special thanks
DESCRIPTION
A465 EGU2011-3321. Climatic interpretation of tree ring stable isotopes in the southeast Tibetan Plateau : links with regional cloud cover. Chunming Shi 1,2 , Valérie Daux 1 , Valérie Masson-Delmotte 1 , Camille Risi 3 , Jing Gao 4 , Xiaochun Wang 2 and Qi-Bin Zhang 2 - PowerPoint PPT PresentationTRANSCRIPT
Special thanks
This study would not have been possible without the financial support from GIS Environnement-Société and from the French Embassy in China, and without the technical support of Monique Pierre and Michel Stievenard
CLIMATIC INTERPRETATION OF TREE RING STABLE ISOTOPES IN THE SOUTHEAST TIBETAN PLATEAU : LINKS
WITH REGIONAL CLOUD COVERChunming Shi1,2, Valérie Daux1, Valérie Masson-Delmotte1, Camille Risi3, Jing Gao4, Xiaochun Wang2 and Qi-Bin Zhang2
Contact : [email protected]
1 IPSL/LSCE, CEA-CNRS-UVSQ, Gif-sur-Yvette, France2 Institute of Botany, CAS, Beijing, China3 U. Colorado, Boulder, USA4 Tibetan Plateau Research Institute, CAS, Beijing, China
Related publications
Gao J., Masson-Delmotte V., Yao T., Tian L., Risi C. and Hoffmann G. (2010) Precipitation water stable isotopes in the south Tibetan Plateau: observations and modeling. J. Clim. doi: 10.1175/2010JCLI3736.1.
Shi C., Masson-Delmotte V., Risi C., Eglin T., Stievenard M., Pierre M., Wang X., Gao J., Bréon F.-M., Zhang Q.-B. and Daux V. (2011) Sampling strategy and climatic implications of tree-ring stable isotopes in Southeast Tibetan Plateau. Earth Planet. Sc. Lett. 301, 307-316.
Shi C., Daux V., Zhang Q.B., Risi C., Hou S., Stievenard M., Pierre M., Li Z., Masson-Delmotte V., Reconstruction of southeast Tibetan Plateau summer cloud cover over the past two centuries using tree ring 18O. Submitted.
A465 EGU2011-3321
CONTEXT : warming trend since the 1960s and importance of precipitation variability linked with monsoon influence on SE Tibetan Plateau
GOAL : characterise the inter-annual to centennial variability in the TP water cycle using tree ring cellulose 18O
STUDY SITE : Gangcun Natural Forest, near Bomi
CLIMATE : strong seasonality in precipitation (winter westerly events and summer monsoon) and temperature allowing the production of relatively wide tree rings
SPECIES: Linzhi spruce (Picea likiangensis var. linzhiensis), the dominant sub-alpine evergreen conifer in southeast Tibet
SAMPLING: 4 young trees (average age : 100 years, 4 cores per tree) and 27 old trees (average age : 215 years, 1 core per tree)
PRECIPITATION ISOTOPIC COMPOSITION : one year of event-based data at Bomi is available. Depleted values are obtained in summer-autumn.
MODELLING: models (LMDZiso and ECHAM4iso) capture some of the features of SE Tibet precipitation isotopic composition, esp. at high res. (50 km)
DISPERSION ANALYSIS: limited intra- and inter-tree variability, 4 trees allow to capture a population signal. No age effect.
CALIBRATION STUDY: strong correlation with summer precipitation, relative humidity, regional cloud cover
CELLULOSE OXYGEN 18 SIMULATION: ORCHIDEE-iso also depicts a strong link with relative humidity
CLIMATE SIMULATION: Bomi summer precipitation isotopic composition is anti-correlated with regional cloud cover in LMDZiso
LINKS WITH REGIONAL CLOUD COVER:R²=0.50 (after removal of one outlier)Mechanisms can involve monsoon dynamics (linking cloudiness and depletion), photosynthesis intermittency, tree water stress
TENTATIVE CLOUD COVER RECONSTRUCTION (226 YEAR LONG):
- recent increase is not unprecedented- lower variability in the 20thC than earlier- regime shift / abrupt decrease in the late 19thC- dry decade in the 1810s, possibly linked with the 1809 and Tambora volcanic eruptions (major famine in nearby Yunan)
CONCLUSIONS AND PERSPECTIVES- clear potential of tree ring stable isotopes in SE Tibet- multi-archive comparisons (e.g. ice cores)- new tree ring isotope records- site monitoring for an improved process based understanding- comparison with multi-centennial climate simulations including stable isotopes (e.g. impact of volcanic activity, regime shifts)