Micrometer‐sized hygroscopic particles in the atmosphere: Aircraft measurement in the Arctic
Bibliographic record
Abstract
Aircraft measurements of concentrations and size distributions of nuclei between 1 and 11 μm diameter were made in cloud‐free air at altitudes below 6.2 km (approximately −30°C), using a new instrument (the cloudscope) north of Barrow, Alaska, during the First International Satellite Cloud Climatology Project Regional Experiment/Arctic Clouds Experiment (FIRE III/ACE) in May 1998. Data were obtained at various flight levels in the vicinity of a Canadian icebreaker frozen into and moving with the Arctic Ocean ice field. Ice field movements caused the frozen ocean surface to develop leads that were visible from the aircraft. Particles were collected at the stagnation point of a forward facing 3 mm diameter optical flat maintained at or above stagnation point temperatures. Images from a 425 μm × 320 μm area were video‐recorded, and concentrations were corrected for collection efficiency based on ambient airspeed, temperature, and assumed particle density. At low ambient relative humidities, crystallized particles were collected directly, and their hygroscopic character was determined by observing growth characteristics following flight into regions of higher relative humidity. Solution drops collected at high relatively humidities were crystallized with controlled heating to approximately a hemispherical shape. Particles with a dry diameter greater than 1 μm, the detection threshold, to 11 μm were found at concentrations up to 4 L−1. Concentrations were variable with altitude, and on occasion no particles were observed for periods up to 1 hour about 50 L of air. Concentrations sufficient to initiate coalescence drizzle as clouds form were observed and may be of importance in ice nucleation. Comparisons with cloud condensation nuclei (CCN) measurements (providing the collected droplets) show that on occasion the large particles (providing the collector drops) comprised a significant component of the mass of hygroscopic material. There is a gap in measurement of particles having known hygroscopic properties in that measurements of CCN have an upper limit of 0.3 μm dry diameter and the cloudscope has a lower limit of 1 μm; substantial mass of hygroscopic material could lie within this range.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".