README: Dataset for
"Gradient Ionosphere Index Estimation Using Ground-Based GEO Observations for Multi-scale Ionospheric Dynamics Monitoring"

This dataset supports the manuscript titled
"Gradient Ionosphere Index Estimation Using Ground-Based GEO Observations for Multi-scale Ionospheric Dynamics Monitoring."

It provides the data necessary to reproduce Figures 3–11 in the main text.
All files are provided in .mat format and can be easily loaded in MATLAB or Python (via SciPy/Mat73).

Data Organization
Each figure is accompanied by a zip file (Figure_X.zip), containing the corresponding .mat files.
Each .mat file name corresponds to a specific panel or parameter plotted in the figure.
Descriptions of the contents are provided below.


Figure 3.zip (Day of Year 265, i.e., 21 Sept 2024-Quiet Day)
All data are sampled at 30-second resolution from 00:00 to 24:00 UT.

Filename              | Description & Corresponding Panel
----------------------|------------------------------------
VTEC_station.mat      | VTEC time series at a single station (Panel a – orange line)
VTEC_region.mat       | Regional mean VTEC (Panel b – orange line)
dTECdS_station.mat    | dTEC/dS at a single station (Panel a – blue line)
dTECdS_region.mat     | Regional mean dTEC/dS (Panel b – blue line)
Xdiff_station.mat     | Mixed partial asymmetry (∂²TEC/∂t∂x − ∂²TEC/∂x∂t) at a station (Panel c – blue line)
Xdiff_region.mat      | Regional mean of X-direction asymmetry (Panel d – blue line)
Ydiff_station.mat     | Y-direction asymmetry (∂²TEC/∂t∂y − ∂²TEC/∂y∂t) at a station (Panel c – orange line)
Ydiff_region.mat      | Regional mean Y-asymmetry (Panel d – orange line)
ROTI_station.mat      | ROTI at a single station (Panel e)
ROTI_region.mat       | Regional mean ROTI (Panel f)

Figure 4.zip (Doy 265, 13:40 LT @ 115°E)
Snapshot maps of various parameters at a specific time. Data spatial resolutions vary by parameter.

Filename             | Description
---------------------|------------
VTEC.mat             | VTEC (1° spatial resolution) – Panel (a)
dTECdS.mat           | dTEC/dS (0.25°) – Panel (b)
std_dTECdS.mat       | Std. dev of dTEC/dS (0.25°) – Panel (c)
dTECdt.mat           | dTEC/dt (1°) – Panel (d)
dTECdx.mat           | dTEC/dx (0.25°) – Panel (e)
dTECdy.mat           | dTEC/dy (0.25°) – Panel (f)
ROTI.mat             | ROTI (1°) – Panel (g)
d²TECdxdt.mat        | ∂²TEC/∂x∂t (0.25°) – Panel (h)
d²TECdydt.mat        | ∂²TEC/∂y∂t (0.25°) – Panel (i)

Figure 5.zip (Doy 265)
Latitude-averaged time series over the region (30s resolution). Rows = latitude grid, columns = time.

Filename            | Description
--------------------|------------
dTECdx.mat          | Zonal gradient (dTEC/dx) – Panel (a)
dTECdy.mat          | Meridional gradient (dTEC/dy) – Panel (b)
dTECdS.mat          | dTEC/dS – Panel (c)
dTECdt.mat          | Temporal gradient (dTEC/dt) – Panel (d)

Figure 6.zip (Doy 265)
Longitude-averaged time series.

Filename            | Description
--------------------|------------
dTECdx.mat          | Zonal gradient – Panel (a)
dTECdS.mat          | Along-track gradient – Panel (c)
dTECdt.mat          | Temporal gradient – Panel (d)
ROTI.mat             | ROTI (1°) – Panel (d)

Figure 7.zip (Doy 265, 22:40 LT @ 115°E)
Same structure as Figure 4.zip, but for nighttime EPB case.

Figure 8.zip (Doy 265, 20:00 LT)
Snapshot spatial gradients at 20:00 LT.
dTECdx_2000LT.mat: dTEC/dx at 20:00 LT, spatial resolution 0.25°
Other .mat files follow the same naming.

Figure 9.zip (Doy 285, 11 Oct 2024)
Same format as Figure 5, but for a different date.

Figure 10.zip (Doy 285, 11 Oct 2024)
Same format as Figure 4, but for a different date.


Figure 11.zip
Filename               | Description
------------------------|------------
dTECdt.mat              | dTEC/dt vs. latitude (1° resolution)
dTECdy.mat              | dTEC/dy vs. latitude (0.25° resolution)
d²TECdydt.mat           | ∂²TEC/∂y∂t vs. latitude (0.25° resolution)