Development of JAXA L2 algorithms to retrieve cloud properties and vertical velocity for the EarthCARE mission

Abstract

JAXA L2-algorithms for cloud properties and vertical velocity were developed for the EarthCARE mission. CPR will be the first 94GHz Doppler cloud radar in space and ATLID is the 355nm-high spectral resolution lidar that can provide backscattering, extinction and depolarization ratio. The JAXA L2 standard cloud products will be derived by using (1) CPR-only algorithms without Doppler velocity, (2) CPR and ATLID algorithms and (3) CPR. ATLID and MSI algorithms. The JAXA L2 research product will be produced by using Doppler velocity (Vd) from CPR in addition to above. The products include cloud mask, cloud particle type, cloud particle categories, terminal velocity and vertical air motion. The L2 algorithms correspond to the extended version to those for CloudSat, CALIPSO (Hagihara et al., 2010 for cloud mask, Yoshida et al., 2010 and Kikuchi et al., 2017 for cloud particle type and Okamoto et al., 2010, Sato and Okamoto 2011 for cloud microphysics) and the latter has been distributed as JAXA EarthCARE A-train products. Vd may be affected by aliasing and the correction algorithm was developed. After the correction, Vd is effective to discriminate clouds and precipitation in cloud particle type products. It is also effective to specify the upward motion in convections. Cloud particle type algorithms for CPR use Vd and Ze for the better discrimination of clouds and precipitation. Two-dimensional diagram of lidar ratio and depolarization ratio from ATLID enables to retrieve ice particle categories (Okamoto et al., 2019, 2020, Sato and Okamoto 2023). The knowledge of particle categories reduce the uncertainties in the retrieved microphysics. Recently developed physical model (Sato et al., 2018) and vectorized physical model (Sato et al., 2019) were implemented into the algorithms to account multiple scattering contribution to the signals. Synergetic ground-based observation system has been constructed in NICT Koganei, Tokyo. The ground-based system consists of 94GHz high-sensitivity-cloud radar (HG-SPIDER) and electric scanning cloud radar (ES-SPIDER), Multi-Field-of-view Multiple Scattering Polarization Lidar (Okamoto et al., 2016, Nishizawa et al., 2021), high spectral resolution lidar (Jin et al., 2020), direct-detection Doppler lidar (Ishii et al., 2022), coherent Doppler lidar (Iwai et al., 2013) and wind profiler. Cloud mask, particle type, cloud particle category, cloud microphysics, terminal velocity and vertical motion are retrieved by the system and can be used to evaluate L2 products.