Programs to Compute ROT and ROTI

The two programs are MATLAB functions to compute 30-seconds Rate of change of TEC (ROT) and 5-minute ROT Index (ROTI) from TEC data

The two programs are MATLAB functions to compute 30-seconds Rate of change of TEC (Total Electron Content) (ROT) and 5-minute ROT Index (ROTI) from TEC data, usually obtained from GPS/GNSS receivers or other instrument.

The function named 'rot30s_mean' is first used to generate the 30-seconds ROT, and then if desired, the function named 'roti5m' is used to generate the 5-minute ROTI.

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The syntax for rot30s is:

[nsecs_out, prn_out, el_out, lon_out, lat_out, rot30s]=rot30s_mean(nsecs, prn, el, lon, lat, el_mask, tec)

The inputs (described below) are column vectors, except for el_mask which is a scalar:

nsecs: number of seconds from midnight (can be UT or LT)

prn: satellite identifier (can be strings/characters/numeric/numbers)

el: satelite elevation angle (degrees)

lon: longitude of IPP (degrees)

lat: latitude of IPP (degrees)

el_mask: elevation mask angle (degrees)

tec: TEC (TECU)

The outputs (described below) are also column vectors:

nsecs_out: output number of seconds from midnight (can be UT or LT, same unit as input nsecs) at resolution of 30s

prn_out: output satellite identifier (strings)

el_out: output satelite elevation angle (degrees) computed at 30s resolution, as the midpoint of satelite elevation angles over which roti5m is computed

lon_out: longitude of IPP (degrees) computed at 30s resolution, as the midpoint of IPP longitudes over which roti5m is computed

lat_out: latitude of IPP (degrees) computed at 30s resolution, as the midpoint of IPP latitudes over which roti5m is computed

rot30s: 30s ROT (TECU/min) computed at 30s resolution

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The syntax for roti5m is:

[nsecs_out, prn_out, el_out, lon_out, lat_out, roti_5m]=roti5m(nsecs, prn, el, lon, lat, el_mask, rot30s)

The function computes 5-minute ROTI from 30s ROT for each reciever-satellite line of sight

The inputs (described below) are column vectors, except for el_mask which is a scalar:

nsecs: number of seconds from midnight (can be UT or LT)

prn: satellite identifier (can be strings/characters/numeric/numbers)

el: satelite elevation angle (degrees)

lon: longitude of IPP (degrees)

lat: latitude of IPP (degrees)

el_mask: elevation mask angle (degrees)

rot30s: 30s ROT (TECU/min)

The outputs (described below) are also column vectors:

nsecs_out: output number of seconds from midnight (can be UT or LT, same unit as input nsecs) at resolution of 30s

prn_out: output satellite identifier (strings)

el_out: output satelite elevation angle (degrees) computed at 5-minute resolution, as the midpoint of satelite elevation angles over which roti5m is computed

lon_out: longitude of IPP (degrees) computed at 5-minute resolution, as the midpoint of IPP longitudes over which roti5m is computed

lat_out: latitude of IPP (degrees) computed at 5-minute resolution, as the midpoint of IPP latitudes over which roti5m is computed

roti5m: 5-minute ROTI (TECU/min) computed at 5-minute resolution