1. University of Illinois OAP Processing Software

2. UIOPS Workflow Decompress Binary Image Process Individual Particles
Timing and image data for each frame/record
Process Individual Particles
Different variations of Dmax
Shape, area, habit
Analyze Inter-arrival Times
For particles sampled by 2DS
Reacceptance of some particles
Generate Size Distributions
Concentration, mass, area f(Dmax)
1-s derived bulk quantities

3. UIOPS Processing Details
Option to compute Dmax following a circular, rectangular, and elliptical fit around particle
Latter 2 use Computational Geometry Algorithms Library
Wu and McFarquhar (2016)
Time-dependent inter-arrival time (𝜏) threshold determined from minimum frequency in bimodal distribution fit (e.g., Field et al. 2003)
Particles w/ potential diffraction fringes marked as shattered reaccepted if 𝜏 < 10-6 s and D > 500 μm
1-s output of number concentration, mass, area, aspect ratio, and area ratio distributions as a function of particle size
1-s output of derived number concentration, effective radius, extinction, mass-weighted fall speed, precipitation rate, mean area ratio, and mean perimeter

4. Determining Inter-arrival Time Threshold
Manual thresholding when 𝜏 doesn’t fit bimodal distribution
Particles reaccepted if 𝜏 < 10-6 s & D > 500 μm

5. December 5 Processing Comparison

6. December 5 Time Series Comparison
Courtesy Aaron Bansemer & Andrew Heymsfield
Differences in how particles below inter-arrival time threshold are reaccepted

7. December 5 Time Series Comparison

8. Size Distribution Comparison

9. References
Field, P. R., R. Wood, P. R. A. Brown, P. H. Kaye, E. Hirst, R. Greenaway, and J. A. Smith, 2003: Ice Particle Interarrival Times Measured with a Fast FSSP. J. Atmos. Ocean. Technol., 20, 249–261, doi: / (2003)020<0249:IPITMW>2.0.CO;2.

10. OLYMPEX Processing Progress
Date
Decompress Binary Image
Particle-by-Particle (PBP) Data
Inter-arrival Analysis
Size Distributions
Nov 12 ✔️
Nov 13
Nov 14
Nov 18
Nov 23 (I)
Nov 23 (II)
Nov 24 (I)
Nov 24 (II)
Dec 01
Dec 03

11. OLYMPEX Processing Progress (cont.)
Date
Decompress Binary Image
Particle-by-Particle (PBP) Data
Inter-arrival Analysis
Size Distributions
Dec 04 (I) ✔️
Dec 04 (II)
Dec 05
Dec 10
Dec 12
Dec 13 (I)
Dec 13 (II)
Dec 18 (I)
Dec 18 (II)
Dec 19