Articles | Volume 35, issue 2
Ann. Geophys., 35, 325–331, 2017
https://doi.org/10.5194/angeo-35-325-2017
Ann. Geophys., 35, 325–331, 2017
https://doi.org/10.5194/angeo-35-325-2017

ANGEO Communicates 01 Mar 2017

ANGEO Communicates | 01 Mar 2017

Error estimate of Taylor's frozen-in flow hypothesis in the spectral domain

Yasuhito Narita Yasuhito Narita
  • Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, 8042 Graz, Austria

Abstract. The quality of Taylor's frozen-in flow hypothesis can be measured by estimating the amount of the fluctuation energy mapped from the streamwise wavenumbers onto the Doppler-shifted frequencies in the spectral domain. For a random sweeping case with a Gaussian variation of the large-scale flow, the mapping quality is expressed by the error function which depends on the mean flow speed, the sweeping velocity, the frequency bin, and the frequency of interest. Both hydrodynamic and magnetohydrodynamic treatments are presented on the error estimate of Taylor's hypothesis with examples from the solar wind measurements.

Short summary
In situ spacecraft data in space plasma are obtained often as time series data. Using Taylor's frozen-in flow hypothesis, one can interpret the time series data as spatial variations swept by the slow and passing by the spacecraft. A quantitative method for estimating the error for Taylor's hypothesis is developed here.