Description: We will design, build and test a multi-color (red, green, blue) particle optical extinction monitor suitable for use in either land or airborne applications. The monitor will also contain a fourth measurement cell to allow for real-time subtraction of interferences caused by gas phase interferents such as nitrogen dioxide. The instrument will fit into a rack-mountable box that less than 13" high (7U). Its time response will be less than 2 seconds and its precision (1 sigma) better than 1 inverse megameter in 1 second. The accuracy of the measurements will be within 5% of the values obtained using measurements of polystyrene latex spheres. It will provide user access through serial and/or USB port connections as well as over the Internet. A working unit will be delivered to NASA langley Research Center.

Benefits: The development of these monitors will allow NASA researchers to routinely measure particle optical extinction levels, a fundamental measurement required for radiation transport calculations in climate change models. These monitors are also highly suitable for the measurement of optical extinction in combustion systems such as aircraft, diesel and gasoline-fueled engines which emit soot.

the commercial market for these instruments comprises several thousand researchers in the atmospheric measurements community. These monitors are suitable for use in existing monitoring networks in the United States and Europe. We expect ready acceptance as these monitors will cost less than buying three single wavelength monitors as well as taking up much less space. There is also a market for these monitors involving the measurement of aircraft engine soot emissions.