Multi-parameter Measurements of Aerosol Properties for Climate Models
The radiative properties of aerosols are one of the biggest uncertainties in climate change models (IPCC Fourth Assessment Report – Topic 2 Causes of Change, 2007), and aerosols are also a crucial element in air quality. Optical measurements of aerosols are key as they provide a direct measurement of the radiative properties, and can provide remote measurements of spatial distribution and evolution.
NPL, as part of the NMS programme, has developed a new facility within which well-controlled dispersions of nano- and micro-particles can be mixed, conditioned and sampled. This facility (described below) is now available for academic groups and instrumentation companies to calibrate and characterise their instruments and work with NPL to disseminate measurement best practice.
A variety of particle generating and detecting instrumentation has been integrated into the facility allowing instruments to be tested against a wide range of mixtures. The facility also offers measurement windows at 0, 45, 90 degrees, so it is possible to measure forward and side scattering. The flow inside the measurement chamber is laminar.
If you would like to find out more, please email analytical@npl.co.uk
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Sources
| Type | Size Range (nm) | Max Concentration (cm-3) | Geometric STD | Particles |
| Atomiser | 40 to 1,000 | 1.E+07 | 1.8 | Solutes, e.g. NaCl, sucrose, nitrates, sulphates, oil |
| Electrospray | 20 to 1,000 | 1.4 | As for Atomiser | |
| Suspension plus DMA to improve selection |
50 to 1,000 | 1.E+07 1.E+04 |
1.1 | PSL reference spheres, gold, proteins |
| CAST - Combustion Aerosol Standard | 26,55,85,117,156 or [ 26+156 ] |
1.E+06 (1.E+07 in 2010) |
Black carbon | |
| FBAG - Fluidised Bed Aerosol Generator | 10 to 10,000+ | 1.E+06 | 1.6 | Dry powders, e.g. silicon, alumina, metal oxides |
| Spark Generator | 2 (primary) 20-100 (agglomerate) |
1.E+07 | 1.6 | Black carbon |
| VOAG - Vibrating Orifice Aerosol Generator | 40 to 1,000 | 1.E+03 | <1.1 | As for Atomiser, but mono-dispersed |
Measurement Instrumentation
| Type | Size Range (nm) | Max Concentration (cm-3) | Response Time |
| CPC - Condensation Particle Counter (UKAS Accreditation) |
10 to 1,000 10 to 100 |
1.E+07 1.E+05 |
1 sec |
| SMPS - Scanning Mobility Particle Sizer | 1 to 1,000 | 1.E+07 | 3 mins |
| FPS - Fast Particulate Spectrometer | 10 to 2,500 | 1.E+04 | 0.1 sec |
| TEOM - Tapered Element Oscillation Microbalance | Mass measurement | >10 ug/m3 | 5 mins |
| Filters and Precipitation | Mass and composition | n/a | n/a |
| OPC - Optical Particle Counter (from 2010) |
500 to 10,000+ | 1.E+04 | tbd |