Development of a Suite of Balloon-borne Aerosol Instruments to Provide Size Resolved Concentration Measurements Between 0.03 and 30 Micrometers

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A suite of new balloon-borne aerosol instruments capable of making size distribution measurements spanning the range from 0.03 - 30 micrometers in radius will be developed. This capability will require the development of two new instruments, and improvements to a third. The present capability consists of instruments to measure condensation nuclei and optically detectable aerosols from the surface to 30 km. These instruments have been developed at the University of Wyoming, and have a long history of successful measurements in the mid latitudes and polar regions. The expanded measurements will include one new instrument with size resolution for small particles, and a second new instrument with sensitivity to particles at the large end of the spectrum.This work will improve present capability to perform balloon-borne measurements of stratospheric aerosol concentrations during volcanically quiescent, or background, periods, to capture the effects of major volcanic eruptions, and to continue investigations into the characteristics of polar stratospheric clouds. Aerosol surfaces play a fundamental role in determining stratospheric ozone through their influence on the nitrogen cycle. Extending present measurement capability to lower sizes will provide more accurate estimates of stratospheric aerosol surface area during periods of low aerosol loading. Under those conditions, the particles are primarily below the size detection capabilities of present balloon-borne instruments and well below the sensitivity of satellite instruments. The new capability will help resolve currently existing discrepancies between in situ and satellite measurements, provide new information on the source and evolution of both background stratospheric aerosol and free tropospheric aerosol, and the sizes of cloud condensation nuclei.The expanded size coverage at the large, low concentration, end of the aerosol spectrum will be directly applicable to answer questions related to the removal of nitrogen oxides from the polar stratosphere. This process of denitrification plays a critical role in determining the longevity of the ozone loss which occurs in the winter polar regions. The role of large particles at low concentrations in denitrification was discovered in 2000 in the Arctic and there are only a few such measurements. It is not known how prevalent this process is, how large the particles can become, or what their size distributions are.