Dual-polarization radar signatures in snowstorms

Role of snowflake aggregation

Forskningsoutput: TidskriftsbidragArtikelVetenskapligPeer review

Sammanfattning

In this article a potential role of snowflake growth by aggregation on formation of dual-polarization radar signatures in winter storms is discussed. We advocate that the observed bands of increased values of specific differential phase (Kdp) can be linked to the onset of aggregation. These bands are caused by high number concentrations of oblate relatively dense ice particles and take place in regions where an ice phase “seeder-feeder” is active. On the other hand, the differential reflectivity (Zdr) bands, in absence of detectable Kdp values, are observed in the areas where crystal growth is the dominating snow growth mechanism and ice particle number concentration is lower. This distinction in underlying processes explains why Kdp and Zdr bands are not always observed at the same time. Furthermore, based on surface observations of snowflakes, it is determined that early aggregates, consisting of a small number of ice crystals, are oblate. These oblate particles could contribute to the reported dual-polarization radar signatures in snow, especially to the Kdp. This could help to explain why, where observed at the same type, Kdp and Zdr bands do not match and the altitude of the peak value of Kdp is usually lower than the Zdr one. It also means that dual-polarization radar signatures of snowflakes may depend on a stage of aggregation.
Originalspråkengelska
TidskriftJournal of Geophysical Research : Atmospheres
Volym120
Utgåva24
Sidor (från-till)12644–12655
Antal sidor12
ISSN2169-897X
DOI
StatusPublicerad - 27 dec 2015
MoE-publikationstypA1 Tidskriftsartikel-refererad

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  • 1171 Geovetenskaper
  • 114 Fysik

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title = "Dual-polarization radar signatures in snowstorms: Role of snowflake aggregation",
abstract = "In this article a potential role of snowflake growth by aggregation on formation of dual-polarization radar signatures in winter storms is discussed. We advocate that the observed bands of increased values of specific differential phase (Kdp) can be linked to the onset of aggregation. These bands are caused by high number concentrations of oblate relatively dense ice particles and take place in regions where an ice phase “seeder-feeder” is active. On the other hand, the differential reflectivity (Zdr) bands, in absence of detectable Kdp values, are observed in the areas where crystal growth is the dominating snow growth mechanism and ice particle number concentration is lower. This distinction in underlying processes explains why Kdp and Zdr bands are not always observed at the same time. Furthermore, based on surface observations of snowflakes, it is determined that early aggregates, consisting of a small number of ice crystals, are oblate. These oblate particles could contribute to the reported dual-polarization radar signatures in snow, especially to the Kdp. This could help to explain why, where observed at the same type, Kdp and Zdr bands do not match and the altitude of the peak value of Kdp is usually lower than the Zdr one. It also means that dual-polarization radar signatures of snowflakes may depend on a stage of aggregation.",
keywords = "1171 Geosciences, meteorology, cloud physics, radar meteorology, 114 Physical sciences",
author = "Dmitriy Moiseev and Lautaportti, {Susanna Kristiina} and Jani Tyynela and S. Lim",
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Dual-polarization radar signatures in snowstorms : Role of snowflake aggregation. / Moiseev, Dmitriy; Lautaportti, Susanna Kristiina; Tyynela, Jani; Lim, S.

I: Journal of Geophysical Research : Atmospheres, Vol. 120, Nr. 24, 27.12.2015, s. 12644–12655.

Forskningsoutput: TidskriftsbidragArtikelVetenskapligPeer review

TY - JOUR

T1 - Dual-polarization radar signatures in snowstorms

T2 - Role of snowflake aggregation

AU - Moiseev, Dmitriy

AU - Lautaportti, Susanna Kristiina

AU - Tyynela, Jani

AU - Lim, S.

PY - 2015/12/27

Y1 - 2015/12/27

N2 - In this article a potential role of snowflake growth by aggregation on formation of dual-polarization radar signatures in winter storms is discussed. We advocate that the observed bands of increased values of specific differential phase (Kdp) can be linked to the onset of aggregation. These bands are caused by high number concentrations of oblate relatively dense ice particles and take place in regions where an ice phase “seeder-feeder” is active. On the other hand, the differential reflectivity (Zdr) bands, in absence of detectable Kdp values, are observed in the areas where crystal growth is the dominating snow growth mechanism and ice particle number concentration is lower. This distinction in underlying processes explains why Kdp and Zdr bands are not always observed at the same time. Furthermore, based on surface observations of snowflakes, it is determined that early aggregates, consisting of a small number of ice crystals, are oblate. These oblate particles could contribute to the reported dual-polarization radar signatures in snow, especially to the Kdp. This could help to explain why, where observed at the same type, Kdp and Zdr bands do not match and the altitude of the peak value of Kdp is usually lower than the Zdr one. It also means that dual-polarization radar signatures of snowflakes may depend on a stage of aggregation.

AB - In this article a potential role of snowflake growth by aggregation on formation of dual-polarization radar signatures in winter storms is discussed. We advocate that the observed bands of increased values of specific differential phase (Kdp) can be linked to the onset of aggregation. These bands are caused by high number concentrations of oblate relatively dense ice particles and take place in regions where an ice phase “seeder-feeder” is active. On the other hand, the differential reflectivity (Zdr) bands, in absence of detectable Kdp values, are observed in the areas where crystal growth is the dominating snow growth mechanism and ice particle number concentration is lower. This distinction in underlying processes explains why Kdp and Zdr bands are not always observed at the same time. Furthermore, based on surface observations of snowflakes, it is determined that early aggregates, consisting of a small number of ice crystals, are oblate. These oblate particles could contribute to the reported dual-polarization radar signatures in snow, especially to the Kdp. This could help to explain why, where observed at the same type, Kdp and Zdr bands do not match and the altitude of the peak value of Kdp is usually lower than the Zdr one. It also means that dual-polarization radar signatures of snowflakes may depend on a stage of aggregation.

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KW - meteorology

KW - cloud physics

KW - radar meteorology

KW - 114 Physical sciences

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JO - Journal of Geophysical Research : Atmospheres

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