The course of acute renal failure can usefully be divided into three phases: an onset phase, a phase of established acute renal failure, and a recovery phase.
The onset phase is dominated by general illness, in which the episode of acute renal failure arises; at this stage there may be evidence of threatened renal damage such as blood in the urine or pain in the loins.
The onset phase takes place around the end of the PSSR.
During the onset phase ('Onset phase: ESF patches and primary EPBs' section), which takes place around the end of the PSSR, the first EPB of the evening is observed.
If EPBs are suppressed during the growth phase, an implication is that the process for EPB generation becomes active during the onset phase.
We will return to the difference between west-wall echoes and EPBs in 'Onset phase: ESF patches and primary EPBs' and 'Structure phase: clustering and EW asymmetry' sections.
The appearance of the primary EPB is noteworthy because EPBs are generally absent during the growth phase, which precedes the onset phase.
Additionally the October 19 and 22 Ground Level Events exhibited very unusual intensity-time profiles including double component structures for the onset phase.
In this paper, we present observational results on various parameters related with the onset phase of a large number (242) of upstream events.
The finding that ESF is associated with a high F layer (e.g., Farley et al. 1970) is consistent with the launching of primary EPBs during the onset phase.
