Baltic Sea multi-mission altimetry subset for power spectral density (PSD) tutorial (March-July 2023)

This dataset is a curated subset of sea level anomaly (SLA) and sea surface height anomaly (SSHA) altimetry products over the Baltic Sea for the period 29 March - 9 July 2023. It was assembled to support a Jupyter notebook tutorial demonstrating power spectral density (PSD) analysis of along-track altimetry, comparing the effective spatial resolution of conventional altimetry, fully-focused SAR (FF-SAR) altimetry, and SWOT wide-swath altimetry. The archive (4dbalt.tar.gz) contains four folders of NetCDF files: FFSAR_0323to0723/ (103 files) - Fully-focused SAR altimetry, optimally-interpolated SLA with derived geostrophic velocities. Produced by the Institute of Geodesy and Geoinformation (IGG), University of Bonn. RADS_0323to0723/ (103 files) - Conventional radar altimetry (Radar Altimeter Database System, RADS), optimally-interpolated SLA with derived geostrophic velocities. Produced by IGG, University of Bonn. SLTAC_0323to0723/ (103 files) - "DT merged all satellites European Seas Gridded SSALTO/DUACS Sea Surface Height L4" product and derived variables, from the Copernicus Marine Service (CMEMS) Sea Level Thematic Assembly Center (SL TAC). SWOT_1dayCalval/ (99 files) - "NRT SWOT KaRIn & nadir Global Ocean swath SSALTO/DUACS Sea Surface Height L3" product, 1-day repeat cal/val orbit phase, produced by CLS/CNES (AVISO+). This is a derived/subset product prepared for teaching purposes. Users should cite the original data providers below in addition to this dataset when reusing the data. See the accompanying tutorial notebook and README at https://github.com/myying/psd-method-4dbalt. Source data acknowledgements / citations: FFSAR and RADS products: Institute of Geodesy and Geoinformation, University of Bonn. SL TAC L4 product: E.U. Copernicus Marine Service Information (CMEMS), https://marine.copernicus.eu, license: https://marine.copernicus.eu/web/27-service-commitments-and-licence.php SWOT L3 product: AVISO/CNES/CLS DUACS, using SWOT KaRIn L2_LR_SSH PGC0/PIC0/PIC2 data (NASA/CNES, DOI: https://doi.org/10.24400/527896/a01-2023.015), product DOI: https://doi.org/10.24400/527896/A01-2023.017, license: https://www.aviso.altimetry.fr/fileadmin/documents/data/License_Aviso.pdf