Toolik Snowfence Experiment: 1994-2002 Active Layer Depth

Summary

This data set contains active layer data collected for the Toolik Snowfence Experiment from 1994 to 2002. The Toolik Snowfence Experiment (part of the International Tundra Experiment network) examines the short- and long-term effects of increased snow depth (shortened growing season) and increased summer temperature on arctic tundra vegetation. The goal of this project is to assess potential changes in tundra plant communities in response to global climate change.

The research project was funded by the following Arctic System Sciences (ARCSS) Program grants:

• 1994 - 1998: OPP-9400083 -- ITEX / Comparative Responses of Moist and Dry Arctic Tundra to Altered Snow and Temperature Regimes
• 1999 - 2003: OPP-9907127 -- ITEX / Collaborative Research: Species Responses to Changes in Climate Across Arctic Gradients Using the North America ITEX Network (NATEX): Influences On Community and Ecosystem Processes
• 1999 - 2003: OPP-9996383 -- ITEX / Comparative Responses of Moist and Dry Arctic Tundra to Altered Snow and Temperature Regimes

Data are available for ordering through NCAR.

Citing These Data:

Walker, M. 2003. Toolik Snowfence Experiment: 1994-2002 Active Layer Depth. Boulder, CO: National Center for Atmospheric Research, ARCSS Data Archive.

Overview Table

Table of Contents

1. Contacts and Acknowledgments:

Investigator(s) Name and Title:

Technical Contact:

2. Detailed Data Description:

Format:

ASCII text files

File Naming Convention:

USTOOLIK_activelayer94-01.txt: This file contains active layer data collected from 1994-2001.

USTOOLIK_activelayer02.txt: This file contains active layer data collected in 2002.

File Size:

USTOOLIK_activelayer94-01.txt: File size is 182 KB.

USTOOLIK_activelayer02.txt: File size is 42 KB.

Spatial Coverage:

Data were collected at Toolik Field Station, Alaska, United States of America. The station is located at the following coordinates.

Southernmost Latitude: 68.620 N
Northernmost Latitude: 68.623 N
Westernmost Longitude: 149.599 W
Easternmost Longitude: 149.596 W

Spatial Resolution:

A 60-m snowfence is aligned on an east-west axis at both the moist and dry sites. Both snowfences are perpendicular to the predominant winter winds from the Brooks Range to the south, effectively creating a leeward drift 50-60 m long on the north side of the fence.

Grid Description:

An established grid on the north side of the fence divides the drift into 6 parallel zones (60 m x 10 m). Zone number increases from 1 to 6, as distance from the snowfence increases. Zones 1, 2, and 3 accumulate the most snow (2-3 m), while zones 4, 5, and 6 accumulate the least snow (0.5-2 m). Zone 0 (the control) is located adjacent to the snowfence grid and does not receive supplemental snow.

Temporal Coverage:

The data were collected between 1994-08-11 to 2002-08-22.

Temporal Resolution:

Data were collected approximately once per week throughout the field season (May through August).

Parameter or Variable:

Parameter Description:

Snowfences were erected and grids established at both a moist tussock site (68.62032 N, 149.59931) and a dry heath site (68.62261 N, 149.59589 W). In addition, monitored plots (known as the snowfield) were established where a natural snowdrift occurs.

The data contain active layer depths measured to the nearest centimeter. A stainless steel probe was forced into the ground until it hit the top of the permafrost. The distance from the soil surface to the bottom of the probe was the depth of the active layer. Data were collected in zones 0, 1, 3, and 5 at the moist tussock site only. The soil at the dry heath site is too rocky to accurately measure the active layer. In each zone, three plots per warming treatment were monitored. Six random measurements were taken at each plot: three tussock and three intertussock.

The warming treatment consisted of placing open-topped fiberglass chambers (OTC) along experimental snow gradients and in control areas outside the fences; each warming plot was paired with an unwarmed (control) plot. The OTCs were constructed according to the International Tundra Experimental (ITEX) design.

Unit of Measurement:

Active layer was measured to the nearest centimeter.

Parameter Source:

Active layer measurements were taken with a stainless steel probe.

Parameter Range:

Active layer depth ranged from 0 to 91 cm.

Sample Data Record:

Column Definitions:

• SITE: country/site/project title
• DATE: date of data collection (YYYYMMDD)
• LOCATION: site; moist only
• ZONE: 0-6
• PLOT: unique plot number
• TREATMENT: ITEX warming treatment using open-top chambers (OTC)
• REPLICATE: sequential numbering of samples
• TUSSOCK_DEPTH (cm)
• INTERTUSSOCK_DEPTH (cm)

Data Remarks:

• In all years, "-9999" indicates missing data.
• Only a single tussock and intertussock measurement per plot were collected in 1994 and 1995.
• Although the zones sampled were consistent from 1994 to 2000, the actual plots sampled varied in 1994 and 1995.
• Only maximum thaw depth was recorded in 1994.
• Active layer data collected in 1996 is not included here due to flawed methods.
• Data were collected in zones 0, 1, 3, and 5 at the moist tussock site only. The soil at the dry heath site was too rocky to accurately measure the active layer.

3. References and Related Publications:

Walker, M. D., D.A. Walker, J.M. Welker, A.M. Arft, T. Bardsley, P.D. Brooks, J.T. Fahnestock, M.H. Jones, M. Losleben, A.N. Parsons, T.R. Seastedt, and P. L. Turner. 1999. Long-term experimental manipulation of winter snow regime and summer temperature in arctic and alpine tundra. Hydrological Processes 13: 2315-2330.

4. Document Information:

Glossary and Acronyms:

Acronyms:

ITEX: International Tundra Experiment

OTC: Open-topped chamber

Document Creation Date:

2003-02-04

Document URL:

http://data.eol.ucar.edu/codiac/dss/id=106.ARCSS900