# Polar Ice Cores 3,000 Year Nitrous Oxide d15N and d18O Data
#----------------------------------------------------------------------- 
#                World Data Service for Paleoclimatology, Boulder 
#                                  and 
#                     NOAA Paleoclimatology Program 
#             National Centers for Environmental Information (NCEI)
#----------------------------------------------------------------------- 
# 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. 
#
# Online_Resource: https://www.ncdc.noaa.gov/paleo/study/25530 
#       Description: NOAA Landing Page
# Online_Resource: https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/siple/siple2018n2o-iso.txt 
#       Description: NOAA location of the template
#
# Original_Source_URL:  
#       Description:
# 
# Description/Documentation lines begin with #
# Data lines have no #
#
# Archive: Ice Core
#
# Dataset DOI: 
#
# Parameter_Keywords: oxygen isotopes, nitrogen isotopes
#--------------------
# Contribution_Date
#	Date: 2018-10-31
#--------------------
# File_Last_Modified_Date
#	Date: 2018-10-31
#--------------------
# Title
#	Study_Name: Polar Ice Cores 3,000 Year Nitrous Oxide d15N and d18O Data
#--------------------
# Investigators
#	Investigators: Prokopiou, M.; Sapart, C.J.; Rosen, J.; Sperlich, P.; Blunier, T.; Brook, E.; van de Wal, R.S.W.; Röckmann, T.
#--------------------
# Description_Notes_and_Keywords
#	Description: Ice core nitrogen and oxygen isotope (d15N and d18O) of nitrous oxide (N2O) data from polar ice cores for the past 3,000 years. 
#	This file contains data from Rosen 2014 from the Siple Dome ice core.
#--------------------
# Publication 
#	Authors: M. Prokopiou, C.J. Sapart, J. Rosen, P. Sperlich, T. Blunier, E. Brook, R.S.W. van de Wal, T. Röckmann
#	Published_Date_or_Year: 2018-09-27     
#	Published_Title: Changes in the Isotopic Signature of Atmospheric Nitrous Oxide and Its Global Average Source During the Last Three Millennia
#	Journal_Name: Journal of Geophysical Research: Atmospheres
#	Volume: 123
#	Edition: 
#	Issue: 18
#	Pages: 10,757-10,773
#	Report_Number: 
#	DOI: 10.1029/2018JD029008
#	Online_Resource: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JD029008
#	Full_Citation: 
#	Abstract: Nitrous oxide (N2O) is a strong greenhouse gas whose mole fraction in the atmosphere has increased over the industrial period. We present a new set of isotope measurements of N2O in air extracted from ice cores covering the last 3,000 years. For the preindustrial (PI) atmosphere, we find an average N2O mole fraction of (267 ± 1) nmol/mol and average tropospheric N2O isotopic values of d15NavPI = (9.5 ± 0.1)permil, d18OPI = (47.1 ± 0.2)permil, d15NalphaPI = (17.8 ± 0.4)permil, and d15NBetaPI = (1.2 ± 0.4)permil. From PI to modern times all isotope signatures decreased with a total change of d15Nav = (-2.7 ± 0.2)permil, d18O = (-2.5 ± 0.4)permil, d15Nalpha = (-2.0 ± 0.7)permil, and d15NBeta (-3.5 ± 0.7)permil. Interestingly, the temporal evolution is not the same for d15Nav and d18O. d18O trends are relatively larger during the early part, and d15Nav trends are larger during the late part of the industrial period, implying a decoupling of sources over the industrial period. Using a mass balance model, we determined the isotopic composition of the total average N2O source. Assuming that the total present source is the sum of a constant natural source and an increasing anthropogenic source, this anthropogenic source has an isotopic signature of d15Navsource,anthrop = (-15.0 ± 2.6)permil, d18Osource,anthrop = (30.0 ± 2.6)permil, d15Nalphasource,anthrop = (-4.5 ± 1.7)permil, and d15NBetasource,anthrop = (-24.0 ± 8.4)permil. The 15N site preference of the source has increased since PI times, which is indicative of a relative shift from denitrification to nitrification sources, consistent with agricultural emissions playing a major role in the N2O increase. 
#------------------
# Publication 
#	Authors: Rosen, J.L.
#	Published_Date_or_Year: 2014     
#	Published_Title: Constraints on Preindustrial-Modern Changes in Atmospheric Nitrous Oxide Sources from Position-Dependent Isotope Measurements in Ice Core Samples. 
#	Journal_Name: PhD Thesis, College of Earth, Ocean and Atmospheric Science, Oregon State University, Corvallis, 2014.
#	Volume: 
#	Edition: 
#	Issue: 
#	Pages:
#	Report_Number: 
#	DOI: 
#	Online_Resource: 
#	Full_Citation: 
#	Abstract: 
#------------------
# Funding_Agency 
#	Funding_Agency_Name: Dutch Science Foundation (NWO)
#	Grant: 851.30.020, 865.07.001
#------------------
# Site_Information 
#	Site_Name: Siple Dome
#	Location: Antarctica
#	Country:  
#	Northernmost_Latitude: -81.65
# 	Southernmost_Latitude: -81.65
# 	Easternmost_Longitude: -148.82
# 	Westernmost_Longitude: -148.82
# 	Elevation: 621 m
#------------------
# Data_Collection   
#	Collection_Name: Siple2014N2Oiso
#	Earliest_Year: 1474
#	Most_Recent_Year: 1913
#	Time_Unit: CE
#	Core_Length: 
#	Notes: 
#------------------
# Chronology_Information
#	Chronology: 
# 	
#----------------	
# Variables 
#
# 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, , , m, , , , ,N,
## age_AD	age, , , AD, , , , ,N,
## d15N	delta 15N, nitrous oxide, , per mil, ,ice cores,corrected,continuous-flow isotope ratio mass spectrometry (IRMS),N,gravity corrected
## d18O	delta 18O, nitrous oxide, , per mil, ,ice cores,corrected,continuous-flow isotope ratio mass spectrometry (IRMS),N,gravity corrected
## d15Na	delta 15Nalpha, nitrous oxide, , per mil, ,ice cores,corrected,continuous-flow isotope ratio mass spectrometry (IRMS),N,gravity corrected
## d15Nb	delta 15Nbeta, nitrous oxide, , per mil, ,ice cores,corrected,continuous-flow isotope ratio mass spectrometry (IRMS),N,gravity corrected
#
#----------------
# Data:
# Data lines follow (have no #)
# Data line format - tab-delimited text, variable short name as header
# Missing Values:  
#
depth_m	age_AD	d15N	d18O	d15Na	d15Nb
110.61	1474.5	9.5	46.96	16.17	2.83
106.45	1502.7	9.72	47.08	22.3	-2.85
102.5	1526.6	9.52	46.02	17.16	1.89
98.38	1551.4	8.63	47.18	16.71	0.54
94.29	1576.1	9.42	47.16	19.74	-0.089
90.01	1613.4	9.75	47.21	21.08	-1.59
85.71	1654.6	9.47	47.01	20.21	-1.26
81.27	1697.1	9.43	46.49	17.58	1.28
77.42	1749	8.7	47.26	14	3.41
73.28	1805.2	9.33	47.93	17.71	0.95
67.73	1838.3	8.86	46.2	15.59	2.13
63.34	1864.5	8.96	47.78	17.11	0.8
59.15	1913.9	7.82	43.64	17.24	-1.61