# northamerica_usa_ak038 - Grasshopper Hill - 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
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# Contribution_Date
#	Date: 2016-01-07
#--------------------
# Title
#	Study_Name: northamerica_usa_ak038 - Grasshopper Hill - 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: Grasshopper Hill
#	Location:
#	Country: United States
#	Northernmost_Latitude: 64.92
#	Southernmost_Latitude: 64.92
#	Easternmost_Longitude: -163.67
#	Westernmost_Longitude: -163.67
#	Elevation: 150 m
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# Data_Collection
#	Collection_Name: northamerica_usa_ak038B
#	Earliest_Year: 1835
#	Most_Recent_Year: 1999
#	Time_Unit: y_ad
#	Core_Length:
#	Notes: {"sensitivity":"temperature"}{"T1":"6.23199718268"}{"T2":"18.980201189"}{"M1":"0.0223470369816"}{"M2":"0.251243698326"}
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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)
#
##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
1835	0.576
1836	0.439
1837	0.685
1838	0.78
1839	0.744
1840	1.035
1841	0.928
1842	0.769
1843	0.786
1844	0.959
1845	1.27
1846	1.076
1847	1.037
1848	1.111
1849	0.914
1850	1.034
1851	1.001
1852	0.989
1853	1.041
1854	0.887
1855	1.183
1856	0.999
1857	1.293
1858	1.145
1859	0.942
1860	1.121
1861	0.778
1862	0.592
1863	0.595
1864	0.415
1865	0.399
1866	0.54
1867	0.542
1868	0.421
1869	0.53
1870	0.69
1871	0.735
1872	0.867
1873	1.028
1874	1.229
1875	1.281
1876	1.332
1877	1.429
1878	1.494
1879	1.332
1880	1.318
1881	1.385
1882	1.538
1883	1.061
1884	1.227
1885	1.264
1886	1.11
1887	1.25
1888	0.714
1889	0.971
1890	0.971
1891	1.291
1892	1.018
1893	1.109
1894	1.21
1895	1.108
1896	0.866
1897	0.896
1898	0.583
1899	0.414
1900	1.032
1901	0.533
1902	0.88
1903	0.777
1904	0.855
1905	0.694
1906	1.115
1907	0.794
1908	1.012
1909	0.912
1910	0.77
1911	1.171
1912	1.084
1913	1.671
1914	1.621
1915	1.359
1916	1.359
1917	0.938
1918	1.06
1919	0.788
1920	0.821
1921	0.895
1922	0.414
1923	0.696
1924	0.355
1925	0.616
1926	0.863
1927	0.849
1928	0.844
1929	1.052
1930	0.706
1931	0.762
1932	0.986
1933	0.963
1934	1.122
1935	1.301
1936	1.174
1937	1.194
1938	0.986
1939	1.066
1940	0.946
1941	1.32
1942	1.381
1943	1.769
1944	1.4
1945	1.235
1946	1.403
1947	1.291
1948	1.305
1949	1.021
1950	1.215
1951	1.227
1952	1.448
1953	1.625
1954	1.184
1955	1.316
1956	1.42
1957	1.217
1958	1.426
1959	1.202
1960	1.704
1961	1.183
1962	1.399
1963	1.014
1964	1.16
1965	0.856
1966	0.981
1967	1.012
1968	0.942
1969	0.922
1970	1.109
1971	1.117
1972	1.249
1973	0.982
1974	1.423
1975	1.032
1976	1.141
1977	1.643
1978	0.87
1979	0.914
1980	0.634
1981	0.538
1982	0.468
1983	0.498
1984	0.56
1985	0.703
1986	0.713
1987	0.76
1988	0.728
1989	0.644
1990	0.666
1991	0.516
1992	0.673
1993	0.69
1994	0.515
1995	0.49
1996	0.748
1997	1.102
1998	0.916
1999	1.016