Response from Authors to Comment on “Detection of Spatial Correlations Among Aerosol Particles”

Abstract

The likelihood of this scenario can be estimated by a closer examination of the counter operation. Our counter (CLIMET CI-8060) has two voltage thresholds for each size bin; a higher one for the detection of a particle (“On”) and another, lower, for the particle exit (“Off”). Hence, in order for a “phantom” to occur, not only must the voltage fall below the “Off” value, but it also must jump back above the large-size “On” value. For the CLIMET CI-8060, we found (and confirmed by direct observation of analog pulses) that the 5‐10 µm bin has Von = 2.85 V and Voff = 2.825 V with the resulting (� V )(5‐10 µm) = 25 mV. Since the smallest size bin (0.3‐0.5 µm) has Von = 22 mV, not all particles will be able to falsely trigger the counter and the following calculation is an overestimate. For data reported in Larsen et al. (2003) and redisplayed in Figure 1, we can estimate from the top panel that the number density in the smallest size bin is (2 × 10 4 )/(5 s) ≈ 4 × 10 3