# northamerica_usa_ak042 - Twelvemile Summit below treeline - Breitenmoser Tree Ring Chronology Data
#-----------------------------------------------------------------------
#		World Data Center for Paleoclimatology, Boulder
#				and
#		NOAA Paleoclimatology Program
#-----------------------------------------------------------------------
# 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
#--------------------
# Contribution_Date
#	Date: 2016-01-07
#--------------------
# Title
#	Study_Name: northamerica_usa_ak042 - Twelvemile Summit below 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 below 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_ak042B
#	Earliest_Year: 1828
#	Most_Recent_Year: 1996
#	Time_Unit: y_ad
#	Core_Length:
#	Notes: {"sensitivity":"moisture"}{"T1":"5.86714904614"}{"T2":"17.9906288996"}{"M1":"0.0229525330449"}{"M2":"0.287018387221"}
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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
1828	1.025
1829	0.831
1830	0.799
1831	0.607
1832	0.972
1833	0.59
1834	0.564
1835	0.293
1836	0.429
1837	0.457
1838	0.63
1839	0.669
1840	0.793
1841	0.747
1842	0.866
1843	0.763
1844	0.92
1845	0.629
1846	0.807
1847	0.637
1848	0.909
1849	0.665
1850	0.487
1851	0.512
1852	0.63
1853	0.976
1854	0.957
1855	0.872
1856	0.827
1857	1.133
1858	0.946
1859	1.03
1860	0.856
1861	1.081
1862	1.078
1863	1.095
1864	1.054
1865	1.178
1866	1.271
1867	1.237
1868	0.907
1869	0.91
1870	0.908
1871	0.83
1872	0.702
1873	0.864
1874	0.808
1875	0.98
1876	1.049
1877	0.973
1878	0.863
1879	0.963
1880	0.985
1881	1.103
1882	0.644
1883	0.513
1884	0.505
1885	0.623
1886	0.71
1887	0.641
1888	0.755
1889	0.818
1890	0.915
1891	0.905
1892	0.566
1893	0.662
1894	0.749
1895	1.106
1896	1.037
1897	1.221
1898	0.979
1899	0.842
1900	1.106
1901	1.291
1902	1.411
1903	1.424
1904	1.154
1905	1.133
1906	1.85
1907	1.594
1908	1.865
1909	1.826
1910	1.586
1911	1.762
1912	0.965
1913	1.467
1914	1.25
1915	1.3
1916	1.097
1917	1.138
1918	1.592
1919	0.774
1920	1.174
1921	1.039
1922	0.692
1923	1.301
1924	0.754
1925	0.853
1926	0.906
1927	0.839
1928	0.83
1929	1.379
1930	1.212
1931	1.039
1932	1.183
1933	1.131
1934	1.428
1935	1.872
1936	1.603
1937	1.383
1938	1.335
1939	1.461
1940	0.952
1941	1.261
1942	1.47
1943	1.593
1944	1.576
1945	1.268
1946	1.585
1947	1.052
1948	1.324
1949	0.789
1950	1.202
1951	0.821
1952	1.102
1953	0.955
1954	0.85
1955	0.951
1956	0.901
1957	0.997
1958	0.889
1959	0.946
1960	1.436
1961	1.363
1962	1.445
1963	0.95
1964	1.333
1965	1.173
1966	1.401
1967	1.319
1968	1.172
1969	0.879
1970	0.637
1971	1.236
1972	0.958
1973	0.686
1974	0.89
1975	0.884
1976	0.748
1977	0.757
1978	0.662
1979	0.703
1980	0.944
1981	0.694
1982	1.053
1983	1.001
1984	0.752
1985	0.81
1986	0.739
1987	0.525
1988	0.487
1989	0.619
1990	0.603
1991	0.577
1992	0.614
1993	0.341
1994	0.391
1995	0.467
1996	0.49