Abstract:
This letter presents an alternative approach for investigating the teleconnections of summer monsoon rainfall in the
state of Kerala, India, with four prominent climatic oscillations
in multiple time scales based on multivariate empirical mode decomposition (EMD) (MEMD) and time-dependent intrinsic correlation (TDIC). First, the multivariate data set constituting summer
monsoon rainfall time series and the climate oscillations such
as the Quasi-Biennial Oscillation, El Niño Southern Oscillation
(ENSO), Atlantic Multidecadal Oscillation, and Equatorial Indian
Ocean Oscillation are decomposed to several rotational modes by
employing MEMD. To capture the associations in shorter time
spells, the TDIC method is employed, in which the sliding window
is adaptively fixed based on instantaneous periods obtained by the
Hilbert transform of the obtained modes. From the analysis, it is
found that the strength and nature of association between summer
monsoon rainfall and the climate oscillations vary with time scales
and time spells. The performance of MEMD-based TDIC analysis
is compared with that of EMD-based TDIC, and it was found
that the former one well captured the direct correlation between
ENSO and summer monsoon rainfall in the 1997–1998 period and
the opposing correlation in the 2002–2003 period, while the latter
approach failed to capture such associations properly
