Numerical Weather Prediction Models

JMA operates NWP models to meet various kinds of requirements on weather forecasting. The suite of the NWP models covers a wide temporal range of forecast periods from a few hours to two seasons providing a seamless sequence of products for the public. The Global Spectral Model (GSM) produces 84-hour forecast four times a day (00, 06, 12, 18 UTC) to support the official short-range forecasting (day 3) and to provide the lateral boundary conditions for the MesoScale Model (MSM). The GSM forecast at 12 UTC is extended to 11 days to support the official one-week forecasting. Four ensemble prediction systems are in operation. The one-week ensemble forecast is performed with 51 ensemble members every day at 12 UTC supporting the official one-week forecasting. The typhoon ensemble forecast with 11 ensemble members runs four times a day (00, 06, 12 and 18 UTC) when typhoons exist or are expected to form or to come in the western-north Pacific. The model produces 132-hour forecast and supports activities of the RSMC Tokyo-Typhoon Center. The one-month ensemble forecast with 50 members is carried out once a week (everyWednesday and Thursday) to support the official one-month forecasting, which is issued on Friday. The two-week ensemble forecast is also executed to support early warning information on extreme weather on every Sunday and Monday using the one-month ensemble forecast system. The seasonal ensemble forecast using an atmosphere-ocean coupled model with 51 members is carried out once a month to support the official seasonal forecasting. MSM is executed eight times a day (00, 03, 06, 09, 12, 15, 18 and 21 UTC). It produces 15-hour forecast from 00, 06, 12 and 18 UTC and 33-hour forecast from 03, 09, 15, 21 UTC, to support the very short-range forecasting and the aviation services. It provides the lateral boundary conditions for the Local Forecast Model (LFM). LFM produces 9-hour forecast eight times a day (00, 03, 06, 09, 12, 15, 18 and 21 UTC) and supports the weather information regarding to severe weather disturbances and aviation services around Tokyo International Airport. JMA also operates a global atmospheric transport model to support the RSMC for Emergency Response activities. The model stands ready to run anytime when an environmental emergency situation occurs. JMA operates three kinds of Chemical Transport Models (CTMs). The Aerosol CTM produces 96-hour forecast to provide Kosa (Aeolian Dust) information, the stratospheric ozone CTM produces 48-hour forecast to support UV index information, and tropospheric-stratospheric ozone CTM produces 72-hour forecast to support the photochemical oxidant information. These CTMs are operated once a day at 12UTC. The radiative transfer model is also used for UV index information. Table 3.1.1 (global) and Table 3.1.2 (regional) shows specifications of the major NWP models respectively. Details on the NWP models, the ensemble prediction systems, the atmospheric transport model and the chemical transport models are described particularly in the following Section 3.2 Section 3.8. The operational verification procedure is explained in Section 3.9.