CLPX-Ground: ISA Snow Depth Transects and Related Measurements, Version 2.0

Summary

This data set consists of snow depth data from nine study areas, within three larger-scale areas in northern Colorado (Fraser, North Park, and Rabbit Ears Meso-cell Study Areas (MSAs)). The study areas range from low-relief (flat topography) unforested areas with shallow snow covers, to high-relief (complex topography) densely forested areas with deep snow covers. Parameters measured include snow depth, snow wetness, snow temperature, soil temperature, and canopy cover. Photos were taken of surface roughness and terrain. Data were collected during February and March 2002 and 2003. This data set is part of the NASA Cold Land Processes Field Experiment (CLPX).

The NASA CLPX is a multi-sensor, multi-scale experiment that focuses on extending a local-scale understanding of water fluxes, storage, and transformations to regional and global scales. Within a framework of nested study areas in the central Rocky Mountains of the western United States, ranging from 1-ha to 160,000 km2, intensive ground, airborne, and spaceborne observations are collected. Data collection focuses on two seasons: mid-winter, when conditions are generally frozen and dry, and early spring, a transitional period when both frozen and thawed, dry and wet conditions are widespread.

Citing These Data

Elder, K. and D. Cline. 2003. CLPX-Ground: ISA Snow Depth Transects and Related Measurements. Version 2. [indicate subset used]. Edited by M. Parsons and M. Brodzik. Boulder, Colorado USA: NASA DAAC at the National Snow and Ice Data Center. http://dx.doi.org/10.5060/D4MW2F23.

Overview Table

Category Description
Data format ASCII files and JPG images
Spatial coverage Fraser, North Park, and Rabbit Ears MSAs in northern Colorado, USA
Temporal coverage and resolution 19-24 February and 25-30 March 2002
20-25 February and 26-31 March 2003
File size 3 - 215 KB for ASCII files; 500 - 750 KB for JPG files
Parameter(s) Snow Depth
Surface Wetness
Surface Roughness
Canopy
Soil Temperature

Table of Contents

1. Contacts
2. Detailed Data Description
Format
File and Directory Structure
File Naming Convention
File Size
Spatial Coverage
Temporal Coverage
Parameters
Quality Assessment
3. Data Access and Tools
4. Data Acquisition and Processing
5. References and Related Publications
6. Document Information

1. Contacts

Investigators

Kelly Elder
Research Hydrologist
Rocky Mountain Research Station
USDA Forest Service
240 W. Prospect Road
Fort Collins, CO USA 80526

Don Cline
National Weather Service
National Operational Hydrologic REmote Sensing Center
1735 Lake Drive W.
Chanhassen, MN 55317

Technical Contact

NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449  USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
e-mail: nsidc@nsidc.org

2. Detailed Data Description

Format

Data are stored in ASCII text files with a file extension of .txt. and JPG images with a file extension of .jpg.

Missing data are identified by "-999". Double quotes are used to delimit text within fields, and commas contained within the double quotes do not indicate a new field. Because of the general lack of snow in North Park, all the depth data were collected on the first day of ground observations.

There are three depth transect files (one per ISA) per MSA. Snow transect filenames are depth_iopNMI_v1.txt, where:

Depth_iop indicates snow depth data
N = IOP number (1-4)
M = MSA letter code
I = ISA letter code
v1 = Data release version 1
.txt = plain text file

Early copies of files with filenames that do not include "_v1" are obsolete and should be replaced with the v1 copies.

Transect files contain one record per transect location, with the following fields:

	Column 1: TRANSECT - transect ID
                  1-letter code for MSA: 
		        F = Fraser
		        N = North Park
		        R = Rabbit Ears
                  1-letter code for ISA: 
		        A = Alpine
		        B = Buffalo Pass
		        F = Fool Creek
		        I = Illinois River
		        M = Michigan River
		        P = Potter Creek
		        S = Spring Creek (if MSA Code = R) or
		              St. Louis Creek (if MSA Code = F)
		        W = Walton Creek
                  1-letter sector ID: A,B,C, or D
                  2-digit cell number: 01-25
                  . decimal point
                  1-digit location number: 1-5
	Column 2: IOP - IOPx (x = 1-4)
	Column 3: DATE - yyyymmdd
	Column 4: TIME - hhmm
	Column 5: UTME - UTM Easting (m)
	Column 6: UTMN - UTM Northing (m)
	Column 7: DEPTH - snow depth (cm)
	Column 8: SWET - surface wetness:
	          d = Dry
	          m = Moist 
	          w = Wet
	          vw = Very Wet
	Column 9: SRUF - surface roughness photo taken (Y or N)
	Column 10: CNPY - canopy 
	          c = Coniferous
	          cs = Snow-covered Coniferous
	          g = Deciduous
	          ds = Snow-covered Deciduous
	          g = Grass (only used in North Park)
	          s = Sage (only used in North Park)
	          n = No Canopy
	Column 11: TEMP(F) - soil temperature, degrees Fahrenheit (only measured in North Park)
	Column 12: SURVEYOR - surveyor names
	Column 13: COMMENTS - surveyor comments, prepended with Quality Control flags for this record ["QC(XXX)", see below for QC flags]

Field comments for depth data were recorded per cell of an ISA sector. For purposes of data consistency, they were reproduced for each data point within that cell.

There are three depth transect summary files (one per ISA) per MSA. Snow transect summary filenames are depth_iopNMI_v1_summary.txt, where:

Depth_iop indicates snow depth data
N = IOP number (1-4)
M = MSA letter code
I = ISA letter code
v1 = data release number 1
summary = content is summary record for each transect
.txt = plain text file

Transect summary files contain one record per transect, with the following fields:

	Column 1: TRANSECT - transect ID
                  1-letter code for MSA: 
		        F = Fraser
		        N = North Park
		        R = Rabbit Ears
                  1-letter code for ISA: 
		        A = Alpine
		        B = Buffalo Pass
		        F = Fool Creek
		        I = Illinois River
		        M = Michigan River
		        P = Potter Creek
		        S = Spring Creek (if MSA Code = R) or
		              St. Louis Creek (if MSA Code = F)
		        W = Walton Creek
                  1-letter sector ID: A,B,C, or D
                  2-digit cell number: 01-25
	Column 2: IOP - IOPx (x = 1-4)
	Column 3: DATE - yyyymmdd
	Column 4: TIME - hhmm
	Column 5: UTME - UTM Easting (m)
	Column 6: UTMN - UTM Northing (m)
	Column 7: #DONE - number of points measured / number of points expected
	Column 8: MEAN - mean of non-missing depth measurements (cm)
	Column 9: SDEV - standard deviation of non-missing depth measurements (cm)
	Column 10: MIN - minimum depth measured (cm)
	Column 11: MAX - maximum depth measured (cm)
	Columns 12,13,14,15,16: WETNESS - count of wetness values by category (dry/moist/wet/very wet/missing
        Column 17: SRUF@PNT - transect point number where surface roughness photo was taken
	Column 18: SURVEYOR - surveyor names
	Column 14: QC() - list of quality control flags triggered by this transect
        Column 15: COMMENTS_FOUND? - YES or NO indicator that surveyors included comments at this transect

Photos

Each JPEG (Joint Photographic Experts Group) file contains one digital photo. At least one snow roughness photo should have been taken at each sector cell. A photo of the general terrain was taken out along the depth transects. These photos should contain a card identifying the location of the photo using the misc.n convention.

Additional photos may also have been taken to show the general field work in progress for public relations purposes.

File and Directory Structure

Data are organized in the following structure:

clp/
    ground_data/
       nsidc0175_snow_transects/
          msa/
             data/
                  iop/
              photos/
                  iop/
                      isa/
                      other/
                      roughness/
                      terrain/

File Naming Convention

The following code, known as "misc.n", are used in filenames (and for site names in the raw data):

  MSA Code 
        F = Fraser
        N = North Park
        R = Rabbit Ears

  ISA Code 
        A = Alpine
        B = Buffalo Pass
        F = Fool Creek
        I = Illinois River
        M = Michigan River
        P = Potter Creek
        S = Spring Creek (if MSA Code = R) or
                St. Louis Creek (if MSA Code = F)
        W = Walton Creek

  ISA Sector 
        A = Lower Left Quadrant - SW
        B = Upper Left Quadrant - NW
        C = Upper Right Quadrant - NE
        D = Lower Right Quadrant - SE

  Sector Cell Number (1-25, referring to 100-m x 100-m grid cells)

  Transect point number (1-5)

File Size

ASCII file sizes range from 3 to 215 KB. JPG file sizes range from 500 to 750 KB.

Spatial Coverage

Fraser, North Park, and Rabbit Ears MSAs in northern Colorado, US.

Schematic diagram of the nested study areas for the CPLX
Study area map
Location of MSAs
Location and characteristics of ISAs

IOP1 Transects Measured:

MSA Planned number of transects Actual number of transects
Fraser 1,500 1,243
North Park 1,500 1,500
Rabbit Ears 1,500 1,484

IOP2 Transects Measured:

MSA Planned number of transects Actual number of transects
Fraser 1,500 1,486
North Park 1,500 1,460
Rabbit Ears 1,500 1,505*

*An extra transect was taken near location RWB08. The pole was moved from its location in IOP1. Surveyors measured at the pole's new location, and at the original location.

IOP3 Transects Measured:

MSA Planned number of transects Actual number of transects
Fraser 2,052 2,042
North Park 2,052 2,047
Rabbit Ears 2,052 1,803

IOP4 Transects Measured:

MSA Planned number of transects Actual number of transects
Fraser 2,052 2,045
North Park 2,052 2,052
Rabbit Ears 2,052 2,036

Temporal Coverage

IOP1 took place 19-24 February 2002.
IOP2 took place 25-30 March 2002.
IOP3 took place 20-25 February 2003.
IOP4 took place 26-31 March 2003.

Parameter or Variable

Parameters include snow depth, surface wetness, surface roughness (photos only), canopy, and soil temperature.

For a complete description of parameters and measurements, please refer to the Measurements section of the CLPX Plan.

Quality Assessment

Snow Depth Quality Control Flags

Code   Description (what was reset/set/estimated: the reason why)
----   ----------------------------------------------------------
000    QC OK: all tests passed
201    Temperature converted from Celsius to Fahrenheit: surveyor's probe measured Celsius.
914    Canopy reset to missing value:  Snow depth is 0.
916    Surface wetness reset to missing value:  Snow depth is 0.
990    Warning: One or both UTM coordinates are missing.
991    Warning: Missing date and/or time field.

Detailed Explanations:
----------------------
000    QC OK: all tests passed

	No problems were detected, values have not been changed from the
	original forms.  

	N.B. Soil temperature measurments were only taken in North Park;
	precision differed by surveying team, some surveyors measured to
	the nearest degree, some measured to the nearest tenth degree.
	During quality control, every effort was made to retain the
	precision recorded by the surveyor.

Temperature QC codes
--------------------

201    Temperature converted from Celsius to Fahrenheit: surveyor's probe measured Celsius.

	Measurement protocol in North Park MSA included soil measurements
	at each transect point.  During IOP1 only, all but one of the
	thermometers used measured Fahrenheit temperatures.  The
	thermometer used by surveyor Armstrong and party was a Celsius
	thermometer.  Actual measurements at the location this surveyor
	measured were taken to the nearest tenth of a Celsius degree, and
	have been converted to the nearest tenth of Fahrenheit degree
	during the QC.

914    Canopy reset to missing value:  Snow depth is 0.

       	Measurement protocol was to record canopy only when snow depth was
	greater than 0.  In this case a recorded canopy was reset to
	missing because the snow depth was 0.

916    Surface wetness reset to missing value:  Snow depth is 0.

       	Measurement protocol was to record surface wetness only when snow
	depth was greater than 0.  In this case a recorded surface wetness
	was reset to missing because the snow depth was 0.

990    Warning: One or both UTM coordinates are missing.

	Transect coordinates are incomplete or missing.

991    Warning: Missing date and/or time field.

        Date and/or time field are missing.  

3. Data Access and Tools

Data Access

Data are available at ftp://sidads.colorado.edu/pub/DATASETS/CLP/data/ground_data/nsidc0175_snow_transects/.

4. Data Acquisition and Processing

For complete information about data acquisition and processing, please see the CLPX Plan Web Site.

5. References and Related Publications

Please see the References section of the CLPX Plan.

ISA Snow Pit Measurements, Version 2.0

6. Document Information

Document Creation Date

12 August 2003

Document Revision Date

12 October 2005

Document URL

http://nsidc.org/data/docs/daac/nsidc0175_clpx.gd.html