Description: | The electronically switched valve that alternately switches flow through 1-um and 10-um
impactors showed an error during this time period. This error invalidated all downstream
data. In the raw data files, aerosol light scattering coefficients for the TSI reference
and humidified nephelometers were assigned missing value codes. The aerosol light
absorption coefficient was observed to stick at a constant value over this period. The problem
went away after the weekly maintenance was performed, although nothing specific was done
to the valve. The flipping of the maintenance switch appears to have solved the problem. |