Impact of observational duty cycle on the measurement of local helioseismic mode parameters
Abstract
The effect of data gaps on the power spectra and the mode parameters can be explored by imposing a simulated observing window function on a continuous time series of predefined length as is used in standard ring diagram analysis. Here, we investigate the effect of these gaps in HMI data on board SDO through a Monte Carlo analysis. It may be noted that in case of HMI observations, the data gaps occur primarily due to the eclipses and calibrations and thus the distribution can be characterized by a two-element quasi-periodic population. From the Monte Carlo simulations, we examine (i) the presence or absence of the individual modes in the different fitting methods, (ii) systematic effects in frequencies and flow parameters, (iii) systematic effects in the inversions, and (iv) the extent to which these effects depend on the length of the analysis interval. As a base line, we use the absolutely continuous HMI data (no gaps) that are available for periods of up to a week but no more due to the weekly calibration of HMI and/or AIA data. The study uses data both from quiet and active periods.
- Publication:
-
Catalyzing Solar Connections
- Pub Date:
- November 2018
- Bibcode:
- 2018csc..confE..56T