** Progress in Earth and Planetary Science is the official journal of the Japan Geoscience Union, published in collaboration with its 50 society members.

    >>Japan Geoscience Union

    >>Links to 50 society members

    • Progress in Earth and Planetary Science
    • Progress in Earth and Planetary Science
    • Progress in Earth and Planetary Science
    • Progress in Earth and Planetary Science
    • Progress in Earth and Planetary Science
    Progress in Earth and Planetary Science

    Gallery View of PEPS Articles

    Methodology

    Atmospheric and hydrospheric sciences

    Theoretical basis of the algorithms and early phase results of the GCOM-C (Shikisai) SGLI cloud products

    Nakajima TY, Ishida H, Nagao TM, Hori M, Letu H, Higuchi R, Tamaru N, Imoto N, Yamazaki A

    GCOM-C, Shikisai, SGLI, Climate change, Cloud properties, Remote sensing, Cloud evolution process, Radiation budget, CLAUDIA, CAPCOM

    (a) True-color RGB combining the VN8, VN5, and VN3 channels of a single SGLI L1B product. (b) CCL for the SGLI cloud flag algorithm. (c) True-color image combining bands 1, 4, and 3 of multiple MODIS L1B products overlapping with the SGLI L1B. (d) MOD35 cloud mask result. Location is around Japan.

    This paper discusses the cloud/clear discrimination algorithm (CLAUDIA) and the cloud microphysical properties algorithm (CAPCOM), which are used by the Second-generation GLobal Imager (SGLI) aboard the GCOM-C satellite, launched in December 2017. Also described are the preliminary results of cloud products’ validation. CLAUDIA was validated by comparing cloud fractions derived from satellite data against data from whole-sky images captured by ground-based fisheye cameras. User’s accuracy and producer’s accuracy were mostly high at around 90%, and the resulting overall accuracy was also high, ranging from 83 to 100% (average of all sites was 90.5%). CLAUDIA has proven to be sufficiently accurate to apply a cloud mask to measurements and meets the requirements for releasing data for SGLI cloud flag products (the minimum for a successful GCOM-C mission). CAPCOM was evaluated by comparing cloud properties obtained by SGLI products against data from MODIS collection 6 products (MOD06). This was done for both ocean and land in the low to middle latitudes (60° N–60° S) from August 22, 2018 to September 14, 2018. The comparison showed good correlation coefficients for cloud optical thickness, effective particle radius, and cloud-top temperature for water clouds: 0.88 (0.83), 0.92 (0.88), and 0.94 (0.92) for ocean (land), respectively. CAPCOM data for ice cloud optical thickness correlated well with data from MODIS products: 0.86 (ocean) and 0.82 (land).