TY  - JOUR
A1  - Eroglu, Deniz
A1  - Marwan, Norbert
A1  - Prasad, Sushma
A1  - Kurths, Jürgen
T1  - Finding recurrence networks' threshold adaptively for a specific time series
JF  - Nonlinear processes in geophysics
N2  - Recurrence-plot-based recurrence networks are an approach used to analyze time series using a complex networks theory. In both approaches - recurrence plots and recurrence networks -, a threshold to identify recurrent states is required. The selection of the threshold is important in order to avoid bias of the recurrence network results. In this paper, we propose a novel method to choose a recurrence threshold adaptively. We show a comparison between the constant threshold and adaptive threshold cases to study period-chaos and even period-period transitions in the dynamics of a prototypical model system. This novel method is then used to identify climate transitions from a lake sediment record.
Y1  - 2014
U6  - https://doi.org/10.5194/npg-21-1085-2014
SN  - 1023-5809
VL  - 21
IS  - 6
SP  - 1085
EP  - 1092
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  -