TY  - JOUR
A1  - Breitenbach, Sebastian Franz Martin
A1  - Rehfeld, Kira
A1  - Goswami, Bedartha
A1  - Baldini, James U. L.
A1  - Ridley, H. E.
A1  - Kennett, D. J.
A1  - Prufer, K. M.
A1  - Aquino, Valorie V.
A1  - Asmerom, Yemane
A1  - Polyak, V. J.
A1  - Cheng, Hai
A1  - Kurths, Jürgen
A1  - Marwan, Norbert
T1  - Constructing Proxy Records from Age models (COPRA)
JF  - Climate of the past : an interactive open access journal of the European Geosciences Union
N2  - Reliable age models are fundamental for any palaeoclimate reconstruction. Available interpolation procedures between age control points are often inadequately reported, and very few translate age uncertainties to proxy uncertainties. Most available modeling algorithms do not allow incorporation of layer counted intervals to improve the confidence limits of the age model in question.
 We present a framework that allows detection and interactive handling of age reversals and hiatuses, depth-age modeling, and proxy-record reconstruction. Monte Carlo simulation and a translation procedure are used to assign a precise time scale to climate proxies and to translate dating uncertainties to uncertainties in the proxy values. The presented framework allows integration of incremental relative dating information to improve the final age model. The free software package COPRA1.0 facilitates easy interactive usage.
Y1  - 2012
U6  - https://doi.org/10.5194/cp-8-1765-2012
SN  - 1814-9324
VL  - 8
IS  - 5
SP  - 1765
EP  - 1779
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Schewe, Jacob
A1  - Levermann, Anders
A1  - Cheng, Hai
T1  - A critical humidity threshold for monsoon transitions
JF  - Climate of the past : an interactive open access journal of the European Geosciences Union
N2  - Monsoon systems around the world are governed by the so-called moisture-advection feedback. Here we show that, in a minimal conceptual model, this feedback implies a critical threshold with respect to the atmospheric specific humidity q(o) over the ocean adjacent to the monsoon region. If q(o) falls short of this critical value q(o)(c), monsoon rainfall over land cannot be sustained. Such a case could occur if evaporation from the ocean was reduced, e.g. due to low sea surface temperatures. Within the restrictions of the conceptual model, we estimate q(o)(c) from present-day reanalysis data for four major monsoon systems, and demonstrate how this concept can help understand abrupt variations in monsoon strength on orbital timescales as found in proxy records.
Y1  - 2012
U6  - https://doi.org/10.5194/cp-8-535-2012
SN  - 1814-9324
VL  - 8
IS  - 2
SP  - 535
EP  - 544
PB  - Copernicus
CY  - Göttingen
ER  -