TITLE:

Toolik Snowfence Experiment: 2002 Snow free date data


PRINCIPAL INVESTIGATOR:

Dr. Marilyn Walker Leader, Boreal Ecology Cooperative Research Unit
USFS PNW Research Station and University of Alaska Fairbanks

Boreal Ecology Cooperative Research Unit
School of Agriculture and Land Resources Management
P.O. Box 756780
University of Alaska Fairbanks
Fairbanks, AK 99775-6780
Phone: 907-474-2424
Fax: 907-474-6251
E-mail: ffmdw@uaf.edu


FUNDING SOURCE:

National Science Foundation 


ARCTIC SYSTEM SCIENCE PROGRAM:

Land-Atmosphere-Ice Interactions (LAII) and The International Tundra Experiment 
(ITEX)


GRANT TITLES AND GRANT NUMBERS:

1999 - 2003: OPP-9996383 -- ITEX / Comparative Responses of Moist and Dry Arctic 
Tundra to Altered Snow and Temperature Regimes


CONDITIONS FOR USE AND CITATION:

For permission to use these data, contact the Principal Investigator.  Grant 
numbers must be cited in any manuscripts resulting from these data.  In 
addition, a copy of the manuscript must be sent to the PI.


DATA SET OVERVIEW:

This file contains snow free date data collected for the Toolik Snowfence 
Experiment in 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.

Time period covered by data: 20020522 to 20020616
Physical location of measurement: Toolik Field Station, Alaska USA (68.62710 N, 
149.59322 W)


DATA COLLECTION AND PROCESSING:

Data were collected in 2002, beginning at site arrival and each day thereafter, 
until all plots were snow free. Plots are consistently monitored in the late 
afternoon and recorded as snow free when three-quarters of the snow within a 
plot has melted.


The Toolik Snowfence Experiment's design and manipulation are described further 
in: 

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.


DATA FORMAT:

File name: USTOOLIK_snowfree02.txt

SUMMARY OF VARIABLES FOR 2002 DATA

1. SITE: country/site/project title
2. SNOW_FREE_DATE: date plot was snow free (YYYYMMDD)
3. LOCATION: site; moist, dry or snowfield
4. ZONE: 0-6
5. PLOT: unique plot number
6. DESCRIPTION: plot treatment or plot type
7. DAY OF YEAR
8. NOTES

DESCRIPTION OF SELECT VARIABLES:

SITE
USTOOLIK: Toolik Field Station, Alaska, USA; Comparative responses of moist and 
dry arctic tundra to altered snow and temperature regimes

LOCATION
Research site: Snowfences are 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 are established where a natural snowdrift 
occurs.  This site is referred to as the snowfield.

ZONE
Snow manipulation: 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.  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.

DESCRIPTION
ITEX warming treatment. OTC:  Open-topped chamber (warming), CTL: No chamber 
(control) or Plot Type: NDVI: Normalized Difference Vegetation Index.  NDVI 
plots are subjected to snow manipulation only.  Temperature is not manipulated 
at any of the NDVI plots.

CODES USED IN DATA SET
In all years "-9999" indicates missing data.  Questionable or bad data is 
indicated by asterisks (****) and estimated data is indicated by an "EEEE" in 
the notes column.


DATA REMARKS:

We arrived at our field site after snowmelt in the ambient zones.  
Consequently,the snow free dates for these plots are not exact.


LOCATION OF ORIGINAL DATA SHEETS:

Boreal Ecology Cooperative Research Unit, University of Alaska, Fairbanks, 
Alaska, USA


DOCUMENTATION AUTHOR:

Original: Amy Breen Carroll, 17 January, 2003


PRINCIPAL FIELD WORKERS:

Amy Breen Carroll
Miyuki Tachibana


PRINCIPAL POSTDOCS:

Henrik Wahren


PUBLICATIONS WHICH INCLUDE THESE DATA: 

None to date.