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KLIMAFORSK-Stort program klima

Assimilating infrasound data for multi-decade constraints on middle atmosphere wind and temperature

Awarded: NOK 83,660

In a recent study, NORSAR researchers worked with University of Reading colleagues on what became the first paper demonstrating that middle atmospheric winds estimated from infrasound data can be assimilated into atmospheric models. This groundbreaking study was published after peer-review, with Dr. Amezcua as first author. During Amezcua’s guest researcher stay, we will build on these results, combining data assimilation ideas from our previous collaboration with a novel atmospheric wind and temperature model inversion approach just published by NORSAR, further exploiting the potential in using infrasound data to improve the stratospheric and mesospheric representation in climate modelling. Specific focus will be put on subseasonal-to-seasonal prediction. In particular, our collaboration will address the following topics: 1) Enhance the data assimilation through integration of infrasound wave-propagation simulations from all members of (updated) ensemble model winds and temperatures into the Ensemble Kalman Filter (EnKF) system. 2) Allow the EnKF framework to not only assimilate winds in one direction (average cross-winds as function of altitude in our previous study), instead assimilating both the meridional and zonal directions as well as temperatures. This will be achieved through incorporation of a temperature and wind model inversion methodology, recently published by NORSAR. 3) Expand the EnKF to resolve wind and temperature also along the full track of the infrasound wave propagation path. This might require hybrid methods and additional ensemble climate / atmosphere models, combining these covariances with climatological covariances to mitigate limitations due to background ensemble sample size. 4) Exploit multi-decade global datasets of infrasound-generating explosions to get a climatology of middle atmospheric wind and temperature based on the novel measurements. These will be interpreted in the context of stratospheric and mesospheric climate modelling.

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KLIMAFORSK-Stort program klima