Particle influx at high latitudes: 2. Solar protons

Solar proton events smaller than those previously recognized have been detected by means of high-sensitivity backscatter sounding of the lower ionosphere at 79°S geomagnetic. Ionosonde fmin data from high-latitude stations confirm these events. For 1960, 37 events are tabulated, including 13 already known. The total duration of proton streams during 1960 was not less than 167 days. Particle influx, including protons, was effective as an ionizing agency at high latitudes for more than 60 per cent of that year.