2026-09-17 国立極地研究所,名古屋大学
図1：本研究の概要図
＜関連情報＞
- https://www.nipr.ac.jp/info2026/20260917-2.html
- https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2026GL123000
モデル、2つの再解析データ、および南極海観測データを用いた低層雲、気温、および地表放射の評価 Evaluation of Low-Level Clouds, Temperature, and Surface Radiation Using a Model, Two Reanalyses, and Southern Ocean Observations
Kazutoshi Sato, Jun Inoue, Hitoshi Matsui
Geophysical Research Letters Published: 31 July 2026
DOI:https://doi.org/10.1029/2026GL123000
Abstract
Low-level clouds over the Southern Ocean (SO) exert a strong influence on surface radiation, yet their representation in reanalyses and climate models remains uncertain. We evaluated cloud properties and surface radiative fluxes from ERA5, MERRA-2, and the CAM-ATRAS model using observations obtained over the SO by Japan’s R/V Shirase during December 2022 and March 2023. ERA5 and MERRA-2 overestimate the frequency of low-level clouds with a base below 1 km. Although CAM-ATRAS also overestimates very low clouds, it shows the best overall agreement with observations in cloud occurrence and phase. Despite the high frequency of low-level clouds, all data sets underestimate downward longwave (DLW) radiation. Cold bias and cloud phase bias likely reduce cloud-base emissivity and contribute to underestimated DLW radiation. Aerosol sensitivity experiments using CAM-ATRAS indicate that enhanced cloud condensation nuclei concentrations increase low-level cloud frequency but have a limited impact on surface radiative fluxes.
