# Ngamring Tso, Tibet 4,100 Year Sediment Data and Precipitation Reconstruction
#----------------------------------------------------------------------- 
#                World Data Service for Paleoclimatology, Boulder 
#                                  and 
#                     NOAA Paleoclimatology Program 
#             National Centers for Environmental Information (NCEI)
#----------------------------------------------------------------------- 
# Template Version 2.0
# 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. 
#
# Online_Resource: https://www.ncdc.noaa.gov/paleo/study/21111 
# Online_Resource: http://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/asia/tibet/ngamringtso2017loi.txt
#
# Original_Source_URL: 
# 
# Description/Documentation lines begin with #
# Data lines have no #
#
# Archive: Paleolimnology
#
# Parameter_Keywords: physical properties, geochemistry, reconstruction
#--------------------
# Contribution_Date
#	Date: 2016-12-21
#--------------------
# Title
#	Study_Name: Ngamring Tso, Tibet 4,100 Year Sediment Data and Precipitation Reconstruction
#--------------------
# Investigators
# 	Investigators: Conroy, J.L.; Hudson, A.M.; Overpeck, J.T.; Liu, K.-B.; Wang, L.; Cole, J.E.
#--------------------
# Description_and_Notes
#	Description: Sediment physical properties (grain size, loss-on-ignition) and geochemical (elemental composition) data 
#	from sediments collected in Ngamring Tso, Tibet, plus summer monsoon (June-September) precipitation reconstruction, 
#	covering the past 4,100 years.  
#	Provided Keywords: grain size, elemental abundance, loi, monsoon precipitation reconstruction, late Holocene  
#--------------------
# Publication 
#	Authors: Jessica L. Conroy, Adam M. Hudson, Jonathan T. Overpeck, Kam-Biu Liu, Luo Wang, Julia E. Cole
#	Published_Date_or_Year: 2017-01-15 
#	Published_Title: The primacy of multidecadal to centennial variability over late-Holocene forced change of the Asian Monsoon on the southern Tibetan Plateau
#	Journal_Name: Earth and Planetary Science Letters
#	Volume: 458
#	Edition: 
#	Issue: 
#	Pages: 337-348
#	Report_Number: 
#	DOI: 10.1016/j.epsl.2016.10.044
#	Online_Resource: http://www.sciencedirect.com/science/article/pii/S0012821X16306094
#	Full_Citation: 
#	Abstract: The nature of multidecadal to centennial variability of the Asian monsoon is largely unknown, hindering our understanding of how the modern precipitation regime compares to preindustrial variability, as well as how the Asian monsoon may change in coming decades. Here we use the sediment record from a closed-basin lake in southern Tibet, Ngamring Tso, along with other published paleoclimatic records, to assess summer monsoon precipitation variability over the 20th century and during the late Holocene (4100 cal yr BP to present). The first principal component of the Ngamring Tso grain size record, which is highly correlated with median grain size, correlates significantly with observed summer (June-September) precipitation. From CE 1940 to 2007, grain size decreased with increasing summer precipitation and increased with decreasing summer precipitation. Satellite images of Ngamring Tso reveal larger lake area in the 1970s and 2000s and smaller lake area in the 1980s and 1990s, suggesting monsoon precipitation-induced changes in lake depth or area likely govern grain size variability. In the context of the last 4100 yr, prolonged periods of relatively weak summer monsoon precipitation occurred from 2800-2600 cal yr BP, 2500-2300 cal yr BP, and 1600-400 cal yr BP. A trend toward increased summer precipitation began around 1000 cal yr BP, with above-average summer precipitation from 400 cal yr BP to present, peaking between 200-100 cal yr BP (CE 1750-1850). Dry and wet periods are coincident with dry and wet periods in other south-central Tibetan lake sediment records that reflect precipitation or moisture balance, and with regional proxies of the ISM and EASM, indicating south-central Tibet is influenced by both monsoon subsystems. However, western Tibet lake sediment records do not covary with the Ngamring Tso record, suggesting the spatial variability in Tibet precipitation that occurs on interannual timescales today may also characterize precipitation on multidecadal and centennial timescales during the late Holocene. 20th century precipitation variability in southern Tibet falls within the range of natural variability in the last 4100 yr, and does not show a clear trend of increasing precipitation as projected by models. Instead, it appears that poorly understood multidecadal to centennial internal modes of monsoon variability remained influential throughout the last 4100 yr. Thus, substantial multidecadal to centennial-scale hydroclimatic variability will complicate our ability to project and prepare for anthropogenic changes in the region's monsoon precipitation.
#------------------
# Funding_Agency 
#	Funding_Agency_Name: US National Science Foundation
#	Grant: SBD-HSD 0611320, DGE0221594, AGS 1243125
#------------------
# Site_Information 
#	Site_Name: Ngamring Tso
#	Location: Asia>Eastern Asia>China
#	Country: China
#	Northernmost_Latitude: 29.3
#	Southernmost_Latitude: 29.3
#	Easternmost_Longitude: 87.2
#	Westernmost_Longitude: 87.2
#	Elevation: m  
#------------------
# Data_Collection   
#	Collection_Name: NgamringTso2017LOI
#	Earliest_Year: 4113
#	Most_Recent_Year: -56
#	Time_Unit: Cal. Year BP
#	Core_Length: 1.4 m
#	Notes: 
#------------------
# Chronology_Information
#	Chronology:  210Pb, 137Cs, and 14C ages used to construct the Ngamring Tso age model. 
#	Asterisk indicates calibration in Calib Bomb (Hua et al., 2013).  
#	Double asterisk indicates sample not used in Bacon age modeling. 					
# 
# Sample type	Depth	Lab Number	FMC	14C yr	cal yr BP
# 	(cm)				
# 210Pb bulk sediment	1.25				-55.0+/-2.5
# 210Pb bulk sediment	2.25				-53.3+/-2.6
# 210Pb bulk sediment	3.25				-52.6+/-2.6
# 210Pb bulk sediment	4.25				-51.4+/-2.6
# 210Pb bulk sediment	5.25				-50.8+/-2.7
# 210Pb bulk sediment	6.25				-49.5+/-2.7
# 210Pb bulk sediment	7.25				-48.5+/-2.7
# 210Pb bulk sediment	8.75				-42.9+/-3.0
# 210Pb bulk sediment	10.75				-35.4+/-3.3
# 210Pb bulk sediment	12.75				-29.3+/-3.7
# 210Pb bulk sediment	14.75				-19.5+/-4.4
# 210Pb bulk sediment	17.75				-10.4+/-5.2
# 210Pb bulk sediment	20.75				-8.0+/-5.9
# 210Pb bulk sediment	26.75				12.6+/-6.2
# 137Cs bomb spike	20.75				-13.0+/-2.0
# 14C aquatic macrophyte	7.375	AA89074	1.1100+/-0.0076	Post-bomb	-47.3+/-3.1*
# 14C modern aquatic macrophyte		AA82310	1.0350+/-0.0050	Post-bomb	**
# 14C modern aquatic macrophyte		AA89073	1.0844+/-0.0047	Post-bomb	**
# 14C bulk OM	8.5	AA91766	0.8884+/-0.0042	951+/-38	**
# 14C bulk OM	30.5	AA91767	0.7700+/-0.0038	2099+/-40	
# 14C bulk OM	60.5	AA91768	0.6973+/-0.0036	2896+/-41	
# 14C bulk OM	120.5	AA91769	0.6570+/-0.0035	3374+/-43	
# 14C bulk OM	138.5	AA91770	0.5477+/-0.0031	4836+/-45	
# 
#----------------
# Variables 
#
# Data variables follow 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) 
#
## depth_cm	depth, , , cm, , , , ,N
## age_calBP	age, , , calendar years before present, , , , ,N
## loi550C	Loss on Ignition at 550C, , , % by weight, , paleolimnology, , ,N 
#
#----------------
# Data:
# Data lines follow (have no #)
# Data line format - tab-delimited text, variable short name as header
# Missing Values:  
#
depth_cm	age_calBP	loi550C
0.25	-56.8	5.3
1.125	-55.8	4.6
2.125	-54.7	1.6
3.125	-53.6	5.8
4.125	-52.5	5.0
5.125	-51.2	6.0
6.125	-49.1	5.7
7.125	-47.0	7.5
8.125	-44.9	6.1
9.5	-42.2	5.3
10.5	-39.1	6.6
11.5	-34.9	6.3
12.5	-30.7	2.8
13.5	-26.5	5.7
14.5	-22.3	6.1
15.5	-19.5	6.2
16.5	-18.2	6.1
17.5	-16.8	7.5
18.5	-15.4	6.1
19.5	-14.1	6.0
20.5	-12.1	7.3
21.5	-9.5	7.1
22.5	-6.9	7.1
23.5	-4.6	7.0
24.5	-2.3	6.1
25.5	3.3	7.0
26.5	11.8	7.0
27.5	19.6	1.8
28.5	27.3	8.3
29.5	35.1	8.3
30.5	60.5	6.3
31.5	101.4	3.6
32.5	139.8	5.7
33.5	178.2	5.6
34.5	216.6	5.4
35.5	264.7	5.6
36.5	322.8	4.9
37.5	380.2	4.6
38.5	436.6	5.5
39.5	489.0	6.0
40.5	540.6	5.3
41.5	598.1	6.6
42.5	656.2	6.3
43.5	713.0	6.2
44.5	767.4	6.2
45.5	821.5	7.6
46.5	876.3	5.3
47.5	932.4	6.3
48.5	989.8	3.4
49.5	1045.9	3.9
50.5	1098.5	7.1
51.5	1151.4	7.6
52.5	1208.1	6.3
53.5	1265.8	5.9
54.5	1321.3	6.3
55.5	1370.2	
56.5	1419.1	6.3
57.5	1471.0	5.4
58.5	1524.5	5.2
59.5	1578.6	4.3
60.5	1620.1	6.6
61.5	1648.7	9.0
62.5	1677.1	6.2
63.5	1704.7	5.1
64.5	1729.0	4.7
65.5	1753.6	4.0
66.5	1778.9	7.1
67.5	1802.1	5.8
68.5	1825.0	6.9
69.5	1847.8	5.3
70.5	1871.5	4.9
71.5	1896.4	4.7
72.25	1914.8	4.7
73.25	1938.4	4.2
74.25	1961.7	4.1
75.25	1984.4	5.7
76.25	2010.0	5.4
77.25	2036.3	5.6
78.25	2061.3	5.3
79.25	2084.9	5.6
80.25	2106.8	5.0
81.25	2132.1	4.8
82.25	2157.6	5.9
83.25	2180.9	5.9
84.25	2204.7	5.8
85.25	2228.5	5.2
86.25	2252.8	5.6
87.25	2276.9	9.9
88.25	2301.4	4.7
89.25	2325.0	5.3
90.25	2349.6	6.7
91.25	2373.2	4.4
92.25	2397.7	7.4
93.25	2422.4	5.1
94.25	2446.3	7.6
95.25	2469.5	6.0
96.25	2494.3	5.9
97.25	2521.4	5.8
98.25	2546.5	5.6
99.25	2570.4	5.1
100.25	2594.2	5.4
101.25	2621.6	5.7
102.25	2649.6	5.6
103.25	2677.3	4.7
104.25	2703.6	6.4
105.25	2728.1	5.7
106.25	2754.4	5.6
107.25	2781.5	4.5
108.25	2807.7	4.1
109.25	2833.1	6.3
110.25	2857.0	4.4
111.25	2883.3	4.2
112.25	2908.0	
113.25	2932.3	5.2
114.25	2957.6	5.7
115.25	2981.8	4.8
116.25	3008.6	6.9
117.25	3035.2	5.6
118.25	3059.7	6.6
119.25	3084.9	6.1
120.25	3114.1	5.9
121.25	3156.8	6.0
122.25	3198.2	6.2
123.25	3238.7	4.8
124.25	3277.5	4.5
125.25	3320.5	5.8
126.25	3380.4	5.9
127.25	3440.0	5.5
128.25	3502.2	4.9
129.25	3565.1	4.7
130.25	3626.1	4.6
131.25	3685.5	4.6
132.25	3747.2	6.3
133.25	3809.5	6.1
134.25	3873.6	6.1
135.25	3934.3	6.6
136.25	3986.8	7.2
137.25	4043.7	6.5
138.4	4113.6	6.1