A model of transient time-dependent magnetic reconnection is used to describe the behavior of nightside flux transfers (NFTEs) in the Earth's magnetotail. On the basis of the analytical approach to reconnection developed by Heyn and Semenov (1996) and Semenov et al. (2004a) we calculate the magnetic field and plasma bulk velocity time series observed by a satellite. The solution for the plasma parameters is given in the form of a convolution integral. The calculation of the reconnection electric field is an ill-posed inverse problem, which we treat in the frame of the theory of regularization. This method is applied to Cluster measurements from 8 September 2002, where a series of earthward propagating 1-min scale magnetic field and plasma flow variations are observed outside of the plasma sheet, which are consistent with the theoretical picture of NFTEs. We analyzed three NFTEs and reconstructed the reconnection electric field. Additionally, the position of the satellite with respect to the reconnection site as well as the Alfv¿n velocity are estimated because they are necessary input parameters for the model. The reconnection electric field is found to be about 1--2 mV/m, while the reconnection site is located about 29--31 RE in the magnetotail.