3:00 PM - 3:15 PM
[ACG54-06] Aircraft Observations of Typhoon T2419 (BARIJAT) under the T-PARCII Project: Data Distribution and Assimilation Usage
Keywords:Tropical cyclone, Aircraft, Data assimilation
Aircraft observations were conducted for Typhoon T2419 (BARIJAT) in 2024 under the Typhoon aircraft observation project T-PARCII. The collected dropsonde data were processed through the newly developed routine system of the Meteorological Research Institute and disseminated globally in real time as TEMP via the Global Telecommunication System (GTS). As a result, these data were assimilated into operational numerical weather prediction (NWP) systems worldwide, including the Japan Meteorological Agency’s (JMA) global NWP system.
Analysis of JMA’s global NWP model’s data assimilation results revealed that the first guess exhibited a moist bias in the northern part of the typhoon compared to observations, and extreme upper-level dryness observed in the dropsonde data was not well represented in the model. Even in the analysis field after data assimilation, the dry region was not reproduced as strongly as in the observations. This discrepancy may be influenced by the rejection of observations through gross error checks (a process that excludes observations when their deviations from the first guess are too large, preventing unstable analysis and numerical instability) and the use of pseudo-observational (typhoon bogus) data.
To further assess the impact of observational data on typhoon forecasts, future numerical experiments will be conducted, including cases without observational data, with relaxed gross error check thresholds, and without the use of bogus data.
Analysis of JMA’s global NWP model’s data assimilation results revealed that the first guess exhibited a moist bias in the northern part of the typhoon compared to observations, and extreme upper-level dryness observed in the dropsonde data was not well represented in the model. Even in the analysis field after data assimilation, the dry region was not reproduced as strongly as in the observations. This discrepancy may be influenced by the rejection of observations through gross error checks (a process that excludes observations when their deviations from the first guess are too large, preventing unstable analysis and numerical instability) and the use of pseudo-observational (typhoon bogus) data.
To further assess the impact of observational data on typhoon forecasts, future numerical experiments will be conducted, including cases without observational data, with relaxed gross error check thresholds, and without the use of bogus data.