Air mass origin signals in delta O-18 of tree-ring cellulose revealed by back-trajectory modeling at the monsoonal Tibetan plateau

Author:	Wernicke, J., P. Hochreuther, J. Griessinger, H. F. Zhu, L. Wang and A. Brauning
Abstract:	A profound consideration of stable oxygen isotope source water origins is a precondition for an unambiguous palaeoenvironmental interpretation of terrestrial delta O-18 archives. To stress the influence of air mass origins on widely used delta O-18 tree-ring chronologies, we conducted correlation analyses between six annually resolved delta O-18 tree-ring cellulose () chronologies and mean annual air package origins obtained from backward trajectory modeling. This novel approach has been tested for a transect at the southeastern Tibetan plateau (TP), where air masses with different isotopic composition overlap. Detailed examinations of daily precipitation amounts and monthly precipitation delta O-18 values () were conducted with the ERA Interim and Laboratoire de M,t,orologie Dynamique General Circulation Model (LMDZiso) data, respectively. Particularly the southernmost study sites are influenced by a distinct amount effect. Here, air package origin relations are generally weaker in contrast to our northern located study sites. We found that tree-ring isotope signatures at dry sites with less rain days per year tend to be influenced stronger by air mass origin than tree-ring isotope values at semi-humid sites. That implies that the local hydroclimate history inferred from archives is better recorded at semi-humid sites.
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Page number:	1109-1124
Issue:	6
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PubYear:	2017
Volume:	61
Publication name:	International Journal of Biometeorology
Abstract:	A profound consideration of stable oxygen isotope source water origins is a precondition for an unambiguous palaeoenvironmental interpretation of terrestrial delta O-18 archives. To stress the influence of air mass origins on widely used delta O-18 tree-ring chronologies, we conducted correlation analyses between six annually resolved delta O-18 tree-ring cellulose () chronologies and mean annual air package origins obtained from backward trajectory modeling. This novel approach has been tested for a transect at the southeastern Tibetan plateau (TP), where air masses with different isotopic composition overlap. Detailed examinations of daily precipitation amounts and monthly precipitation delta O-18 values () were conducted with the ERA Interim and Laboratoire de M,t,orologie Dynamique General Circulation Model (LMDZiso) data, respectively. Particularly the southernmost study sites are influenced by a distinct amount effect. Here, air package origin relations are generally weaker in contrast to our northern located study sites. We found that tree-ring isotope signatures at dry sites with less rain days per year tend to be influenced stronger by air mass origin than tree-ring isotope values at semi-humid sites. That implies that the local hydroclimate history inferred from archives is better recorded at semi-humid sites.
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