High-resolution vertical E x B drift model derived from ROCSAT-1 data

The measurements of vertical ion velocity from the first Republic of China satellite (ROCSAT-1) provide a unique database for the development of an annually and longitudinally high-resolution vertical plasma drift model in the equatorial ionosphere. Currently, the ROCSAT-1-based empirical vertical drift models are available for three seasons: equinox and solstices. However, the vertical drift patterns are not precisely divided by the three seasons. A monthly vertical drift model with high longitudinal resolution is desirable to accurately model the low-latitude ionosphere and to identify the coupling between the ionosphere and atmospheric tide. Here we introduce an empirical vertical drift model derived by using the ROCSAT-1 data in three solar flux conditions (F-10.7 < 150, 130 < F-10.7 < 200, and F-10.7 > 180) under Kp <= 3(+). The local time, day of the year, and longitude of the model are binned by 15 min, 1 month, and 10 degrees, respectively, under each solar flux condition. Our vertical drift model is validated by comparing the model with the measurements of the vertical drift velocity at the Jicamarca Radio Observatory. The characteristics and variability of the vertical drift are briefly discussed.