These size distributed aerosol ion data were obtained by H. Sievering and J. Slavich (University of Colorado-Denver) at the 50-m level on the Cape Grim tower. Given the bluff on which the Cape Grim sampling station resides and wind tunnel modeling of this bluff, the equivalent height of sampling was 120-130 m a.s.l. Based on comparison with samples take from 30-m tower level and the station's roof, it can be stated that these 120-130 m a.s.l. samples were not contaminated by local (bluff-derived) sea spray aerosols or soil particles. Roughly, the 120-130 m a.s.l. level was at a height within the MBL which had half the MBL sea salt mass above and half below this measurement height under the 10.2 (sigma = 2.4) ms-1 wind speed conditions encountered. The Sierra six-stage high volume cascade impactor sampled air at 1.1 m3 min-1. This did not allow for any treatment [e.g., heating] of the air. Thus, ambient air was sampled at a mean relative humidity of 76% (sigma = 6%). This impactor data complement data obtained by low volume impactors during ACE-1 in least 2 ways: 1) ambient air (nearly 100% efficient) sea salt mode data in five size cuts across the ~0.5 to ~15 micrometer dia. range; and 2) non-sea-salt SO4 (nssSO4) in the sea salt mode of relatively high accuracy, since sample air volumes were ~900 m3 (on average). Data cells without a value indicate the sample ion concentration is below it's blank concentration level. The nssSO4 was calculated by subtracting .06[Na+] from the observed [SO4=]. No Cl- deficit (Cldef) values are presented since they are generally too uncertain. Only for the 0.5-1 micrometer dia. range are the Cldef occasionally above uncertainty; yet in these cases the Cldef magnitude is quite small. Given that Cape Grim baseline conditions had to be met for ambient air sampling to be activated these are time periods between the indicated start and stop times per sample during which air sampling was interrupted. NOTE: the stated size cuts of <0.5, 0.5-1, 1-2.5, 2.5-4, 4-7, and >7 micrometer dia. are--at this point in time based on past experience--labeled as nominal. For the Cape Grim site conditions calibrated checks against APS (Covert--U. of Wash.) and optical sizing probe (Murphy--NOAA Boulder) data need still to be performed. An update of this data base regarding size cuts may be provided in the future. Acknowledgments: We thank the Cape Grim staff for their assistance in obtaining samples at the 50-m tower level. We also thank John Ivey and the Australian Govt. Anal. Lab, in Kingston Tasmania, for their ion chromatography (IC) analysis and intercomparison with our IC data. Please request approval to use these data in publications/documents/reports. Address request for such approval to H. Sievering at email: HSIEVERI@CARBON.CUDENVER.EDU