Models for horizontal E- and F-region drifts

Plasma transport is very important for understanding the space-time variations of the ionosphere. Therefore, following a resolution of URSI Subcommission G4, an effort is made to create a computer code describing the main results of investigations the ionospheric drift which were not considered in IRI-1979.

The experimental data from 23 stations in the Northern Hemisphere were obtained between 1957 and 1970. The worldwide coverage in geographic latitude is 7°N to 71°N (7.5° to 64.1° geomagnetic) and O° to 131°E geographic longitude.

We have developed appropriate procedure which allow us to infer from these data the main parameters of the global ionospheric motions at E- and F-region levels.

An algorithm for computing the zonal and meridional drift components VX, VY can be found in IRI-1990.

The last version of the computer programm called DRIFT which does the test calculation of Ionospheric Drifts Global Model whith printing the tables at the Epson printer is written in Turbo ascal for the IBM PC AT 286/287 compatible computers. Program code (execute module) is about 25 Kbyte. Data files are about 10 Kbyte.

E- and F-region horizontal ionospheric irregularities drift data, worldwide obtained from 1957 to 1970 by D1 and D3 methods, are statistically analysed and a computer code for the average velocity variations in latitude and local time for some solar activity levels is constructed. The PC program DRIFT allows to determine zonal and meridional drift velocities of ionospheric irregularities at the lower (90 < h < = 140 km) and upper (h > 140 km) ionosphere.

The main block of the program DRIFT is the procedure DRIRR for calculating VX and VY for a period (P), geomagnetic (geographic) latitude (FI) and local time (LT) to be specified.

The example of the program DRIFT calculation for F-region (REG=2) and for the whole period of observations (P=1) is in Table. VX > 0 to east, VY > 0 to north. FI is geomagnetic latitude.