Table 63: Reference fixed index values

 

Long-term (27+ days)

Short-term (daily)

 

Low

Moderate

High

Low

Moderate

High

F10.7

65

140

250

65

140

300

S10.7

60

125

220

60

125

235

M10.7

60

125

220

60

125

240

Ap

0

15

45

0

15

240

NOTE 1   The reference index values are rounded numbers from the last solar cycle 23.

NOTE 2   Low, moderate or high values for Ap can occur at any time in the solar cycle.

NOTE 3   For short terms, higher values than those given in this table have been measured (e.g. F10.7 = 380 over a day and ap= 400 for 3 hours). However, present atmosphere models are not developed for such high index values and its use leads to large and unknown errors.

 

Table 64: Reference index values for variations of ap

Time [hrs]

ap

0

15

3

15

6

300

9

130

12

50

15

15

18

15

21

15

24

15