Ranking of tree-ring based hydroclimate reconstructions of the past millennium

To place recent hydroclimate changes, including drought occurrences, in a long-term historical context, tree-ring records serve as an important natural archive. Here, we evaluate 46 millennium-long tree-ring based hydroclimate reconstructions for their Data Homogeneity, Sample Replication, Growth Coherence, Chronology Development, and Climate Signal based on criteria published by Esper et al. (2016) to assess tree-ring based temperature reconstructions. The compilation of 46 individually calibrated site reconstructions includes 37 different tree species and stem from North America (n = 29), Asia (n = 10); Europe (n = 5), northern Africa (n = 1) and southern South America (n = 1). For each criterion, the individual reconstructions were ranked in four groups, and results showed that no reconstruction scores highest or lowest for all analyzed parameters. We find no geographical differences in the overall ranking, but reconstructions from arid and semi-arid environments tend to score highest. A strong and stable hydroclimate signal is found to be of greater importance than a long calibration period. The most challenging trade-off identified is between high continuous sample replications, as well as a well-mixed age class distribution over time, and a good internal growth coherence. Unlike temperature reconstructions, a high proportion of the hydroclimate reconstructions are produced using individual series detrending methods removing centennial-scale variability. By providing a quantitative and objective evaluation of all available tree-ring based hydroclimate reconstructions we hope to boost future improvements in the development of such records and provide practical guidance to secondary users of these reconstructions.Fil: Charpentier Ljungqvist, Fredrik. Stockholms Universitet; SueciaFil: Piermattei, Alma. University of Cambridge; Estados UnidosFil: Seim, Andrea. Albert Ludwig University of Freiburg; AlemaniaFil: Krusic, Paul J.. University of Cambridge; Estados Unidos. Stockholms Universitet; SueciaFil: Büntgen, Ulf. University of Cambridge; Estados Unidos. Masaryk University; República Checa. CZECH ACADEMY OF SCIENCES (AVCR);Fil: He, Minhui. Northwest Agriculture and Forestry University; ChinaFil: Kirdyanov, Alexander V.. University of Cambridge; Estados UnidosFil: Luterbacher, Jürg. Justus Liebig University; AlemaniaFil: Schneider, Lea. Justus Liebig University; AlemaniaFil: Seftigen, Kristina. University Goteborg; Suecia. Université Catholique de Louvain; BélgicaFil: Stahle, David W.. University of Arkansas for Medical Sciences; Estados UnidosFil: Villalba, Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Yang, Bao. Chinese Academy of Sciences; República de ChinaFil: Esper, Jan. Johannes Gutenberg Universitat Mainz; Alemani