Diurnal cycle of radiative and turbulent fluxes during clear sky conditions.

<p>Case of 30 July (Day of Year 211) at the experiment site. Horizontal axis is in AKST time in [hrs.] and vertical axis is in W m^-2. <i>R</i>_<i>net</i> = net radiation, <i>LE</i> = latent heat flux, <i>H</i> = sensible heat flux, <i>G</i> = ground heat flux.</p

Frequency distribution of the wind speed and direction during summer.

<p>Left panel 2012 and right panel 2013 at the experiment site during the period of study at 2 m height.</p

Time-series of soil temperatures.

<p>Soil temperature at 15 cm depth at the experiment site during 1 June to 17 September 2012 (black trace) and 2013 (gray trace). The horizontal axis represents fractional Julian day in local AKST.</p

Time-series of average surface air temperature during growing season 2012 and 2013 compared with the thirty years climate data.

<p>The green line shows the daily mean of air temperature in 2012, the red line shows the daily mean of air temperature in 2013, and the black line shows the 30-year average of air temperature. Shading of each color provides an indication of the confidence range of the air temperature. The horizontal axis represents fractional Julian day in local AKST.</p

Monthly mean meteorological parameters measured at the FEF.

<p>Monthly means calculated between June to September during the 2012^a and 2013^a growing season in comparison with historical data of the climate normal^b in the 30-year time period from 1981–2010 for Fairbanks, Alaska, USA, provided by the National Climatic Data Center. Hist. represents the mean monthly historical climatological data in the 30-year period. The second-four columns indicate mean air temperatures with standard deviation (Std dev) during two summer seasons compared to the 30-year average.</p><p>^a Meteorological station at the study site</p><p>^bThe climate normal (a 30-year mean) at the Fairbanks International Airport (<a href="http://climate.gi.alaska.edu/Climate/Normals" target="_blank">http://climate.gi.alaska.edu/Climate/Normals</a>).</p><p>^C Here the growing period is calculated from 1 June to 20 September</p><p>Monthly mean meteorological parameters measured at the FEF.</p

Scatterplot of energy balance closure.

<p>Horizontal axis is the available energy (<i>R</i>_<i>net</i> – <i>G</i>) for fluxes at the surface [W m^-2] and vertical axis is the sum of turbulent fluxes of sensible (H) and latent heat (<i>LE</i>). Period of study (11 July to 31 August, summer 2013). Values were obtained are 30 minute averages under stationary conditions (1540 measurement points). Correlation coefficient was 95% with an offset of 10 W m^-2.</p

Mean summer values of the energy balance partitioning for Arctic and Subarctic ecosystems calculated and/or collected from various published data sources.

<p>First column represents the ecosystem types, second column is the location of measuring site, third to fifth columns are energy partitioning values for <i>LE</i> /<i>R</i>_<i>net</i>, <i>H</i> /<i>R</i>_<i>net</i>, <i>G</i> /<i>R</i>_<i>net</i> (derived from daily midday flux averages), sixth column is VPD (kPa) for each ecosystem type, seventh column is the Bowen ratio (β), eigth column is the measuring method used for energy budget components measured, and nineth column is the reference for data. EC = Eddy covariance method. BREB = Bowen ratio-energy balance method.</p><p>^aAverage over two years growing season data in 2012 and 2013 from this present work during 1 June—20 September.</p><p>Mean summer values of the energy balance partitioning for Arctic and Subarctic ecosystems calculated and/or collected from various published data sources.</p

Seasonal means of surface energy partitions, Bowen ratio (β), vapor pressure deficit (VPD), Priestley Taylor alpha coefficient (α) and energy balance closure (<i>C</i>_<i>F</i>) at the FEF.

<p>Values are calculated between 1 June to 15 September in 2012 and 2013 growing season. Average midday (1100–1500 AKST) energy balance energy partitioning obtained from a total 352 and 364 samples in 2012 and 2013, respectively. An average over the two-year period was calculated based on 716 data-points shown in the fourth column.</p><p>Seasonal means of surface energy partitions, Bowen ratio (β), vapor pressure deficit (VPD), Priestley Taylor alpha coefficient (α) and energy balance closure (<i>C</i>_<i>F</i>) at the FEF.</p

Daily means of evapotranspiration.

<p>Measured by pan evaporation (E_P) and estimated based on Penman Monteith (ET_PM) from 10 July to 16 September 2013. Some data gaps were caused by power interruptions and instrument failure and repair.</p

Fairbanks Experiment Farm (FEF) site at the UAF AFES.

<p>The location of the instrumentation is illustrated with a different pattern. The farm dimensions are: more than 1 kilometer on East to West direction and about 600 m North to South. EC tower (A), lysimeter plot (B), Meteorological station (C), LAS system (D). Airborne survey photo was provided by the UAF Department of Design and Construction obtained by AeroMap Inc summer of 2003.</p