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Tundra permafrost thaw causes significant shifts in energy partitioning Cover

Tundra permafrost thaw causes significant shifts in energy partitioning

Open Access
|Jan 2016

Figures & Tables

Fig. 1

Diurnal trend of surface energy fluxes. Measured mean net radiation (R net ), sensible heat flux (H), latent heat flux (LE) and ground heat flux (G) at the peat plateau (left), at the collapsed peat plateau (middle) and at the wet fen (right) during the period JuneAugust 2013.

Fig. 2

Mean heat fluxes. Mean sensible heat flux (H), latent heat flux (LE) and ground heat flux (G) at the well-developed peat plateau (left), at the collapsed peat plateau (middle) and at the wet fen (right) in relation to the global solar radiation (R G ). Mean values represent the period June to August 2013 (Storflaket, Torneträsk, Stordalen) and the period January to December 2013 (Stordalen). The error bars represent the standard error. The histogram shows the distribution of the global solar radiation (R G ) in classes of 100 W m−2.

Fig. 3

Mean resistances, Bowen ratio and albedo. Mean surface resistance (Res. s ), atmospheric resistance (Res. a ), Bowen ratio (H/LE) and albedo at the three peatland complexes in relation to the global solar radiation (R G ). The error bars represent the standard error. The histogram shows the distribution of the global solar radiation (R G ) in classes of 100 W m−2.

Table 1. Energy balance and environmental characteristics

ParameterPeat plateau (Storflaket), June – Aug.St. dev.Collapsed peat plateau (Torneträsk), June – Aug.St. dev.Wet fen (Stordalen), June – Aug.St. dev.Wet fen (Stordalen), 2013St. dev.R G (W m−2)a249.6192.1225.4193.4211.2213.7101.3170.6RL↑ (W m−2)b378.924.3380.222.3393.923.3349.846.7RL↓ (W m−2)c318.126.9320.029.0343.228.3310.045.8RS↑ (W m−2)d47.837.741.135.944.243.625.746.7RS net (W m−2)e201.0152.9186.1157.4167.1170.675.6135.1RL net (W m−2)f−60.439.6−59.729.5−50.730.3−39.828.0R net (W m−2)g141.0121.8124.2138.0116.4149.437.1121.0Albedo0.1870.0200.1790.0190.1910.0130.2980.235H (W m−2)h45.153.227.850.829.557.82.945.3LE (W m−2)i59.236.864.348.6––––G (W m−2)j7.25.08.611.41.34.51.93.9H/LE0.760.450.430.35––––H/Rnet 0.320.160.220.190.250.190.070.22LE/Rnet 0.420.150.520.16––––G/Rnet 0.050.130.070.150.010.130.050.16Tair (°C)k10.32.612.13.113.23.46.07.9Tsurf. (°C)l12.54.512.94.215.54.26.69.4Tsoil (°C)m9.52.610.71.811.82.06.05.6Air pressure (hPa)969.35.2976.26.5––––Mixing ratio (g kg−1)8.51.79.52.1––––RH (%)n75.616.176.814.8––––VPD (Pa)o333.6263.6363.3292.0––––ET (mm h−1)p2.050.582.270.80––––αq0.930.160.980.13––––u (m s−1)r3.41.53.41.23.11.53.61.7u* (m s−1)s0.260.110.350.140.330.150.320.14Res.a (s m−1)t73.238.445.120.248.122.052.523.9Res.s (s m−1)u92.953.465.642.1––––Ωv0.570.180.530.19––––

[i] List of mean surface energy balance and environmental characteristics during the measurement period in 2013.

[ii] aGlobal radiation.

[iii] bUpwelling longwave radiation.

[iv] cDownwelling longwave radiation.

[v] dReflected shortwave radiation.

[vi] eNet shortwave radiation.

[vii] fNet longwave radiation.

[viii] gNet radiation.

[ix] hSensible heat flux.

[x] iLatent heat flux.

[xi] jGround heat flux.

[xii] kAir temperature, measured at 2.7 m height in Storflaket and Torneträsk and at 2.0 m height in Stordalen.

[xiii] lGround surface temperature.

[xiv] mSoil temperature, measured at 2 cm depth.

[xv] nRelative humidity.

[xvi] oVapour pressure deficit.

[xvii] pEvapotranspiration.

[xviii] qAlpha-value.

[xix] rWind speed.

[xx] sFriction velocity.

[xxi] tAerodynamic resistance.

[xxii] uSurface resistance.

[xxiii] vOmega-value.

Fig. 4

Differences in heat fluxes. Differences of mean sensible heat fluxes (ΔH), latent heat fluxes (ΔLE) and ground heat fluxes (ΔG) between the collapsed peat plateau (Torneträsk) and the well-developed peat plateau (Storflaket) (left), between the well-developed peat plateau (Storflaket) and the wet fen (Stordalen) (middle), and between the collapsed peat plateau (Torneträsk) and the wet fen (Stordalen) (right) in relation to the global solar radiation (R G ). The error bars represent the standard error. The histogram shows the distribution of the global solar radiation (R G ) in classes of 100 W m−2.

Fig. 5

Energy flux ratios. Mean ratios of sensible heat flux (H) (left), latent heat flux (LE) (middle) and soil heat flux (G) (right) to net radiation (R net ) at the well-developed peat plateau, collapsed peat plateau and wet fen in relation to the global solar radiation (R G ). The error bars represent the standard error. The histogram shows the distribution of the global solar radiation (R G ) in classes of 100 W m−2.

Fig. 6

Energy balance closure. Balance between the turbulent fluxes of sensible and latent heat (H+LE) and the available energy (R net – G) at the peat plateau (left) and at the collapsed peat plateau (right).

Language: English
Page range: 30467 - 30467
Submitted on: Nov 22, 2015
Accepted on: Mar 11, 2016
Published on: Jan 1, 2016
Published by: Stockholm University Press
In partnership with: Paradigm Publishing Services

© 2016 Christian Stiegler, Margareta Johansson, Torben R. Christensen, Mikhail Mastepanov, Anders Lindroth, published by Stockholm University Press
This work is licensed under the Creative Commons Attribution 4.0 License.