# northamerica_usa_ak043 - Twelvemile Summit treeline - Breitenmoser Tree Ring Chronology Data
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#		World Data Center for Paleoclimatology, Boulder
#				and
#		NOAA Paleoclimatology Program
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# NOTE: Please cite Publication, and Online_Resource and date accessed when using these data.
# If there is no publication information, please cite Investigators, Title, and Online_Resource and date accessed.
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# Online_Resource:
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# Original_Source_URL:
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# Description/Documentation lines begin with #
# Data lines have no #
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# Archive: Tree Rings
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# Contribution_Date
#	Date: 2016-01-07
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# Title
#	Study_Name: northamerica_usa_ak043 - Twelvemile Summit treeline - Breitenmoser Tree Ring Chronology Data
#--------------------
# Investigators
#	Investigators:  Breitenmoser, P.; Bronnimann, S.; Frank, D.
#--------------------
# Description_and_Notes
#	Description: Data from Breitenmoser 2014 Journal of past Climate supplementary, see publication for ARSTAN standardization details
#--------------------
# Publication
#	Authors: Breitenmoser, P.; Bronnimann, S.; Frank, D.
#	Published_Date_or_Year: 2014-03-11
#	Published_Title: Forward modelling of tree-ring width and comparison with a global network of tree-ring chronologies
#	Journal_Name: Climate of the Past
#	Volume: 10 
#	Edition:
#	Issue:
#	Pages: 437-449
#	DOI: 10.5194/cp-10-437-2014
#	Online_Resource: www.clim-past.net/10/437/2014/
#	Full_Citation:
#	Abstract: We investigate relationships between climate and tree-ring data on a global scale using the process-based Vaganov–Shashkin Lite (VSL) forward model of tree-ring width formation. The VSL model requires as inputs only latitude, monthly mean temperature, and monthly accumulated precipitation. Hence, this simple, process-based model enables ring-width simulation at any location where monthly climate records exist. In this study, we analyse the growth response of simulated tree rings to monthly climate conditions obtained from the CRU TS3.1 data set back to 1901. Our key aims are (a) to assess the VSL model performance by examining the relations between simulated and observed growth at 2287 globally distributed sites, (b) indentify optimal growth parameters found during the model calibration, and (c) to evaluate the potential of the VSL model as an observation operator for data-assimilation-based reconstructions of climate from tree-ring width. The assessment of the growth-onset threshold temperature of approximately 4–6 C for most sites and species using a Bayesian estimation approach complements other studies on the lower temperature limits where plant growth may be sustained. Our results suggest that the VSL model skilfully simulates site level treering series in response to climate forcing for a wide range of environmental conditions and species. Spatial aggregation of the tree-ring chronologies to reduce non-climatic noise at the site level yielded notable improvements in the coherence between modelled and actual growth. The resulting distinct and coherent patterns of significant relationships between the aggregated and simulated series further demonstrate the VSL model’s ability to skilfully capture the climatic signal contained in tree-ring series. Finally, we propose that the VSL model can be used as an observation operator in data assimilation approaches to reconstruct past climate.
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# Funding_Agency
#	Funding_Agency_Name: Swiss National Science Foundation
#	Grant:
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# Site_Information
#	Site_Name: Twelvemile Summit treeline
#	Location:
#	Country: United States
#	Northernmost_Latitude: 65.37
#	Southernmost_Latitude: 65.37
#	Easternmost_Longitude: -145.93
#	Westernmost_Longitude: -145.93
#	Elevation: 945 m
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# Data_Collection
#	Collection_Name: northamerica_usa_ak043B
#	Earliest_Year: 1847
#	Most_Recent_Year: 1996
#	Time_Unit: y_ad
#	Core_Length:
#	Notes: {"sensitivity":"temperature"}{"T1":"6.17473438063"}{"T2":"18.4213892289"}{"M1":"0.0217975454173"}{"M2":"0.265521954858"}
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# Species
#	Species_Name: white spruce
#	Species_Code: PCGL
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# Chronology:
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# Variables
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# Data variables follow that are preceded by ## in columns one and two.
# Data line variables format:  Variables list, one per line, shortname-tab-longname-tab-longname components (9 components: what, material, error, units, seasonality, archive, detail, method, C or N for Character or Numeric data)
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##age	age, , ,years AD, , , , ,N
##trsgi	tree ring standardized growth index, tree ring, ,percent relative to mean growth, , Tree Rings, , ,N
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# Data:
# Data lines follow (have no #)
# Data line format - tab-delimited text, variable short name as header
# Missing Values: nan
#
age	trsgi
1847	1.158
1848	1.159
1849	1.249
1850	0.978
1851	1.056
1852	1.193
1853	1.163
1854	1.167
1855	1.309
1856	1.219
1857	1.145
1858	1.251
1859	1.144
1860	1.277
1861	1.063
1862	1.045
1863	1.352
1864	1.496
1865	1.573
1866	1.364
1867	1.277
1868	1.098
1869	0.947
1870	1.012
1871	0.695
1872	0.777
1873	0.794
1874	0.982
1875	1.095
1876	0.998
1877	1.04
1878	0.935
1879	1.366
1880	1.189
1881	1.454
1882	0.884
1883	0.531
1884	0.462
1885	0.545
1886	0.711
1887	0.574
1888	0.377
1889	0.448
1890	0.63
1891	0.385
1892	0.238
1893	0.288
1894	0.305
1895	0.487
1896	0.512
1897	0.699
1898	0.706
1899	0.578
1900	0.661
1901	0.816
1902	0.794
1903	0.815
1904	0.913
1905	0.706
1906	0.888
1907	0.825
1908	0.924
1909	1.017
1910	0.83
1911	0.883
1912	0.808
1913	0.816
1914	1.101
1915	1.144
1916	1.037
1917	1.283
1918	1.207
1919	0.931
1920	0.767
1921	0.829
1922	0.613
1923	0.887
1924	0.75
1925	0.688
1926	1.012
1927	1.113
1928	1.164
1929	1.386
1930	1.337
1931	1.067
1932	1.249
1933	1.273
1934	1.511
1935	1.476
1936	1.246
1937	0.867
1938	0.813
1939	1.088
1940	0.881
1941	1.124
1942	1.217
1943	1.636
1944	1.12
1945	1.118
1946	1.424
1947	1.01
1948	1.018
1949	0.722
1950	1.151
1951	0.88
1952	1.075
1953	1.207
1954	1.22
1955	1.303
1956	1.032
1957	1.246
1958	1.245
1959	1.14
1960	1.481
1961	1.383
1962	1.256
1963	1.043
1964	1.374
1965	1.36
1966	1.215
1967	1.177
1968	1.165
1969	1.05
1970	0.575
1971	1.025
1972	0.829
1973	0.707
1974	0.878
1975	0.831
1976	0.665
1977	0.731
1978	0.62
1979	0.61
1980	0.9
1981	0.706
1982	1.209
1983	1.157
1984	1.04
1985	1.204
1986	1.115
1987	0.702
1988	0.725
1989	0.955
1990	0.974
1991	0.803
1992	0.825
1993	0.577
1994	0.6
1995	0.634
1996	0.726