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Improving atmospheric angular momentum forecasts by machine learning
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  • Robert Dill,
  • Jan Saynisch-Wagner,
  • Christopher Irrgang,
  • Maik Thomas
Robert Dill
Deutsches GeoForschungsZentrum GFZ

Corresponding Author:[email protected]

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Jan Saynisch-Wagner
Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences
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Christopher Irrgang
Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences
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Maik Thomas
Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences
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Earth angular momentum forecasts are naturally accompanied by forecast errors that typically grow with increasing forecast length. In contrast to this behavior, we have detected large quasi-periodic deviations between atmospheric angular momentum wind term forecasts and their subsequently available analysis. The respective errors are not random and have some hard to define yet clearly visible characteristics which may help to separate them from the true forecast information. These kinds of problems, which should be automated but involve some adaptation and decision-making in the process, are most suitable for machine learning methods. Consequently, we propose and apply a neural network to the task of removing the detected artificial forecast errors. We found, that a cascading forward neural network model performed best in this problem. A total error reduction with respect to the unaltered forecasts amounts to about 30% integrated over a 6 day forecast period. Integrated over the initial 3 day forecast period, in which the largest artificial errors are present, the improvements amount to about 50%. After the application of the neural network, the remaining error distribution shows the expected growth with forecast length. However, a 24 hourly modulation and an initial baseline error of 2*10-8 became evident that were hidden before under the larger forecast error.
Dec 2021Published in Earth and Space Science volume 8 issue 12. 10.1029/2021EA002070