Net CO2, evaporation and heat flux data have been collected at the Alice Holt Flux tower since 1999, these data are used in combination with the data set ‘Meteorological and climatological data from the Alice Holt plantation tower (1999-2013)’ to examine the main drivers in inter-annual variation in CO2 fluxes at an oak forest in the south of England.
See also: Wilkinson, M., Eaton, E.L., Broadmeadow, M.S.J. and Morison, J.I.L. (2012). Inter-annual variation of carbon uptake by a plantation oak woodland in south-eastern England. Biogeosciences 9: 5373-5389.
The columns have the following definitions:
Label Units, Format, or Range Description
filename,-,Name of the raw file (or the first of a set) from which the dataset for the current averaging interval was extracted
date,yyyy-mm-dd,Date of the end of the averaging period
time,HH:MM,Time of the end of the averaging period
filerecords,#,Number of valid records found in the raw file (or set of raw files)
usedrecords,#,Number of valid records used for current the averaging period
Tau,kg m-1 s-2,Corrected momentum flux
qcTau,#,Quality flag for momentum flux
randerrTau,kg m-1 s-2,Random error for momentum flux, if selected
H,W m-2,Corrected sensible heat flux
qcH,#,Quality flag for sensible heat flux
randerrH,W m-2,Random error for momentum flux, if selected
LE,W m-2,Corrected latent heat flux
qcLE,#,Quality flag latent heat flux
randerrLE,W m-2,Random error for latent heat flux, if selected
gasflux,µmol m-2 s-1(†),Corrected gas flux
qcgasflux,#,Quality flag for gas flux
randerrgasflux,µmol s-1 m-2(†),Random error for gas flux, if selected
Hstrg,W m-2,Estimate of storage sensible heat flux
LEstrg,W m-2,Estimate of storage latent heat flux
gasstrg,µmol s-1 m-2(†),Estimate of storage gas flux
gasv-adv,µmol s-1 m-2(†),Estimate of vertical advection flux
gasmolardensity,mmol m-3,Measured or estimated molar density of gas
gasmolefraction,µmol mol-1(†),Measured or estimated mole fraction of gas
gasmixingratio,µmol mol-1(†),Measured or estimated mixing ratio of gas
gastimelag,s,Time lag used to synchronize gas time series
gasdeftimelag,T/F,Flag: whether the reported time lag is the default (T) or calculated (F)
sonictemperature,K,Mean temperature of ambient air as measured by the anemometer
airtemperature,K,Mean temperature of ambient air, either calculated from high frequency air temperature readings, or estimated from sonic temperature
airpressure,Pa,Mean pressure of ambient air, either calculated from high frequency air pressure readings, or estimated based on site altitude (barometric pressure)
airdensity,kg m-3,Density of ambient air
airheatcapacity,J K-1 kg-1,Specific heat at constant pressure of ambient air
airmolarvolume,m3 mol-1,Molar volume of ambient air
ET,mm hour-1,Evapotranspiration flux
watervapordensity,kg m-3,Ambient mass density of water vapor
e,Pa,Ambient water vapor partial pressure
es,Pa,Ambient water vapor partial pressure at saturation
specifichumidity,kg kg-1,Ambient specific humidity on a mass basis
RH,%,Ambient relative humidity
VPD,Pa,Ambient water vapor pressure deficit
Tdew,K,Ambient dew point temperature
uunrot,m s-1,Wind component along the u anemometer axis
vunrot,m s-1,Wind component along the v anemometer axis
wunrot,m s-1,Wind component along the w anemometer axis
urot,m s-1,Rotated u wind component (mean wind speed)
vrot,m s-1,Rotated v wind component (should be zero)
wrot,m s-1,Rotated w wind component (should be zero)
windspeed,m s-1,mean wind speed
maxwindspeed,m s-1,Maximum instantaneous wind speed
winddir,° (degrees),Direction from which the wind blows, with respect to Geographic or Magnetic north
yaw,° (degrees),First rotation angle
pitch,° (degrees),Second rotation angle
u,m s-1,Friction velocity
TKE,m-2 s-1,Turbulent kinetic energy
L,M,Monin-Obukov length
(z-d)/L,#,Monin-Obukhov stability parameter
bowen_ratio,#,Sensible heat flux to latent heat flux ratio
T,K,Scaling temperature
(footprint) model,-,Model for footprint estimation
xoffset,m,Along-wind distance providing <1% contribution to turbulent fluxes
xpeak,m,Along-wind distance providing the highest (peak) contribution to turbulent fluxes
x10%,m,Along-wind distance providing 10% (cumulative) contribution to turbulent fluxes
x30%,m,Along-wind distance providing 30% (cumulative) contribution to turbulent fluxes
x50%,m,Along-wind distance providing 50% (cumulative) contribution to turbulent fluxes
x70%,m,Along-wind distance providing 70% (cumulative) contribution to turbulent fluxes
x90%,m,Along-wind distance providing 90% (cumulative) contribution to turbulent fluxes
unTau,kg m-1 s-2,Uncorrected momentum flux
Tauscf,#,Spectral correction factor for momentum flux
unH,W m-2,Uncorrected sensible heat flux
Hscf,#,Spectral correction factor for sensible heat flux
unLE,W m-2,Uncorrected latent heat flux
LEscf,#,Spectral correction factor for latent heat flux
ungasflux,µmol s-1 m-2(†),Uncorrected gas flux
gasscf,#,Spectral correction factor for gas flux
spikes,HFu/v/w/ts/co2 /h2o/ch4/n2,Hard flags for individual variables for spike test
ampres,HFu/v/w/ts/co2 /h2o/ch4/n2,Hard flags for individual variables for amplitude resolution
dropout,HFu/v/w/ts/co2 /h2o/ch4/n2,Hard flags for individual variables for drop-out test
abslim,HFu/v/w/ts/co2 /h2o/ch4/n2,Hard flags for individual variables for absolute limits
skwkur,HFu/v/w/ts/co2 /h2o/ch4/n2,Hard flags for individual variables for skewness and kurtosis
skwkur,HFu/v/w/ts/co2 /h2o/ch4/n2,Soft flags for individual variables for skewness and kurtosis test
discontinuities,HFu/v/w/ts/co2 /h2o/ch4/n2,Hard flags for individual variables for discontinuities test
discontinuities,HFu/v/w/ts/co2 /h2o/ch4/n2,Soft flags for individual variables for discontinuities test
timelag,HFu/v/w/ts/co2 /h2o/ch4/n2,Hard flags for gas concentration for time lag test
timelag,HFu/v/w/ts/co2 /h2o/ch4/n2,Soft flags for gas concentration for time lag test
attackangle,HFu/v/w/ts/co2 /h2o/ch4/n2,Hard flag for attack angle test
nonsteadywind,HFu/v/w/ts/co2 /h2o/ch4/n2,Hard flag for non-steady horizontal test
varspikes,#,Number of spikes detected and eliminated for variable var
AGC,#,Mean value of AGC for LI 7500RS or LI 7200RS
RSSI,#,Mean value of RSSI for LI 7700, if present
varvar,-(‡),Variance of variable var
w/varcov,-(‡),Covariance between w and variable var
extravarmean,(‡),Mean value of extravar
The quality flags (e.g. qc_Tau) used are described on the following link. They range from 0 to 2; 0 is the best quality data and 2 the worst.
https://www.licor.com/env/help/eddypro/topics_eddypro/Flux_Quality_Flags.html?Highlight=quality%20flag
Missing values are denoted with a -9999 Attribution statement: Forest Research must be acknowledged as the source of the data in any subsequent papers/products