Readme:,This table includes metadata describing the columns in the file annual_growingseason_CO2flux.csv. More details can be found in Virkkala et al. 2021. The actual data table is in long format: each row in the table includes either annual or growing season fluxes.
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Column,Definition
region,The region where the site is located (Alaska/Fennoscandia/Greenland/Canada/Russia).
site,"Site name that was reported in the paper, by the PI, or in the flux data repository."
sitenr,"Site number, used to identify observations in the same site."
biome,"Biome of the site, extracted from the Dinerstein et al. 2017 data (Tundra/Boreal)."
permafrost,"Permafrost zone of the site, extracted from Brown et al. 2002 (C=Continuous, D=Discontinuous, S=Sporadic, I=isolated, NO=no permafrost)."
lat,Latitude of the site in decimal degrees (WGS 1984). 
lon,Longitude of the site in decimal degrees (WGS 1984). Negative longitudes are west from Greenwich
siteveg,Vegetation description of the site.
envsitename,More detailed vegetation information of the site. Can also list the different names used to describe individual chamber plots.
method,"Flux measurement method (EC=Eddy covariance, CH=chamber)."
qc,"The data source for the flux extraction (Q1=estimated from a figure in a publication, Q2=estimated from text in a publication, Q3=estimated from a table in a publication, Q4=Contributed by the site principal investigator, Q5=extracted from FluxNet)"
ref,"If flux values extracted from a paper, the authors and publication year of the paper."
title,"If flux values extracted from a paper, the  title of the paper."
year,Year of the cumulative flux value
end_year,"If the cumulative flux value is spread over two years, or if it's an average of several years, this column indicates the end year of that (column year defines the start year)."
anngpp_all,"Cumulative gross primary productivity budget over the entire year (g C m-2). If there were several chamber plots within the site, this value is a median of those."
anner_all,"Cumulative ecosystem respiration budget over the entire year (g C m-2). If there were several chamber plots within the site, this value is a median of those."
annee_all,"Cumulative net ecosystem exchange budget over the entire year (g C m-2). If there were several chamber plots within the site, this value is a median of those. Negative =net uptake."
gsgpp_length_all,"Cumulative gross primary productivity budget over the growing season (g C m-2). If there were several chamber plots within the site, this value is a median of those."
gser_length_all,"Cumulative ecosystem respiration budget over the growing season (g C m-2). If there were several chamber plots within the site, this value is a median of those."
gsnee_length_all,"Cumulative net ecosystem exchange budget over the growing season (g C m-2). If there were several chamber plots within the site, this value is a median of those. Negative =net uptake."
gsgpp_daily_all,"Daily average gross primary productivity during the growing season. Derived by dividing the growing season budget by the measurement length (number of measurement days).  If there were several chamber plots within the site, this value is a median of those."
gser_daily_all,"Daily average ecosystem respiration during the growing season.  Derived by dividing the growing season budget by the measurement length (number of measurement days).  If there were several chamber plots within the site, this value is a median of those."
gsnee_daily_all,"Daily average net ecosystem exchange during the growing season.  Derived by dividing the growing season budget by the measurement length (number of measurement days).  If there were several chamber plots within the site, this value is a median of those. Negative =net uptake."
length,Measurement length (number of days) for the growing season budget. One can get back to the growing season budget reported in a paper or contributed by the PI by multiplying the daily fluxes by this variable.
length_raster,Growing season length estimated from the average temperature rasters (number of days with daily average temperatures >3 °C). We used this value to multiply the daily fluxes and derive growing season budgets that can be compared with each other (variables gsgpp_length_all-gsnee_length_all).
FDD,Freezing degree days (°C; sum of days < 0 °C multiplied by the temperature). Need to be divided by 10.
GDD3,"Growing degree days (°C), cumulative air temperature over the growing season (sum of days above base temperature 3 °C multiplied by the temperature). Need to be divided by 10."
WAB,"Annual water balance (mm; difference between total annual precipitation and potential evapotranspiration, PET). Need to be divided by 10."
NDVI_downscaled,Maximum Normalized Difference Vegetation Index during the growing season. Derived from MODIS and GIMMS3g imagery. Need to be divided by 10000.
twi,Topographic wetness index. Derived from GMTED2010 digital elevation model.
rad,Potential incoming direct annual radiation (MJ cm–2 yr–1). Derived from GMTED2010 digital elevation model.
soc,Soil organic carbon stocks in the upper 0-2 m (tonnes/ha). Derived from SoilGrids.
clay,Clay content in the upper 0-5 cm soils (%). Derived from SoilGrids.
ph,Soil acidity in the upper 0-5 cm soils (pH/10; pH estimated with H2O). Derived from SoilGrids.
esa,"Land cover (1=Mixed or broadleaved forest, 2=Needleleaved forest, 4=Grassland & shrubland, 5=Sparse vegetation, 6=Wetland). Modified from ESA CCI land cover product. "
notes,Notes about the flux data extracted from a paper