The Stabilitron: Leveraging Mobile Devices for Snowpack Assessment

Christian Skalka, University of Vermont

Introduction The Stabilitron (patent pending) is a new standards-based program for wireless mobile devices that assists in snowpack stability assessment. It is intended for a general backcountry user population, including both avalanche professionals and recreationalists. The Stabilitron takes advantage of mobile device features to put decision procedures designed for professionals [1] literally in the hands of less-experienced travelers. Our contributions include a proof-of-concept Stabilitron webapp available for download to the IPhone and IPod Touch. We also propose a new XML standard for symbolic representation, communication, and computational manipulation of Avalanche Roses, and a new JSON standard for encoding avalanche assessment decision trees. Existing Products and Assessment Approximations Several products exist for assisting backcountry recreationalists in assessing snowpack stability, including the Avaluator [2] and the Check & Ride. These tools are simple, lightweight visual or mechanical devices designed to be easily carried in the backcountry. One of the main principles behind these tools is simplification of decision procedures-- that is, while avalanche professionals such as guides and snow scientists may take into account a myriad of factors in snowpack assessment, these tools are designed to reduce these factors for the relatively inexperienced recreationalist.

Screenshot of the Stabilitron. Installation and user notes below.

The Avaluator combines two parameters, regional ratings and terrain complexity, to yield a snowpack assessment via a simple visual computation. The Check & Ride combines a similarly small number of parameters in a mechanical computation. These tools essentially provide primitive analog computational support for approximating more complex decision procedures [2]. We hypothesize that more sophisticated computational devices would support a more accurate replication of optimal decision procedures by the novice user. Indeed, this can be viewed as just another incarnation of so-called expert systems.

Supporting Decisions with Mobile Wireless Devices

Computer programs have previously been used to support snow pack snow assessment for backcountry travel, most notably the Avaluator Trip Planner. However, traditional computers are obviously too large to bring into the backcountry and these programs have therefore been used only to support pre-trip planning. However, mobile computing devices such as Blackberries, IPhones, and even cellphones present new possibilities. Small and lightweight, these devices are being carried into the backcountry by many skiers already, and more every day as their popularity continues to explode. Indeed, these devices offer a myriad of features to support decision-making in the backcountry:

• Small size and light weight for backcountry convenience.
• Internet access for automatic download of up-to-date regional forecasts (cached before arrival at the trailhead if necessary).
• Program interfaces that can automatically prompts users for relevant conditions data.
• Automation of decision procedures as digital computer programs.
• Automated, modular update of decision trees underlying expert systems.
• Integrated accelerometers for measuring slope angle.

Leveraging Standards for Tool Update

Snow pack assessments will change daily on the basis, and optimal decision procedures themselves evolve as avalanche professionals refine them. Our programmatic approach is signficantly enhanced by related stantards.

An XML standard for the Avalanche Rose. The "Avalanche Rose" is becoming a de-facto standard for reporting regional avalanche danger ratings, especially in the United States. As more computational tools are inevitably developed that take as input regional ratings, we believe it is crucial for avalanche centers to develop standards for representing Avalanche Roses in a computationally-friendly (non-graphical) format. This will allow tools such as ours to retrieve regional danger assessments online from arbitrary centers via a uniform protocol, for subsequent processing and/or display. We have proposed an XML standard for encoding Avalanche Roses; the Stabilitron currently takes this sort of XML data as input and extracts a regional data rating for integration in the decision procedure, and also uses vector graphics to display the Rose in a familiar graphical format. The Stabilitron is capable of retrieving such XML data from online avalanche centers once standards are adapted.

A JSON standard for encoding decision trees. The decision trees implemented by the Stabilitron are statically represented by a single JSON object. JSON is a lightwieght data format which is easy to parse and has bindings in many other languages. The JSON object can be encoded into a text document and posted on any web server. The Stabilitron can then download that decison tree and functionally integrate it without any modifications to its codebase. The upshot of this is twofold: (1) avalanche professionals can easily express new decision procedures in a standardized format, and (2) Stabilitron users can update the tool to integrate the most up-to-date decision procedures with a click, or even automatically.

Installing and Using the Stabilitron

We have developed the Stabilitron in a proof-of-concept javascript format that can be downloaded and installed as a web-app on an IPhone or IPod Touch (it can be viewed in a standard web browser as well, but the rendering is a little odd in that format). This version allows user input of observational data, and automatically updates the danger assessment based on Jamieson et al.'s recently developed decision procedure [1]. Future versions will also retrieve Avalanche Roses and updated decision procedures online, and can be conveniently distributed via e.g. the "App Store".