Instrument Payload for the NOAA -PMEL Manta:

The instrument payload provides in situ measurements of aerosol chemical, physical, and optical properties in order to tie changes in surface albedo to pollution aerosol. The instruments consist of the following.

  1. A chemical sampling filter system with an 8 position sampling carousel. A pump pulls sample air at 2.5 liters per minute through filters that can be analyzed after the mission for chemical constituents. The filter flow and be commanded from the ground station to start and stop. Also, the sample flow can be switched to any filter in the sampling carousel by command from the ground at any time during the flight.

  2. A condensation nucleus counter, CNC, that measures the total number concentration of particles with sizes greater than about 10 nanometers in diameter. This instrument uses butyl alcohol vapor to grow small particles to a detectable range and provides data at a one second interval.

  3. An aerosol absorption photometer. This instrument passes a flow of sample air through a small filter, which is illuminated is series with red, green and blue (624, 525, and 450 nm) light from an LED light source. The amount of light that passes through this filter decreases during the flight as black carbon aerosol is collected on the filter. A photodiode detector measures the transmission of light through the filter and the rate at which the light transmission decays is related to the concentration of absorbing aerosol in the atmosphere. Although this instrument provided data at a one second rate, to get useful measurements, 30 to 60 seconds averages of the data must be used.

  4. As part of the flow control for all of the above instruments the payload also measures the ambient pressure. The air temperature and humidity, RH, are measured with a probe that extends below the main body of the aircraft. Because the priority of the payload was to measure aerosol properties, the sampling rate for the temperature and RH is set to one reading per 10 seconds.

The data are stored at one second intervals on a “micro SD” data card during the flight. The data are also sent in real time to the ground station through the RF and iridium satellite link.