Abstract
The wet/dry spells of the Indian summer monsoon (ISM) rainfall are governed by northward propagating boreal summer monsoon intraseasonal oscillations (MISO). Unlike for the Madden Julian Oscillation (e.g. RMM indices, Wheeler and Hendon in Mon Weather Rev 132:1917–1932, 2004), a low dimensional real-time monitoring and forecast verification metric for the MISO is not currently available. Here, for the first time, we present a real time monitoring index developed for identifying the amplitude and phase of the MISO over the ISM domain. The index is constructed by applying extended empirical orthogonal function (EEOF) analysis on daily unfiltered rainfall anomalies averaged over the longitudinal domain 60.5°E–95.5°E. The gravest two modes of the EEOFs together explain about 23 % of the total variance, similar to the variance explained by MISO in observation. The pair of first two principal components (PCs) of the EEOFs is named as MISO1 and MISO2 indices which together represent the evolution of the MISOs in a low dimensional phase space. Power spectral analysis reveals that the MISO indices neatly isolate the MISO signal from the higher frequency noise. It is found that the current amplitude and phase of the MISO can be estimated by preserving a memory of at least 15 days. Composite pictures of the spatio-temporal evolution of the MISOs over the ISM domain are brought out using the MISO indices. It is further demonstrated that the MISO indices can be used in the quantification of skill of extended range forecasts of MISOs. Since the MISO index does not rely on any sort of time filtering, it has great potential for real time monitoring of the MISO and may be useful in developing some prediction scheme.
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References
Flatau Maria K, Flatau Piotr J, Rudnick Daniel (2001) The dynamics of double monsoon onsets. J Climate 14:4130–4146
Goswami BN (2005) South Asian monsoon, Chapter 2. In: Lau WKM, Waliser DE (eds) Intraseasonal variability of the atmosphere-ocean climate system. Praxis, Springer, Berlin, pp 19–61
Goswami BN, Ajaya Mohan RS (2001) Intra-seasonal oscillations and inter-annual variability of the Indian summer monsoon. J Clim 14:1180–1198
Goswami BN, Wu G, Yasunari T (2006) Annual cycle, intraseasonal oscillations and roadblock to seasonal predictability of the Asian summer monsoon. J Clim 19:5078–5099
Hendon HH, Wheeler MC (2008) Some space–time spectral analyses of tropical convection and planetary-scale waves. J Atmos Sci 65:2936–2948
Huffman GJ, Adler RF, Arkin P, Chang A, Ferraro R, Gruber A, Janowiak J, McNab A, Rudolf B, Schneider U (1997) The global precipitation climatology project (GPCP) combined precipitation dataset. Bull Am Meteor Soc 78:5–20
Kemball-Cook S, Wang B (2001) Equatorial waves and air-sea interaction in the boreal summer intraseasonal oscillation. J Clim 14:2923–2942
Kessler WS (2001) EOF representations of the Madden–Julian oscillation and its connection with ENSO. J Clim 14:3055–3061
Kikuchi K, Wang B, Kajikawa Y (2011) Bimodal representation of the tropical intraseasonal oscillation. Clim Dyn. doi:10.1007/s00382-011-1159-1
Lau KM, Chan PH (1985) Aspects of 40–50 day oscillation during the northern winter as inferred from outgoing longwave radiation. Mon Weather Rev 113:1889–1909
Lau KM, Chan PH (1986) Aspects of 30–50 day oscillation during summer as inferred from out going longwave radiation. Mon Weather Rev 114:1354–1369
Lau WKM, Waliser DE (2005) Intraseasonal Variability of the Atmosphere-Ocean Climate System. Praxis, Springer Berlin Heidelberg
Madden RA (1986) Seasonal variations of the 40–50 day oscillation in the tropics. J Atmos Sci 43:3138–3158
Maloney ED, Hartmann DL (1998) Frictional moisture convergence in a composite lifecycle of the Madden-Julian oscillation. J Clim 11:2387–2403
Neena JM, Suhas E, Goswami BN (2011) Leading role of internal dynamics in the 2009 Indian summer monsoon drought. J Geophys Res 116:D13103. doi:10.1029/2010JD015328
North GR, Bell TL, Cahalan RF, Moeng FJ (1982) Sampling errors in the estimation of empirical orthogonal functions. J Atmos Sci 110:699–706
Pai DS, Bhate J, Sreejith OP, Hatwar HR (2009) Impact of MJO on the intraseasonal variation of summer monsoon rainfall over India, Clim Dyn. doi:10.1007/s00382-009-0634-4
Roundy PE, Schreck CJ III (2009) A combined wave-number-frequency and time-extended EOF approach for tracking the progress of modes of large-scale organized tropical convection. Q J R Meteorol Soc 135:161–173
Rui H, Wang B (1990) Development characteristics and dynamic structure of tropical intraseasonal convection anomalies. J Atmos Sci 47:357–379
Sikka D, Gadgil S (1980) On the maximum cloud zone and the ITCZ over Indian, longitudes during the southwest monsoon. Mon Weather Rev 108:1840–1853
Suhas E, Goswami BN (2010) Loss of significance and multidecadal variability of the Madden-Julian oscillation. J Clim 23:3739–3759. doi:10.1175/2010JCLI3180.1
Suhas E, Neena JM, Goswami BN (2012) Interannual variability of Indian summer monsoon arising from interactions between seasonal mean and intraseasonal oscillations. J Atmos Sci. doi:10.1175/JAS-D-11-0211.1 (in press)
Waliser DE, Murtugudde R, Lucas LE (2003) Indo-Pacific Ocean response to amopsheric intraseasonal variability: 1. Austral summer and the Madden-Julain oscillation. J Geophys Res 108(C5): 3160. doi:10.1029/2002JC001620
Wang B, Webster P, Kikuchi K, Yasunari T, Qi YJ (2006) Boreal summer quasi-monthly oscillation in the global tropics. Clim Dyn 27:661–675
Wheeler MC, Hendon HH (2004) An all-season real-time multivariate MJO Index: development of an index for monitoring and prediction. Mon Weather Rev 132:1917–1932
Zhang C, Dong M (2004) Seasonality of the Madden-Julian oscillation. J Clim 17:3169–3180
Acknowledgments
BNG and IITM are fully supported by the Ministry of Earth Sciences, Government of India, New Delhi. We thank Dr. A.K. Sahai and Dr. Abhilash S for providing the CFSv1 data used in the study. We thank two anonymous reviewers for their insightful comments leading to improvement of the manuscript.
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Suhas, E., Neena, J.M. & Goswami, B.N. An Indian monsoon intraseasonal oscillations (MISO) index for real time monitoring and forecast verification. Clim Dyn 40, 2605–2616 (2013). https://doi.org/10.1007/s00382-012-1462-5
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DOI: https://doi.org/10.1007/s00382-012-1462-5