@prefix this: <https://w3id.org/sciencelive/np/RA0vq7OGc7G5we208CYmsu_3De-9IY0BN0yCLcXYBGBFA> .
@prefix sub: <https://w3id.org/sciencelive/np/RA0vq7OGc7G5we208CYmsu_3De-9IY0BN0yCLcXYBGBFA/> .
@prefix np: <http://www.nanopub.org/nschema#> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix prov: <http://www.w3.org/ns/prov#> .
@prefix npx: <http://purl.org/nanopub/x/> .
@prefix dc: <http://purl.org/dc/terms/> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

sub:Head {
  this: a np:Nanopublication;
    np:hasAssertion sub:assertion;
    np:hasProvenance sub:provenance;
    np:hasPublicationInfo sub:pubinfo .
}

sub:assertion {
  sub:wgs84-vs-sphere-sst-study a <https://w3id.org/sciencelive/o/terms/FORRT-Replication-Study>,
      <https://w3id.org/sciencelive/o/terms/Replication-Study>;
    <http://www.w3.org/2000/01/rdf-schema#label> "WGS84 vs sphere HEALPix geometry for FOSCAT SST gap-filling at operational resolution";
    <http://www.w3.org/2004/02/skos/core#related> <http://www.wikidata.org/entity/Q11902211>,
      <http://www.wikidata.org/entity/Q131089>, <http://www.wikidata.org/entity/Q1507383>,
      <http://www.wikidata.org/entity/Q3241540>, <http://www.wikidata.org/entity/Q5629401>;
    <https://w3id.org/sciencelive/o/terms/hasDeviationDescription> "This study extends the chain #3 fiesta-scattering-sst workflow (Zenodo 10.5281/zenodo.19686691), which used standard perfect-sphere HEALPix at nside=32, to higher operational resolution (nside=128) with paired sphere-vs-WGS84 comparison. The FOSCAT method, the Copernicus Marine data sources, and the FOSCAT hyperparameters (NORIENT, KERNELSZ, optimiser, iterations) are identical to chain #3; the new variables are (a) the resolution (nside=128 vs nside=32), and (b) the explicit two-arm geometry comparison enabled by the healpix-resample package's ellipsoid parameter. As with chain #3, FOSCAT was used via the annefou/FOSCAT@v0.1.0-cpu fork for CPU execution; that CPU patch has since been merged upstream and is included in foscat>=2026.4.1 on PyPI.";
    <https://w3id.org/sciencelive/o/terms/hasDiscipline> <http://www.wikidata.org/entity/Q1348989>;
    <https://w3id.org/sciencelive/o/terms/hasMethodologyDescription> "The pipeline uses Copernicus Marine L3S PMW SST (cmems_obs-sst_glo_phy_l3s_pmw_P1D-m, with cloud gaps) and L4 SST analysis (cmems_obs-sst_glo_phy-temp_nrt_P1D-m, gap-free reference) for 2026-04-01, both at 0.25° native resolution. The L3S product is regridded onto the L4 grid via nearest-neighbour interpolation. The two products are then independently resampled to HEALPix nside=128 (level=7) under each geometry: standard perfect-sphere (the healpy default) and WGS84 oblate ellipsoid. WGS84 resampling is performed via healpix_resample.GroupByResampler(level=7, reduce='mean', ellipsoid='WGS84'); sphere resampling uses the same package with ellipsoid='sphere' to ensure the implementation difference between the two runs is exactly the geometry argument. Cloud-gap pixels are identified as ocean cells (defined by the L4 mask) without L3S observations. A spherical-harmonic baseline (lmax=60) on the L4 product provides an initial guess for the gaps. FOSCAT scattering synthesis (scat_cov.funct(NORIENT=4, KERNELSZ=3), 300 L-BFGS iterations, CPU) is then run separately under each geometry, using L4's scattering coefficients as the statistical reference and a cloud-only mask for gradient updates. Each geometry's gap-filled output is compared against L4 in cloudy pixels via RMSE in millikelvin.";
    <https://w3id.org/sciencelive/o/terms/hasScopeDescription> "This study tests the research question posed by the parent PCC nanopublication: whether using WGS84 ellipsoid geometry instead of the perfect-sphere assumption when binning lat/lon SST observations to HEALPix cells improves the accuracy of FOSCAT scattering-transform gap-filling at operational resolution. We compare the two geometries on a single day of Copernicus Marine SST data (2026-04-01) at HEALPix nside=128, using the L4 gap-free analysis as ground truth in cloudy pixels.";
    <https://w3id.org/sciencelive/o/terms/targetsClaim> <https://w3id.org/sciencelive/np/RAMDVUPB2XRLXYwtggM0GXIRqhavuPaaRHmVezbsxtdS0/wgs84-vs-sphere-sst-claim> .
}

sub:provenance {
  sub:assertion prov:wasAttributedTo <https://orcid.org/0000-0002-1784-2920> .
}

sub:pubinfo {
  <https://orcid.org/0000-0002-1784-2920> <http://xmlns.com/foaf/0.1/name> "Anne Fouilloux" .
  
  this: dc:created "2026-04-26T18:52:46.842Z"^^xsd:dateTime;
    dc:creator <https://orcid.org/0000-0002-1784-2920>;
    dc:license <https://creativecommons.org/licenses/by/4.0/>;
    npx:introduces sub:wgs84-vs-sphere-sst-study;
    npx:wasCreatedAt <https://platform.sciencelive4all.org>;
    <http://www.w3.org/2000/01/rdf-schema#label> "NP created using Declaring a replication study design according to FORRT";
    <https://w3id.org/np/o/ntemplate/wasCreatedFromTemplate> <https://w3id.org/np/RAuLEjPp-4dTvPwMkfHggTto1CgjIftiGRAgHlyeEonjQ> .
  
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    npx:hasSignatureTarget this:;
    npx:signedBy <https://orcid.org/0000-0002-1784-2920> .
}