This paper parametrizes ice crystal number concentration (Ni) versus aerosol number concentration (Na) at various thermodynamical conditions (e.g. Supersaturation with respect to ice, Si, and temperature, T). The observations were gathered during the First International Regional Experiment-The Arctic Cloud Experiment (FIRE.ACE) that took place over the Arctic Ocean during April of 1998. Data collected during 19 research flights were analyzed. Ten second (~1 km) averages of Ni, Na, and Si within glaciated clouds were calculated from the measurements of the Particle Measuring Systems (PMS) 2-Dimensional Cloud (2DC) probe, Particle Cavity Aerosol Spectral Probe (PCASP), Forward Scattering Spectrometer Probe (FSSP), and the LiCor infrared gas analyzer (Li-Cor 6262 CO2/H2O). The total Ni versus total Na, and Ni versus aerosol surface area were analyzed at 5C intervals. Glaciated conditions were determined based on the Rosemount icing detector and the cloud microphysical measurements. Ni from the FSSP was also used for a qualitative estimate of a relationship between Ni and Na. The results from the analysis will be discussed to understand ice crystal nucleation processes versus Na and aerosol surface area and their importance for climate change and modeling studies. The results will also be compared with those from earlier studies.