2 Esper J, Cook E R, Schweingruber F H. Low frequency signals in long tree-ring chronologies for reconstructing past temperature variability.Science, 2002, 295: 2250-2253？？
[2]
5 Cook B I, Miller R L, Seager R. Amplification of the North American “Dust Bowl” drought through human-induced land degradation.Proc Natl Acad Sci USA, 2009, 106: 4997-5001？？
[3]
7 Yang B, Kang X C, Brauning A, et al. A 622-year regional temperature history of southeast Tibet derived from tree rings. Holocene, 2010,20: 181-190？？
19 Liu Y, Bao G, Song H M, et al. Precipitation reconstruction from Hailar pine tree rings in the Hailar region, Inner Mongolia, China backto 1865 AD. Paleogeogr Paleoclimatol Paleoecol, 2009, 282: 81-87
38 Meehl G A, Arblaster J M. The Tropospheric biennial oscillation and Indian Monsoon rainfall. Geophys Res Lett, 2001, 28: 1731-1734？？
[18]
？？
[19]
1 Briffa K R, Osborn T J, Schweingruber F H, et al. Low-frequency temperature variations from a northern tree-ring density network. JGeophys Res A, 2001, 106: 2929-2941？？
[20]
3 D’Arrigo R, Jacoby G A. 1000-year record of winter precipitation from northwestern New Mexico, USA: A reconstruction from tree-ringsand its relation to El Ni？o and the Southern Oscillation. Holocene, 1991, 1: 95-101
[21]
4 Pederson N, Jacoby G C, D’Arrigo R D, et al. Hydrometeorological reconstructions for Northeastern Mongolia derived from Tree Rings:AD 1651-1995. J Clim, 2001, 14: 872-881？？
9 Liang E Y, Shao X M, Qin N S. Tree-ring based summer temperature reconstruction for the source region of the Yangtze River on theTibetan Plateau. Global Planet Change, 2008, 61: 313-320？？
13 Zhang Q B, Cheng G D, Yao T D, et al. A 2326-year tree-ring record of climate variability on the northeastern Qinghai-Tibetan Plateau.Geophys Res Lett, 2003, 30: 1739-1742？？
[27]
14 Liu Y, Sun J Y, Song H M, et al. Tree-ring hydrologic reconstructions for the Heihe River watershed, western China since AD 1430. WaterRes, 2010, 44: 2781-2792
20 Liu Y, Tian H, Song H Y, et al. Tree ring precipitation reconstruction in the Chifeng-Weichang region, and East Asian summer monsoonvariation since AD 1777. J Geophys Res, 2010, 115: D06106
[30]
21 Liu Y, Sun J Y, Yang Y K, et al. Tree-ring precipitation records from Inner Mongolia, China, and the East Asian summer monsoon frontvariation since 1627 AD. Tree-ring Res, 2007, 63: 3-14
[31]
22 Liu Y, Cai Q F, Shi J F, et al. Seasonal precipitation in the south-central Helan Mountain region, China, reconstructed from tree-ringwidth for the past 224 years. Can J For Res, 2005, 35: 2403-2412
[32]
25 Stokes M A, Smiley T L. An Introduction to Tree-ring Dating. Chicago: University of Chicago Press, 1968. 1-73？？
[33]
26 Holmes R L. Computer-assisted quality control in tree-ring dating and measurement. Tree-Ring Bull, 1983, 43: 69-78
[34]
27 Cook E R, Kairiukstis L A. Methods of Dendrochronology. The Netherlands, Dordrecht: Kluwer Academic Publishers, 1990. 1-200？？
[35]
28 Wigley T M L, Briffa K R, Jones P D. On the average value of correlated time series with applications in dendroclimatology and hydrometeorology.J Clim Appl Meteor, 1984, 23: 201-213？？
[36]
29 Kohler M A. On the use of double-mass analysis for testing the consistency of meteorological records and for making required adjustments.Bull Amer Meteorol Soc, 1949, 30: 188-189
[37]
35 Ding Y H, Wang Z Y, Sun Y. Inter-decadal variation of the summer precipitation in East China and its association with decreasing Asiansummer monsoon. Part I: Observed evidences. Int J Climatol, 2007, 28: 1139-1161
[38]
36 Ding Y H, Sun Y, Wang Z Y, et al. Inter-decadal variation of the summer precipitation in East China and its association with decreasingAsian summer monsoon. Part II: Possible causes. Int J Climatol, 2009, 29: 1926-1944？？
