7.2.2 Earth wind model

a. The HWM-93 model [RN.6] shall be used.

b. High daily short-term values shall be used as worst-case for the daily activity but the 81-day average activity shall not exceed the high long-term value.

NOTE 1 Reference values for the key Indices needed as inputs for the wind model are given in Clause 6.

NOTE 2 The F10.7 81-day average activity can also be estimated by averaging three successive monthly predicted values as given in Clause 6.

NOTE 3 The use of the HWM-93 model at high geomagnetic latitudes and for disturbed geomagnetic periods necessitates caution.