Weather radar observations of the Hekla 2000 eruption cloud, Iceland

C. Lacasse; S. Karlsdóttir; G. Larsen; H. Soosalu; W. I. Rose; G. G.J. Ernst

doi:10.1007/s00445-003-0329-3

Weather radar observations of the Hekla 2000 eruption cloud, Iceland

C. Lacasse
, S. Karlsdóttir
, G. Larsen
, H. Soosalu
, W. I. Rose
, G. G.J. Ernst

University of Iceland

Research output: Contribution to journal › Article › peer-review

Abstract

The Hekla eruption cloud on 26-27 February 2000 was the first volcanic cloud to be continuously and completely monitored advecting above Iceland, using the C-band weather radar near the Keflavík international airport. Real-time radar observations of the onset, advection, and waning of the eruption cloud were studied using time series of PPI (plan-position indicator) radar images, including VMI normal, Echotop, and Cappi level 2 displays. The reflectivity of the entire volcanic cloud ranges from 0 to >60 dBz. The eruption column above the vent is essentially characterised by VMI normal and Cappi level 2 values, >30 dBz, due to the dominant influence of lapilli and ash (tephra) on the overall reflected signal. The cloud generated by the column was advected downwind to the north-northeast. It is characterised by values between 0 and 30 dBz, and the persistence of these reflections likely result from continuing water condensation and freezing on ash particles. Echotop radar images of the eruption onset document a rapid ascent of the plume head with a mean velocity of ∼30 to 50 m s^-1, before it reached an altitude of ∼11-12 km. The evolution of the reflected cloud was studied from the area change in pixels of its highly reflected portions, >30 dBz, and tied to recorded volcanic tremor amplitudes. The synchronous initial variation of both radar and seismic signals documents the abrupt increase in tephra emission and magma discharge rate from 18:20 to 19:00 UTC on 26 February. From 19:00 the >45 dBz and 30-45 dBz portions of the reflected cloud decrease and disappear at about 7 and 10.5 h, respectively, after the eruption began, indicating the end of the decaying explosive phase. The advection and extent of the reflected eruption cloud were compared with eyewitness accounts of tephra fall onset and the measured mass of tephra deposited on the ground during the first 12 h. Differences in the deposit map and volcanic cloud radar map are due to the fact that the greater part of the deposit originates by fallout off the column margins and from the base of the cloud followed by advection of falling particle in lower level winds.

Original language	English
Pages (from-to)	457-473
Number of pages	17
Journal	Bulletin of Volcanology
Volume	66
Issue number	5
DOIs	https://doi.org/10.1007/s00445-003-0329-3
Publication status	Published - Jul 2004

Bibliographical note

Funding Information: Acknowledgements The authors would like to thank the Icelandic Meteorological Office and the Science Institute at the University of Iceland for their support, and especially Philippe Crochet, Hreinn Hjartarson, Hrafn Gudmundsson, Erik Sturkell, Kjartan Haraldsson, and Stef n rnason for fruitful discussions and for giving access to unpublished data. The Icelandic Civil Aviation Administration provided very constructive comments throughout the study. C.L.’s research work was supported by internal funds from the Open University. G.G.J.E. acknowledges the support of the Fondation Belge de la Vocation, the Belgian NSF (FWO-Vlaanderen), and Ghent colleagues. Peter Mouginis-Mark, David Pieri, and an anonymous reviewer are acknowledged for thorough reviews of the manuscript.

Other keywords

Aircraft safety
Hekla 2000 eruption
Iceland
Radar observations
Tephra fall
Volcanic cloud
Volcanic tremor

Access to Document

10.1007/s00445-003-0329-3

Cite this

@article{a792df0cbfaa472b9154c9b77c9afe6a,

title = "Weather radar observations of the Hekla 2000 eruption cloud, Iceland",

abstract = "The Hekla eruption cloud on 26-27 February 2000 was the first volcanic cloud to be continuously and completely monitored advecting above Iceland, using the C-band weather radar near the Keflav{\'i}k international airport. Real-time radar observations of the onset, advection, and waning of the eruption cloud were studied using time series of PPI (plan-position indicator) radar images, including VMI normal, Echotop, and Cappi level 2 displays. The reflectivity of the entire volcanic cloud ranges from 0 to >60 dBz. The eruption column above the vent is essentially characterised by VMI normal and Cappi level 2 values, >30 dBz, due to the dominant influence of lapilli and ash (tephra) on the overall reflected signal. The cloud generated by the column was advected downwind to the north-northeast. It is characterised by values between 0 and 30 dBz, and the persistence of these reflections likely result from continuing water condensation and freezing on ash particles. Echotop radar images of the eruption onset document a rapid ascent of the plume head with a mean velocity of ∼30 to 50 m s-1, before it reached an altitude of ∼11-12 km. The evolution of the reflected cloud was studied from the area change in pixels of its highly reflected portions, >30 dBz, and tied to recorded volcanic tremor amplitudes. The synchronous initial variation of both radar and seismic signals documents the abrupt increase in tephra emission and magma discharge rate from 18:20 to 19:00 UTC on 26 February. From 19:00 the >45 dBz and 30-45 dBz portions of the reflected cloud decrease and disappear at about 7 and 10.5 h, respectively, after the eruption began, indicating the end of the decaying explosive phase. The advection and extent of the reflected eruption cloud were compared with eyewitness accounts of tephra fall onset and the measured mass of tephra deposited on the ground during the first 12 h. Differences in the deposit map and volcanic cloud radar map are due to the fact that the greater part of the deposit originates by fallout off the column margins and from the base of the cloud followed by advection of falling particle in lower level winds.",

keywords = "Aircraft safety, Hekla 2000 eruption, Iceland, Radar observations, Tephra fall, Volcanic cloud, Volcanic tremor",

author = "C. Lacasse and S. Karlsd{\'o}ttir and G. Larsen and H. Soosalu and Rose, \{W. I.\} and Ernst, \{G. G.J.\}",

note = "Funding Information: Acknowledgements The authors would like to thank the Icelandic Meteorological Office and the Science Institute at the University of Iceland for their support, and especially Philippe Crochet, Hreinn Hjartarson, Hrafn Gudmundsson, Erik Sturkell, Kjartan Haraldsson, and Stef n rnason for fruitful discussions and for giving access to unpublished data. The Icelandic Civil Aviation Administration provided very constructive comments throughout the study. C.L.{\textquoteright}s research work was supported by internal funds from the Open University. G.G.J.E. acknowledges the support of the Fondation Belge de la Vocation, the Belgian NSF (FWO-Vlaanderen), and Ghent colleagues. Peter Mouginis-Mark, David Pieri, and an anonymous reviewer are acknowledged for thorough reviews of the manuscript.",

year = "2004",

month = jul,

doi = "10.1007/s00445-003-0329-3",

language = "English",

volume = "66",

pages = "457--473",

journal = "Bulletin of Volcanology",

issn = "0258-8900",

publisher = "Springer Verlag",

number = "5",

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TY - JOUR

T1 - Weather radar observations of the Hekla 2000 eruption cloud, Iceland

AU - Lacasse, C.

AU - Karlsdóttir, S.

AU - Larsen, G.

AU - Soosalu, H.

AU - Rose, W. I.

AU - Ernst, G. G.J.

N1 - Funding Information: Acknowledgements The authors would like to thank the Icelandic Meteorological Office and the Science Institute at the University of Iceland for their support, and especially Philippe Crochet, Hreinn Hjartarson, Hrafn Gudmundsson, Erik Sturkell, Kjartan Haraldsson, and Stef n rnason for fruitful discussions and for giving access to unpublished data. The Icelandic Civil Aviation Administration provided very constructive comments throughout the study. C.L.’s research work was supported by internal funds from the Open University. G.G.J.E. acknowledges the support of the Fondation Belge de la Vocation, the Belgian NSF (FWO-Vlaanderen), and Ghent colleagues. Peter Mouginis-Mark, David Pieri, and an anonymous reviewer are acknowledged for thorough reviews of the manuscript.

PY - 2004/7

Y1 - 2004/7

N2 - The Hekla eruption cloud on 26-27 February 2000 was the first volcanic cloud to be continuously and completely monitored advecting above Iceland, using the C-band weather radar near the Keflavík international airport. Real-time radar observations of the onset, advection, and waning of the eruption cloud were studied using time series of PPI (plan-position indicator) radar images, including VMI normal, Echotop, and Cappi level 2 displays. The reflectivity of the entire volcanic cloud ranges from 0 to >60 dBz. The eruption column above the vent is essentially characterised by VMI normal and Cappi level 2 values, >30 dBz, due to the dominant influence of lapilli and ash (tephra) on the overall reflected signal. The cloud generated by the column was advected downwind to the north-northeast. It is characterised by values between 0 and 30 dBz, and the persistence of these reflections likely result from continuing water condensation and freezing on ash particles. Echotop radar images of the eruption onset document a rapid ascent of the plume head with a mean velocity of ∼30 to 50 m s-1, before it reached an altitude of ∼11-12 km. The evolution of the reflected cloud was studied from the area change in pixels of its highly reflected portions, >30 dBz, and tied to recorded volcanic tremor amplitudes. The synchronous initial variation of both radar and seismic signals documents the abrupt increase in tephra emission and magma discharge rate from 18:20 to 19:00 UTC on 26 February. From 19:00 the >45 dBz and 30-45 dBz portions of the reflected cloud decrease and disappear at about 7 and 10.5 h, respectively, after the eruption began, indicating the end of the decaying explosive phase. The advection and extent of the reflected eruption cloud were compared with eyewitness accounts of tephra fall onset and the measured mass of tephra deposited on the ground during the first 12 h. Differences in the deposit map and volcanic cloud radar map are due to the fact that the greater part of the deposit originates by fallout off the column margins and from the base of the cloud followed by advection of falling particle in lower level winds.

AB - The Hekla eruption cloud on 26-27 February 2000 was the first volcanic cloud to be continuously and completely monitored advecting above Iceland, using the C-band weather radar near the Keflavík international airport. Real-time radar observations of the onset, advection, and waning of the eruption cloud were studied using time series of PPI (plan-position indicator) radar images, including VMI normal, Echotop, and Cappi level 2 displays. The reflectivity of the entire volcanic cloud ranges from 0 to >60 dBz. The eruption column above the vent is essentially characterised by VMI normal and Cappi level 2 values, >30 dBz, due to the dominant influence of lapilli and ash (tephra) on the overall reflected signal. The cloud generated by the column was advected downwind to the north-northeast. It is characterised by values between 0 and 30 dBz, and the persistence of these reflections likely result from continuing water condensation and freezing on ash particles. Echotop radar images of the eruption onset document a rapid ascent of the plume head with a mean velocity of ∼30 to 50 m s-1, before it reached an altitude of ∼11-12 km. The evolution of the reflected cloud was studied from the area change in pixels of its highly reflected portions, >30 dBz, and tied to recorded volcanic tremor amplitudes. The synchronous initial variation of both radar and seismic signals documents the abrupt increase in tephra emission and magma discharge rate from 18:20 to 19:00 UTC on 26 February. From 19:00 the >45 dBz and 30-45 dBz portions of the reflected cloud decrease and disappear at about 7 and 10.5 h, respectively, after the eruption began, indicating the end of the decaying explosive phase. The advection and extent of the reflected eruption cloud were compared with eyewitness accounts of tephra fall onset and the measured mass of tephra deposited on the ground during the first 12 h. Differences in the deposit map and volcanic cloud radar map are due to the fact that the greater part of the deposit originates by fallout off the column margins and from the base of the cloud followed by advection of falling particle in lower level winds.

KW - Aircraft safety

KW - Hekla 2000 eruption

KW - Iceland

KW - Radar observations

KW - Tephra fall

KW - Volcanic cloud

KW - Volcanic tremor

UR - https://www.scopus.com/pages/publications/5144231836

U2 - 10.1007/s00445-003-0329-3

DO - 10.1007/s00445-003-0329-3

M3 - Article

SN - 0258-8900

VL - 66

SP - 457

EP - 473

JO - Bulletin of Volcanology

JF - Bulletin of Volcanology

IS - 5

ER -

Weather radar observations of the Hekla 2000 eruption cloud, Iceland

Abstract

Bibliographical note

Other keywords

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