Data Assimilation by Artificial Neural Networks for an Atmospheric General Circulation Model: Conventional Observation

This paper presents an approach for employing artificial neural networks (NN) to emulate an ensemble Kalman filter (EnKF) as a method of data assimilation. The assimilation methods are tested in the Simplified Parameterizations PrimitivE-Equation Dynamics (SPEEDY) model, an atmospheric general circulation model (AGCM), using synthetic observational data simulating localization of balloon soundings. For the data assimilation scheme, the supervised NN, the multilayer perceptrons (MLP-NN), is applied. The MLP-NN are able to emulate the analysis from the local ensemble transform Kalman filter (LETKF). After the training process, the method using the MLP-NN is seen as a function of data assimilation. The NN were trained with data from first three months of 1982, 1983, and 1984. A hind-casting experiment for the 1985 data assimilation cycle using MLP-NN were performed with synthetic observations for January 1985. The numerical results demonstrate the effectiveness of the NN technique for atmospheric data assimilation. The results of the NN analyses are very close to the results from the LETKF analyses, the differences of the monthly average of absolute temperature analyses is of order 0.02. The simulations show that the major advantage of using the MLP-NN is better computational performance, since the analyses have similar quality. The CPU-time cycle assimilation with MLP-NN is 90 times faster than cycle assimilation with LETKF for the numerical experiment.Comment: 17 pages, 16 figures, monthly weather revie

The image of the throne in Ibn Gabirol and the Merkabah mysticism

The subject of the Throne is common to the three abrahamic monotheistic religions and it is an important presence in medieval thought. Specifically in Judaism it has a prominent place, since the first great trend in Jewish mysticism is characterized by the contemplation of the Merkabah (Charriot/Throne) images described from the vision of Prophet Ezekiel. At the same time, many medieval Jewish philosophers also mention the subject. Although the philosophical work of Ibn Gabirol is characterized by the absence of religious references, there is one single passage in the Fons vitae that seems to refer to the Throne. In this article we will try to improve the interpretation of this passage from the Fons vitae by verifying the presence of the Merkabah mystical images in Ibn Gabirol poetry in the light of the indications from the mystical literature and the Jewish imaginary