The Arctic Airborne Measurement Program (AAMP) was planned to investigate the transport, exchange and chemical processes of gas and aerosol in the Arctic in early spring, and further to understand their roles in global change. An instrumented Gulfstream II twin-jet plane was used for airborne measurements in the troposphere and lower stratosphere of the Arctic. In the AAMP March 1998 campaign, the aircraft, equipped with CO2 and O3 concentration monitor systems, gas and aerosol sampling systems, aerosol particle counters, and PMS 1D and 2D airborne particle probes, was flown from Alaska, USA to Svalbard, Norway across the North Pole, and the reverse route. Vertical profiles of aerosol concentrations were acquired up to about 12km altitude over Barrow and Anchorage, Alaska. Results from two different-type optical particle counters and FSSP-300 are shown and discussed on the concentration and size distribution