Table of contents
- 1.0 General
- 1.1 The problem of determining the water content of the snow cover
- 1. .2 Definitions of important terms
- 1.2.1. Water equivalent of snow cover:
- 1.2.2. Snow depth
- 1.2.3. Snow density
- 1.2.4 Snow load
- 1.3 Measurement methods
- 1.3.1. The avalanche method
- 1.3.2. The isotope method
- 1.3.3. The volumetric method
- 1.3.4. The microwave method
- 1.3.5. The dielectric method
- 1.4 Introduction to measurement technology 9
- 1.4.1. Technical data WS43
- 1.4.2. Technical data Metrasonde
- 1.4.3 General notes on using the scale
- 1.4.4. Technical data of the Hancvencl probe
- 1.4.5. Method for measuring snow depth
- 1.4.6. Method for measuring the water equivalent of snow
- 1.4.7. HIM300-23
- 2. Description of the current status and project objectives
- 2.1 Snow probe HIM150-50
- 2.1.1 General
- 2.1.2. HIM150-50 mK
- 2.1.3. HIM150-50 OK
- 2.2 Methodological principles
- 2.2.1. Standards and requirements
- 2.2.2. Mathematical foundations
- 2.2.3. Information processing
- 2.2.4. Measurement method
- 2.3 Technical requirements of the snow probe
- 2.3.1. Handle with bayonet adapter26
- 2.3.2. Measuring cylinder with applied scale for measurements up to 150 cm
- 2.3.3. 100 cm handle with bayonet adapter and scale
- 2.3.4. Hanging device for the digital scale
- 2.3.5. Measuring cylinder adapter for electromechanical operation
- 2.3.6. Digital scale
- 2.3.7. Vertical suspension device
- 2.3.8. Horizontal suspension device
- 2.3.9. Carrying bag
- 2.3.10. Evaluation boards
- 2.3.11. Shovel
- 2.3.12. Cover
- 2.3.13. Compression rod
- 2.3.14. GPS Tracker
- 3. Recommendations
- 4. Summary
- 5. Bibliography / Sources
1.0 General
1.1 The problem of determining the water content of the snow cover
Regular, network-based determination of the water content of the snowpack is of great importance from a hydrological perspective. Determining the water content allows the negative component of precipitation (evaporation) to be determined.
The main significance of this parameter lies in the assessment of snowmelt for hydrological purposes (calculating meltwater discharge and inflow for dams, flood forecasting, and thawing floods) and as an input for water balance models. The risk of thawing floods is particularly high when snowmelt and rainfall coincide. The water content of the snowpack can be used as a correction factor for estimating precipitation.
In the future, the network-based determination of the water content of the snow cover will become even more important as reference data for remote sensing.
1.2 Definitions of important terms
0.3.1. Water equivalent of snow cover:
The water equivalent of the snow cover is determined from the height of the water layer in mm that would form after melting of the snow cover if the meltwater remained on a horizontal surface without infiltration or evaporation.
1 mm water equivalent corresponds to 1 l meltwater / m²
The specific water equivalent refers to the snow cover depth. It is expressed in mm/cm. The water equivalent is determined using a snow cutter or a snow probe.
0.3.2. Snow depth
Snow depth is generally measured in centimeters, unlike precipitation (millimeters per hour). Since snow can remain on the ground and melt depending on the temperature, snow cover doesn't necessarily have to increase despite new snowfall.
Simply stating the snow depth does not necessarily mean that snow has fallen recently.
A precise distinction is therefore made between snow cover thickness as the total height and fresh snow depth as the increase in the last assessment period - whereby in today's meteorology and avalanche science 24 hours are used as a basis and measurements are taken at 7:30 in the morning.
The new snow total is then determined over longer periods (e.g. 3-day new snow total as the increase in snow depth over the last 72 hours).
Because the snow "stuck" together due to its own weight and other weather parameters (humidity, temperature changes), meaning its volume changes – independent of melting and sublimation – the total new snowfall and the total snowpack thickness are not the total of the new snow depths. It is typically one to two-thirds of the new snowfall totals of the last snowfall period.
Ultimately, the total amount of new snow in a season in the glaciers' erosion zone is often reduced to layers of compressed ice that are only a few centimeters thick.
Conversely, wind drift can cause enormous snow cover thicknesses to build up in small areas, far exceeding the depth of the fresh snow.
Even where avalanches have occurred (mass transport), abnormal snow depths are found, so that avalanche debris remains until well after the surrounding areas have melted.
0.3.3. Snow density
The density of a body (ρ), also called mass density to distinguish it from other volume-related quantities such as energy or charge density, is the ratio of its mass to its volume
,
Snow density is the mass of fallen snow per unit volume in the state of natural storage, expressed in g/cm³.
The snow density, Indicates the water content of an undisturbed snow layer per unit volume. "Undisturbed" means that the snow cover has not been altered by external influences, such as walking, driving, or artificial heat sources.
The usual unit is g/cm³
By weighing the cut-out snow cover and measuring the snow cover height, the amount of water in the snow cover [mm] and the snow density [g/cm³] can be determined.
Snow density is the mass of fallen snow per unit volume in the state of natural storage, expressed in g/cm³.
The conversion from snow density to specific water equivalent (and back) is as follows:
1 g / cm³ = 10 mm / cm or 1 mm / cm = 0.1 g / cm³
Classification of snow types according to density ranges (focused on Germany):
| Snow density [kg/m³ ] | Type of snow |
| 50 -150 | Fresh snow |
| 100 - 200 | powder snow |
| 150 - 450 | grainy snow |
| 350 - 600 | stored snow |
| 500 - 850 | Firn snow |
| 700 - 900 | Glacier snow / glacier ice |
The highest possible density is 917 kg/m³ and means pore-free ice.
Water has a density of 1000 kg/m³, so ice always floats on the water surface due to its lower density.
0.3.4. Snow load
Snow load is one of the climate-related, variable influences on structures. It depends on the geographical location and the shape of the structure in question and generally acts as a distributed load perpendicular to the base area.
Snow is frozen precipitation whose density and weight depend on temperature. One meter of powder snow corresponds to a water column approximately six to ten centimeters high; for paper snow, it's about 20 centimeters.
For static analysis, wet snow and a specific weight of 2 kN/m³ are used for simplification and to be on the safe side.
1.3.1. The snow slab method
The avalanche method is based on estimating the water content of the snow cover based on snow depth, temperature and wind speed.
1.3.2. The isotope method
The isotope method is widely used internationally.
To determine the water content, gamma sources are arranged horizontally and vertically, radiating through the snow cover.
1.3.3. The volumetric method
The gravimetric method is based on the relative change in weight. A measuring cylinder is weighed. Snow density and water content are derived from the determined scale divisions.
Automatic stations measure the amount of snow using temperature-compensating strain gauge sensors (e.g. electronic snow scales).
This procedure is currently being used by the DWD at some measuring points.
1.3.4. The microwave method
The microwave method is used to determine the water content of large snow-covered areas using satellites. Reference measurement points are required for this method.
1.3.5. The dielectric method
In this method, the change in Dielectric constant is taken as a measure of the specific water content of the snow cover.
1.4 Introduction to measurement technology
The weather service presented the current situation in the measurement network. The DWD is currently working with a total of three different models:
- WS43 in the lowland area
- Metrasonde and the (from GDR stocks for mountain stations)
- Hancvencl probe SM 150-50 and SM 100-50 (in modified prototypes)
Additionally, the HIM300-23 presented here is examined. The individual probes and their technical parameters are briefly described below.
1.4.1. Technical data WS43
Fig. 1: Snow probe WS43 with scale, measuring cylinder and shovel, photo: HIM
| Length: | 70 cm |
| Cutting surface: | 50 cm2 ±0.4 |
| Measuring accuracy of the scale: | ± 5 g |
| Snow depth measurement accuracy: | ± 10 g |
| Material: | aluminum |
| Telecopiable | No |
| Dimensions: | 710 x 150 x 150 mm |
| Mass: | 3 kg |
The snow probe (Fig. 1) consists of a metal cylinder and a beam balance with barrel weight. The metal cylinder is designed as a ring saw at one end trained and can be closed at the other end with a lid.
To measure the height of the cut snow column, a cm scale is attached to the outside of the cylinder, starting at the lower edge of the ring saw.
A ring with a bracket that can be freely moved over the cylinder is used to suspend the cylinder from the beam balance.
The beam balance consists of a metal rail which is suspended by the prismatic cutting edge of the balance suspension is divided into two unequal arms and a running weight with reading window. The right prismatic cutting edge, which is located under the pointer and is turned with its tip downwards, rests on a bearing in the tab.
The ring on this tab serves to hold the entire scale. The second prismatic cutting edge another tab with hook hanged.
To weigh the cut snow sample, the filled metal cylinder is hung on the hook using the bracket.
1.4.2. Technical data Metrasonde
Fig. 2: Metrawatt snow probe with digital scale, photo: DWD Hamburg
1.4.3 General notes on using the scale
When using the components of the measuring tube, no use of force is required as they are easy to handle.
In exceptional weather conditions, the measuring cylinders can be frozen with the bayonet adapter. The connection can then be released mechanically or by heating.
The snow depth can be read on the side of the measuring cylinders.
The bayonet system for connecting individual pipes is symmetrical.
The tube of the bayonet adapter is fixed by slightly turning the bayonet pins on the side to engage them in the bayonet adapter.
Disassembly takes place in the reverse direction.
| Length: | 70 cm |
| Cutting surface: | 50 cm2 ±0.4 |
| Measuring accuracy of the scale: | ± 5 g |
| Snow depth measurement accuracy: | ± 10 g |
| Material: | aluminum |
| Telecopiable | Yes |
| Dimensions: | 710 x 150 x 150 mm |
| Mass: | 3 kg |
0.5.4. Technical data Hancvencl probe
Fig. 3: Hancvencl probe with digital scale, photo DWD Hamburg
Fig. 4: Hancwencel probe with digital scale, photo HIM
The snow probes SM 150-50 are known under the term Hancvencl probe (after Rudolf Hancvencl). and SM 100-50 summarized.
| Type: | SM 150-50 | SM 150-50 |
| Length: | 150 cm ±0.4 | 100 cm ±0.4 |
| Cutting surface: | 50 cm2 ±0.4 | 50 cm2 ±0.4 |
| Resolution: | ± 10 g | ± 10 g |
| Material: | GRP | GRP |
| Telecopiable | Yes | Yes |
| Dimensions: | 710 x 150 mm | 710 x 150 mm |
| Mass: | 3 kg |
3 kg |
The SM 100 and 150-50 snow probes are used to measure snow depth and snow water equivalent. They consist of a sampling cylinder, a turning device, a probe rod holder, and transport packaging. The sampling cylinder has a length of 150 or 100 cm and a cross-section of 50 cm². The cylinder is made of fiberglass laminate and equipped with a metal toothed crown.
The probe rod made of aluminum tube is equipped with a scale and a circular plate for compressing the snow and removing it from the sampling cylinder.
The turning device is used to rotate and press the sampling cylinder during snow sampling after it has been inserted. The suspension is designed for weighing the cylinder in a horizontal position. The transport packaging is rubberized.
The total weight of the snow probe is about 2.2 kg. The collecting cylinder weighs about 1.3 kg.
Any scale with a minimum sensitivity of 10 g can be used to weigh the snow. (Not included)
0.5.5. Method for measuring snow depth
The probe rod is placed upright in the snow, and after reaching the ground, the snow depth is read from its scale.
0.5.6. Method for measuring the water equivalent of snow
The sampling cylinder is drilled into the soil in a vertical position using the turning device, rotating in both directions and applying sufficient pressure. Once the cylinder reaches the ground, the snow cover height is read.
The full cylinder is withdrawn as needed. Before withdrawal, the snow is lightly compacted. Reaching the surface is visually checked. Using the suspension, the cylinder is weighed in a horizontal position.
Digital scales are equipped with the camouflage function; mechanical scales can also be tared or the weight of the empty sampling cylinder can be deducted.
Since the cross-sectional area of the crown is 50 cm², a weight of 10 g corresponds to a water equivalent of 2 mm.
In practice, the water equivalent of snow is calculated in mm, so the weight in kg is calculated to two decimal places, regardless of the decimal point is multiplied by two.
The sampling cylinder is then turned with the crown upwards and emptied by gently tapping it with the turning device.
If the sampling cylinder cannot be pressed into the ground with a force of 200 N while rotating, there is no snow in the sampling cylinder, but rather it is compressed and squeezed outside the cylinder. Therefore, the cylinder is pulled out, weighed, and reinserted after emptying, and sampling continues until the soil is reached.
The sampling cylinder is then weighed again and the water equivalent is calculated from the sum of both weights.
The same method can be used for snow depths above 1.5 m after the top layer of snow has been removed.
The set is made of stainless material and requires no maintenance.
After use, it's advisable to let it dry. Hard surfaces can cause the crown to deform, so the edges should be sanded with a file.
0.5.7. HIM300-23
Presented was the Snow precipitation measuring station (HIM300-23 / Art. No. 06.04.05)
Fig. 5: Snow probe HIM300-23, photos: CHMI Prague
0.5.7.1.Technical data of the HIM300-23.
| Length: | 100 cm extendable up to 360 cm |
| Cutting surface: | 23 cm2 |
| Diameter: | 55 mm |
| Resolution: | 10 g |
| Material: | aluminum |
0.5.7.2.General notes on the use of the scale
The scale is not designed for outdoor use. Therefore, it is necessary to protect it from moisture or water as much as possible.
It is recommended to allow the scale and camouflage weights to acclimatise to the ambient temperature for approximately 20 minutes.
On the right side is a plug adapter that charges the internal battery. The scale automatically turns off after 10 minutes. It is necessary to ensure sufficient charge before measuring in the field.
The scale is calibrated so that the measuring cylinder with a cut-out area of 23 cm2 indicates the water value (1 kg/m2). This device corresponds to the observations/measurements of precipitation in mm. l mm of precipitation on an area of one l m2 corresponds to l kg water.
0.5.7.3.Assembly of the parts
No force is required when using the measuring tube components. In extreme weather conditions, the measuring cylinders with the bayonet adapter may freeze. In this case, the connection can be released mechanically or by heating.
The snow depth can be read on the side of the measuring cylinders.
The bayonet system for connecting individual tubes is symmetrical. The tube of the bayonet adapter is moved downward by loosening the locking knob. The second tube is inserted from below and rotated 20° clockwise.
The coupling tube of the bayonet adapter is then moved upwards by another 2 cm. This creates a secure connection.
Disassembly takes place in the reverse direction.
2. Description of the current status and project objectives
All mobile probes are controlled using digital scales model KERN HCB 20K50 or Model KERN CH 15K20 evaluated.
The goal of the 2015 measurement network is to harmonize the entire system. To achieve this, the properties of the aforementioned probe types must be combined, functionally enhanced, and additional features developed.
The aim is to develop a modular snow probe system that can be used throughout the DWD's measuring network.
In particular, these are:
- Electromechanical drive for drilling through ice layers
- Recording tracks
- Hammer adapter
- Telescopic measuring cylinders up to 150 cm and
- Non-telescopic measuring cylinders up to 150 cm
The use of a uniform probe system ensures a uniform evaluation of the values obtained in the measuring network.
Due to the nature of the different probe types, a uniform evaluation of the values obtained in the measuring network is currently only possible to a limited extent, as the WS43 and the Hancvencl probes differ in terms of the material used on the measuring cylinder (aluminum and GRP).
The use of aluminum measuring cylinders with different surface structures as well as a measuring cylinder made of GRP leads to a higher surface tension and thus to a water loss compared to hydrophobic surfaces due to the material-specific roughness parameters.
This effect is generally known from precipitation measurement with the Hellmann precipitation gauge in conjunction with the use of glass, plastic and hydrophobic gauges.
Corresponding deviations (on average +2%) of the Hancvencl probe compared to the WS43 were determined in comparative measurements conducted by the DWD. The results are based on a representative series of 300 measurements.
Our own empirical measurements with all of the above-mentioned systems have produced almost identical measurement results.
Current monitoring practice allows a period of approximately 45 minutes to determine the water content of the snowpack. Within this period, an electromechanical snow probe, if used, must be set up and dismantled approximately three times, and the water content of the snowpack must be determined in several partial measurements. The samples must be measured, and the measurement results entered into the AMS.
The provisional name of the development is agreed to be HIM150-50.
2.1 Snow probe HIM150-50
2.1.1. General
The name includes the maximum length of the snow probe (150 cm) and the
Surface (50 cm2). The following product variants are suggested:
- HIM50-50
- HIM100-50
- HIM150-50
The abbreviations stand for electric (E) and gasoline (B) drive. Product variants without abbreviations have the familiar manual drive.
It is proposed that the overall snow probe system consists of the following components:
- Handle with bayonet adapter
- Measuring cylinder with applied scale for measuring up to 50 cm with reversing ring
- Measuring cylinder with applied scale for measuring up to 100 cm
- Measuring cylinder with applied scale for measuring up to 150 cm
- Extended 100cm handle with bayonet adapter with scale for use of the 50cm2 measuring cylinder at greater depths (1m).
- Suspension device for suppressing torsional forces for the digital scale)
- Hammer adapter
- rubber hammer
- digital scale
- Suspension device for horizontal suspension of the measuring cylinder
- Suspension device for vertical Suspension of the measuring cylinder
- Carrying bag
- Evaluation boards
- shovel
- multi-part compression rod
- Cap
- GPS tracker to record the position of the measuring points
The system is designed so that it can also be purchased in components.
It is useful to divide the methods into the following variants:
- HIM150-50 mK - with compression
- HIM150-50 oK - without compression
2.1.2. HIM150-50 mK
- Handle with bayonet adapter
- Measuring cylinder with applied scale for measuring up to 50 cm with reversing ring
- Measuring cylinder with applied scale for measuring up to 100 cm
- Measuring cylinder with applied scale for measuring up to 150 cm
- Extended 100cm handle with bayonet adapter with scale for using the 50cm measuring cylinder at greater depths (1m).
- Suspension device for suppressing torsional forces for the digital scale
- Hammer adapter
- rubber hammer
- digital scale
- Suspension device for horizontal suspension of the measuring cylinder
- . Suspension device for vertical Suspension of the measuring cylinder
- Carrying bag
- Evaluation boards
- shovel
- multi-part compression rod
- Cap
It is proposed to introduce the compression method as standard at lowland stations to increase measurement accuracy.
The introduction of the compression method is associated with an improvement in handling due to the higher strength of the sample.
2.1.3. HIM150-50 OK
- Handle with bayonet adapter
- Measuring cylinder with applied scale for measuring up to 50 cm with reversing ring
- Suspension device for suppressing torsional forces for the digital scale
- Hammer adapter
- rubber hammer
- digital scale
- Suspension device for horizontal suspension of the measuring cylinder
- Suspension device for vertical Suspension of the measuring cylinder
- Carrying bag
- Evaluation boards
- shovel
- Cap
When using the snow probe without compression, there is a risk that parts of the snow sample will fall out of the measuring cylinder due to its low density.
2.2 Methodological principles
2.2.1. Standards and requirements
It Here are just a few norms and standards that are relevant for the theory and practice of developing the snow measuring station.
A detailed bibliography and list of sources can be found at the end of the presentation.
/4/ DIN EN 1991-1-3:2010-12 (D): Eurocode 1: Actions on structures - Part 1-3: General actions, snow loads; German version EN 1991-1-3:2003 + AC:2009; formerly: DIN 1055-5, July 2005: Actions on structures - Part 5: Snow and ice loads.
/5/ DVWK leaflets 112-113, 230, DVWK German Association for Water Management
/6/ DIN SPEC 1107; DIN Technical Report CEN/TR 15996:2010-05: Hydrometry - Measurement of the water content of the total snow cover using a snow mass meter; German version CEN/TR 15996:2010;
/9/ VDE 0839-81-1:1993-03: Electromagnetic compatibility
/10/ VDE 0875-11:2011-04: Industrial, scientific and medical devices
/11/ VDI 3786 Sheet 7
/12/ WMO CIMO Guide No. 8 Chapter 6.7.3., 7th Edition, 2008
/13/ WMO Guide to Hydrological Practices No. 168, 5th Edition, 1994 or
WMO Guide to Hydrological Practices No. 168, 6th Edition, Vol. I, 2008
2.2.2. Mathematical foundations
The formulas listed below apply to snow probes with a cutting area of 50 cm2
2.2.2.1.Absolute water equivalent (absWE)
Absolute water equivalent = read scale value n multiplied by 10 (mm)
2.2.2.2.Specific water equivalent (specWE)
where n the read scale value and h Height of the excavated snow cover is.
For snow depths of more than 60 cm, the measurement must be repeated layer by layer and the sum of the scale values read (multiplied by 10) must be divided by the total height of the snow cover.
e.g.
| Height of the excavated snow cover: | h = 38 cm |
| read scale value | n = 9.5 g |
| absolute water equivalent: | 9.5 * 10 = 95 mm |
| specific water equivalent: | 2.5 mm/cm |
1.2.2.3.Snow load
The snow load is calculated according to the following algorithm:
- Sampling area of the snow scale: S1 = 0.005 m 2
- Determination of a sampling area roof of size S = 1 m 2 on the roof
- From the relationship between sampling area roof S and the sampling area S1 results Number K of samples:
K= S / S1.
According to VDI 3786 the sampling area roof S is set at 1 m2.
This gives the value K 2 00.
4. Weighing the snow on the roof, exemplary on a sampling area S
This results in ( M1 + M2 + . . . + M200) [g])
5. The snow load MSL [kg] is therefore calculated from the following formula:
First, the total mass of snow from the samples is determined:
Mass: M [kg] M = M1 + M2 +….+ M200 [G]
= (M1 + M2 +….+ M200 )/1000 [kg]
With the average mass per sampling surrendered
MSLD = (M1 + M2 +….+ M200) [kg] / (1000 * 200* 0.005 [m2])
= (M1 + M2 +….+ M200) /1000 [kg/m2]
With the conversion to N/m2 with 1 kg/m2 = 9.81 N/m2 results for the
Snow load MSL [KN/m2] the following:
MSL = (M1 + M2 +….+ M200) [N] * 9.81/1000 / [m2]
= (M1 + M2 +….+ M200 [KN]).) * 9.81/ [m2]
If M1 = M2 = … = M200:
Snow load MSL [kg/m2] = 200 * M1 [kg]/(1000 * 1.0 / [m2]
= 0.2 * M1 [kg/m2]
Snow load MSL [KN/m2] = 0.2 * M1 * 9.81 [N/m2]
6. For area-dependent and roof-related assessment of the obtained values must be DIN EN 1991-1-3:2010-12 (formerly DIN 1055-5) be used. (see also http://www.snowload.info )
1.2.3. Information processing
The specific water equivalent is reported or entered:
Synoptic-climatological stations:
SYNOP Section 5, Group 4RwRwwtwt and section 555 80000, Group 9/RRR
Part-time Climate stations: Sheet 1, Column 49 and NSD reporting service
Part-time precipitation stations: NSD reporting service
1.2.4. Measurement method
The following measurement methods are possible with the HIM150-50:
1.2.4.1.Compressionless measurement methods
The compression-free measuring method is based on the one already used with the WS43
practiced procedures using components 1, 4, 6, 8, 9, 11 and 13.
- Handle with bayonet adapter
- Measuring cylinder with applied scale for measuring up to 50 cm with reversing ring
- Suspension device for suppressing torsional forces for the digital scale
- Hammer adapter
- rubber hammer
- digital scale
- Suspension device for horizontal suspension of the measuring cylinder
- Suspension device for vertical Suspension of the measuring cylinder
- Carrying bag
- . Evaluation boards
- shovel
- . Cap
- GPS tracker to record the position of the measuring points
1.2.4.2.Compressive measurement methods
The compressive measuring method is based on the method already practiced with the Metra and Hancvencl probes using components 1 to 13.
HIM150-50mK
- 1. Handle with bayonet adapter
- 2. Measuring cylinder with applied scale for measuring up to 50 cm with reversing ring
- 3. Measuring cylinder with applied scale for measuring up to 100 cm
- 4. Measuring cylinder with applied scale for measuring up to 150 cm
- 5. Extended 100cm handle with bayonet adapter with scale for use
of the 50 cm measuring cylinder at greater depths from 1 m.
- Suspension device for suppressing torsional forces for the digital scale
- Hammer adapter
- rubber hammer
- digital scale
- . Suspension device for horizontal suspension of the measuring cylinder
- . Suspension device for vertical Suspension of the measuring cylinder
- . Carrying bag
- . Evaluation boards
- . shovel
- multi-part compression rod
- Cap
- GPS tracker to record the position of the measuring points
The compression method is currently the most widely used.
1.3 Technical requirements of the snow probe
Based on the practical experience from the measuring network, the following 2.1. The following technical requirements are formulated:
1.3.1. Handle with bayonet adapter
Fig. 6: Handle of the HIM150-50, photo HIM
The handle with bayonet adapter must be designed to be shatter-proof even for approximately 100 kN. To improve the handling of the handles, it is recommended to use either treated wood, soft handles or high-quality plastic with a rough surface.
The handle should be foldable to ensure high mobility.
Material: aluminum
Pipe diameter: 55 mm
Handle length: 400 mm
Handle diameter: 15 mm
1.3.2. Measuring cylinder with applied scale for measuring up to 150 cm
The measuring cylinders are proposed in two variants:
- telescopic and
- non-telescopic
1.3.2.1.Telescopic measuring cylinders
Fig. 7: Future components of the HIM150-50, photo CHMI, Prague
The telescopic measuring cylinders ensure modular and flexible handling of the entire HIM150-50 system, thus ensuring high mobility.
A disadvantage of using telescopic measuring cylinders is the longer measurement time.
1.3.2.2.Non-telescoping measuring cylinders
Various state environmental agencies expressed the desire to have a system that is flexible and at the same time ensures that it is as simple and quick as possible for the observer to use.
For this purpose, the state environmental agencies have proposed various measuring cylinders in the lengths
- 50 cm
- 100 cm and
- 150 cm
to offer as a system.
The advantage is faster measurement and overall easier handling for the observer. Mobility is severely limited. The measuring cylinder will be made of aluminum. The following design changes to the measuring cylinder are required:
1.3.2.3.Measuring cylinder
measuring cylinder
Material: aluminum
Diameter, inside: 80 mm, ±0.4 mm
Outside diameter: 85 mm, 0.4 mm
Scaling: 10 mm
Measuring range: 0 to 50 cm,
51 to 100 cm,
101 to 150 cm
For better visibility, the scale should be highlighted in black.
1.3.2.4.Core bit
Fig. 8: Future core bit of the HIM150-50, photo HIM
The core bit of the HIM150-50 is intended to be a 3D-optimized version of the WS 43. One core bit is retained for practical reasons. During the new development, all possible practical scenarios must be considered. The goal is to optimize the number of bits and the number and orientation of the teeth on the core bit to ensure optimal power transmission. It must be able to withstand use with an electromechanical drive.
Outer drill bit
Material: Galvanized steel, hardened
Diameter, inside: 85 mm, ±0.4 mm
Outside diameter: 90 mm, 0.4 mm
Angle 1: 45°
Angle 2: 80°
Depth: 10 mm
Inner core bit
Material: Galvanized steel, hardened
Diameter, inside: 80 mm
Outside diameter: 83 mm
Angle 1: 45°
Angle 2: 80°
Depth: 5 mm
It is suggested that the crowns be shaped conically, ground for better durability and hardened for use with a drive.
1.3.2.5.Reversing ring
Fig. 9: Future reversing ring of the HIM150-50, photo HIM
Each measuring cylinder should be equipped with a permanently installed reversing ring for suspension the digital scale.
Suspension:
Material: aluminum
Diameter, inside: 85 mm
Outside diameter: 90 mm
Suspension: 80 mm
1.3.2.6.Cutting surface
For methodological reasons, the cutting area must be 50cm2 in order to be able to connect to existing measurement series.
Empirical measurements between both systems showed no advantage in a larger cutting area compared to a cutting area of 23 cm2.
An increase in measurement accuracy is not discernible. Recommendations or requirements regarding the cutting surface by / 1/2/3 /6/ and /13/ are not detectable.
1.3.2.7.The bayonet system
Fig. 10: The future bayonet system of the HIM150-50, photo HIM
The bayonet system for connecting individual tubes is symmetrical. The tube of the bayonet adapter is moved downward by loosening the locking knob. The second tube is inserted from below and rotated 20° clockwise.
The coupling tube of the bayonet adapter is then moved upwards by another 2 cm. This creates a secure connection.
Disassembly takes place in the reverse direction.
This principle is proven in practice and creates a permanent connection between the snow probe components. The surface of the tube is designed to allow for handling while wearing gloves. The tube is permanently connected to the tube.
1.3.2.8.Bayonet pin
Lateral attachment of bayonet pins at the upper end of the measuring cylinder to For measurements without compression, the measuring cylinder can be closed and attached to the scale using the reversing ring. The bayonet pins also serve to connect the drive unit.
Length: 5 mm?
Diameter: 5 mm?
Ring diameter, outside: 90 mm
Ring diameter, inside: 85 mm
1.3.3. 100 cm handle with bayonet adapter and scale
Fig. 11: Future design of the handle of the HIM150-50, photo Eijelkamp
The 100 cm handle with bayonet adapter is used to use the 50 cm measuring cylinder at greater depths (1 m).
The handle with bayonet adapter must be designed to be shatter-proof, even at approximately 100 kN. For improved handling, we recommend using either treated wood or high-quality plastic with a rough surface.
The handle and bayonet adapter are separated by approximately 100 cm.
The adapter should be scaled. The adapter must be captive and protected against torsion.
The surface must be designed for glove handling.
handle
Length: 120 mm
Diameter: 30 mm
Material: plastic
extension
Total width: 40 mm
Diameter: 80 mm
Length: 1000 mm
Bayonet:
Length: 45 mm
Width: 10 mm
Offset: 45 mm / 90°
Outer diameter: 85 mm
Inner diameter: 80 mm
1.3.4. Hanging device for the digital scale
The torsion-suppressing suspension device is approximately 15 cm long and made of metal. Both hooks are separated by a ball bearing.
When using the device, please note that gloves must be worn during the winter.
Material:
Total length: 15 cm
Hook diameter: 3 cm
Ball bearing diameter: 3 cm
1.3.5. Measuring cylinder adapter for electromechanical operation
(Drill, cordless screwdriver or petrol-powered version)
Due to the sometimes very high expenditure of energy in determining the water content of the snow cover in the specific climates of the locations (e.g. Feldberg) In connection with the partly advanced age of the observation personnel, it was suggested to examine the possibility of an electromechanical drive.
Some measuring points are characterized by higher ice ingress into the snow cover, which can lead to the above-mentioned physical strain on the observation personnel
(e.g. Feldberg).
Current observation practice allows for a period of approximately 45 minutes. Within this time, an electromechanical snow probe, if used, must be set up and dismantled approximately three times, and the water content determined.
The samples must be measured and the measurement results entered into the AMS.
The above requirement results in the following
1.3.5.1.Technical requirements:
- Low speed
- Adjustable speed
- 2-speed gearbox
- Outdoor suitability
- High mobility
- Compliance with occupational health and safety regulations
In current observation practice, the actual time spent outdoors is approximately 20 minutes.
This allows the temperature-dependent capacity change of the batteries to be empirically verified as a function of air temperature. However, a halving of the capacity due to cooling is unlikely to be expected.
Nevertheless, the use of commercially available indoor devices for semi-professional use is not recommended for reasons of occupational safety.
1.3.5.2.Possible solutions:
- Cordless drill/driver (Kress, Bosch, Hilti)
- drill
- Integrated special drive with forward and reverse rotation
- gasoline engine
- Hammer blow
1.3.5.3.Mechanical variant
Taking into account the small thickness of ice layers in the snow cover that occur in practice, it is recommended to use a rubber hammer with an impact adapter that prevents the destruction of the measuring cylinder of the snow scale.
Negative influences on the measurement accuracy of the overall system are not to be expected.
Advantages:
- High mobility
- Easy handling
- Low weight
- Low weight of the entire system
Disadvantages are not apparent
1.3.6. digital scale
The snow cover weight is determined using a mobile device within the DWD measurement network. For this purpose, a digital scale with an LCD display and tare function is used, which is easy to transport by the observer. These scales are commercially available. Temperature-dependent failures of the LCD display and a temperature function of the strain gauge are unknown. However, this issue should be further investigated. The digital scale with temperature display proposed here provides a simple, practical, and cost-effective method for correcting the strain gauge error, assuming, for example, that several scales are being measured.
Fig. 14: Digital scale with temperature display, photo Voltcraft
Technical data: HS-10
Weighing range: 0 to 10 kg
Resolution: 0.01 kg
Power supply: 3 x AAA
Dimensions: 92 x 53 x 19 mm
Temperature measuring range: -25 to +50°C
Fig. 15: Digital scale with temperature display, photo core
General HDB10K10
Type: Hanging scale with handle
Construction: S-hook made of stainless steel
Execution: max. 10.0 kg
Battery type: 2 x Micro (AAA)
Special features
Specification: Auto-off function
Manufacturer's warranty: 2 years
Display type LCD
Resolution: 10 g
Display format: 12 mm
Tare function: Yes
Weight: 0.15 kg
Mass
Width: 70 mm
Height: 105 mm
Depth: 25 mm
1.3.7. Vertical suspension device
The suspension device is used for vertical weighing of the 50 cm measuring cylinder using the reversing ring and the closure cap. It is designed as a butcher's hook.
1.3.8. Hanging device horizontal
The suspension device is used for horizontal weighing of the 100 and 150 cm measuring cylinder.
Material: stainless steel
Weight: 0.25 kg
Leg length: 200 mm
Diameter: 5 mm
Opening angle: 180°
Opening diameter: 85 mm
1.3.9. Carrying bag
A carrying case must be designed for the HIM150-50 that has similar features to the tripod case already supplied with the WS43. This tripod case allows the entire system to be transported as a backpack. This allows the observer to go skiing, for example.
1.3.10. Evaluation boards
The evaluation tables allow the determination
- the water content
- the specific water content and
- the snow load
The evaluation tables are available in printed form with ISBN number.
Alternatively, they can be made available as a PDF file.
1.3.11. shovel
Fig. 16: Shovel, photo HIM
The scoop is used for measurements in flat areas.
For easier handling in winter, it has a wooden handle and is angled at 30°. The shovel is scaled.
Handle:
Length: 150 mm
Diameter: 25 mm
Material: WOOD
Shovel:
Angle: 30°
Length: 95 mm
Width: 90 mm
Shaft length 45 mm
shaft diameter; 35 mm
Scaling: 0 to 9 cm
Division: 0.5 cm
Length, full ticks: 10 mm
Length, subdivision: 5 mm
1.3.12. Cap
Fig. 17: Cap, photo: HIM
In the case of compressionless measurement, the cap serves to close the measuring cylinder.
Material: aluminum
Outer diameter: 85 mm
Inner diameter: 80 mm
Length: 10 mm
1.3.13. compression rod
Fig. 18: Compression stick with rubber grip, photo HIM
Fig. 19: Upper part of the compression rod of the HIM150-50, photo HIM
Fig. 20: Compression plug of the HIM150-50 on the bottom of the
Compression tab, photo: HIM
To compress the snow sample, a rod is used. At one end, a slightly conical, dimensionally accurate plate is attached, matching the diameter of the measuring cylinder. For ease of handling, the compression rod should have a double or triple thread. When designing the compression rod, care must be taken to ensure that snow loss during compression is as minimal as possible (dimensional accuracy).
handle
Length: 120 mm
Diameter: 30 mm
Material: plastic
Length: 440 mm
rod
Number of parts: 3
Length: 700 mm
Diameter: 10 mm
Material: aluminum
Thread: 3-fold
Plate diameter: 59 mm
Angle: 45°
1.3.14. GPS tracker
To determine the water content of areas, multiple measurements must be taken over a longer route (e.g., 10 measuring points spread over a distance of 3 km). To store measurements at widely separated locations, the use of a GPS tracker is recommended. Existing smartphones or commercial GPS trackers can be used for this purpose.
1.3.14.1. Android - Mytracks
https://play.google.com/store/apps/details?id=com.google.android.maps.mytracks&feature=search_result#?t= W251bGwsMSwxLDEsImNvbS5nb29nbGUuYW5kcm9pZC5tYXBzLm15dHJhY2tzIl0.
MyTracks records the GPS tracks. "My Tracks" also collects other useful statistical data such as time, speed, Distance and height.
All of this data can be viewed live or saved for later use. relevant waypoints can be marked and automatic announcements about progress can be heard.
1.3.14.2. iPhone - GPS Tracker
http://itunes.apple.com/de/app/gps-tracker/id286658744?mt=8
InstaMapper allows you to store GPS trackers and share the tracks.
1.3.14.3. Rugged size mobile phone for outdoor use XP1301
http://www.sonimtech.com/pdf/XP1301_datasheet.pdf
Fig. 21: XP1301, Photo: Sonim
Outdoor NFC phone for data collection and processing.
Operating temperature range: -20 to +55°C,
Programmable mobile phone for data storage and processing with Java platform
1.3.14.4. GPS data logger
Fig. 22: GPS data logger with CMOs and GPS sensor including USB interface,
Photo: Conrad Electronics
It is proposed to integrate the GPS data logger into the snow probe to reduce the number of parts of the system.
http://www.conrad.de/ce/de/product/373686/GPS-DATENLOGGER-GT-730-MIT-AKKU/SHOP_AREA_22085&promotionareaSearchDetail=005
Highlights & Details
- Integrated lithium polymer battery
- Real-time tracking and route tracking via Google Earth™
- Data Logger & Photo Tracker Function
Description
The USB GPS data logger GT-730 is a GPS receiver with Venus 6 chipset and 65-channel “All-in-View” tracking technology for position tracking and recording of up to 256,000 values.
Thanks to its extremely compact design, it's the ideal companion for easily recording data. The route traveled can be viewed or saved later on your PC.
The built-in rechargeable battery offers a usage time of up to 18 hours.
equipment
- Data Logger & Photo Tracker Function
- Google Earth™ compatible
- Support for WAAS and EGNOS for greater accuracy
- Can also be used as a GPS mouse for notebooks.
| Technical data | |
| Battery life (max.) | 6 p.m. |
| Chipset | Venus 6 |
| Power supply | 5 V (USB) |
| Connection: | USB |
| Dimension: | (W x H x D) 29 x 76 x 18 mm |
| Suitable for: | Notebooks, netbooks, tablet PCs etc. |
2. Recommendations
Taking into account the formulated requirements
- Electromechanical drive for drilling through ice layers
- Recording tracks
- Hammer adapter
- Telescopic measuring cylinders up to 150 cm and
- non-telescopic measuring cylinders up to 150 cm
can be derived from the developed concept The following recommendations for the network operation of the HIMXXX-50 snow probe can be derived:
1. In order to ensure the most economical, quick and simple measurement possible, it seems sensible to introduce non-telescopic measuring cylinders that can be driven through ice layers with the help of a rubber hammer.
2. It is proposed that for economic, labour law and practical considerations to forego the development of a powered snow probe.
3. For hydrological applications for recording measurements over several kilometers, it is proposed to use a highly mobile system to develop.
3. Summary
The proposed concept was the HIM150-50 snow scale, which features a modular design.
The HIM150-50 can be used in the overall measuring network of the DWD and the water management to ensure uniform measurement uncertainty.
The homogenization of the measuring systems leads to an increase in data quality in accordance with EN ISO 9000 ff.
Thanks to its modular design, the HIM 150-50 can be optimally adapted to the conditions of the measuring site and the requirements of the observer in terms of its measuring range, drive mode and mobility.
This concept took into account the wishes of various state environmental agencies regarding the design of the measuring cylinder as well as the measurement data acquisition and processing. Recommendations for the system design were provided.
4. Bibliography / Sources
- /1/ Operating instructions HIM300-23, HIM
- /2/ Operating instructions SM150-50 and SM100-50, Hancvencl
- /3/ Operating instructions WS43, ZKB
- /4/ DIN EN 1991-1-3:2010-12 (D): Eurocode 1: Actions on structures - Part 1-3: General actions, snow loads; German version EN 1991-1-3:2003 + AC:2009; formerly DIN 1055-5, July 2005: Actions on structures - Part 5: Snow and ice loads
- /5/ DVWK leaflets 112-113, 230, DVWK German Association for Water Management
- /6/ DIN SPEC 1107; DIN Technical Report CEN/TR 15996:2010-05: Hydrometry - Measurement of the water content of the total snow cover using a snow mass meter; German version CEN/TR 15996:2010;
- /7/ Meteorology and Hydrologia, 1976, No.12
- /8/ Sevruk, B.: 2004. Precipitation as a water cycle element. Zurich, Switzerland: Institute for Atmospheric and Climate Science, ETH Zurich, Zurich-Nitra.
- /9/ VDE 0839-81-1:1993-03: Electromagnetic compatibility
- /10/ VDE 0875-11:2011-04: Industrial, scientific and medical devices
- /11/ VDI 3786 Part 7: Environmental Meteorology - Meteorological Measurements - Precipitation
- /12/ WMO CIMO Guide No. 8 Chapter 6.7.3, 7th Edition, 2008
- /13/ WMO Guide to Hydrological Practices No. 168, 5th Edition, 1994 or WMO Guide to Hydrological Practices No. 168, 6th Edition, Vol. I, 2008