@article {Garcia2008, title = {{Robust processing of magnetotelluric data in the AMT dead band using the continuous wavelet transform}}, journal = {GEOPHYSICS}, volume = {73}, number = {6}, year = {2008}, month = {nov}, pages = {F223{\textendash}F234}, abstract = {The energy sources for magnetotellurics (MT) at frequencies above 8 Hz are electromagnetic waves generated by distant lightning storms propagating globally within the earth-ionosphere waveguide. The nature of the sources and properties of this waveguide display diurnal and seasonal variations that can cause significant signal amplitude attenuation, especially at 1-5 kHz frequencies - the so-called audiomagnetotelluric (AMT) dead band. This lack of energy results in unreliable MT response estimates; and, given that in crystalline environments ore bodies located at some 500-1000-m depth are sensed initially by AMT data within the dead band, this leads to poor inherent geometric resolution of target structures. We propose a new time-series processing technique that uses localization properties of the wavelet transform to select the most energetic events. Subsequently, two coherence thresholds and a series of robust weights are implemented to obtain the most reliable MT response estimates. Finally, errors are estimated using a nonparametric jackknife algorithm. We applied this algorithm to AMT data collected in northern Canada. These data were processed previously using traditional robust algorithms and using a telluric-telluric magnetotelluric (TTMT) technique. The results show a significant improvement in estimates for the AMT dead band and permit their quantitative interpretation. {\textcopyright} 2008 Society of Exploration Geophysicists. All rights reserved.}, issn = {0016-8033}, doi = {10.1190/1.2987375}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-57149105924\&partnerID=tZOtx3y1}, author = {Garcia, Xavier and Jones, Alan G.} }