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Pre-ABoVE: Vegetation, NDVI, Snow and Thaw Depths, in North Slope, Alaska and NWT, CA

Documentation Revision Date: 2017-09-14

Data Set Version: 1

Summary

This dataset includes vegetation cover maps, Normalized Difference Vegetation Index (NDVI) maps, snow depth and thaw depth data that were obtained as part of a biocomplexity project on the North Slope of Alaska, USA, and the Northwest Territories (NWT), Canada. In Alaska, seven sites are located along the Dalton Highway and in the Prudhoe Bay Oilfield area, forming a transect across the climate gradient of the North Slope. From South to North, the sites are Happy Valley, Sagwon (an acidic and nonacidic site), Franklin Bluffs, Deadhorse, West Dock and Howe Island. Four sites are in the NWT, forming a latitudinal gradient from South to North; the sites include Inuvik, Green Cabin, Mould Bay, and Isachsen.

At each site, permanent 10 x 10 m grids were established for repeated long-term measurements. Snow depth and thaw depth measurements started at selected Alaska sites in 2000, NWT sites in 2003, and continued at selected sites at varying intervals through 2006. In 2006, vegetation cover was mapped at the Alaska sites. In 2012, spectral measurements were acquired at the Alaska sites and NDVI was calculated. A table of study sites, that displays when the different measurements were collected, is included.

There are 50 data files with this dataset. This includes 21 shapefiles (compressed in .zip format) with vegetation and NDVI data, and 29 files with snow and thaw depth data in comma-separated (.csv) format.

Figure 1. Locations of the study sites. Note that seven locations are indicated along Dalton Highway as there were two for Sagwon for acidic and nonacidic tundra areas (Walker et al., 2008).

Citation

Walker, D.A. 2017. Pre-ABoVE: Vegetation, NDVI, Snow and Thaw Depths, in North Slope, Alaska and NWT, CA. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/1386

Table of Contents

  1. Data Set Overview
  2. Data Characteristics
  3. Application and Derivation
  4. Quality Assessment
  5. Data Acquisition, Materials, and Methods
  6. Data Access
  7. References

Data Set Overview

This dataset provides measurements obtained as part of a biocomplexity project on the North Slope of Alaska and the NWT, Canada. In Alaska, seven sites are located along the Dalton Highway and in the Prudhoe Bay Oilfield area, forming a transect across the climate gradient of the North Slope. From South to North, the sites are Happy Valley, Sagwon (an acidic and nonacidic site), Franklin Bluffs, Deadhorse, West Dock and Howe Island. Four sites are in the NWT, forming a latitudinal gradient from South to North; the sites include Inuvik, Green Cabin, Mould Bay, and Isachsen.

At each site, one to three permanent 10 x 10 m grids were established for repeated long-term measurements. Snow depth and thaw depth measurements started at selected Alaska sites in 2000, NWT sites in 2003, and continued at selected sites at varying intervals through 2006. In 2006, vegetation cover was mapped at the Alaska sites. In 2012, spectral measurements were acquired at the Alaska sites and NDVI was calculated. A table of study sites, that displays when the different measurements were collected, is included.

Project: Arctic-Boreal Vulnerability Experiment (ABoVE)

The Arctic-Boreal Vulnerability Experiment (ABoVE) is a NASA Terrestrial Ecology Program field campaign based in Alaska and western Canada between 2016 and 2021. Climate change in the Arctic and Boreal region is unfolding faster than anywhere else on Earth. ABoVE seeks a better understanding of the vulnerability and resilience of ecosystems and society to this changing environment.

Acknowledgements:

These data were obtained from the Alaska Arctic Geoecological Atlas (http://agc.portal.gina.alaska.edu), which provides access to existing Arctic vegetation plot and map data in support of the ABoVE campaign.

Related publications:

Barreda, J.E., J. Knudson, D.A. Walker, M. K. Raynolds, A. Kade, and C. Munger. 2006. Biocomplexity of Patterned Ground Data Report Dalton Highway, 2001-2005.

Buchhorn, M., D. A. Walker, B. Heim, M. K. Raynolds, H. E. Epstein, and M. Schwieder. 2013. Ground-based hyperspectral characterization of Alaska tundra vegetation along environmental gradients. Remote Sensing 5:3971-4005.

Kade, A. N., D. A. Walker, and M. K. Raynolds. 2005. Plant communities and soils in cryoturbated tundra along a climate gradient in the Low Arctic, Alaska. Phytocoenologia 35:761–820.

Raynolds, M. K., D. A. Walker, C. A. Munger, C. M. Vonlanthen, and A. N. Kade. 2008. A map analysis of patterned-ground along a North American Arctic transect. Journal of Geophysical Research 113:G03S03, doi:10.1029/2007JG000512.

Vonlanthen, C. M., D. A. Walker, M. K. Raynolds, A. N. Kade, H. P. Kuss, F. J. A. Daniels, and N. V. Matveyeva. 2008. Patterned-ground plant communities along a bioclimate gradient in the High Arctic, Canada. Phytocoenologia 38:23-63.

Walker, D. A., H. E. Epstein, V. E. Romanovsky, C.-L. Ping, G. J. Michaelsen, R. P. Daanen, Y. Shur, R. A. Peterson, W. B. Krantz, M. K. Raynolds, W. A. Gould, G. Gonzalez, D. J. Nicolsky, C. M. Vonlanthen, A. N. Kade, H. P. Kuss, A. M. Kelley, C. A. Munger, C. T. Tarnocai, N. V. Matveeva, and F. J. A. Daniels. 2008. Arctic patterned-ground ecosystems: A synthesis of studies along a North American Arctic Transect. Journal of Geophysical Research - Biogeosciences 113:G03S01. doi:10.1029/2007JG000504

 

 

Data Characteristics

Spatial Coverage:  Seven sites on the North Slope of Alaska along the Dalton Highway and in the Prudhoe Bay Oilfield area and four sites in the NWT, Canada. See Figure 2.

ABoVE Grid Locations:

Domain: Core ABoVE

State/territory: Alaska and NWT, Canada

Grid cells:  Ah1Av0Bh2Bv2; Ah1Av0Bh4Bv5; Ah2Av0Bh3Bv2; Ah2Av0Bh3Bv4; Ah2Av0Bh5Bv1

Region: Northern Alaska and the NWT

Spatial Resolution: 10 x 10 m plots and point measurements

Temporal Coverage: Snow depth and thaw depth measurements started at selected Alaska sites in 2000, NWT sites in 2003, and continued at selected sites at varying intervals through 2006. In 2006, vegetation cover was mapped at the Alaska sites. In 2012, spectral measurements were acquired at the Alaska sites and NDVI was calculated

Temporal Resolution: Varied

Study Area (These coordinates are the approximate locations of the study sites and may not match the extents of data files. All latitude and longitude given in decimal degrees.)

Site Westernmost Longitude Easternmost Longitude Northernmost Latitude Southernmost Latitude
Seven sites along the Dalton Highway, North Slope, Alaska -148.85222 -147.99336 70.37475 69.14678
Four sites in the NWT, Canada -133.73056 -103.55078 78.78565 68.36167

 

Data file information

This dataset provides 21 compressed shapefiles (.zip) with vegetation and NDVI data for seven sites in Alaska, and 29 comma-separated files (.csv) with snow and thaw depth data for those seven sites as well as four sites in the NWT. Measurements were made on one to three grids established at each site.

All vegetation and NDVI shapefile data are also provided as a companion files in .kmz format for viewing in Google Earth.

 

Table 1. List of study sites and year range when each measurement type was collected or ‘Not collected’.

  Snow Depth Thaw Depth Vegetation Mapping NDVI
Alaska        
   Happy Valley 2002-2006 2001-2002, 2006 2006 2012
   Sagwon - acidic 2001-2005 2000-2002 2006 2012
   Sagwon - nonacidic 2001-2005 2001-2002, 2006 2006 2012
   Franklin Bluffs 2001-2006 2001-2002, 2006 2006 2012
   Deadhorse 2001-2005 2000-2006 2006 2012
   West Dock 2000-2005 2000-2006 2006 2012
   Howe Island 2003-2005 2001-2006 2006 2012
Northwest Territories        
   Inuvik Not collected 2004, 2006 Not collected Not collected
   Green Cabin Not collected 2003, 2006 Not collected Not collected
   Mould Bay 2006 2004, 2006 Not collected Not collected
   Isachsen 2006 2005-2006 Not collected Not collected

 

 

Table 2: Data file names and descriptions.

From South to North, the sites are Happy Valley, Sagwon (two sites), Franklin Bluffs, Deadhorse, West Dock, Howe Island, Inuvik (NWT), Green Cabin (NWT), Mould Bay ( NWT), and Isachsen (NWT).

Vegetation and NDVI Data Files Descriptions
happy_valley_X_vegetation.shp There are three vegetation maps for Happy Valley in shapefile (.shp) format provided in compressed (*.zip) files. There were three 10 x 10 m grids along a hill-slope where X denotes the location of the grid on the slope: hillcrest-on the crest of the hill ( grid G3-dry), midslope-on the mid-slope (grid G2-mesic), and toeslope-on the toe slope (grid G1-wet) (three individual files)
happy_valley_X_ndvi.shp There are three NDVI maps for Happy Valley in shapefile (.shp) format provided in compressed (*.zip) files. There were three 10 x 10 m grids along a hill-slope where X in the file names denotes the location of the grid on the slope: hillcrest-on the crest of the hill ( grid G3-dry), midslope-on the mid-slope (grid G2-mesic), and toeslope-on the toe slope (grid G1-wet) (three individual files)
sagwon_X_vegetation.shp There are two vegetation maps for Sagwon in shapefile (.shp) format provided in compressed (*.zip) files; one file for an acidic tundra site and one file for a nonacidic site tundra site (two individual files). There was one grid at the acidic site and two grids at the nonacidic site
sagwon_X_ndvi.shp There are two NDVI maps for Sagwon in shapefile (.shp) format provided in compressed (*.zip) files; one file for an acidic tundra site and one file for a nonacidic site tundra site (two individual files). There was one grid established at the acidic site and two grids at the nonacidic site
franklin_bluffs_X_vegetation.shp There are three vegetation maps for Franklin Bluffs in shapefile (.shp) format provided in compressed (*.zip) files. There were three 10 x 10 m grids established where X in the file names denotes dry, moist, and wet (three individual files)
franklin_bluffs_X_ndvi.shp There are three NDVI maps for Franklin Bluffs in shapefile (.shp) format provided in compressed (*.zip) files. There were three 10 x 10 m grids established where X in the file names denotes dry (grid 3), moist (grid 2), and wet (grid 1); three individual files for each area
deadhorse_vegetation.shp A vegetation map in shapefile (.shp) format provided in a compressed (*.zip) file. There was only one grid established at Deadhorse
deadhorse_ndvi.shp NDVI data in shapefile (.shp) format provided in a compressed (*.zip) file. There was only one grid established at Deadhorse
west_dock_vegetation.shp A vegetation map in shapefile (.shp) format provided in a compressed (*.zip) file
howe_island_vegetation.shp A vegetation map in shapefile (.shp) format provided in a compressed (*.zip) file.
   
Snow and Thaw Depth Files Descriptions
Site_snowdepth_gridG#_Xm_YYYYDDMM Snow depth measured at each site for each established grid. There were 1-3 grids per site (gridG#). Measurements were made every meter. YYYYDDMM is the sampling date or sampling date range YYYYMMDD-YYYYMMDD
Site_thawdepth_gridG#_Xm_YYYYDDMM Thaw depth measured at each site for each established grid. There were 1-3 grids per site (gridG#). Measurements were made every meter or half meter (Xm=1m or half meter).  YYYYDDMM is the sampling date or sampling date range YYYYMMDD-YYYYMMDD

 

Properties of the shapefiles

Table 3: Attributes of the shapefiles.

File Name Attribute
All shapefiles with “ndvi” in the file name NDVI:
NOTE: The NDVI remote data using band widths of 2-7 were not data from the remote sources listed, but were calculated based on the PSII data as though they were the band widths of the remote sources for comparative purposes only

Tabelle1_1: NDVI from PSII field spectrometer
Tabelle1_2: NDVI from GeoEye
Tabelle1_3: NDVI from AVHRR
Tabelle1_4: NDVI from Landsat 5
Tabelle1_5: NDVI from Landsat 7
Tabelle1_6: NDVI from MERIS
Tabelle1_7: NDVI from MODIS
happy_valley_hillcrest_vegetation.shp VEGTYPE:
1             B1b - Barren
2             P1a – Prostrate dwarf-shrub, herb tundra with thin organic layer
3             P1b – Prostrate dwarf-shrub, herb tundra with thick moss and organic layer
7             G4 – Tussock-sedge, dwarf-shrub, moss tundra (acidic)
8             S1 – Erect dwarf-shrub tundra
happy_valley_midslope_vegetation.shp VEGTYPE:
1             B1b - Barren
2             P1a – Prostrate dwarf-shrub, herb tundra with thin organic layer
3             P1b – Prostrate dwarf-shrub, herb tundra with thick moss and organic layer
7             G4 – Tussock-sedge, dwarf-shrub, moss tundra (acidic)
8             S1 – Erect dwarf-shrub tundra
happy_valley_midslope_vegetation.shp VEGTYPE:
1             B1b - Barren
2             P1a – Prostrate dwarf-shrub, herb tundra with thin organic layer
3             P1b – Prostrate dwarf-shrub, herb tundra with thick moss and organic layer
7             G4 – Tussock-sedge, dwarf-shrub, moss tundra (acidic)
8             S1 – Erect dwarf-shrub tundra
sagwon_nonacidic2_vegetation.shp (*.lyr file included) VEGTYPE:
1             B1b - Barren
3             P1b – Prostrate dwarf-shrub, herb tundra with thick moss and organic layer
5             W2 – Sedge, moss, dwarf-shrub wetland
7             G3 – Nontussock sedge, dwarf-shrub, moss tundra (nonacidic)
sagwon_nonacidic1_vegetation.shp (*.lyr file included) VEGTYPE:
1             B1b - Barren
2             P1 –Prostrate dwarf-shrub, herb tundra with thin organic layer
7             G3 – Nontussock sedge, dwarf-shrub, moss tundra (nonacidic)
9             P1b –Prostrate dwarf-shrub, herb tundra with thick moss and organic layer
sagwon_acidic_vegetation.shp (*.lyr file included) VEGTYPE:
1             B1b - Barren
2             P1 – Prostrate dwarf-shrub, herb tundra
4             S1 – Erect dwarf-shrub tundra
7             G4 – Tussock-sedge, dwarf-shrub, moss tundra (acidic)
franklin_bluffs_wet_vegetation.shp (*.lyr file included) VEGTYPE:
1             B1b - Barren
3             P1a – Prostrate dwarf-shrub, herb tundra with thin organic layer
7             W2 – Sedge, moss, dwarf-shrub wetland within non-sorted circle
10           W2 – Sedge, moss, dwarf-shrub wetland between non-sorted circles
11           G3 – Nontussock sedge, dwarf-shrub, moss tundra (nonacidic)
franklin_bluffs_moist_vegetation.shp (*.lyr file included) VEGTYPE:
1             B1b - Barren
3             P1a – Prostrate dwarf-shrub, herb tundra with thin organic layer
7             W2 – Sedge, moss, dwarf-shrub wetland within non-sorted circle
10           W2 – Sedge, moss, dwarf-shrub wetland between non-sorted circles
11           G3 – Nontussock sedge, dwarf-shrub, moss tundra (nonacidic)
franklin_bluffs_dry_vegetation.shp (*.lyr file included) VEGTYPE:
1             B1b - Barren
2             P1a – Prostrate dwarf-shrub, herb tundra with thin organic layer
7             G3 – Nontussock sedge, dwarf-shrub, moss tundra (nonacidic)
deadhorse_vegetation.shp (*.lyr file included) VEGTYPE:
1             B1b - Barren
2             P1a – Prostrate dwarf-shrub, herb tundra with thin organic layer
3             P1b – Prostrate dwarf-shrub, herb tundra with thick moss and organic layer
4             G3 – Nontussock sedge, dwarf-shrub, moss tundra (nonacidic) on circle rim
5             W2 – Sedge, moss, dwarf-shrub wetland
7             G3 – Nontussock sedge, dwarf-shrub, moss tundra (nonacidic) between non-sorted circles
west_dock_vegetation.shp (*.lyr file included))

VEGTYPE:
7             G3 –Nontussock sedge, dwarf-shrub, moss tundra (nonacidic)

howe_island_vegetation.shp (*.lyr file included) VEGTYPE:
1             B1a - Barren
5             B1b – Barren with cryptogamic crust
6             P1 – Prostrate dwarf shrub, herb tundra

 

Table 4:  Coordinates for the individual 10 x 10 m sampling grids at each Alaskan site. These are the extents of the vegetation and NDVI shapefile data..

File Name Grid North South East West
happy_valley_hillcrest_ndvi.shp G3 69.146846 69.146752 -148.851952 -148.852217
happy_valley_hillcrest_vegetation.shp G3 69.146851 69.146747 -148.851939 -148.852229
happy_valley_midslope_ndvi.shp G2 69.14684 69.146757 -148.848126 -148.84836
happy_valley_midslope_vegetation.shp G2 69.146844 69.146753 -148.848116 -148.84837
happy_valley_toeslope_ndvi.shp G1 69.147069 69.146978 -148.84682 -148.847076
happy_valley_toeslope_vegetation.shp G1 69.147074 69.146974 -148.846809 -148.847088
sagwon_acidic_ndvi.shp G1 69.425502 69.425409 -148.695726 -148.695991
sagwon_acidic_vegetation.shp G1 69.425506 69.425404 -148.695714 -148.696003
sagwon_nonacidic1_vegetation.shp G1 69.433423 69.433295 -148.669909 -148.670272
sagwon_nonacidic2_ndvi.shp G2 69.433554 69.433458 -148.671571 -148.671846
sagwon_nonacidic2_vegetation.shp G2 69.43356 69.433453 -148.671556 -148.671857
franklin_bluff_dry_ndvi.shp G3 69.67479 69.674684 -148.720751 -148.721057
franklin_bluff_moist_ndvi.shp G2 69.674581 69.674474 -148.720995 -148.721304
franklin_bluff_wet_ndvi.shp G1 69.674194 69.674087 -148.716946 -148.717254
franklin_bluffs_dry_vegetation.shp G3 69.674795 69.674679 -148.720737 -148.721071
franklin_bluffs_moist_vegetation.shp G2 69.674586 69.674468 -148.720981 -148.721319
franklin_bluffs_wet_vegetation.shp G1 69.674198 69.674082 -148.716933 -148.717269
deadhorse_vegetation.shp G1 70.161485 70.161384 -148.466644 -148.46694
deadhorse_ndvi.shp G1 70.161481 70.161389 -148.466656 -148.466928
west_dock_vegetation.shp G1 70.374752 70.374636 -148.552269 -148.552615
howe_island_vegetation.shp G1 70.315169 70.315052 -147.99336 -147.993707

 

Snow and thaw depth data files

There are 29 files in comma-separated (.csv) format which provide snow depth (9 sites) and thaw depth (active layer, 11 sites) measurements in cm made at the established grids. Snow depth measurements were only made every meter. Thaw depth measurements were made every half meter or meter. There were 1-3 grids per site.

The files are named by Site, variable, grid# (s), meter or half meter (1m or halfmeter) and  YYYYDDMM for the sampling date or sampling date range YYYYMMDD-YYYYMMDD:  Site_snowdepth_gridG#_1m_YYYYDDMM

Example file names and descriptions:

Inuvik_thawdepth_gridG1_halfmeter_20040714.csv: Provides thaw depth measurements in cm taken every half meter at the one established grid at the Inuvik NWT site on 2004-07-14.

HappyValley_snowdepth_gridsG1-G3_1m_20020425-20060418.csv: Provides snow depth measurements in cm taken every one meter at the Happy Valley Site at all three established grids during the date range of 2002-04-25 to 2006-04-18.

 

Variables

All files have the same column header names.

The 1-m files for snow depth and thaw depth have measurements recorded at 11 grid points x 11 grid points as shown in Figure 5. The top row/column names are column_point_1 to column_point_11. The half meter thaw depth files have measurements recorded at 22 gridpoints x 22 gridpoints, every half meter.  The number of measurements made at each site varied. The data can be sorted by by grid, date, and row_point.

Table 5. Variable descriptions in the snow and thaw depth data files (.csv).

Variable Description
site Study site: seven sites in Alaska and four sites in the NWT, Canada
date Date of measurement
grid Grid number where measurement was taken. Sites had 1-3 grids
row_point_a  through row_point_k  Grid point where measurement was taken on the grid when associated with the column_point below. The one meter grids had 11 x 11 points established; 11 rows (points) x 11 points (column_points). The half meter grids had 22 x 22 points established; 22 rows (points) x 22 points (column_points). In the half meter files, the column_points are named to reflect half meter increments-1, 1_5, 2, 2_5, etc.  The row_points are named a, ab, b, bc through k to provide 22 rows
column_points_1 through 11 Grid point where measurement was taken on the grid when associated with the row_point above. The one meter grids had 11 x 11 points established; 11 rows (points) x 11 points (column_points). The half meter grids had 22 x 22 points established; 22 rows (points) x 22 points (column_points). In the half meter files, the column_points are named to reflect half meter increments-1, 1_5, 2, 2_5, etc.  The row_points are named a, ab, b, bc through k to provide 22 rows

 

Table 6. Example snow depth 1m data file (showing only 7/15 columns and 3 rows of data):

site date grid row_point column_point_1 column_point_2 column_point_3
Franklin Bluffs 2001-04-20 G1 row_point_a 18 25 20
Franklin Bluffs 2001-04-20 G1 row_point_b 22 21 15
Franklin Bluffs 2001-04-20 G1 row_point_c 10 11 9

 

Table 7.  Example thaw depth half meter data file (showing only 8/26 columns and 5 rows of data).

In the half meter files, the column_points are named to reflect half meter increments-1, 1_5, 2, 2_5, etc.  The row_points are named a, ab, b, bc through k to provide 22 rows.

site date grid row_point column_point_1 column_point_1_5 column_point_2 column_point_2_5
Franklin Bluffs 2001-08-23 G2 row_point_a 51 52 55 52
Franklin Bluffs 2001-08-23 G2 row_point_ab 50 49 53 53
Franklin Bluffs 2001-08-23 G2 row_point_b 53 48 51 53
Franklin Bluffs 2001-08-23 G2 row_point_bc 60 54 62 54
Franklin Bluffs 2001-08-23 G2 row_point_c 50 55 60 52

 

Extents of the .csv data files

Table 8.  Extents for the snow and thaw depth comma-separated data files for all sites and grid locations.

File Name North South East West
Deadhorse_thawdepth_gridG1_halfmeter_20000801-20060903.csv 70.161481 70.161389 -148.467 -148.47
Deadhorse_snowdepth_gridG1_1m_20010420-20050413.csv 70.161481 70.161389 -148.467 -148.47
FanklinBluffs_thawdepth_gridsG1-G3_halfmeter_20000801-20020809.csv 69.67479 69.67453 -148.721306 -148.721306
FanklinBluffs_thawdepth_gridsG1-G3_1m_20060903.csv 69.67479 69.67453 -148.721306 -148.721306
FanklinBluffs_snowdepth_gridsG1-G3_1m_20010420-20060416.csv 69.67479 69.67453 -148.721306 -148.721306
GreenCabin_thawdepth_gridsG1-G3_halfmeter_20030709 73.224472 73.218833 -119.555694 -119.555694
GreenCabin_thawdepth_gridsG1-G3_1m_20060824 73.224472 73.218833 -119.555694 -119.55925
HappyValley_thawdepth_gridsG1-G3_halfmeter_20010709-20020810.csv 69.147 69.146778 -148.847028 -148.85222
HappyValley_thawdepth_gridsG1-G3_1m_20060905.csv 69.147 69.146778 -148.847028 -148.85222
HappyValley_snowdepth_gridsG1-G3_1m_20020425-20060418.csv 69.147 69.146778 -148.847028 -148.85222
HoweIsland_ snowdepth_gridG1_1m_20030412-20050415.csv 70.315169 70.315052 -147.99336 -147.993707
HoweIsland thawdepth_gridG1_1m_20010824-20060904.csv 70.315169 70.315052 -147.99336 -147.993707
HoweIsland thawdepth_gridG1_halfmeter_20020816.csv 70.315169 70.315052 -147.99336 -147.993707
Inuvik_thawdepth_gridG1_1m_20060824.csv 68.36166667 68.36166667 -133.73055556 -133.73055556
Inuvik_thawdepth_gridG1_halfmeter_20040714.csv 68.36166667 68.36166667 -133.73055556 -133.73055556
Isachsen_snowdepth_gridsG1-G3_1m_20060512.csv 78.78565 78.7851 -103.55078 -103.551517
Isachsen_thawdepth_gridsG1-G3_1m_20050725-20060823.csv 78.78565 78.7851 -103.55078 -103.551517
Isachsen_thawdepth_gridsG1-G3_halfmeter_20050725-20050728.csv 78.785317 78.7851 -103.55078 -103.551517
MouldBay_snowdepth_gridsG1-G2_1m_20060512.csv 76.228139 76.225889 -119.292222 -119.296806
MouldBay_thawdepth_gridsG1-G2_1m_20060823.csv 76.228139 76.225889 -119.292222 -119.296806
MouldBay_thawdepth_gridsG1-G2_halfmeter_20040718-20040719.csv 76.228139 76.225889 -119.292222 -119.296806
SagwonAcidic_snowdepth_gridG1_1m_20010420-20050414.csv 69.4255 69.4255 -148.695972 -148.695972
SagwonAcidic_thawdepth_gridG1_halfmeter_20000801-20020806.csv 69.4255 69.4255 -148.695972 -148.695972
SagwonNonacidic_snowdepth_gridsG1-G2_1m_20010420-20050415.csv 69.433583 69.433361 -148.671833 -148.673306
SagwonNonacidic_thawdepth_gridsG1-G2_1m_20060905.csv 69.433583 69.433361 -148.671833 -148.673306
SagwonNonacidic_thawdepth_gridsG1-G2_halfmeter_20000801-20020806.csv 69.433583 69.433361 -148.671833 -148.673306
WestDock_thawdepth_gridG1_halfmeter_20010628-20020809.csv 70.374752 70.374636 -148.552269 -148.552615
WestDock_thawdepth_gridG1_1m_20000801-20060903.csv 70.374752 70.374636 -148.552269 -148.552615
WestDock_snowdepth_gridG1_1m_20010420-20050414.csv 70.374752 70.374636 -148.552269 -148.552615

 

Table 9.  Coordinates for the individual 10 x 10 m sampling grids at each NWT site.

Site North South East West
Green Cabin        
Grid 1 73.2195 73.2195 -119.55925 -119.55925
Grid 2 73.218833 73.218833 -119.555694 -119.555694
Grid 3 73.224472 73.224472 -119.558806 -119.558806
Mould Bay        
Grid 1 76.228139 76.228139 -119.296806 -119.296806
Grid 2 76.225889 76.225889 -119.292222 -119.292222
Isachsen        
Grid 1 78.785317 78.785317 -103.550783 -103.550783
Grid 2 78.78565 78.78565 -103.55135 -103.55135
Grid 3 78.7851 78.7851 -103.551517 -103.551517
Inuvik        
Grid 1 68.110917 68.110917 -133.477278 -133.477278

Application and Derivation

These data could be useful to climatic change and climate impact studies.

Quality Assessment

Refer to the related publications.

Data Acquisition, Materials, and Methods

This dataset provides measurements obtained as part of a biocomplexity project on the North Slope of Alaska and the NWT, Canada. Seven sites were on the North Slope of Alaska located along the Dalton Highway and in the Prudhoe Bay Oilfield area, forming a north-south transect across the climate gradient of the North Slope. Vegetation and NDVI were mapped for the seven sites which included, from South to North, Happy Valley, Sagwon (two sites), Franklin Bluffs, Deadhorse, West Dock and Howe Island. Snow depth and thaw depth measurements were also made at the seven sites as well as four additional sites in the Northwest Territories (NWT), Canada. From South to North, these sites include Inuvik, Green Cabin, Mould Bay, and Isachsen.

At each site, permanent 10 x 10 m grids were established for repeated long-term measurements. Thaw depth, snow depth, and NDVI were sampled on the grids, usually every meter. The 10 x 10 m grids were mapped to characterize the heterogeneity of vegetation in the patterned ground ecosystems created by soils, climate and vegetation interactions. The vegetation maps were hand-drawn in the field, and later digitized as shapefiles.

Descriptions of Alaskan Sites

The Happy Valley biocomplexity sites are located in the warmest part of the Arctic, in the foothills of the Brooks Range, located just west of the Dalton Highway in the foothills of the Arctic Slope approximately 82 km (52 mi) north of Toolik Lake, Alaska at an elevation of about 320 m. Three 10 x 10 m grids were established along a hill-slope, one on the crest of the hill (dry), one on the mid-slope (mesic), and one on the toe slope (wet). Vegetation at all three included tussock-sedge, erect dwarf-shrub, moss vegetation.

The Sagwon biocomplexity sites are located at the northern edge of the rolling foothills, at the boundary with the flatter coastal plain, northwest of the Dalton Highway at an elevation of 300 m. This is also the boundary between Subzones E and D, and between the acidic tundra to the south and the nonacidic tundra to the north. Three 10 x 10 m grids were established, one with acidic tussock-sedge, erect dwarf-shrub, moss vegetation, and two grids in the nonacidic nontussock-sedge, prostrate dwarf-shrub, moss tundra.

The Franklin Bluffs biocomplexity sites are located in Subzone D, on the coastal plain of the Alaska North Slope, just west of the Sagavanirktok River. Three 10 x 10 m grids were established: one near the rim of an abandoned river terrace (dry), one on the same terrace, but further back from the edge and a little lower in elevation (mesic), and one on the lower abandoned river terrace below the first two (wet). A complex of vegetation types were at all three created by non-sorted circles, with sparser vegetation in the circles and more continuous vegetation between the circles.

The Deadhorse biocomplexity site is located near the industrial center of Deadhorse, AK, within 15-km of the Beaufort Sea coast, at an elevation of 15 m. One 10 x 10 m grid was established, with a complex of vegetation types created by non-sorted circles, with sparser vegetation in the circles and more continuous vegetation between the circles.

The West Dock biocomplexity site is located near the water pumping facility at West Dock in the Prudhoe Bay oilfield, AK, within 1-km of the Beaufort Sea coast, at an elevation of 1.5 m. One 10 x 10 m grid was established with non-tussock sedge, prostrate dwarf-shrub, moss tundra on sandy soils.

The Howe Island biocomplexity site is located on a 1.5 x 0.5-km island off the delta of the Sagavanirktok River, west of the Endicott Causeway in the Prudhoe Bay oilfield, AK, at sea level. One 10 x 10 m grid was established with a complex of vegetation types created by 10 to 30-m polygonal cracking due to permafrost ice-wedges, smaller 1 to 3-m non-sorted circles, and small 10-20 cm surficial desiccation cracking. There is sparse vegetation on the sorted circles and more continuous vegetation between the sorted circles and in the troughs between the polygons (Barreda et al., 2006).

Howe Island nonsorted circles

Figure 2. Small non-sorted polygons at Howe Island, AK.

Vegetation Mapping

For the seven sites in Alaska; there are no vegetation maps for the four sites in the NWT.

In 2006, maps of the vegetation types within each grid were created. Following identification of the vegetation communities, their location within the marked 10 x 10 m grid was mapped by hand on a 15-cm paper grid (1:66.7 scale). Maps of grid vegetation were hand digitized. Example maps for Howe Island are provided in Figure 4 (Barreda et al., 2006).

Vegetation map, Howe Island

Figure 3. Vegetation map for the Howe Island site.

Snow and Thaw Depth Measurements

Beginning in August of 2000 and continuing a various sites and intervals through September 2006, thaw depth and snow depth measurements were taken by hand using a probe at each grid point located every meter (snow depth only) and sometimes at half meter on the 10 x 10 m grids.

Data were collected at flags spaced every meter along the edges and within the 10 x 10 m grid, for a total of 121 points (11 for each row and column).

See Figure 5, where: sampling point A1 is the SW corner; A11 is the SE corner; K1 is the NW corner; and K11 is the NE corner. Compass directions are approximate.

sampling grid

Figure 4: Sampling layout for 10 x 10 m grid plot, where sampling point A1 is the SW corner; A11 is the SE corner; K1 is the NW corner; and K11 is the NE corner. Compass directions are approximate.

snow depth measurements taken at a site

Figure 5. Snow depth measurements being taken at a site (Barreda et al., 2006).

NDVI Measurements

In 2012, measurements of NDVI were made with an Analytical Spectral Devices field spectrometer (PSII) on the same grids at all 121 points at the seven Alaskan sites.  The NDVI remote data provided in the shapefiles were not data from the remote sources listed (from Geoeye, MODIS, Landsat, AVHRR, and MERIS), but were calculated based on the PSII data as though they were from those sources for comparative purposes only.

  Franklin Bluffs  map

Figure 6. Franklin Bluffs dry vegetation NDVI overlay. NDVI measurements are shown as circles at each gridpoint.

 

Data Access

These data are available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

Pre-ABoVE: Vegetation, NDVI, Snow and Thaw Depths, in North Slope, Alaska and NWT, CA

Contact for Data Center Access Information:

References

Barreda, J.E., J. Knudson, D.A. Walker, M. K. Raynolds, A. Kade, and C. Munger. 2006. Biocomplexity of Patterned Ground Data Report Dalton Highway, 2001-2005.

Walker, D. A., H. E. Epstein, V. E. Romanovsky, C.-L. Ping, G. J. Michaelsen, R. P. Daanen, Y. Shur, R. A. Peterson, W. B. Krantz, M. K. Raynolds, W. A. Gould, G. Gonzalez, D. J. Nicolsky, C. M. Vonlanthen, A. N. Kade, H. P. Kuss, A. M. Kelley, C. A. Munger, C. T. Tarnocai, N. V. Matveeva, and F. J. A. Daniels. 2008. Arctic patterned-ground ecosystems: A synthesis of studies along a North American Arctic Transect. Journal of Geophysical Research - Biogeosciences 113:G03S01. doi:10.1029/2007JG000504