Hilbert-Huang transform and S-transform of geomagnetic pulsations at auroral expansion onset

Details Hilbert-Huang transform and S-transform of geomagnetic pulsations at auroral expansion onset Hilbert-Huang transform and S-transform of geomagnetic pulsations at auroral expansion onset

Dec 2009

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009agufmsm41a1700k&link_type=abstract

American Geophysical Union, Fall Meeting 2009, abstract #SM41A-1700

Physics

Geophysics

[2704] Magnetospheric Physics / Auroral Phenomena, [2752] Magnetospheric Physics / Mhd Waves And Instabilities, [2790] Magnetospheric Physics / Substorms, [3270] Mathematical Geophysics / Time Series Analysis

Scientific paper

The waveform of geomagnetic pulsations at auroral expansion onset looks irregular and is hardly resolved by Fourier transform. Here we perform a novel analysis of the Hilbert-Huang Transform (HHT) to address this problem, focusing on the event investigated in detail by Morioka et al. [2008], in which the AKR (auroral kilometric radiation) breakup was clearly identified. From the HHT analysis of high-latitude search-coil ground magnetometer data, Pi1, Pc3, and Pi2 pulsations are extracted as the first, second, and third intrinsic mode functions, respectively. Amplification of the Pi1 and Pc3 pulsations is first detected as a clear precursor to the AKR breakup. The Pi1 and Pc3 pulsations show sudden enhancement at the AKR breakup. We suggest that the HHT is capable of automatically extracting the Pi1, Pi2, and Pc3 from the irregular high-latitude geomagnetic pulsations, providing a new type of diagnostic tools for understanding the onset mechanism of auroral substorms. A comprehensive time-frequency spectral view is obtained from the instantaneous frequency, especially when complemented with the S-transform, and the instantaneous frequency provides a new objective criterion to identify the type of geomagnetic pulsations such as Pi and Pc. It would be useful to apply the HHT to all the available both ground- and space-based magnetic datasets across all local times and latitudes for diagnosing the wave activities and underlying physics associated with the substorm onset.

Affiliated with

Also associated with

No associations

Rating

Hilbert-Huang transform and S-transform of geomagnetic pulsations at auroral expansion onset does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Hilbert-Huang transform and S-transform of geomagnetic pulsations at auroral expansion onset, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hilbert-Huang transform and S-transform of geomagnetic pulsations at auroral expansion onset will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1880008