# Astronomical Solutions 3.49-0 Ga for Earth's Orbital Eccentricity and Inclination, Obliquity, and Climatic Precession
#-----------------------------------------------------------------------
#               World Data Service for Paleoclimatology, Boulder
#                                   and
#                      NOAA Paleoclimatology Program
#-----------------------------------------------------------------------
# Template Version 4.0
# Encoding: UTF-8
# Data License: 
# NOTE: Please cite original publication, NOAA Landing Page URL, dataset and publication DOIs (where available), and date accessed when using downloaded data.
# If there is no publication information, please cite investigator, study title, NOAA Landing Page URL, and date accessed.
#
# Description/Documentation lines begin with '#' followed by a space
# Data lines have no '#'
#
# NOAA_Landing_Page: https://www.ncei.noaa.gov/access/paleo-search/study/39199
#   Landing_Page_Description: NOAA Landing Page of this file's parent study, which includes all study metadata.
#
# Study_Level_JSON_Metadata: https://www.ncei.noaa.gov/pub/data/metadata/published/paleo/json/noaa-forcing-39199.json
#   Study_Level_JSON_Description: JSON metadata of this data file's parent study, which includes all study metadata.
#
# Data_Type: Climate Forcing
#
# Dataset_DOI:
#
# Science_Keywords: 
#---------------------------------------
# Resource_Links
#
# Data_Download_Resource: https://www.ncei.noaa.gov/pub/data/paleo/climate_forcing/orbital_variations/zeebe2024/zeebe2024-eiop_readme.txt
#   Data_Download_Description: NOAA Template File; EIOP Readme Data
#
#---------------------------------------
# Contribution_Date
#   Date: 2024-03-20
#---------------------------------------
# File_Last_Modified_Date
#   Date: 2024-05-07
#---------------------------------------
# Title
#   Study_Name: Astronomical Solutions 3.49-0 Ga for Earth's Orbital Eccentricity and Inclination, Obliquity, and Climatic Precession
#---------------------------------------
# Investigators
#   Investigators: Zeebe, Richard; Lantink, Margriet
#---------------------------------------
# Description_Notes_and_Keywords
#   Description: https://www.ncei.noaa.gov/pub/data/paleo/climate_forcing/orbital_variations/zeebe2024/pgigk/ contains output for each solution for the computed periods of short and long eccentricity cycles (P[g*-g*].dat) and the averaged main precession
(P1-P5) and obliquity periods (O1-O4, O6) over 3.5 Gyr (P[PrecOblq].dat). https://www.ncei.noaa.gov/pub/data/paleo/climate_forcing/orbital_variations/zeebe2024/zb23-n64-eiop/ contains the split output. The full (non-split) output is
available here: https://www.soest.hawaii.edu/oceanography/faculty/zeebe_files/Astro/3.5Gyr/
#         Provided Keywords: Astronomical Forcing, Milankovitch Forcing
#---------------------------------------
# Publication
#   Authors: Zeebe, R.E. and Lantink, M.L.
#   Published_Date_or_Year: 2024 
#   Published_Title: A secular solar system resonance that disrupts the dominant cycle in Earth's orbital eccentricity (g2-g5): Implications for astrochronology
#   Journal_Name: The Astronomical Journal
#   Volume: 
#   Edition: 
#   Issue: 
#   Pages: 
#   Report_Number: 
#   DOI: 10.3847/1538-3881/ad32cf
#   Online_Resource:
#   Full_Citation: 
#   Abstract: The planets' gravitational interaction causes rhythmic changes in Earth's orbital parameters (also called Milankovic cycles), which have powerful applications in geology and astrochronology. For instance, the primary astronomical eccentricity cycle due to the secular frequency term (g2-g5) (~405 kyr in the recent past) utilized in deep-time analyses is dominated by Venus' and Jupiter's orbits, aka long eccentricity cycle. The widely accepted and long-held view is that (g2-g5) was practically stable in the past and may hence be used as a "metronome" to reconstruct accurate ages and chronologies. However, using state-of-the-art integrations of the solar system, we show here that (g2-g5) can become unstable over long time scales, without major changes in, or destabilization of, planetary orbits. The (g2-g5) disruption is due to the secular resonance o12 = (g1 - g2) + (s1 - s2), a major contributor to solar system chaos. We demonstrate that entering/exiting the o12 resonance is a common phenomenon on long time scales, occurring in ~40% of our solutions. During o12-resonance episodes, (g2-g5) is very weak or absent and Earth's orbital eccentricity and climate-forcing spectrum are unrecognizable compared to the recent past. Our results have fundamental implications for geology and astrochronology, as well as climate forcing because the paradigm that the longest Milankovic cycle dominates Earth's astronomical forcing, is stable, and has a period of ~405 kyr requires revision.
#---------------------------------------
# Funding_Agency
#   Funding_Agency_Name: US National Science Foundation
#   Grant: 2021-2800, 2021-2797
#---------------------------------------
# Funding_Agency
#   Funding_Agency_Name: Heising-Simons Foundation
#   Grant: 2021-2800, 2021-2797
#---------------------------------------
# Site_Information
#   Site_Name: Global
#   Location: Global
#   Northernmost_Latitude: 90
#   Southernmost_Latitude: -90
#   Easternmost_Longitude: 180
#   Westernmost_Longitude: -180
#   Elevation_m: 
#---------------------------------------
# Data_Collection
#   Collection_Name: eiop_readme
#   First_Year: 3500000000
#   Last_Year: 0
#   Time_Unit: calendar year before present
#   Core_Length_m: 
#   Parameter_Keywords: other 
#   Notes: Solutions ZB23 (number of runs=64) for eccentricity, inclination, obliquity, climatic precession spanning 0 to -3.5 Gyr at 400-year resolution. Each run (run number designated as RXX) has been split into 10 files (01 through 10), each of which spans a consecutive 3.5 Myr slice.
#---------------------------------------
# Chronology_Information 
# Chronology: 
#---------------------------------------
# Variables
# PaST_Thesaurus_Download_Resource: https://www.ncei.noaa.gov/access/paleo-search/skos/past-thesaurus.rdf
#   PaST_Thesaurus_Download_Description: Paleoenvironmental Standard Terms (PaST) Thesaurus terms, definitions, and relationships in SKOS format.
#
# Data variables follow that are preceded by "##" in columns one and two.
# Variables list, one per line, shortname-tab-var components: what, material, error, units, seasonality, data type, detail, method, C or N for Character or Numeric data)
#
## time	age,,,calendar kiloyear before present,,Climate Forcing,,,N,[kyr] in the past; negative numbers are times before present
## ecc	orbital parameter,,,dimensionless,,Climate Forcing,,,N,eccentricity
## inc	orbital parameter,,,radian,,Climate Forcing,,,N,inclination; frame = HCI
## oblq	orbital parameter,,,radian,,Climate Forcing,,,N,obliquity
## clim-prec	orbital parameter,,,dimensionless,,Climate Forcing,,,N,climatic precession; e*sin(\bar\omega)
#------------------------
# Data:
# Data lines follow (have no #)
# Data line format - tab-delimited text, variable short name as header
# Missing_Values: NaN