[smitchell333]

Anyone aware of objective, quantitative gathering techniques for snowpack profiles and stability? Seems to me this is the future since most or all of our techniques are subjective - for example:

- your pencil hard is my knife hard
- your R-block 3 is my 4 since I weigh more or penetrate further
- your moderate shear is my easy shear


I tend to think that all the measurements we take are simply qualitative in the end and that experience evaluating combinations of quantitative and qualitative data is where we'll be left no matter the technology, but wouldn't it be usefull to have an objective tool that would provide you trully quantitative data that could be directly compared with other data sets - eventually algorithims could even be developed to predict the likely hood in a given snowpack of avalanching.

[Ava Blanche]

This is an interesting issue that you bring up. Avalanche science has a strange combination of both quantitative and qualitative information.

Here are a few that examples that I've noticed.

The Avalanche Hazard Scale is a quantitative scale: Low, Moderate, Considerable, High, Extreme.



Hardness is defined, as you note, by whether a knife, pencil, four fingers, one finger, or fist penetrates a layer. You can also use a ram penetrometer, but these are expensive and heavy and take time; and thus are not used that often.

Another example of a qualitative scale is the avalanche size scale:



Notice that it is a scale based on a consideration of both quantitative factors (mass) and qualitative ones (description). To make matters even more difficult, note that the mass increases logorithmically.

Anyway, I think some of these "measurements" have a long history of useage and will probably not change. Others probably should- at least for specific applications. For example, for runout calculations, it is best to use just mass in the size classification- both to calculate runout and to measure the effects of any mitigative measures.
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There are no easy solutions, only intelligent choices

[carl]

The American Avalanche Association has just a set of standards. They are available for downloading at:
http://www.avalanche.org/~research/guidelines/
You cannot print a copy; however you can order a bound copy from them for a reasonable price $25 or so.

Standardization of measurement technique should reduce variability in results (your R3 is always an R3) and improve the ability to correlate results (your R3 is always the same as my R4). For the specific Rutschblock question, investigate the Stuffblock it is a more widely reproducible test.

Ablanche-
I'm not sure why logrthyms are a bad approach for avalanche size - they are used in many fields earthquakes and sound come to mind first.

[Valdez Telehead]

[wow]

I use a snow density guage for calibrating hand hardness twice a year when teaching others how to measure.
Small and lightweight, fits in the pack or snow study kit easily if a person is into that sort of thing.
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[Valdez Telehead]

[Gary Brill]

Was it Jamieson or Schweizer that wrote a paper calibrating hand hardness and density, finding reasonable relationships? Hardness is similar to density but also includes a parameter of bond strength. But bond strength can also be obtained with a paintbrush, sweeping the pit face with a gloved hand, or my favorite sweeping the pit face with the corner of a snow profile card.

Oops! (an edit) Or the most obvious things of all on bond strength:

1) How hard the snow is to dig.
2) How it squeaks when prying out rounded snow.
3) Whether the blocks come out in large, irregular shapes.
4) What happens when you throw a block - does it shear, does it fall apart, does it remain intact.
5) Whether or not the pit wall holds sharp edges, or the corners crumble away.

[carl]

[snoboy]

Also shear frame.

[sierra_randoman]

The new guidelines are an attempt to do just that, to standardize the data set taken. Obviously there will always be some subjectivity due to the observer, but this will be less with trained and experienced observers. The SnowPilot project has attempted to standardize and quantify the snow pit measurements as much as possible based on the most recent guidlines, using computer validation and automation. The SnowPilot project is also building a central data base of the snow pit data that is sent in from observers in many locations, the data set for each snow pit is in the same format, and all the snow pit data is entered into to a relational database, such that the data can be queried and compared. Obviously much of the snow pit data tends to be more qualitative, but we've made everything as robust and quantitative as possible. It is a quite a challenge to objectify snow data, but I think we've made some good progress towards that end. Hopefully the extensive data collected by SnowPilot can be leveraged for basic research as well as forecasting.



Mark Kahrl
SnowPilot Developer
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Got SnowPilot? http://www.snowpilot.org

[Valdez Telehead]

[carl]

You are confusing quantification with experimental error. All of the methods I list have a quantifiable result - a numeric output, that's not subject to interpretation. That different operators acheive different results is from nonstandard measurement technique, what we'll call "measurement error". Temperature and angle are also subject to measurement error. Like I mentioned earlier - by following standard procedures one should reduce the measurement error and acheive better coordination in the results.

Mark-
Kudos to you and the Snowpilot team!

[Valdez Telehead]

[carl]

[Valdez Telehead]