DOI: 10.5061/dryad.2rbnzs822
title: Tracing stratospheric transport using sub-annual plutonium-239 fallout in polar ice cores

description: Polar ice cores preserve high-resolution archives of historical
 atmospheric transport, providing unique insights into long-term
 stratospheric processes. Here, we present the first sub-annual
 plutonium-239 (239Pu) deposition records from Greenland and Antarctic ice
 cores (1940–1980 CE). The limited or delayed fallout from Ivy Mike (1952
 CE) compared to Operation Castle (1954 CE), despite their detonation in
 close proximity, exemplifies how stratospheric circulation and seasonal
 dynamics create periods of reduced transport to Antarctica. These records
 also reveal seasonal fallout patterns in Antarctica, with enhanced
 deposition during austral summers driven by stratosphere-troposphere
 exchange. Our findings refine the understanding of global aerosol
 dispersion and offer additional insight for modeling atmospheric
 processes, including those related to volcanic eruptions and
 geoengineering.
description: # Tracing stratospheric transport using sub-annual plutonium-239 fallout
 in polar ice cores Dataset DOI:
 [10.5061/dryad.2rbnzs822](10.5061/dryad.2rbnzs822) ## Description of the
 data and file structure This dataset contains high-resolution measurements
 of plutonium-239 concentrations from polar ice cores, used to investigate
 stratospheric transport processes. The data were obtained from one
 Greenland ice core (NEEM) and three Antarctic ice cores (GV7, Styx,
 Hercules Névé) covering the period 1940–1980 CE. Sub-annual resolution
 sampling and analysis provide records of fallout from atmospheric nuclear
 weapons tests, revealing seasonal variability, the influence of major
 tests such as Ivy Mike (1952 CE) and Operation Castle (1954 CE), and the
 timing of long-range transport to Antarctica. ### Files and variables ####
 File: Pu239_icecore_concentration.xlsx **Description:** Excel file
 containing ice-core measurements of ^239^Pu concentrations, δ^18^O, and
 non-sea-salt sulfate (GV7 only), along with depth, year, and analytical
 uncertainty. Two sample sets are provided for the GV7 core: * GV7 1st set:
 Higher-resolution samples (~4.2 cm spacing), used for synchronized δ¹⁸O
 and ²³⁹Pu analyses. * GV7 2nd set: Lower-resolution replicate samples
 (~7.3 cm spacing), used to verify reproducibility and refine flux
 estimates. ##### Variables * Depth (m) – Depth of ice core sample in
 meters. * Year (CE) – Calendar year assigned to the sample (decimal year
 where available). * δ^18^O (‰) – Stable oxygen isotope ratio (per mil, ‰,
 relative to VSMOW), used as a seasonal proxy (where available). *
 non-sea-salt sulfate (ppb) – nss-SO~4~^2-^ concentrations (available for
 GV7 ice core), used for annual layer counting and volcanic
 synchronization. * ^239^Pu (fg g^-1^) – Concentration of plutonium-239 in
 femtograms per gram of ice. * CI (95%) – Analytical 95% confidence
 interval for ^239^Pu concentrations. * bdl – Indicates “below detection
 limit” values (detection limits vary between 0.037 and 0.15 fg g^-1^
 depending on core). 
 
 ## Access information Other publicly accessible locations of the data: *
 None Data was derived from the following sources: * Original measurements
 of ^239^Pu concentrations, δ^18^O, and nss-SO~4~^2-^ were conducted by the
 authors, as detailed in the associated publication.