Data Set ID: 

SnowEx17 SnowMicroPen (SMP) Raw Penetration Force Profiles, Version 1

This data set contains raw penetration force profiles measured at snow pits and along linear transects at Grand Mesa, Colorado using the SnowMicroPen (SMP), a digital snow penetrometer. The data files contain force measurements (in Newtons) at various snow depths.

This is the most recent version of these data.

Version Summary: 

Initial release

STANDARD Level of Service

Data: Data integrity and usability verified

Documentation: Key metadata and user guide available

User Support: Assistance with data access and usage; guidance on use of data in tools

See All Level of Service Details

Data Format(s):
  • Comma-Separated Values (.csv)
  • PNG
  • XML
Spatial Coverage:
N: 37.940572, 
N: 39.02767999670631, 
S: 37.856078, 
S: 38.980648493921876, 
E: -107.6725, 
E: -107.84605082281008, 
W: -107.752128
W: -108.22919239513443
Spatial Resolution:
  • Varies x Varies
Temporal Coverage:
  • 7 February 2017 to 25 February 2017
Temporal ResolutionNot specifiedMetadata XML:View Metadata Record
Data Contributor(s):Chris Derksen, Michaela Teich, Mike Brady

Geographic Coverage

Other Access Options

Other Access Options


As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.

Derksen, C., M. Teich, M. Brady, and J. King. 2017. SnowEx17 SnowMicroPen (SMP) Raw Penetration Force Profiles, Version 1. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: [Date Accessed].

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Detailed Data Description

Measurements are raw SnowMicroPen (SMP) profiles, to a maximum depth of 120 cm. In some cases, when snow depth exceeded 120 cm, two profiles were acquired to cover the entire depth.

Summary of SnowEx 2017 SMP measurements at pits and transects.

  • Snow Pits
    • 62 SnowEx snow pits with SMP profiles for a total of 571 profiles. Snow depth distribution shown in Figure 1.
    • 61 SMP profiles at SnowEx pits have coincident SnowEx17 Laser Snow Microstructure Specific Surface Area Data (SNEX17_SSA) profiles.
    • 3 SMP profiles at SnowEx pits have casting for microCT analysis.
  • Transects
    • 43 transects of SMP measurements acquired along SnowEx transect lines, for a total of 1084 profiles.
    • SMP transect lengths vary from 10 to 300 m in length; measurement spacing varies from 10 cm to 20 m.

Figure 1: Snow Depth Distribution


Data files are in Comma Separated Values (.csv) format.

A quicklook plot (.png) of each profile is included.

A single index file with reference information for each of the profiles is available as a technical reference.

Extensible Markup Language (.xml) files with associated metadata are also provided.

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File and Directory Structure

Data are available at:

Within this directory, folders are organized by date in YYYY/MM/DD format, for example /2017.02.24/.

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File Naming Convention

Data files are named according to the following conventions and as described in Table 1:



Table 1. File Naming Convention
Variable Description
SnowEx17_SMP Short name for SnowEx17 SnowMicroPen (SMP) Raw Penetration Force Profiles
_N_ Identifies and differentiates between three SMP units used in the field, where:
A = SMP Serial Number 2
B = SMP Serial Number 34
C = SMP Serial Number 40
PitNNL Pit, trench, or transect identifier
YYYY 4-digit year of survey
MM 2-digit month of survey
DD 2-digit day of survey
XNNNNNNN Instrument-assigned file number
.xxx Indicates file type:  .csv, .xml, or png
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File Size

CSV (.csv) files range from approximately 3 to 5 MB.

XML (.xml) are approximately 4 KB each.

PNG (.png) files range from approximately 37 to 45 KB.

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CSV files are approximately 8 GB.

XML files are approximately 5 MB.

PNG files are approximately 61 MB.

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Spatial Coverage

Spatial coverage during the SnowEx 2017 snow-on campaign includes Grand Mesa, Colorado Local Scale Observation Site (LSOS).

Southernmost Latitude 38.98° N
Northernmost Latitude: 39.03° N
Westernmost Longitude: 108.23° W
Easternmost Longitude: 107.85° W

Spatial Resolution

Each individual profile was acquired at a single point, with a vertical resolution of less than 1 mm.

Point measurements along transect from 10 to 300 m in length. Measurement spacing varies from 10 cm to 20 m.

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Temporal Coverage

These data were collected as part of the SnowEx campaign from 07 February 2017 to 25 February 2017

Temporal Resolution

Measurements were made at a single point in time and were not repeated. Data were collected during the snow-on season in February 2017, from February 07 to 11, February 14 to 18, and February 20 to 25.

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Parameter or Variable

Parameter Description

Parameter Description Units
Table 1. Data File Parameter Descriptions
Depth Depth of snow measurement Millimeters (mm)
Force Force required to drive a motorized probe into the snow at a constant measurement speed of 20 mm/s Newtons (N)

Sample Data Record

Below is a sample of data file SnowEx17_SMP_A_Pit36N_20170207_A7380059.csv.

Figure 2 illustrates a quicklook plot of the SnowEx17_SMP_A_Pit36N_20170207_A7380059.csv profile.

Figure 2: Profile (SnowEx17_SMP_A_Pit36N_20170207_A7380059.png)

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Software and Tools

CSV files can be read with any text editor or word processing program capable of reading ASCII text files.

XML files can be read with browsers such as Firefox and Internet Explorer.

PNG files can be displayed by a wide selection of image displaying software.

Python code for vertically smoothing the raw SMP profiles, and converting force to snow microstructure parameters is available at

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Quality Assessment

SMP profiles were screened to ensure complete profiles were acquired. If the vertical profiles were incomplete (due to instrument malfunction or ice layers/obstructions in the snowpack) the data were not retained. In very limited cases, negative force measurements were obtained for a small proportion of measurements within a profile. These negative values were removed.

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Data Acquisition and Processing

Theory of Measurements

The Snow MicroPen acquires high vertical resolution measurements of the force required to move a sensor downward through the snowpack at a constant measurement speed of 20 mm/s. Details are provided in Schneebeli and Johnson (1998), Johnson and Schneebeli (1999), and Proksch et al. (2015).

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Data Acquisition Methods

Spatial variability in snow microstructure was measured during SnowEx 2017 using the rapid sampling capabilities of the SMP. The SMP acquires high vertical resolution  (~250 measurements per mm) profiles of the force measured in Newtons (N) required to drive a motorized probe into the snow at a constant measurement speed of 20 mm/s. Typical force measurements range from 0.01 N for soft snow up to 40 N for very hard snow, to a maximum depth of 1.2 m.

From these force measurements, snow microstructure parameters such as density, layering, snow grain type, and snow grain specific surface area (SSA) can be derived, but only the raw force profiles are provided in this data set. Users will need to apply algorithms for identifying the air/snow and snow/ground interfaces, vertically smoothing the raw data, and converting the force measurements to snow microstructure parameters (see

SMP measurements were made at snowpit locations, and in transects of variable length/spacing through all three weeks of the SnowEx 2017 campaign.

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Derivation Techniques and Algorithms

Processing Steps

  • The SMP generates a data file and header file for each profile measurement.
  • Relevant fields from the header (date, time, lat/lon etc.) were stripped and inserted to the top of the data file.
  • The data file contains two fields: depth and force.
  • A single index file is also provided with reference information for each of the profiles.

Error Sources

In very limited cases, negative force measurements were obtained for a small proportion of measurements within a profile. These negative values were removed. Other potential sources of uncertainty include the probe not entering the snowpack orthogonally to the surface (due to imprecise placement of the instrument base) and shifting of the probe during measurement due to snowpack settling.

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Sensor or Instrument Description

The SMP measures the bonding force between snow grains. As described by the manufacturer, the SnowMicroPen is a cone penetrometer used to measure bonding forces between snow grains for snow profiling, stratigraphy, and other applications. The SMP drives a rod with a force sensor at a constant speed of approximately 20 mm/s into snow and samples penetration force every four micrometers (see Schnee- und Lawinenforschung (SLF)).

Table 2. Instrument Specifications (see SLF full specifications: SnowMicroPen)
Parameter Value Units
Measurable snow depth 0.27, 0.83, 1.25 (default), 1.72 or 2.2 m
Vertical penetration velocity 20 mm/s
Vertical sampling resolution 4 μm
Vertical layer resolution .05 mm
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References and Related Publications

Contacts and Acknowledgments

Chris Derksen, Mike Brady, and Joshua King
Environment and Climate Change Canada
4905 Dufferin Street
Toronto, Ontario M3H5T4 Canada

Michaela Teich
Utah State University
Department of Wildland Resources
5230 Old Main Hill
Logan, UT 84322-5230  USA

Document Information


26 September 2017



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