Lake Isotope-Climate Model comparisons: forward modelling of Lake Nar, central Turkey

Lake delta-18O records provide an important window into variability in hydroclimate on timescales longer than those available to us via instrumental records. Here we describe an approach for lake isotope data - climate model comparison, which could ultimately result in an iterative approach to a better understanding of both. With climate models increasingly becoming isotope enabled, understanding isotope palaeoarchive systematics is vital for fulfilling the potential for data model comparisons. A case study from Nar Golu, Turkey will be presented. Long term (>10 year) monitoring of the lake system allows the development of robust lake isotope models that explain the measured variability. These models can be used to forward model lake isotope variability and allow the comparison of isotope records from sedimentary archives and climate model output. Forward modelling of the Nar isotope system driven by climate model output, in this case from the CSIRO Mk3L climate system model (Phipps et al., 2011 Geoscientific Model Development 4, 483-509), can be compared to the lake isotope record (Jones et al., 2006 Geology 34, 361-364) over the last 1500 years. The comparison highlights the differences between the isotope data interpretation and the climate model output which can be investigated and ultimately iteratively reduced, improving performance of the model and our interpretation of lake isotope records.