, Wijffels S, Freeland H, Ignaszewsky M, Jianping X, Pouliquen S, Desaubies Y, Send U, Radhakrishnan K, Takeuchi K, Kim K, Danchenkov M, Sutton P, King B, Owens B, Riser S (2004) Argo profiling floats bring new era of in situ ocean observations. Eos 85:179190–179191CrossRefGoogle Scholar
- Heywood KJ, Barton ED, Allen GL (1994) South equatorial current of the Indian Ocean—a 50-day oscillation. Oceanol Acta 17:255–261Google Scholar
- Kalnay E, Kanamitsu M, Kistler R, Collins W, Deaven D, Gandin L, Iredell M, Saha S, White G, Woollen J, Zhu Y, Chelliah M, Ebisuzaki W, Higgins W, Janowiak J, Mo KC, Ropelewski C, Wang J, Leetma A, Reynolds R, Jenne R, Joseph D (1996) The NCEP/NCAR 40-year reanalysis project. Bull Am Meteorol Soc 77:437–471CrossRefGoogle Scholar
- Lau WKM, Waliser DE (2005) Intraseasonal variability in the atmosphere–ocean climate system. Springer, BerlinGoogle Scholar
- Liebmann B, Smith CA (1996) Description of a complete (interpolated) OLR dataset. Bull Am Meteorol Soc 77:1275–1277Google Scholar
- Locarnini RA, Mishonov AV, Antonov JI, Boyer TP, Garcia HE (2006) World Ocean Atlas 2005, volume 1: temperature. NOAA Atlas NESDIS 61, U.S. Government Printing Office, Washington, DCGoogle Scholar
- Zhang C (2005) Madden–Julian oscillation. Rev Geophys 43:RG2003. doi: 10.1029/2004RG000158