Abstract
The low frequency spatio-temporal intraseasonal evolution of monsoon rainfall over India is studied by considering the pentad rainfall averages taken over 2.5° wide and 5.0° long blocks lying across the central longitudinal and latitudinal transacts. The time-latitude cross sections show south to north progressions of rainfall anomalies with a recurrence period of about 40 days. The progressions show considerable inter-annual and intra-seasonal variation in frequency, amplitude and rate of progression. The extended empirical orthogonal function analysis shows that the first two most important functions correspond to this northward progression of rain anomalies recurring after an interval of about 40 days. The rate of progression of anomalies is about 0.5° Lat./day. The time-longitude cross sections show the movement of rainfall anomalies towards both directions east and the west, with slight preference towards the east. The importance of these signals in rainfall forecasting is foreseen.
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Singh, S.V., Kripalani, R.H. The south to north progression of rainfall anomalies across India during the summer monsoon season. PAGEOPH 123, 624–637 (1985). https://doi.org/10.1007/BF00877458
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DOI: https://doi.org/10.1007/BF00877458