| Tree-ring based mass-balance reconstruction of Garabashi glacier (Central Caucasus) |
| Paper ID : 1064-ADA2013 |
| Authors: |
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Ekaterina Dolgova *1, Vladimir Matskovskiy2 129, Staromonetny Pereulok, Moscow 119017, Russia 2119017, Staromonetny pereulok 29, Moscow, Russia |
| Abstract: |
| It was previously established tree-ring data successfully used for reconstructions of past climate variation (e.g. Fritts, 1999; Mann et al., 2003) as well as glacier mass balance change (Nicolussi, Patzelt, 1996; Larocque, Smith, 2005; Linderholm et al., 2007).The exploration whether tree-ring data can be effectually applied for the mass balance reconstruction was the main goal of this research. Tree-ring width and maximum density chronologies of high-elevation pine (Pinus sylvestris L.) were investigated at 7 sites in Northern Caucasus. It was found that as well as in other places of temperate zone tree- ring width has complex climate signal and controlled both temperature and precipitation. Tree-ring maximum density in Caucasus has clear climate response to summer temperatures that allowed to reconstruct April-September temperatures since 1800 ss. (Dolgova, Solomina, 2010). Instrumental mass balance records of Garabashi glacier started since 1983 ss. were used for further analyses. It is well known that Caucasus glaciers intensively retreat in the last decades (Panov, 2008) and according to instrumental data mass balance variations mostly controlled by the ablation, i.e. summer temperature variations. Maximum density chronology has statistically significant correlation with mass balance due to summer temperature sensitivity and great loading of ablation to total mass balance variations. In this case mass balance reconstruction would be restricted by ablation variations. To include in our reconstruction different climatically sensitive parameters, stepwise multiple regression model was used. The strongest relation (r = 0.88; r2 = 0.78; p < 0.05) between 2 ring-width and 1 maximum density chronologies was determined. Cross-validation test (r = 0.79; r2 = 0.62; p < 0.05) confirmed model adequacy and it allowed to reconstruct Garabashi glacier mass balance since 1800 ss. The reconstruction length threshold by Expressed Population Signal (>0.85) values counted for chronologies. Detailed response functions analysis of included in the final model chronologies revealed their weak sensitivity to winter precipitation. Reconstructed and instrumental values coincide well except 2000 s. when reconstructed mass balance underestimated but still left negative. Based tree-ring data reconstructed mass balance values were compared with ones based on meteorological data since 1905 ss. (Rototaeva et.al., 2003). Both reconstructions have good interannual agreement (r = 0.53; p<0.05) particularly for the late period 1975-2005 ss. According to reconstruction 2 distinct periods of positive mass balance values occurred in 1830ss., 1860ss., which coincide with early historical data (Abich, 1875) as well as old photographs (M. von Déchy, 1905). Recently Solomona and Bushueva (2012) used tree-rings to date one of the moraines of Kashkatash glacier in Central Caucasus. Their results (1839-1840 ss.) indirectly confirm our reconstruction. |
| Keywords: |
| tree-ring width and maximum density, mass-balance reconstruction, Garabashi glacier, Central Caucasus, Scots pine |
| Status : Abstract Accepted |
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