5:15 PM - 6:45 PM
[ACG47-P04] The seasonal variation of ocean buoy observation impacts in tropical regions evaluated by EFSO
★Invited Papers
Keywords:EFSO, ensemble data assimilation, moored buoy
Ensemble-based Forecast Sensitivity to Observations (EFSO) is an index that quantifies how each individual observation improves subsequent forecasts by assuming that the impact of observations on forecast errors results from a linear combination of the impacts of each individual observation. It has the advantage of estimating the impact of observations on forecasts without conducting additional Observing System Experiments (OSE) and calculating the individual sensitivity of all observations to forecast errors simultaneously.
Marine meteorological observations using moored buoys are deployed at approximately 150 locations worldwide, providing valuable in-situ data at sea. In tropical regions where large-scale phenomena such as ENSO and IOD prevail, these observations are highly valuable for capturing atmospheric-ocean interactions, and they also contribute to understanding local meteorological phenomena, including those over the ocean. However, maintaining moored buoy observations incurs significant costs, making it challenging to increase the number of buoys or to operate many buoys continuously over the long term. Therefore, there is a desire for the efficient and effective deployment of observation networks, and understanding the forecast sensitivity to individual observations is deemed crucial.
In this study, we investigated the seasonal variation of moored buoy observation impacts in the tropical region in 2019 using the EFSO calculated by AFES (Atmospheric General Circulation Model for Earth Simulator) - LETKF (Local Ensemble Transform Kalman Filter) ensemble data assimilation system (ALEDAS3).
The moored buoys located at 5°S 95°E, and 8°S 95°E, within the RAMA observational network in the Indian Ocean, exhibited a tendency for larger beneficial EFSO values in the winter of 2019 and smaller beneficial values in the summer. However, focusing on the buoy at 8°N 137°E in the Philippine Sea, there was a tendency for EFSO values to be smaller in winter and slightly larger in summer. Additionally, the buoys at 0° 165°E, and 0° 155°E in the western Pacific equatorial region within the TAO/TRITON array showed a trend of large beneficial EFSO values both in winter and summer. The equatorial eastern Indian Ocean and the equatorial western Pacific are regions strongly influenced by the Madden-Julian Oscillation (MJO) during winter, while the Philippine Sea and the western Pacific are regions affected by the summer monsoon. These findings suggest that the observation sensitivity may vary due to changes in predominant phenomena near the observation points. We intend to analyze EFSO data over an extended period to thoroughly investigate the characteristics of predominant phenomena and the sensitivity of the observations.
Marine meteorological observations using moored buoys are deployed at approximately 150 locations worldwide, providing valuable in-situ data at sea. In tropical regions where large-scale phenomena such as ENSO and IOD prevail, these observations are highly valuable for capturing atmospheric-ocean interactions, and they also contribute to understanding local meteorological phenomena, including those over the ocean. However, maintaining moored buoy observations incurs significant costs, making it challenging to increase the number of buoys or to operate many buoys continuously over the long term. Therefore, there is a desire for the efficient and effective deployment of observation networks, and understanding the forecast sensitivity to individual observations is deemed crucial.
In this study, we investigated the seasonal variation of moored buoy observation impacts in the tropical region in 2019 using the EFSO calculated by AFES (Atmospheric General Circulation Model for Earth Simulator) - LETKF (Local Ensemble Transform Kalman Filter) ensemble data assimilation system (ALEDAS3).
The moored buoys located at 5°S 95°E, and 8°S 95°E, within the RAMA observational network in the Indian Ocean, exhibited a tendency for larger beneficial EFSO values in the winter of 2019 and smaller beneficial values in the summer. However, focusing on the buoy at 8°N 137°E in the Philippine Sea, there was a tendency for EFSO values to be smaller in winter and slightly larger in summer. Additionally, the buoys at 0° 165°E, and 0° 155°E in the western Pacific equatorial region within the TAO/TRITON array showed a trend of large beneficial EFSO values both in winter and summer. The equatorial eastern Indian Ocean and the equatorial western Pacific are regions strongly influenced by the Madden-Julian Oscillation (MJO) during winter, while the Philippine Sea and the western Pacific are regions affected by the summer monsoon. These findings suggest that the observation sensitivity may vary due to changes in predominant phenomena near the observation points. We intend to analyze EFSO data over an extended period to thoroughly investigate the characteristics of predominant phenomena and the sensitivity of the observations.