Astronomy and Astrophysics – Astronomy
Scientific paper
Mar 2005
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005geoji.160.1123c&link_type=abstract
Geophysical Journal International, Volume 160, Issue 3, pp. 1123-1130.
Astronomy and Astrophysics
Astronomy
1
Calibration Of The Entrainment Function, Database, Entrainment Function, Plinian Columns, Sensitivity Analysis
Scientific paper
Many of the processes involved in volcanic eruptive columns may be described through physical models based on conservation laws in which a physical parametrization called the entrainment function plays an important role. The solution of inverse problems and the estimation of the characteristics of ancient eruptions are among the purposes of these models that require a better knowledge of the characteristics and properties of this function. The first part of the study shows that the three usual shapes chosen for this function yield apparently the same behaviour of the column. However, we prove that a piecewise constant shape may be unsuitable in optimization processes based on gradient methods. It also turns out that the parameters defining the entrainment function cannot be considered constant.
In the second part of the paper, the unique parameter of the remaining two functions is viewed as dependent on the boundary conditions and specified with respect to them. A calibration of the entrainment function with respect to real data is achieved through a power law established between column height and discharge, the latter being related to velocity, radius and bulk density at the vent. According to a discussion on eruptive data, the construction of a mathematical parametrization for ɛ, with respect to boundary conditions and the heights of the vent and the tropopause, appears to be an unwarranted and difficult task since any new addition to the observed data will definitely modify the power law.
A 4-D database covering the range of boundary conditions usually found in Plinian eruptions, together with an interpolation operator, are constructed in order to provide an approximated parameter for any set of boundary conditions in the range considered. Numerical results with a database of dimension 94 show that the approximated parameter allows one to recover column height very accurately.
Charpentier I.
Espindola J. M.
No associations
LandOfFree
A study of the entrainment function in models of Plinian columns: characteristics and calibration does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with A study of the entrainment function in models of Plinian columns: characteristics and calibration, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A study of the entrainment function in models of Plinian columns: characteristics and calibration will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1216336