# northamerica_usa_ak017 - Grewingk Glacier - 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_ak017 - Grewingk Glacier - 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: Grewingk Glacier
#	Location:
#	Country: United States
#	Northernmost_Latitude: 59.62
#	Southernmost_Latitude: 59.62
#	Easternmost_Longitude: -151.15
#	Westernmost_Longitude: -151.15
#	Elevation: 20 m
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# Data_Collection
#	Collection_Name: northamerica_usa_ak017B
#	Earliest_Year: 1785
#	Most_Recent_Year: 1988
#	Time_Unit: y_ad
#	Core_Length:
#	Notes: {"sensitivity":"temperature"}{"T1":"4.18436751857"}{"T2":"14.8711341508"}{"M1":"0.0228903084209"}{"M2":"0.508176690037"}
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# Species
#	Species_Name: Sitka spruce
#	Species_Code: PCSI
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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
1785	1.278
1786	1.186
1787	0.958
1788	0.718
1789	0.596
1790	0.652
1791	0.497
1792	0.695
1793	0.76
1794	1.175
1795	1.315
1796	1.381
1797	1.354
1798	1.001
1799	1.037
1800	0.907
1801	1.237
1802	1.348
1803	1.365
1804	0.82
1805	0.685
1806	1.052
1807	1.107
1808	1.031
1809	0.936
1810	0.859
1811	0.724
1812	0.671
1813	0.611
1814	0.808
1815	1.056
1816	0.971
1817	0.948
1818	0.814
1819	0.955
1820	1.005
1821	0.672
1822	1.032
1823	1.018
1824	1.24
1825	1.044
1826	0.949
1827	0.946
1828	0.761
1829	1.005
1830	0.738
1831	0.98
1832	1.288
1833	0.88
1834	0.939
1835	1.163
1836	1.199
1837	0.883
1838	1.042
1839	1.167
1840	1.0
1841	1.067
1842	0.719
1843	0.838
1844	1.207
1845	1.33
1846	1.449
1847	1.324
1848	0.802
1849	0.646
1850	0.552
1851	0.462
1852	0.584
1853	0.607
1854	0.651
1855	0.623
1856	0.441
1857	0.579
1858	0.551
1859	0.709
1860	0.714
1861	0.66
1862	0.524
1863	0.731
1864	0.701
1865	0.782
1866	0.701
1867	0.849
1868	0.585
1869	0.493
1870	0.594
1871	0.459
1872	0.594
1873	0.542
1874	0.692
1875	0.8
1876	0.701
1877	0.822
1878	0.853
1879	0.804
1880	1.121
1881	1.534
1882	1.213
1883	1.654
1884	1.757
1885	1.287
1886	1.308
1887	1.237
1888	1.492
1889	0.957
1890	1.511
1891	1.555
1892	1.364
1893	1.632
1894	1.281
1895	0.98
1896	0.9
1897	0.913
1898	0.69
1899	0.984
1900	1.059
1901	0.956
1902	1.044
1903	0.784
1904	0.914
1905	0.942
1906	0.768
1907	0.951
1908	1.051
1909	0.986
1910	0.957
1911	0.98
1912	0.838
1913	0.796
1914	0.819
1915	1.031
1916	0.769
1917	0.999
1918	1.064
1919	1.055
1920	1.178
1921	0.888
1922	0.777
1923	0.831
1924	0.857
1925	0.857
1926	0.885
1927	0.811
1928	1.005
1929	1.042
1930	1.127
1931	0.969
1932	1.161
1933	1.339
1934	1.23
1935	1.161
1936	1.169
1937	1.067
1938	1.209
1939	1.25
1940	1.559
1941	1.548
1942	1.317
1943	1.449
1944	1.49
1945	1.28
1946	1.436
1947	1.629
1948	1.403
1949	1.453
1950	1.358
1951	1.211
1952	1.009
1953	1.093
1954	0.828
1955	0.774
1956	0.767
1957	0.905
1958	0.828
1959	1.024
1960	1.027
1961	1.116
1962	1.174
1963	1.034
1964	1.171
1965	0.971
1966	0.964
1967	0.85
1968	0.854
1969	0.78
1970	0.768
1971	0.851
1972	0.656
1973	0.568
1974	0.652
1975	0.59
1976	0.811
1977	0.736
1978	0.59
1979	0.945
1980	0.882
1981	1.132
1982	0.901
1983	0.897
1984	0.843
1985	0.883
1986	0.882
1987	0.841
1988	1.014