# South Pole Ice Core (SPICEcore) SP19 Age Model
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#                World Data Service for Paleoclimatology, Boulder 
#                                  and 
#                     NOAA Paleoclimatology Program 
#             National Centers for Environmental Information (NCEI)
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# Template Version 3.0
# Encoding: UTF-8
# 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: https://www.ncdc.noaa.gov/paleo/study/27690
#       Description: NOAA Landing Page
# Online_Resource: https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/sp19dens.txt 
#       Description: NOAA location of the template
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# Original_Source_URL:  
#       Description:
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# Description/Documentation lines begin with #
# Data lines have no #
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# Archive: Ice Core
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# Dataset DOI: 
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# Parameter_Keywords: age control, chemistry, accumulation, nitrogen isotopes
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# Contribution_Date
#	Date: 2019-10-08
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# File_Last_Modified_Date
#	Date: 2019-10-08
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# Title
#	Study_Name: South Pole Ice Core (SPICEcore) SP19 Age Model
#--------------------
# Investigators
#	Investigators: Winski, D.A.; Fudge, T.J.; Ferris, D.G.; Osterberg, E.C.; Fegyveresi, J.M.; Cole-Dai, J.; Thundercloud, Z.; Cox, T.S.; Kreutz, K.J.; Ortman, N.; Buizert, C.; Epifanio, J.; Brook, E.J.; Beaudette, R.; Severinghaus, J.; Sowers, T.; Steig, E.J.; Kahle, E.C.; Jones, T.R.; Morris, V.; Aydin, M.; Nicewonger, M.R.; Casey, K.A.; Alley, R.B.; Waddington, E.D.; Iverson, N.A.; Dunbar, N.W.; Bay, R.C.; Souney, J.M.; Sigl, M.; McConnell, J.R.
#--------------------
# Description_Notes_and_Keywords
#	Description: The SP19 timescale: depth-age relationship and associated uncertainties for the South Pole Ice Core (SPICEcore), with supporting data. 
#--------------------
# Publication 
#	Authors: Dominic A. Winski, Tyler J. Fudge, David G. Ferris, Erich C. Osterberg, John M. Fegyveresi, Jihong Cole-Dai, Zayta Thundercloud, Thomas S. Cox, Karl J. Kreutz, Nikolas Ortman, Christo Buizert, Jenna Epifanio, Edward J. Brook, Ross Beaudette, Jeffrey Severinghaus, Todd Sowers, Eric J. Steig, Emma C. Kahle, Tyler R. Jones, Valerie Morris, Murat Aydin, Melinda R. Nicewonger, Kimberly A. Casey, Richard B. Alley, Edwin D. Waddington, Nels A. Iverson, Nelia W. Dunbar, Ryan C. Bay, Joseph M. Souney, Michael Sigl, and Joseph R. McConnell
#	Published_Date_or_Year: 2019-10-08     
#	Published_Title: The SP19 Chronology for the South Pole Ice Core - Part 1: volcanic matching and annual layer counting
#	Journal_Name: Climate of the Past 
#	Volume: 15
#	Edition: 
#	Issue: 5
#	Pages:
#	Report_Number: 
#	DOI: 10.5194/cp-15-1793-2019
#	Online_Resource: https://www.clim-past.net/15/1793/2019/
#	Full_Citation: 
#	Abstract: The South Pole Ice Core (SPICEcore) was drilled in 2014-2016 to provide a detailed multi-proxy archive of paleoclimate conditions in East Antarctica during the Holocene and late Pleistocene. Interpretation of these records requires an accurate depth-age relationship. Here, we present the SPICEcore (SP19) timescale for the age of the ice of SPICEcore. SP19 is synchronized to the WD2014 chronology from the West Antarctic Ice Sheet Divide (WAIS Divide) ice core using stratigraphic matching of 251 volcanic events. These events indicate an age of 54302±519BP (years before 1950) at the bottom of SPICEcore. Annual layers identified in sodium and magnesium ions to 11341BP were used to interpolate between stratigraphic volcanic tie points, yielding an annually resolved chronology through the Holocene. Estimated timescale uncertainty during the Holocene is less than 18 years relative to WD2014, with the exception of the interval between 1800 to 3100 BP when uncertainty estimates reach ±25 years due to widely spaced volcanic tie points. Prior to the Holocene, uncertainties remain within 124 years relative to WD2014. Results show an average Holocene accumulation rate of 7.4cm yr-1 (water equivalent). The time variability of accumulation rate is consistent with expectations for steady-state ice flow through the modern spatial pattern of accumulation rate. Time variations in nitrate concentration, nitrate seasonal amplitude and d15N of N2 in turn are as expected for the accumulation rate variations. The highly variable yet well-constrained Holocene accumulation history at the site can help improve scientific understanding of deposition-sensitive climate proxies such as d15N of N2 and photolyzed chemical compounds.
#------------------
# Funding_Agency 
#	Funding_Agency_Name: US National Science Foundation
#	Grant: 1443105, 1141839 (Steig), 1443336 (Osterberg), 1443397 (Kreutz), 1443663 (Cole-Dai), 1443232 (Waddington, Fudge), 1142517, 1443470 (Aydin), 1443464 (Sowers), 1443710 (Severinghaus), 1542778 (Alley, Fegyveresi), 1443472, 1643722 (Brook), 1543454 (Dunbar)
#------------------
# Site_Information 
#	Site_Name: South Pole Ice Core (SPICEcore)
#	Location: Antarctica
#	Country:  
#	Northernmost_Latitude: -89.99
# 	Southernmost_Latitude: -89.99 
# 	Easternmost_Longitude: -99.16
# 	Westernmost_Longitude: -99.16
# 	Elevation: 2835 m 
#------------------
# Data_Collection   
#	Collection_Name: SP19dens
#	Earliest_Year: 1100
#	Most_Recent_Year: -65
#	Time_Unit: Cal. years BP
#	Core_Length: 127 m
#	Notes: Bag average density data from two shallow 3-inch firn cores drilled at the site of the SPC14 deep core. Bag average core density was measured in the field after logging and core cutting. 
#------------------
# Chronology_Information
#	Chronology: Chronology is constrained by volcanic events linked with the WAIS-Divie ice core and annual layer counting of sodium and magnesium.  
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# Variables 
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# Data variables follow are preceded by "##" in columns one and two.
# Data line variables format:  one per line, shortname-tab-variable components (what, material, error, units, seasonality, data type,detail, method, C or N for Character or Numeric data, free text) 
#
## depth_m	depth, , , meter, , , , ,N, mid-depth
## density	density, ice, , gram per cubic centimeter, , ice core, , ,N, Core mass was measured using an analog triple beam balance scale; core diameter was measured at three points along the core using calipers and averaged. Core drilling by Trevor Popp; core logging and density measurements by Todd Sowers and Christo Buizert; Nov-Dec 2015. Data from the two cores have been combined here - with the third column identifying the core number
## core	core identifier, , , , , ice core, , ,N, core identifier
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#----------------
# Data:
# Data lines follow (have no #)
# Data line format - tab-delimited text, variable short name as header
# Missing Values:  
#
depth_m	density	core
0.51	0.4305	1
1.53	0.3877	1
2.51	0.3624	1
3.5	0.4165	1
4.5	0.4182	2
4.51	0.4302	1
5.49	0.4288	2
5.51	0.4327	1
6.49	0.431	2
6.52	0.4452	1
7.5	0.4552	2
7.53	0.4464	1
8.5	0.4643	2
8.53	0.477	1
9.5	0.4692	2
9.54	0.4717	1
10.5	0.4665	2
10.55	0.4807	1
11.5	0.4895	2
11.55	0.5057	1
12.48	0.4992	2
12.55	0.4967	1
13.45	0.5056	2
13.57	0.5002	1
14.45	0.504	2
14.57	0.5162	1
15.44	0.5083	2
15.57	0.5166	1
16.44	0.5163	2
16.59	0.5118	1
17.4	0.5191	2
17.59	0.5328	1
18.39	0.5247	2
18.59	0.5416	1
19.39	0.5349	2
19.6	0.5389	1
20.37	0.5357	2
20.59	0.5488	1
21.35	0.5402	2
21.59	0.5488	1
22.34	0.55	2
22.59	0.5533	1
23.32	0.545	2
23.59	0.5625	1
24.31	0.5514	2
24.6	0.5566	1
25.31	0.5556	2
25.6	0.5665	1
26.31	0.5621	2
26.6	0.5689	1
27.31	0.5681	2
27.61	0.5671	1
28.3	0.5776	2
28.61	0.575	1
29.29	0.5838	2
29.61	0.5875	1
30.3	0.5894	2
30.61	0.5869	1
31.32	0.5863	2
31.61	0.5912	1
32.32	0.5986	2
32.61	0.592	1
33.37	0.5938	2
33.61	0.5944	1
34.4	0.6	2
34.62	0.5999	1
35.36	0.6002	2
35.62	0.6021	1
36.39	0.6061	2
36.62	0.6049	1
37.42	0.6139	2
37.63	0.6066	1
38.42	0.6132	2
38.64	0.6113	1
39.39	0.6155	2
39.64	0.6135	1
40.4	0.6258	2
40.65	0.6163	1
41.4	0.6311	2
41.64	0.6231	1
42.37	0.6286	2
42.64	0.625	1
43.4	0.6281	2
43.65	0.627	1
44.42	0.6285	2
44.65	0.6303	1
45.37	0.6341	2
45.64	0.6311	1
46.36	0.6385	2
46.64	0.6354	1
47.36	0.6393	2
47.64	0.643	1
48.38	0.6459	2
48.67	0.6482	1
49.38	0.6446	2
49.71	0.6557	1
50.38	0.652	2
50.71	0.6573	1
51.38	0.6542	2
51.72	0.6577	1
52.39	0.6585	2
52.72	0.6569	1
53.37	0.6579	2
53.73	0.6624	1
54.36	0.6631	2
54.73	0.6692	1
55.3	0.6639	2
55.73	0.6676	1
56.32	0.6628	2
56.74	0.6713	1
57.28	0.6643	2
57.75	0.6787	1
58.3	0.6733	2
58.75	0.6848	1
59.22	0.6753	2
59.75	0.6823	1
60.16	0.6784	2
60.75	0.6874	1
61.09	0.6841	2
61.75	0.6858	1
62.09	0.6849	2
62.76	0.6869	1
63.04	0.6886	2
63.76	0.6894	1
63.98	0.6891	2
64.76	0.6999	1
64.93	0.6946	2
65.77	0.6964	1
65.93	0.6939	2
66.76	0.704	1
66.94	0.6937	2
67.76	0.7019	1
67.94	0.6931	2
68.76	0.7019	1
68.94	0.6964	2
69.76	0.7099	1
69.94	0.705	2
70.76	0.7136	1
70.94	0.7046	2
71.76	0.7152	1
71.94	0.7025	2
72.76	0.7181	1
72.94	0.7025	2
73.76	0.7215	1
73.93	0.7117	2
74.76	0.7271	1
74.93	0.7128	2
75.76	0.731	1
75.89	0.7148	2
76.76	0.7335	1
76.88	0.7228	2
77.77	0.723	1
77.89	0.7213	2
78.78	0.7292	1
78.89	0.7257	2
79.77	0.7336	1
79.87	0.7318	2
80.71	0.7452	1
80.85	0.7258	2
81.67	0.7391	1
81.85	0.729	2
82.59	0.7474	1
82.84	0.7351	2
83.59	0.7308	1
83.82	0.7397	2
84.59	0.7316	1
84.82	0.7377	2
85.59	0.739	1
85.8	0.7481	2
86.6	0.7472	1
86.78	0.7479	2
87.6	0.7511	1
87.7	0.7601	2
88.6	0.7527	1
88.69	0.7547	2
89.59	0.7579	1
89.7	0.7589	2
90.54	0.7606	1
90.7	0.7595	2
91.45	0.7773	1
91.7	0.7678	2
92.45	0.7689	1
92.7	0.7613	2
93.45	0.7728	1
93.7	0.767	2
94.43	0.7736	1
94.7	0.7672	2
95.43	0.7708	1
95.7	0.7726	2
96.44	0.7766	1
96.71	0.7707	2
97.7	0.7897	2
98.69	0.7777	2
99.68	0.7785	2
100.67	0.7773	2
101.65	0.7942	2
102.66	0.7944	2
103.66	0.7976	2
104.66	0.7939	2
105.65	0.8012	2
106.65	0.8012	2
107.7	0.8065	2
108.7	0.8038	2
109.7	0.8121	2
110.7	0.8099	2
111.7	0.8112	2
112.7	0.8186	2
113.71	0.8155	2
114.71	0.8164	2
115.69	0.8219	2
116.69	0.8286	2
117.68	0.8342	2
118.61	0.8405	2
119.6	0.8401	2
120.61	0.8306	2
121.6	0.841	2
122.6	0.8399	2
123.56	0.8369	2
124.56	0.8381	2
125.56	0.842	2
126.55	0.8402	2
127.53	0.844	2