Reconstruction And Analysis Of Climate Based On The Width Of Tree Rings In Altay Region

In this paper，three types of tree-ring width chronologies were developed，byusing3larch ring samples of Xinjiang collected from13sampling points of thesouthern slope of Altai in August，2012．It’s found between meteorological data ofseven weather stations in the Altay region and Chronology: the residual chronologiesof the average six lower lines of the forest have the best relevance to the relatedrainfall of the average seven weather stations from July last year to April current year,the correlation coefficient was0.582(0.000009)； Standardized tree-ring widthchronologies on five forests’ average upper limit of the forest have the best relevanceto the mean temperature of June of seven weather stations, correlation coefficientreaches0.6(0.000003). By stepwise regression analysis, the equation reconstructionof temperature and precipitation is established which represents the Altay region overthe past264years from July last year to April current year and the averagetemperature in June current year over past294years. Meanwhile several statistics areused to verify the reconstruction results. The results showed that the reconstructionvalue is credible. Reconstruction value analysis conclusions are as follows:(1) the precipitation in Altay region from July last year to April current year andthe average monthly temperature in June current year have a significant positivecorrelation with the growth of tree rings. Both have significant effects on thephysiological role of trees.(2) precipitation reconstruction sequence roughly has seven humid periods andeight partial dry periods. Humid ’s longest period spans48years (1825-1872), thelongest partial dry years is across24years (1965-1988years); in humid years(1934-1942years), the maximum average rainfall is148.16mm,7.8mm more thanthe average, which is5%above normal. In humid period (1943-1951) the minimumaverage rainfall is128.93mm,11.43mm less than the average, which is8%less thannormal.Average temperature reconstruction sequence roughly has10warm periods and9cold periods. The longest warm period spans41years (1887-1927), the longest coldperiod spans40years (1764-1803); In warm period (1804-1813), the maximumaverage temperature in June was21.63℃, and it’s0.46℃more than the average,which is higher by2%. In cold period(1814-1824) the lowest average temperature inJune is20.6℃, which is0.57℃less and3%lower than the average.(3) As for the frequency and extreme, precipitation sequence of the264years rebuilt (1749-2012) includes5dampish years,55wet years,148normal years, eightdry years,47dryish years, respectively, the number of years takes up2%to21%,56%,3%and18%on the total. The most extreme wet year was in1841, rainfall was189.92mm,35.3%higher than the average of reconstruction. The most extremedrought was in1963, precipitation was68.9mm,50.9%lower than the averagereconstruction.The average temperature sequence of reconstruction of294years (1719-2012)includes a warm year,27partial warm years,241normal years, a cold year, the22cool years, as follows which respectively takes up0.3%,9%,82%,0.3%and7%.The extreme warm year occurred in1915, the average temperature in June was23.24℃,10%higher than the average of reconstruction. The extreme cold occurred in1797, the average temperature in June is18.96℃, which is10.4%lower than theaverage of reconstruction.(4) It’s depicted from the data of dps software: in1807, as a abrupt point ofprecipitation, precipitation changes from abundant to less;1760,1802,1888and1958are abrupt points of monthly average temperature. Roughly in1760and1958,the average temperature in June changes from warm to cold, in1802and1888, itchanges from cold to warm.(5) The reconstructed precipitation in Altay region has cycles of2.4-2.5a,8-8.8a and9.3a,(In July last year-in April current year), the monthly average temperaturereconstruction has3.9a,7.3-7.5a cycles (in June current year).