Detailed Description

Implementations of various algorithms useful for evaluating the stability. These algorithms fall within the following categories:

the structural stability, that selects the potential weak layer, for example the SK38, SSI or Relative Threshold;
the stability index, based on a strength/stress relation, such as the natural stability index. This evaluates the stability of a selected layer;
the critical crack length that also evaluates the stability of a selected layer, for example the critical cut length or the anti-crack model.

These methods will then be used by the Stability class to effectively compute the stability for a given profile, according to the user's configuration.

#include <StabilityAlgorithms.h>

Static Public Member Functions
static void	classifyStability_SchweizerBellaire (const double &Swl_ssi, const double &Swl_Sk38, SnowStation &Xdata)
	Returns the Profile Stability Classification based on re-analysis by Schweizer/Bellaire, see Schweizer, J., Bellaire, S., Fierz, C., Lehning, M. and Pielmeier, C., "Evaluating and improving the stability predictions of the snow cover model SNOWPACK", Cold Regions Science and Technology, 2006, 46(1), pp.52-59. More...

static void	classifyStability_Bellaire (const double &Swl_ssi, SnowStation &Xdata)
	Returns the Profile Stability Classification based on the master thesis of S. Bellaire (September 2005) More...

static void	classifyStability_SchweizerBellaire2 (const double &Swl_ssi, const size_t &Swl_lemon, const double &Swl_Sk38, SnowStation &Xdata)
	Returns the Profile Stability Classification based on re-analysis after recalibration of settling (Nov. 2007) This is based on Schweizer, J., Bellaire, S., Fierz, C., Lehning, M. and Pielmeier, C., "Evaluating and improving the stability predictions of the snow cover model SNOWPACK", Cold Regions Science and Technology, 2006, 46(1), pp.52-59. More...

static bool	classifyStability_SchweizerWiesinger (SnowStation &Xdata)
	Returns the Profile Stability Classification (Schweizer-Wiesinger Method) More...

static bool	classifyType_SchweizerLuetschg (SnowStation &Xdata)
	"Pattern recognition" of 10 profile types according to Schweizer, J. and M. Luetschg (2001). Schweizer, J. and M. Luetschg, Characteristics of human-triggered avalanches, 2001, Cold Reg. Sci. Technol. 33(2-3): 147-162. Note that analysis is done on vertical snow height. More...

static bool	setShearStrengthDEFAULT (const double &cH, const double &cos_sl, const mio::Date &date, ElementData &Edata, NodeData &Ndata, StabilityData &STpar)
	DEFAULT: Estimates the critical shear stress based on appropriate parameterisations. More...

static bool	setShearStrength_NIED (const double &cH, const double &cos_sl, const mio::Date &date, ElementData &Edata, NodeData &Ndata, StabilityData &STpar)
	STRENGTH_NIED: Estimates the critical shear stress based on appropriate parameterisations adapted for Japan. More...

static double	getHandHardnessBELLAIRE (const ElementData &Edata, const double &buried_hoar_density)
	Assign hardness to snow types according to density, Swiss version by Sascha Bellaire. More...

static double	getHandHardnessASARC (const ElementData &Edata, const double &buried_hoar_density)
	Assign hand hardness to snow types according to density and grain size, original Canadian version. More...

static double	getHandHardnessMONTI (const ElementData &Edata, const double &buried_hoar_density)
	Assign hardness to snow types according to density Implementation according to Fabiano Monti's work, June 2012 (all types except MFcr). More...

static double	getHandHardnessMONTI (const int &F, const double &rho, const double &water_content, const double &buried_hoar_density)
	Compute hand hardness for a given grain type and density All the information about hardness parameterizations for PP DF RG FC DH MF FCxf are published in Monti et al. (in progress) More...

static double	compCriticalStress (const double &epDotn, const double &T_s)
	Returns the critical stress state of a layer given the temperature and plastic strain rate. More...

static double	setDeformationRateIndex (ElementData &Edata)
	Returns the layer stability index The intra-layer stability criteria is given by the ratio S_f = S_c/S_n where S_n is the neck stress and S_c is the critical stress. The critical stress is determined in the function st_CriticalStress. This function might get a little more involved as time goes on. More...

static double	compPenetrationDepth (const SnowStation &Xdata)
	Returns the skier's penetration depth Pk Adapted from Jamieson & Johnston, Ann. Glaciol., 26, 296-302 (1998) More...

static void	compReducedStresses (const double &stress, const double &cos_sl, StabilityData &STpar)
	Computes normal and shear stresses (kPa) reduced to psi_ref. More...

static double	getNaturalStability (const StabilityData &STpar)
	Returns the natural stability index Sn The classic natural stability index Sn, that is, the ratio of shear stress to shear strength (static) More...

static double	getLayerSkierStability (const double &penetrationDepth, const double &depth_lay, const StabilityData &STpar)
	Returns the skier stability index Sk reduced to psi_ref (usually 38 deg => Sk_38) The classic skier stability index Sk(psi_ref), using P. Foehn's formula (IAHS No162, 1987, p201) for the skier (load of 85 kg on 1.7 m long skis) induced shear stress. More...

static bool	getRelativeThresholdSum (SnowStation &Xdata)
	Returns the Relative Threshold Sum approach (RTA) weak layer. This is according to Monti, Fabiano, and Jürg Schweizer, "A relative difference approach to detect potential weak layers within a snow profile", 2013, Proceedings ISSW. More...

static double	CriticalCutLength (const double &H_slab, const double &rho_slab, const double &cos_sl, const ElementData &Edata, const StabilityData &STpar, const double &stress)
	Critical cut length: Estimates the critical cut length. More...

Member Function Documentation

◆ classifyStability_Bellaire()

void StabilityAlgorithms::classifyStability_Bellaire	(	const double &	Swl_ssi,
		SnowStation &	Xdata
	)

static

Returns the Profile Stability Classification based on the master thesis of S. Bellaire (September 2005)

Parameters

Swl_ssi
Xdata

◆ classifyStability_SchweizerBellaire()

void StabilityAlgorithms::classifyStability_SchweizerBellaire	(	const double &	Swl_ssi,
		const double &	Swl_Sk38,
		SnowStation &	Xdata
	)

static

Returns the Profile Stability Classification based on re-analysis by Schweizer/Bellaire, see Schweizer, J., Bellaire, S., Fierz, C., Lehning, M. and Pielmeier, C., "Evaluating and improving the stability predictions of the snow cover model SNOWPACK", Cold Regions Science and Technology, 2006, 46(1), pp.52-59.

Parameters

Swl_ssi
Swl_Sk38
Xdata

◆ classifyStability_SchweizerBellaire2()

void StabilityAlgorithms::classifyStability_SchweizerBellaire2	(	const double &	Swl_ssi,
		const size_t &	Swl_lemon,
		const double &	Swl_Sk38,
		SnowStation &	Xdata
	)

static

Returns the Profile Stability Classification based on re-analysis after recalibration of settling (Nov. 2007) This is based on Schweizer, J., Bellaire, S., Fierz, C., Lehning, M. and Pielmeier, C., "Evaluating and improving the stability predictions of the snow cover model SNOWPACK", Cold Regions Science and Technology, 2006, 46(1), pp.52-59.

Parameters

Swl_ssi
Swl_lemon
Swl_Sk38
Xdata

◆ classifyStability_SchweizerWiesinger()

bool StabilityAlgorithms::classifyStability_SchweizerWiesinger ( SnowStation & Xdata )

static

Returns the Profile Stability Classification (Schweizer-Wiesinger Method)

Parameters

Xdata

Returns: false if error, true otherwise

◆ classifyType_SchweizerLuetschg()

bool StabilityAlgorithms::classifyType_SchweizerLuetschg ( SnowStation & Xdata )

static

"Pattern recognition" of 10 profile types according to Schweizer, J. and M. Luetschg (2001). Schweizer, J. and M. Luetschg, Characteristics of human-triggered avalanches, 2001, Cold Reg. Sci. Technol. 33(2-3): 147-162. Note that analysis is done on vertical snow height.

Parameters

*Xdata

Returns: false on error, true otherwise

◆ compCriticalStress()

double StabilityAlgorithms::compCriticalStress	(	const double &	epsNeckDot,
		const double &	Ts
	)

static

Returns the critical stress state of a layer given the temperature and plastic strain rate.

Parameters

epsNeckDot	Neck strain rate (s-1)
Ts	Temperature of layer (K)

Returns: Critical stress (Pa)

◆ compPenetrationDepth()

double StabilityAlgorithms::compPenetrationDepth ( const SnowStation & Xdata )

static

Returns the skier's penetration depth Pk Adapted from Jamieson & Johnston, Ann. Glaciol., 26, 296-302 (1998)

Parameters

*Xdata

◆ compReducedStresses()

void StabilityAlgorithms::compReducedStresses	(	const double &	stress,
		const double &	cos_sl,
		StabilityData &	STpar
	)

static

Computes normal and shear stresses (kPa) reduced to psi_ref.

Parameters

stress	Overload perpendicular to slope (Pa)
cos_sl	Cosine of slope angle (1)
STpar

◆ CriticalCutLength()

double StabilityAlgorithms::CriticalCutLength	(	const double &	H_slab,
		const double &	rho_slab,
		const double &	cos_sl,
		const ElementData &	Edata,
		const StabilityData &	STpar,
		const double &	stress
	)

static

Critical cut length: Estimates the critical cut length.

Author: Johan Gaume, Nander Wever

Date: 2016-20-01

Parameters

H_slab	Slab depth (m)
rho_slab	Slab density (kg/m^3)
*Edata	Xdata->Edata[e-1]
cos_sl	cosinus of the simulated slope angle
STpar
stress	stress to apply to the current slab, usually the sum of all layers above

Returns: return critical cut length (m)

◆ getHandHardnessASARC()

double StabilityAlgorithms::getHandHardnessASARC	(	const ElementData &	Edata,
		const double &	buried_hoar_density
	)

static

Assign hand hardness to snow types according to density and grain size, original Canadian version.

Author: Implemented by C. Fierz: Regression from ASARC database by Bruce Jamieson on 2002-08-14

Parameters

Edata
buried_hoar_density	density of the burried hoar (kg m-3)

Returns: hand hardness index (1)

◆ getHandHardnessBELLAIRE()

double StabilityAlgorithms::getHandHardnessBELLAIRE	(	const ElementData &	Edata,
		const double &	buried_hoar_density
	)

static

Assign hardness to snow types according to density, Swiss version by Sascha Bellaire.

Author: Implemented by C. Fierz: Regression by Sascha Bellaire January 2005 (all types except MFcr). The original Swiss regression has been modified for PP, RG and FC to get a better agreement to observed hardness. If there is a new settlement formulation in future, and therefore a better agreement to observed density,it must be checked whether the new or the original regression is the better choice. (18 September 2005; Fierz / S. Bellaire) Original regression values are added as comments where needed.

Parameters

Edata
buried_hoar_density	density of the burried hoar (kg m-3)

Returns: hand hardness index (1)

◆ getHandHardnessMONTI() [1/2]

double StabilityAlgorithms::getHandHardnessMONTI	(	const ElementData &	Edata,
		const double &	buried_hoar_density
	)

static

Assign hardness to snow types according to density Implementation according to Fabiano Monti's work, June 2012 (all types except MFcr).

Author: Fabiano Monti

Date: 2012-06-27

Parameters

Edata
buried_hoar_density	density of the burried hoar (kg m-3)

Returns: hand hardness index (1)

◆ getHandHardnessMONTI() [2/2]

double StabilityAlgorithms::getHandHardnessMONTI	(	const int &	F,
		const double &	rho,
		const double &	water_content,
		const double &	buried_hoar_density
	)

static

Compute hand hardness for a given grain type and density All the information about hardness parameterizations for PP DF RG FC DH MF FCxf are published in Monti et al. (in progress)

Author: Fabiano Monti

Date: 2012-06-27

Parameters

F	grain type
rho	snow density
water_content
buried_hoar_density	density of the burried hoar (kg m-3)

Returns: hand hardness index (1)

◆ getLayerSkierStability()

double StabilityAlgorithms::getLayerSkierStability	(	const double &	Pk,
		const double &	depth_lay,
		const StabilityData &	STpar
	)

static

Returns the skier stability index Sk reduced to psi_ref (usually 38 deg => Sk_38) The classic skier stability index Sk(psi_ref), using P. Foehn's formula (IAHS No162, 1987, p201) for the skier (load of 85 kg on 1.7 m long skis) induced shear stress.

This represents the skier contribution to shear stress at psi_ref and is around 0.1523 kPa / layer_depth at psi_ref = 38 deg and Alpha_max = 54.3 deg.

Parameters

Pk	Skier penetration depth (m)
depth_lay	Depth of layer to investigate (m)
STpar

◆ getNaturalStability()

double StabilityAlgorithms::getNaturalStability ( const StabilityData & STpar )

static

Returns the natural stability index Sn The classic natural stability index Sn, that is, the ratio of shear stress to shear strength (static)

Parameters

STpar

◆ getRelativeThresholdSum()

bool StabilityAlgorithms::getRelativeThresholdSum ( SnowStation & Xdata )

static

Returns the Relative Threshold Sum approach (RTA) weak layer. This is according to Monti, Fabiano, and Jürg Schweizer, "A relative difference approach to detect potential weak layers within a snow profile", 2013, Proceedings ISSW.

Parameters

Xdata all the element and node data for all the layers

Returns: false if error, true otherwise

◆ setDeformationRateIndex()

double StabilityAlgorithms::setDeformationRateIndex ( ElementData & Edata )

static

Returns the layer stability index The intra-layer stability criteria is given by the ratio S_f = S_c/S_n where S_n is the neck stress and S_c is the critical stress. The critical stress is determined in the function st_CriticalStress. This function might get a little more involved as time goes on.

Parameters

*Edata

Returns: Deformation rate index

◆ setShearStrength_NIED()

bool StabilityAlgorithms::setShearStrength_NIED	(	const double &	cH,
		const double &	cos_sl,
		const mio::Date &	date,
		ElementData &	Edata,
		NodeData &	Ndata,
		StabilityData &	STpar
	)

static

STRENGTH_NIED: Estimates the critical shear stress based on appropriate parameterisations adapted for Japan.

Parameters

*Edata	Xdata->Edata[e+1]
*Ndata	Xdata->Ndata[e+1]
STpar
cH	Computed height of snow (m)
cos_sl	Cosine of slope angle (1)
date

Returns: return false on error, true otherwise

◆ setShearStrengthDEFAULT()

bool StabilityAlgorithms::setShearStrengthDEFAULT	(	const double &	cH,
		const double &	cos_sl,
		const mio::Date &	date,
		ElementData &	Edata,
		NodeData &	Ndata,
		StabilityData &	STpar
	)

static

DEFAULT: Estimates the critical shear stress based on appropriate parameterisations.

Parameters

*Edata	Xdata->Edata[e+1]
*Ndata	Xdata->Ndata[e+1]
STpar
cH	Computed height of snow (m)
cos_sl	Cosine of slope angle (1)
date

Returns: return false on error, true otherwise

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

Detailed Description

Static Public Member Functions

Member Function Documentation

◆ classifyStability_Bellaire()

◆ classifyStability_SchweizerBellaire()

◆ classifyStability_SchweizerBellaire2()

◆ classifyStability_SchweizerWiesinger()

◆ classifyType_SchweizerLuetschg()

◆ compCriticalStress()

◆ compPenetrationDepth()

◆ compReducedStresses()

◆ CriticalCutLength()

◆ getHandHardnessASARC()

◆ getHandHardnessBELLAIRE()

◆ getHandHardnessMONTI() [1/2]

◆ getHandHardnessMONTI() [2/2]

◆ getLayerSkierStability()

◆ getNaturalStability()

◆ getRelativeThresholdSum()

◆ setDeformationRateIndex()

◆ setShearStrength_NIED()

◆ setShearStrengthDEFAULT()