Dashed lines represent ±6° and ±60° dip latitude.
Fig. 4. Local time variation of the residual ratios for the F3/C (blue) and IRI (red) models in (a) dip latitude = −30 ∼ −10, (b) dip latitude = −10 ∼ 10 and (c) dip latitude = 10 ∼ 30.
Since HYB is at 12.79° dip latitude and PBR is at 4.77° dip latitude, EEJ strength at VEN is overestimated with respect to CBY.
The test was conducted in ionograms recorded in the Brazilian sector (São José dos Campos (23.2°S, 45.9°W, dip latitude 17.6°S-low latitude) and Palmas (10.2°S, 48.2°W, dip latitude 5.5°S-near the magnetic equatorial)).
Further the lower layer flows westward between 4° and 7° dip latitude.
These factors vary with altitude, modified dip latitude, and local time.
Moreover, the EUEL observed at the station near the dip equator (θ° dip latitude) was normalized to the dip equator (0° dip latitude) directly using the CM4 model profile and the same formula.
While Chumphon is close to the magnetic equator (Geomagnetic dip latitude +3.0°N), Chiang Mai is located at the northern anomaly crest (Geomagnetic dip latitude +12.7°N), causing higher NmF2 median values at Chiang Mai.
The Chumphon station (10.72°N, 99.37°E) is located at the equatorial latitude and the dip latitude of 3°N.
In the study we note that the equatorial stations located north (Manaus, dip latitude 6.4°N) and south (Palmas, dip latitude 5.5°S) of the dip equator presented significant F-layer height asymmetries during the storm main phase.
