GOAMAZON-NAIS

Observations and Modeling of the Green Ocean Amazon: Neutral cluster Air Ion Spectrometer (NAIS)

1 January 2014 - 31 October 2014

Lead Scientist: Tuukka Petaja

Observatory: AMF, MAO

As a part of the GoAmazon campaign, a Neutral cluster and Air Ion Spectrometer (NAIS) and a Particle Size Magnifier (PSM) performed size distribution measurements, at the smaller end of aerosol particle sizes. These instruments were able to measure the size distribution of aerosol particles below the size range of standard SMPS instruments. Both the NAIS and the PSM provided valuable information on the population of neutral and naturally charged clusters, and their formation down to a size of 1 nm. The instruments were deployed at the T3 site in Manacapuru and were operational during both IOPs. The NAIS measures both naturally charged and artificially charged particles of both polarities in the size range of 0.8 – 42 nm. The particles are size separated according to their electrical mobility. Naturally charged particles and artificially charged neutral particles are subsequently measured with a time resolution of five minutes. The PSM can detect particles down to a size of 1 nm; regardless of the charge. The PSM is able to grow down to 1 nm sized particles to detectable sized using diethylene glycol as a working fluid; which are then detectable using a condensation particle counter (CPC). The supersaturation of the diethylene glycol in the growth tube can be changed by varying the saturator flow in the PSM; which will change the cutoff size of the PSM. This allows for the retrieval of aerosol size distributions in the size range of 1 – 3 nm.