Sea Ice and Atmosphere-Ocean Forcing Dataset for Isfjorden, Svalbard (2000–2024)

Description

This dataset contains a comprehensive time series of sea ice coverage and atmospheric conditions within Isfjorden, Svalbard. It was developed as the foundational dataset for the Master's thesis: "The Evolution of Isfjorden’s Sea Ice Regime: A 25-Year Analysis of Atmosphere-Ocean Forcing and Atlantification" (Lindlmayer, 2026).

The sea ice data, spanning from January 1967 to February 2025, was derived from sea ice shapefiles provided by the Norwegian Meteorological Institute (MET Norway) and processed into NetCDF format. Alongside the sea ice data, the dataset includes local daily air temperature records.

To ensure full transparency, reproducibility, and utility for different research needs, this repository includes the processed daily and monthly NetCDF files (raw classifications, grouped categories, and gap-filled interpolations), the raw atmospheric temperature dataset, as well as the original source shapefiles and the coastline boundary used for spatial clipping.

Data Files Included

Processed Data (NetCDF & CSV)

seaIceIsfjorden.nc (Combined Categories) Description: A daily time series where original ice types are grouped into broader, simplified categories (Fast Ice, Drift Ice, Water).

seaIceIsfjorden_Detailed.nc (Uncombined / Original Classifications) Description: A daily time series that preserves the specific, detailed sea ice classifications present in the original MET Norway data.

seaIceIsfjorden_Interpolated.nc (Gap-Filled Data) Description: Based on the combined category dataset, this file utilizes mathematical interpolation to fill temporal gaps on days where no satellite or manual observations were available.

seaIceIsfjorden_Hovmoller_Monthly.nc (Climatological Matrix) Description: A 2D matrix (Year × Month) from 2000 to 2024 representing the monthly averaged percentage of Fast Ice relative to the total area of Isfjorden.

svalbard_lufthavn.csv (Daily Air Temperature) Description: A tabular dataset containing daily mean air temperature records from the Svalbard Lufthavn meteorological station (Station ID: SN99840) located at Longyearbyen Airport. This data was exported directly from the SeKlima interface and used to calculate derived thermodynamic metrics such as Freezing Degree Days (FDD).

Raw & Spatial Boundary Data (Shapefiles)

icecharts_isfjorden_epsg3996_edited.zip (Raw Sea Ice Observations) Description: The original, unclipped sea ice shapefiles provided by MET Norway, serving as the foundational data source for the derived time series.

isfjorden_coastline.zip (Fjord Boundary) Description: The spatial polygon used to assess the boundary of the fjord and clip the MET Norway ice charts so that they only contain data strictly within Isfjorden.

Methodology & Provenance

Spatial sea ice data from MET Norway were clipped using the Isfjorden coastline boundary. The area of specific ice types within this boundary was calculated and aggregated. This spatial data was then converted into a tabular daily time series using Python, and interpolated for missing values. Daily mean air temperature data was retrieved from the Norwegian Centre for Climate Services (NCCS) to allow for the computation of atmospheric forcing metrics. Finally, the daily and monthly sea ice data were exported to multi-dimensional NetCDF formats utilizing CF-standard metadata to ensure ease of use in geospatial and atmospheric software.

Code Availability & Replication

The Python codebase and Jupyter Notebook(s) used to process this dataset and perform the thesis analysis are open-source, actively maintained, and freely available on GitHub: https://github.com/lindlmam/seaIceIsfjorden

Note on full replication: While all the foundational sea ice and atmospheric data are provided in this Zenodo archive, certain restricted oceanographic datasets (specifically, Volume-Weighted Mean Temperatures, VTs) used in the final thesis analysis are not hosted here due to publication constraints. Please refer to the README.md in the GitHub repository for detailed instructions on data requirements and how to request access to the restricted files.

Acknowledgements & Source Data

Primary Ice Data: The Norwegian Meteorological Institute (MET Norway) Ice Service for providing the original operational sea ice observation shapefiles.

Atmospheric Data: Daily air temperature records were obtained from the Norwegian Centre for Climate Services (NCCS) through their SeKlima web portal (https://seklima.met.no/), maintaining World Meteorological Organization standards.

Coastline Boundary: The Isfjorden coastline shapefile used for spatial clipping was provided by Stefan Muckenhuber, based on the methodology outlined in: Muckenhuber, S., Nilsen, F., Korosov, A., & Sandven, S. (2016). Sea ice cover in Isfjorden and Hornsund, Svalbard (2000–2014) from remote sensing data. The Cryosphere, 10(1), 149-158.