TY  - JOUR
A1  - Agarwal, Ankit
A1  - Marwan, Norbert
A1  - Maheswaran, Rathinasamy
A1  - Merz, Bruno
A1  - Kurths, Jürgen
T1  - Multi-scale event synchronization analysis for unravelling climate processes: a wavelet-based approach
JF  - Nonlinear processes in geophysics
N2  - The temporal dynamics of climate processes are spread across different timescales and, as such, the study of these processes at only one selected timescale might not reveal the complete mechanisms and interactions within and between the (sub-) processes. To capture the non-linear interactions between climatic events, the method of event synchronization has found increasing attention recently. The main drawback with the present estimation of event synchronization is its restriction to analysing the time series at one reference timescale only. The study of event synchronization at multiple scales would be of great interest to comprehend the dynamics of the investigated climate processes. In this paper, the wavelet-based multi-scale event synchronization (MSES) method is proposed by combining the wavelet transform and event synchronization. Wavelets are used extensively to comprehend multi-scale processes and the dynamics of processes across various timescales. The proposed method allows the study of spatio-temporal patterns across different timescales. The method is tested on synthetic and real-world time series in order to check its replicability and applicability. The results indicate that MSES is able to capture relationships that exist between processes at different timescales.
Y1  - 2017
U6  - https://doi.org/10.5194/npg-24-599-2017
SN  - 1023-5809
VL  - 24
SP  - 599
EP  - 611
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Lechleitner, Franziska A.
A1  - Breitenbach, Sebastian Franz Martin
A1  - Cheng, Hai
A1  - Plessen, Birgit
A1  - Rehfeld, Kira
A1  - Goswami, Bedartha
A1  - Marwan, Norbert
A1  - Eroglu, Deniz
A1  - Adkins, Jess F.
A1  - Haug, Gerald
T1  - Climatic and in-cave influences on delta O-18 and delta C-13 in a stalagmite from northeastern India through the last deglaciation
JF  - Quaternary research : an interdisciplinary journal
N2  - Northeastern (NE) India experiences extraordinarily pronounced seasonal climate, governed by the Indian summer monsoon (ISM). The vulnerability of this region to floods and droughts calls for detailed and highly resolved paleoclimate reconstructions to assess the recurrence rate and driving factors of ISM changes. We use stable oxygen and carbon isotope ratios (delta O-18 and delta C-13) from stalagmite MAW-6 from Mawmluh Cave to infer climate and environmental conditions in NE India over the last deglaciation (16-6ka). We interpret stalagmite delta O-18 as reflecting ISM strength, whereas delta C-13 appears to be driven by local hydroclimate conditions. Pronounced shifts in ISM strength over the deglaciation are apparent from the delta O-18 record, similarly to other records from monsoonal Asia. The ISM is weaker during the late glacial (LG) period and the Younger Dryas, and stronger during the BOlling-Allerod and Holocene. Local conditions inferred from the delta C-13 record appear to have changed less substantially over time, possibly related to the masking effect of changing precipitation seasonality. Time series analysis of the delta O-18 record reveals more chaotic conditions during the late glacial and higher predictability during the Holocene, likely related to the strengthening of the seasonal recurrence of the ISM with the onset of the Holocene.
KW  - Indian Summer Monsoon
KW  - stalagmite
KW  - oxygen isotopes
KW  - carbon isotopes
KW  - deglaciation
Y1  - 2017
U6  - https://doi.org/10.1017/qua.2017.72
SN  - 0033-5894
SN  - 1096-0287
VL  - 88
SP  - 458
EP  - 471
PB  - Cambridge Univ. Press
CY  - New York
ER  -