MEASUREMENTS OF THE RELATIONSHIP BETWEEN SUBMICRON AEROSOL NUMBER ANDVOLUME CONCENTRATION

The relationship between aerosol number concentration and volume, or m ass, concentration is a key linkage for the impact of aerosols on clou d albedo and thus climate forcing. Furthermore, this relationship is i mportant in interpreting aerosol remote retrievals by satellites. We r eport here aircraft data, primarily from the TARFOX (Tropospheric Aero sol Radiative Forcing Experiment) study, which suggest a general linea r relationship between aerosol number and mass concentration in the ef fective cloud condensation nucleus (CCN) size range (diameter >0.1 mu m) for the locations examined. Limited data on the relationship betwee n aerosol number concentration and chemical composition are also prese nted, which show a preferential dependence of effective CCN number con centration on sulfate mass. However, an implicit dependence on organic mass is also suggested.