[A-CG40] Earth System Observation Impacts on Climate and Ocean Predictions

[ACG40-10] A climatology of atmospheric observation impacts estimated by EFSO

*Akira Yamazaki¹, Miki Hattori¹, Shiori Sugimoto¹, Qoosaku MOTEKI¹ (1.Japan Agency for Marine-Earth Science and Technology)

Keywords:Atmospheric observations, Forecast sensitivity, Ensemble data assimilation

Ensemble forecast sensitivity to observations (EFSO) technique enables us to estimate individual observation impacts in an ensemble-based data assimilation system. More than 15-year outputs (2005–2022) of observation impacts by EFSO have been obtained in an atmospheric reanalysis called ALERA (AFES-LETKF ensemble experimental reanalysis), which provides climatology distribution of those impacts for different geographical regions and various observation types. Observation impacts for the periods of boral summer (June–August) and winter (December–February) are evaluated. Observation impacts are divided into 4 observation types and distinguished as those over the oceans and lands; the 4 observation types are in-situ, satellites, aircrafts, and others including the wind profilers and the radars. Seventeen-year averages of those impacts show that the most contributed observations are satellites over the oceans, and subsequently in-situ over the lands, in-situ over the oceans, and satellites over the lands. Distribution of in-situ observation impacts visualize several “hotspots” with local extrema of large observation impacts; the regions of the westside of Arabian Island, southwest of Tibetan Plateau, around Hawaii Islands in the summer, and the northern part of Argentina in both seasons. Those spots could improve analysis and subsequent forecasts by increasing observations near there. It is implied that interannual variations of the observation impacts over the Arabian and Tibetan spots relate to large-scale summer monsoonal circulations, and that around Hawaii Islands relates to subtropical large scale atmospheric circulations over the North Pacific.