10.5878/mkm0-b191
Kuhn, Thomas
Thomas
Kuhn
0000-0003-3701-7925
Department of Computer Science, Electrical and Space Engineering, Luleå University of Technology
Snow ice particle microphysical properties and fall speed from particle images taken in Kiruna (Sweden) 2014–2018 - Data 2
Mikrofysikaliska egenskaper och fallhastighet av snöpartiklar från partikelbilder tagna i Kiruna (Sverige) 2014–2018 - Data 2
Luleå University of Technology
2022
Atmospheric conditions
Atmosfäriska förhållanden
snow fall speed
snöfallshastighet
snowfall
snöfall
snow crystals
snökristaller
snow
snö
Earth and Related Environmental Sciences
Geovetenskap och miljövetenskap
Natural Sciences
Naturvetenskap
Meteorology and Atmospheric Sciences
Meteorologi och atmosfärforskning
Climatology / Meteorology / Atmosphere
Klimatologi och meteorologi
2022-03-28
2014-10-19/2018-05-11
eng
10.5878/4pth-9m71
10.3390/app10031163
urn:nbn:se:smhi:diva-5682
urn:nbn:se:ltu:diva-82170
10.5194/acp-21-7545-2021
10.5194/amt-13-1273-2020
urn:nbn:se:ltu:diva-78097
10.5194/acp-21-18669-2021
2 variables
1
Accurate predictions of snowfall require good knowledge of the microphysical properties of the snow ice crystals and particles. Shape is an important parameter as it strongly influences the scattering properties of the ice particles, and thus their response to remote sensing techniques such as radar measurements. The fall speed of ice particles is another important parameter for both numerical forecast models as well as representation of ice clouds and snow in climate models, as it is responsible for the rate of removal of ice from these models. The particle mass is also a key quantity as it connects the cloud microphysical properties to radiative properties.
The ground-based in-situ instrument Dual Ice Crystal Imager (D-ICI) has been used in Kiruna, Sweden, to determine snow ice particle properties and fall speed simultaneously. D-ICI takes two high-resolution images of the same falling ice particle from two different viewing directions, a top view and a side view. Both images have a pixel resolution of approximately 4 μm/pixel and an optical resolution of approximately 10 μm.
The top-view image with its close to vertical viewing direction is used to provide particle size (maximum dimension), cross-sectional area, and shape of the ice particle. This viewing geometry is chosen instead of a horizontal one because shape and size of ice particles as viewed in the vertical direction are more relevant than these properties viewed horizontally as the vertical fall speed is more strongly influenced by the vertically viewed properties. In addition, a comparison with remote sensing instruments that mostly have a vertical or close to vertical viewing geometry is favoured when the particle properties are measured in the same direction.
The side-view image with its horizontal viewing direction is used both to aid shape determination as well as to determine fall speed by means of a double exposure. Two bright flashes of a light-emitting diode behind the camera illuminate the falling ice particle and create this double exposure, from which the vertical displacement of the particle is measured and used to determine its fall speed.
To add ice particle mass to the data from D-ICI, an empirical relationship between the dimensionless Reynolds and Best numbers can be used. Then, mass of individual ice particles can be derived from measured fall speed, particle size, and cross-sectional area.
During four winter seasons, 2014/2015–2017/2018, D-ICI was employed in Kiruna, northern Sweden (67.8N, 20.4E). The dataset presented here has resulted from the D-ICI measurements during this period and consists of the determined snow ice particle properties and the dual images of the same particles.
The dataset is the basis of the articles:
Vázquez-Martín, S., Kuhn, T., & Eliasson, S. (2021): Shape dependence of snow crystal fall speed, Atmospheric Chemistry and Physics, 21(10), 7545–7565. https://doi.org/10.5194/acp-21-7545-2021
Vázquez-Martín, S., Kuhn, T., & Eliasson, S. (2021). Mass of different snow crystal shapes derived from fall speed measurements, Atmospheric Chemistry and Physics, 21(24), 18669–18688. https://doi.org/10.5194/acp-2021-203
Description
Instrumentet Dual Ice Crystal Imager (D-ICI) mäter samtidigt mikrofysikaliska egenskaper och fallhastighet av snöpartiklar. D-ICI tar bilder av partiklar från två olika riktningar med en upplösning av 4μm/pixel. Mätningar med D-ICI i Kiruna, norra Sverige (67.8N, 20.4E), under vintrarna 2014/2015 till 2017/2018 presenteras. Både bilder och egenskaper framtagna av dessa ingår i datasetet.
Datasetet ligger till grund för artiklarna
Vázquez-Martín, S., Kuhn, T., & Eliasson, S. (2021): Shape dependence of snow crystal fall speed, Atmospheric Chemistry and Physics, 21(10), 7545–7565. https://doi.org/10.5194/acp-21-7545-2021
Vázquez-Martín, S., Kuhn, T., & Eliasson, S. (2021). Mass of different snow crystal shapes derived from fall speed measurements, Atmospheric Chemistry and Physics, 21(24), 18669–18688. https://doi.org/10.5194/acp-2021-203
För mer information se den engelska katalogsidan: https://snd.gu.se/en/catalogue/study/2021-125
Beskrivning
20.40907
67.84097
20.40907
67.83388
20.414852
67.83388
20.414852
67.84097
20.40907
67.84097
20.41196
67.837425
Sweden
Norrbotten County
Kiruna Municipality