Assimilation of all-sky IR radiances of Himawari-8/AHI and reflectivities of GPM-Core/DPR

Kozo Okamoto
Noon Mar 8 in Room 2155

Although a wide variety of satellite have been used in data assimilation in NWP system, assimilating all-sky radiances and space-borne radars are still challenging. We have been studying the assimilation of all-sky IR radiances of the Advanced Himawari Imager (AHI) onboard Himawari-8 satellite and reflectivity factor profiles of the Dual Precipitation Radar (DPR) onboard Global Precipitation Mission (GPM) – Core satellite using the regional JMA’s non-hydrostatic model (JMA-NHM). Recent results of these two different studies will be presented in the seminar.

Toward the all-sky AHI radiance assimilation, we are investigating the reproducibility of model simulation. The reproducibility depends on characteristics of observation, NWP model, radiative transfer model (RTM), and matching technique (e.g. interpolation, super-observation). Preliminary result on how two major fast RTMs, CRTM and RTTOV, reproduce cloud-affected radiances will be discussed.

Regarding DPR, we developed an ensemble-based variational assimilation scheme that incorporated a radar simulator and a RTM for all-sky MW radiances. We implemented single-cycle assimilation experiments including DPR and GPM MW imager (GMI) in combination or separately in a tropical cyclone case, and found that a combined use brought most accurate analysis and forecast.