Predicting abundance and variability of ice nucleating particles in precipitation at the high-altitude observatory Jungfraujoch
Nucleation of ice affects the properties of clouds and the formation of precipitation. Quantitative data on how ice nucleating particles (INPs) determine the distribution, occurrence and intensity of precipitation are still scarce. INPs active at −8 °C (INPs<sub>−8</sub>) were observe...
Main Authors: | , , , , , , |
---|---|
Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2016-07-01
|
Series: | Atmospheric Chemistry and Physics |
Online Access: | https://www.atmos-chem-phys.net/16/8341/2016/acp-16-8341-2016.pdf |
Summary: | Nucleation of ice affects the properties of clouds and the formation of
precipitation. Quantitative data on how ice nucleating particles (INPs)
determine the distribution, occurrence and intensity of precipitation are
still scarce. INPs active at −8 °C (INPs<sub>−8</sub>) were observed for
2 years in precipitation samples at the High-Altitude Research Station
Jungfraujoch (Switzerland) at 3580 m a.s.l. Several environmental
parameters were scanned for their capability to predict the observed
abundance and variability of INPs<sub>−8</sub>. Those singularly presenting the
best correlations with observed number of INPs<sub>−8</sub> (residual fraction of
water vapour, wind speed, air temperature, number of particles with diameter
larger than 0.5 µm, season, and source region of particles) were
implemented as potential predictor variables in statistical multiple linear
regression models. These models were calibrated with 84 precipitation samples
collected during the first year of observations; their predictive power was
successively validated on the set of 15 precipitation samples collected
during the second year. The model performing best in calibration and
validation explains more than 75 % of the whole variability of
INPs<sub>−8</sub> in precipitation and indicates that a high abundance of
INPs<sub>−8</sub> is to be expected whenever high wind speed coincides with air
masses having experienced little or no precipitation prior to sampling. Such
conditions occur during frontal passages, often accompanied by precipitation.
Therefore, the circumstances when INPs<sub>−8</sub> could be sufficiently abundant
to initiate the ice phase in clouds may frequently coincide with
meteorological conditions favourable to the onset of precipitation events. |
---|---|
ISSN: | 1680-7316 1680-7324 |