Stability Class Reference

Detailed Description

This class contains the stability routines for the snowpack model. Stability is found for each LAYER (i.e. finite element) and INTERFACE (i.e. node). Subsequently, the element data contains a variable S_dr (layer stability for direct action avalanches) and the nodal data contains the varialble S_i (interface stability). The station data contain S_class an overall stability estimation for the profile based on hand hardness, grain class and a slab characterization. At the end, the stability index approach is compared to this profile characterization to check consistency/reliability.

TODO: update description 2009-10-20

#include <Stability.h>

Public Member Functions
	Stability (const SnowpackConfig &i_cfg, const bool &i_classify_profile=false)
void	checkStability (const CurrentMeteo &Mdata, SnowStation &Xdata)
	The stability information is based on a very empirical principle. First a distinction is made between "direct action" and "slab" situations. The former have to do with strain weakening during heavy snowfalls or during melt situations. The original Bob intra-layer stability has been adapted for this situation and complemented by the Conway approach. The latter is handled by an adaptation of the Schweizer - Wiesinger profile classification in combination with a more conventional stability index based on critical shear strength values. More...

Static Public Attributes
static const double	psi_ref = 38.0
	Reference slope angle. More...
static const double	max_stability = 6.0
	Upper stability limit. More...
static const double	minimum_slab = 0.1
	Minimum slab thickness for natural and deformation stability index (m) More...
static const double	ground_rough = 0.2
	The first GROUND_ROUGH m of snow will not be unstable due to ground roughness. More...
static const double	min_depth_ssi = 0.1
	MIN_DEPTH_SSI m of snow must be left after discarding penetration depth. More...
static const double	skier_depth = 1.0
	Skiers will not trigger failures SKIER_DEPTH m below penetration depth. More...
static const double	min_thick_crust = 0.03
	Minimum thickness for a supporting melt-freeze crust (perp to slope, in m) More...
static const int	sh_mod = 2
	Defines regression model for surface hoar shear strength. More...
static const int	prof_classi = 2
	Defines classification scheme for snow profiles. More...
static const size_t	nmax_lemon = 2
	Maximum number of structural instabilities looked at ("lemons") More...

Constructor & Destructor Documentation

Stability()

Stability::Stability	(	const SnowpackConfig &	i_cfg,
		const bool &	i_classify_profile = false
	)

Member Function Documentation

checkStability()

void Stability::checkStability	(	const CurrentMeteo &	Mdata,
		SnowStation &	Xdata
	)

The stability information is based on a very empirical principle. First a distinction is made between "direct action" and "slab" situations. The former have to do with strain weakening during heavy snowfalls or during melt situations. The original Bob intra-layer stability has been adapted for this situation and complemented by the Conway approach. The latter is handled by an adaptation of the Schweizer - Wiesinger profile classification in combination with a more conventional stability index based on critical shear strength values.

Parameters

Mdata	CurrentMeteo
Xdata	Profile

Member Data Documentation

ground_rough

const double Stability::ground_rough = 0.2

static

The first GROUND_ROUGH m of snow will not be unstable due to ground roughness.

max_stability

const double Stability::max_stability = 6.0

static

Upper stability limit.

min_depth_ssi

const double Stability::min_depth_ssi = 0.1

static

MIN_DEPTH_SSI m of snow must be left after discarding penetration depth.

min_thick_crust

const double Stability::min_thick_crust = 0.03

static

Minimum thickness for a supporting melt-freeze crust (perp to slope, in m)

minimum_slab

const double Stability::minimum_slab = 0.1

static

Minimum slab thickness for natural and deformation stability index (m)

nmax_lemon

const size_t Stability::nmax_lemon = 2

static

Maximum number of structural instabilities looked at ("lemons")

prof_classi

const int Stability::prof_classi = 2

static

Defines classification scheme for snow profiles.

• 0: Based on Skier Stability Index (SSI) thresholds (3 classes)
• 1: Based on re-analysis by Schweizer/Bellaire of SSI and SK38 (2006)
• 2: Nov 2007: re-analysis after recalibration of settling (see rev 250/251)
• 3: According to Schweizer and Wiesinger (5 classes)

psi_ref

const double Stability::psi_ref = 38.0

static

Reference slope angle.

sh_mod

const int Stability::sh_mod = 2

static

Defines regression model for surface hoar shear strength.

skier_depth

const double Stability::skier_depth = 1.0

static

Skiers will not trigger failures SKIER_DEPTH m below penetration depth.

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The documentation for this class was generated from the following files:

• Stability.h
• Stability.cc