DOI: 10.5281/zenodo.11536584
title: ULF wave events during THEMIS-CMO-FAIR magnetic conjunctions

description: This dataset corresponds to an hdf5 file with stored information on Ultra Low Frequency (ULF) wave events during magnetic conjunctions between (1) NASA's Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites, (2) USGS College Alaska (CMO) magnetic observatory, and (3) the FAIR GNSS receiver near Fairbanks, Alaska. Magnetic field measurements are used for THEMIS (~3s sampling interval) and CMO (1s sampling interval), while 1s Total Electron Content (TEC) measurements are used from high-rate RINEX data for FAIR obtained from the NASA Crustal Dynamics Data Information System (CDDIS) archive of space geodesy data. The file also contains solar wind measurements and geomagnetic activity indices from NASA's OMNIWeb (https://omniweb.gsfc.nasa.gov/) database for the same magnetic conjunction intervals. 

ULF wave events are identified in different components of the magnetic field measured at THEMIS and/or CMO. They are also identified Total Electron Content (TEC) measured between FAIR and various GNSS satellites. Several properties of the waves are recorded, including wave power (nT^2 or TECU^2, see below for conversion factor to TECU^2/Hz or nT^2/Hz) and frequency, as well as supporting information. 

 

The HDF5 file contains the following components:

- Groups: Logical containers that hold datasets and other groups.

- Datasets: Multi-dimensional arrays holding the actual data.

- Attributes: Metadata attached to datasets or groups providing additional information.  

 

The top-level groups contain the names of each conjunction event including the conjunction date (YYYY-MM-DD) and middle time (HHMM), THEMIS satellite probe name (tha, thd, or the), ground magnetometer name (cmo), and GPS receiver name (fair).

 

The second-level groups contain group names of individual GPS satellite (GPS**_psd_peak_info), three components of ground magnetic field perturbations (dgB*_psd_peak_info), three components of satellite magnetic field perturbations (dsB*_psd_peak_info), solar wind and geomagnetic indices (omni_data), and THEMIS electron flux (thm_eflux_data).

 

Under each GPS satellite group (GPS**_psd_peak_info), relevant datasets are: 

common_peak_arr: this is a 1 by 6 array contains information on if a common peak to the TEC PSD is identified in any magnetic field perturbations from the THEMIS satellite or ground magnetometer. It is organized by [dgBx, dgBy, dgBz, dsBx, dsBy, dsBz]. [0,0,1,0,0,0] means a common peak with TEC PSD is identified in the ground magnetometer perturbation in the Bz component. Note that TEC data from a GPS satellite may not have any common peaks with magnetic field perturbations from the THEMIS satellite or ground magnetometer, in this case, this dataset (common_peak_arr) will be missing in this GPS satellite group.

common_peak_freq [HZ]: the frequencies of all the common peaks identified.

end_lat [degree]: latitude of IPP at 450 km at the end of the conjunction time.

end_lon [degree]: longitude of IPP at 450 km at the end of the conjunction time.

mad_dVTEC [TECU]: the median absolute deviation of the detrended VTEC time series during the conjunction interval.

max_Elev [degree]: maximum elevation angle of the GPS satellite during the conjunction interval.

max_VTEC [TECU]: maximum value of the VTEC time series during the conjunction interval.

max_dVTEC [TECU]: maximum value of the detrended VTEC time series during the conjunction interval.

mean_Elev [degree]: mean elevation angle of the GPS satellite during the conjunction interval.

mean_lat [degree]: mean latitude of IPP at 450 km during the conjunction interval.

mean_lon [degree]: mean longitude of IPP at 450 km during the conjunction interval.

mean_VTEC [TECU]: mean value of VTEC time series during the conjunction interval.

mid_lat [degree]: latitude of IPP at 450 km at the middle of the conjunction time.

mid_lon [degree]: longitude of IPP at 450 km at the middle of the conjunction time.

min_Elev [degree]: minimum elevation angle of the GPS satellite during the conjunction interval.

min_VTEC [TECU]: minimum value of the VTEC time series during the conjunction interval.

min_dVTEC [TECU]: minimum value of the detrended VTEC time series during the conjunction interval.

peak_freq [HZ]: the frequencies of all peaks identified in the dVTEC PSD.

peak_power [TECU^2]: the power of all peaks identified in the dVTEC PSD. To convert to TECU^2/Hz, multiply by 0.000868 .

peak_prominence: the prominences of all peaks identified in the dVTEC PSD

peak_width: FWHM of all peaks identified in the dVTEC PSD

start_lat [degree]: latitude of IPP at 450 km at the beginning of the conjunction time.

start_lon [degree]: longitude of IPP at 450 km at the beginning of the conjunction time.

 

Under each magnetic field perturbation group (d*B*_psd_peak_info), relevant datasets are: 

common_peak_freq [HZ]: the frequencies of all the common peaks identified. This will be missing if no common peak is identified.

peak_freq [HZ]: the frequencies of all peaks identified in the PSD of specific magnetic field component perturbation.

peak_power [nT^2]: the power of all peaks identified in the PSD of specific magnetic field component perturbation. To convert to nT^2/Hz, multiply by 0.000868 .

peak_prominence: the prominences of all identified in the PSD of specific magnetic field component perturbation.

peak_width: FWHM of all peaks identified in the PSD of specific magnetic field component perturbation.

 

Under the omni_data group, relevant datasets are: 

AE_INDEX [nT]: mean AE index during the conjunction interval.

AL_ INDEX [nT]: mean AL index during the conjunction interval.

ASY_D [nT]: mean ASY_D index during the conjunction interval.

ASY_H [nT]: mean ASY_H index during the conjunction interval.

AU_INDEX [nT]: mean AU index during the conjunction interval.

BX_GSE [nT]: mean IMF Bx in the GSE coordinates during the conjunction interval.

BY_GSE [nT]: mean IMF By in the GSE coordinates during the conjunction interval.

BZ_GSE [nT]: mean IMF Bz in the GSE coordinates during the conjunction interval.

DST [nT]: mean Dst index during the conjunction interval.

F10_INDEX: mean F10 index during the conjunction interval.

KP: mean Kp index during the conjunction interval.

Pressure [nPa]: mean solar wind dynamic pressure during the conjunction interval.

SYM_D [nT]: mean SYM_D index during the conjunction interval.

SYM_H [nT]: mean SYM_H index during the conjunction interval.

Vx [km/s]: mean solar wind speed in the X direction during the conjunction interval.

Vy [km/s]: mean solar wind speed in the Y direction during the conjunction interval.

Vz [km/s]: mean solar wind speed in the Z direction during the conjunction interval.

proton_density [cc]: mean solar wind proton density during the conjunction interval.

 

Under the thm_eflux_data group, the relevant dataset is:

thm_eflux [ergs/cm^2/s]: mean THEMIS electron flux during the conjunction interval.