scholarly journals A new method of simulating volcanic eruption column formation and dispersion of ejected ash clouds

2017 ◽  
Vol 25 (1) ◽  
pp. 151-160 ◽  
Author(s):  
F. Espinosa Arenal ◽  
R. Avila ◽  
S. S. Raza
Keyword(s):  
Volcanic Eruption ◽  
New Method ◽  
Eruption Column ◽  
Column Formation

scholarly journals Geometric estimation of volcanic eruption column height from GOES-R near-limb imagery – Part 2: Case studies

2021 ◽  
Author(s):  
Ákos Horváth ◽  
Olga A. Girina ◽  
James L. Carr ◽  
Dong L. Wu ◽  
Alexey A. Bril ◽  
...  
Keyword(s):  
Volcanic Eruption ◽  
Temperature Inversion ◽  
Companion Paper ◽  
Column Height ◽  
Eruption Column ◽  
Side View ◽  
Temperature Method ◽  
A New Technique ◽  
Tropopause Temperature ◽  
Good Agreement

Abstract. In a companion paper (Horváth et al., 2021), we introduced a new technique to estimate volcanic eruption column height from extremely oblique near-limb geostationary views. The current paper demonstrates and validates the technique in a number of recent eruptions, ranging from ones with weak columnar plumes to subplinian events with massive umbrella clouds and overshooting tops that penetrate the stratosphere. Due to its purely geometric nature, the new method is shown to be unaffected by the limitations of the traditional brightness temperature method, such as height underestimation in subpixel and semitransparent plumes, ambiguous solutions near the tropopause temperature inversion, or the lack of solutions in undercooled plumes. The side view height estimates were in good agreement with plume heights derived from ground-based video and satellite stereo observations, suggesting they can be a useful complementary to established techniques.

scholarly journals Geometric estimation of volcanic eruption column height from GOES-R near-limb imagery – Part 1: Methodology

2021 ◽  
Author(s):  
Ákos Horváth ◽  
James L. Carr ◽  
Olga A. Girina ◽  
Dong L. Wu ◽  
Alexey A. Bril ◽  
...  
Keyword(s):  
Volcanic Eruption ◽  
Near Field ◽  
Estimation Method ◽  
Column Height ◽  
Eruption Column ◽  
Large Set ◽  
Point Estimates ◽  
Temperature Method ◽  
Geometric Technique ◽  
Wind Profiles

Abstract. A geometric technique is introduced to estimate the height of volcanic eruption columns using the generally discarded near-limb portion of geostationary imagery. Such oblique observations facilitate a height-by-angle estimation method by offering close to orthogonal side views of eruption columns protruding from the Earth ellipsoid. Coverage is restricted to daytime point estimates in the immediate vicinity of the vent, which nevertheless can provide complementary constraints on source conditions for the modelling of near-field plume evolution. The technique is best suited to strong eruption columns with minimal tilting in the radial direction. For weak eruptions with severely bent plumes or eruptions with expanded umbrella clouds the radial tilt/expansion has to be corrected for either visually or using ancillary wind profiles. Validation on a large set of mountain peaks indicates a typical height uncertainty of ±500 m for near-vertical eruption columns, which compares favourably with the accuracy of the common temperature method.

Ku-Band High-Speed Scanning Doppler Radar for Volcanic Eruption Monitoring

2019 ◽  
Vol 14 (4) ◽  
pp. 630-640
Author(s):  
Masayuki Maki ◽  
Shinobu Takahashi ◽  
Sumiya Okada ◽  
Katsuyuki Imai ◽  
Hiroshi Yamaguchi ◽  
...  
Keyword(s):  
Volcanic Eruption ◽  
High Speed ◽  
Doppler Radar ◽  
Volcanic Eruptions ◽  
Radio Station ◽  
Japan Meteorological Agency ◽  
Doppler Spectrum ◽  
Doppler Velocity ◽  
Eruption Column ◽  
Ku Band

This paper presents the major specifications and characteristics of the Ku-band high-speed scanning Doppler radar for volcano observation (KuRAD) introduced to Kagoshima University in March 2017 as well as the results of a test observation at Sakurajima. KuRAD is a Doppler radar for research with a wavelength of approximately 2 cm and uses a 45 cm diameter Luneberg lens antenna as a transmitting and receiving antenna to observe the development of a volcanic eruption column immediately following eruption at a maximum rotation speed of 40 rpm. The maximum transmitter power is 9.6 W and the maximum observational range is 20 km. Observed data includes radar reflectivity factor, Doppler velocity, and Doppler spectrum width. Another feature of KuRAD is an obtained radio station license for observation of a total of seven active volcanos in Kyushu. To assess the basic performance of KuRAD, we carried out test observations of volcanic eruptions at Sakurajima, Kagoshima Prefecture, Japan and collected a total of 87 eruptions (20 of which are explosive eruptions and 7 of which had 3,000 m or higher eruptive smoke from vents). From the eruption data of Showa vent on May 2, 2017, it was confirmed that KuRAD could monitor the three-dimensional internal structure of a volcanic eruption column immediately following eruption. Eruption data from Minamidake of Sakurajima on March 5, 2018, showed that KuRAD successfully observed the eruptive smoke reaching a height of 4,000 m, although the eruptive smoke was covered with clouds and could not be detected by optical instruments of the Japan Meteorological Agency.

scholarly journals Geometric estimation of volcanic eruption column height from GOES-R near-limb imagery – Part 1: Methodology

2021 ◽  
Vol 21 (16) ◽  
pp. 12189-12206 ◽  
Author(s):  
Ákos Horváth ◽  
James L. Carr ◽  
Olga A. Girina ◽  
Dong L. Wu ◽  
Alexey A. Bril ◽  
...  
Keyword(s):  
Volcanic Eruption ◽  
Near Field ◽  
Estimation Method ◽  
Column Height ◽  
Eruption Column ◽  
Large Set ◽  
Point Estimates ◽  
Temperature Method ◽  
Geometric Technique ◽  
Wind Profiles

Abstract. A geometric technique is introduced to estimate the height of volcanic eruption columns using the generally discarded near-limb portion of geostationary imagery. Such oblique observations facilitate a height-by-angle estimation method by offering close-to-orthogonal side views of eruption columns protruding from the Earth ellipsoid. Coverage is restricted to daytime point estimates in the immediate vicinity of the vent, which nevertheless can provide complementary constraints on source conditions for the modeling of near-field plume evolution. The technique is best suited to strong eruption columns with minimal tilting in the radial direction. For weak eruptions with severely bent plumes or eruptions with expanded umbrella clouds the radial tilt/expansion has to be corrected for either visually or using ancillary wind profiles. Validation on a large set of mountain peaks indicates a typical height uncertainty of ±500 m for near-vertical eruption columns, which compares favorably with the accuracy of the common temperature method.

scholarly journals Geometric estimation of volcanic eruption column height from GOES-R near-limb imagery – Part 2: Case studies

2021 ◽  
Vol 21 (16) ◽  
pp. 12207-12226 ◽  
Author(s):  
Ákos Horváth ◽  
Olga A. Girina ◽  
James L. Carr ◽  
Dong L. Wu ◽  
Alexey A. Bril ◽  
...  
Keyword(s):  
Volcanic Eruption ◽  
Temperature Inversion ◽  
Companion Paper ◽  
Column Height ◽  
Eruption Column ◽  
Side View ◽  
Temperature Method ◽  
A New Technique ◽  
Tropopause Temperature ◽  
Good Agreement

Abstract. In a companion paper (Horváth et al., 2021), we introduced a new technique to estimate volcanic eruption column height from extremely oblique near-limb geostationary views. The current paper demonstrates and validates the technique in a number of recent eruptions, ranging from ones with weak columnar plumes to subplinian events with massive umbrella clouds and overshooting tops that penetrate the stratosphere. Due to its purely geometric nature, the new method is shown to be unaffected by the limitations of the traditional brightness temperature method, such as height underestimation in subpixel and semitransparent plumes, ambiguous solutions near the tropopause temperature inversion, or the lack of solutions in undercooled plumes. The side view height estimates were in good agreement with plume heights derived from ground-based video and satellite stereo observations, suggesting they can be a useful complement to established techniques.

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