TephraProb v.1.7

TephraProb v1.7 includes access to ERA-5 wind data, a different sampling of masses and some bug fixes.

TephraProb troubleshoot

This is an attempt to track issues that could not be solved within the code. Keep in mind that having a code that works on everybody’s computers is hard, especially on Windows where errors can arise because of loaaaaads of different factors. Also, please keep in mind I am not a personal hotline :)

Random tools

Just a repository of cool and handy tools.

Python Resources

Keeping track of interesting resources on Python.

GEE Resources

Keeping track of interesting resources on the Google Earth Engine.

Find wind profiles most similar to an average

Ever needed to find the one wind profile most similar to an average wind profile? A new function in the Analyse wind profiles of TephraProb does just that!

TephraProb v.1.6

There has been a change in the access to the Google Map API used by the function plot_google_map by Zohar Bar-Yehuda that can cause problems when TephraProb attempts to retrieve the map background. Google now requires to get an API Key, which needs to be associated with a Google Project and, tadaaaa, a billing account. Although this is likely to remain free for a small number of requests, some might be reluctant to add a billing account to get a key. A new function offering to export maps to Google Earth was therefore implemented, which relies on the Google Earth Toolbox by Scott Lee Davis.

Wind data for Tephra2

I thought I’d share some problems I’ve recently encountered with the format of wind files used in Tephra2. Just as a reminder, wind file should be a 3-columns, tab-delimited ASCII file containing:

TephraProb v.1.5

Version releases were never systematically attributed to TephraProb until now. This new version was labeled v1.5 as some important changes have been made.

TephraProb on a cluster

There is a relatively easy way to parallelise TephraProb on a computer cluster without having to struggle with Matlab’s Parallel Computing Toolbox. Matlab is not even needed on the cluster, and it is just a matter of sending single occurrences of Tephra2 on different nodes. Here is how to do so:

Tephra2 Inversion

The current set of functions helps running the advection-diffusion model Tephra2 in inversion mode to estimate the best eruption source parameters (ESP) of a tephra deposit. The functions contain two sections. A first section contains a mixture of bash and python scripts for running the inversion of OpenPBS and SLURM clusters. A second section contains Matlab scripts for processing the inversion output designed to help its interpretation.

Access sampled ESP in TephraProb

This note shows how to access the ESPs sampled during Monte Carlo simulations and how to link them to a given output. This note has been updated on 2020-02-12 to work with v1.7.1 of TephraProb. Two files are needed:

• The file located in RUNS/runName/runNb/ named runName_runNb.mat. This contains a structure called data, which contains a field named stor where all the ESPs are stored. data.stor contains sub-fields for the different parameter (e.g. plume height, duration, mass, MER, TGSD). These parameters are stored as vectors that can have different sizes. If the duration of each simulated eruption is <6 h, the size of all vectors should equal the number of simulated eruptions. If durations are >6 h, the size of those parameters that change at each 6 h increment (e.g. plume height, MER) represents the number of times each was sampled. For instance, in the case of a 15 h-long eruption, 3 plume heights are sampled. However, other parameters (e.g. TGSD) are constant over the entire duration of the eruption, so the resulting vectors will have a size equal to the number of simulated eruptions.
• The file located in RUNS/runName/runNb/DATA/ named dataT2_all.mat, which contains two variables:
  • dataT2 is a m by n matrix, where m is the number of points over which accumulations are computed and n is the number of runs. This variable contains all the summed Tephra2 outputs in kg/m2;
  • runNb is a m by 1 vector, where m is the number of runs.

Manual compilation of Tephra2

TephraProb compiles Tephra2 through a bit of Matlab hocus pocus to facilitate problems of OS dependancy, but the mighty Matlab can sometime fail us. In this case, it becomes necessary to manually compile Tephra2 from the command line to see what the error message is. I spent a fair amount of time writing this procedure in emails to people who encountered problems and I thought I would write it down here.

Plot the output of Tephra2 in Matlab

This function plots the output of Tephra2 runs on a map. Output files generated by Tephra2 are in a column format (i.e. easting, northing, elevation and mass accumulation), with the number of rows equal to the total number of points in the grid. For some obscure reason, most of Matlab’s plotting functions only accept inputs in a matrix format, i.e. separate m x n matrices for easting, northing, elevation and mass accumulation, where m and n are the numbers of northing and easting values, respectively. Matlab, unlike other plotting tools (e.g. GMT, Python), therefore requires a transformation the data.

Quantifying probabilities from ballistic models

Here is presented an extended version of the Matlab post-processing function developed for the Great Balls of Fire model for the probabilistic hazard assessment of ballistic impact.

Manually importing ERA-Interim files in TephraProb

When accessing ERA-Interim data in batch, the behaviour of the ECMWF Python API is often unpredictable, which sometime complicates the automatic downloading of wind data in TephraProb. If the API does not work for you, the option of importing NetCDF files that were manually downloaded from the ERA-Interim website was added to TephraProb. Ain’t that nice?

The effect of particle shape on the estimation of plume height

The method of Carey and Sparks (1986) allows to estimate the height of strong plumes based on the geometry of isopleth maps. Although the method has its limitations, it is still the most used in the literature and remains important for the characterisation of eruption source parameters for eruptions that have no direct observations.

Manually importing NOAA Reanalysis files in TephraProb

It is sometime necessary to import into TephraProb some NOAA Reanalysis NetCDF files downloaded manually. One of the reasons is that the NOAA server is accessed via FTP, and firewalls (such as those installed in University networks) might result in an error such as this: