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126 40 20.0 15.4 8.1 -0.7 -8.7 -11.2 -10.5 -5.6 1.7 8.9 14.8 18.6 -5.8 144 100 17.3 13.7 9.9 4.4 -1.5 -5.0 -6.4 -4.7 -1.1 2.9 9.0 13.3 -2.4 141 HG 20 21.1 15.0 6.3 -3.8 -12.4 -14.1 -12.5 -6.0 2.8 11.4 17.2 20.3 -7.7 146 2 22.1 15.9 4.6 -6.6 -15.8 -16.4 -13.8 -5.8 3.9 15.0 19.0 21.5 -9.1 150 8 21.7 15.4 5.2 -5.7 -14.6 -15.7 -13.5 -5.9 3.6 13.6 19.5 21.7 -8.6 147 100 14.0 13.4 9.8 4.7 -1.0 -4.7 -5.5 -3.8 -0.8 3.4 8.1 12.0 -1.9 136 40 19.2 15.1 7.2 -1.6 -9.6 -12.1 -10.7 -5.3 2.1 9.9 15 18.3 -6.2 144 WG 20 19.8 15.2 6.8 -2.5 -11.1 -13.2 -11.4 -5.3 2.5 10.9 15.9 19.0 -6.8 145 2 21.7 16.0 4.9 -5.5 -14.8 -15.5 -12.6 -4.5 4.7 15.9 19.0 21.1 -8.0 143 8 20.9 15.3 4.9 -5.2 -14.3 -15.3 -12.8 -5.2 3.8 14.0 17.8 20.4 -8.2 146 100 13.0 12.3 8.7 3.0 -1.2 -4.3 -5.2 -4.5 -1.6 2.9 7.7 11.6 -2.3 141 40 16.8 13.5 6.9 -0.7 -6.1 -8.5 -8.2 -5.4 0 7.3 12.8 16.3 -4.8 157 UG 99 20 18.3 13.8 5.8 -3.1 -9.9 -11.4 -10.3 -5.9 1.1 9.6 14.9 17.9 -6.6 157 2 19.5 14.4 4.7 -4.7 -12.7 -13.2 -11.6 -5.4 2.6 12.4 16.5 19.1 -7.5 154 8 19.1 14.1 5.0 -3.9 -10.4 -11.4 -10.2 -5.2 2.2 11.4 16 18.8 -6.5 150 100 15.0 14.1 10.2 4.6 -1.0 -4.2 -5.2 -4.0 -0.9 4.3 9.4 13.1 -1.8 136 40 18.4 14.9 8.0 -0.1 -6.9 -9.4 -8.9 -5.0 0.9 8.4 13.9 17.1 -4.9 148 UG 79 20 20.0 15.2 6.7 -2.5 -9.8 -11.5 -10.3 -4.9 2.4 11.2 16.1 19.0 -6.1 145 8 21.1 15.7 5.7 -4.3 -11.8 -12.9 -11.2 -4.6 3.5 13.8 17.6 20.2 -6.9 146 2 21.9 16.1 5.1 -5.3 -12.9 -13.6 -11.5 -4.3 4.2 15.5 18.5 20.8 -7.2 144 Treat- Depth Month (August 2005 – July 2006) Average Period of gro<strong>und</strong> ment (cm) 8 9 10 11 12 1 2 3 4 5 6 7 in winter freezing (day) Table 6.1. Monthly-averaged soil temperatures at 2, 8, 20, 40, and 100 cm depth in four sites from August 2005 to July 2006.
Chapter 6 Modeling of Coupled Water and Heat Transfer in Freezing and Thawing Soil Simulated Soil Temperatures and Water Contents Soil water and heat fluxes are numerically simulated for the whole hydrological year in 2006. This is exemplified by two sites of UG 79 (Fig. 4) and WG (Fig. 5). In general, the simulated and measured soil water contents (SWC) are comparable during the studied periods (Figs. 4-5; RMSE of 0.02-0.07 cm 3 cm -3 for UG 79 and 0.02-0.08 cm 3 cm -3 for WG). Particularly, the freezing model simulates well the diurnal water dynamics caused by phase changes between water and ice, i.e. soil moisture increases with increasing soil temperature and vice versa (Figs. 4b and 5b). This suggests the freezing and thawing processes can be accurately simulated by the applied freezing code. However, the snow routine is only available for the simulation of soil water contents <strong>und</strong>er unfrozen condition. Under frozen condition, there is a clear disparity between the liquid water content line simulated by the freezing model and the total water content line simulated by the snow routine (Fig. 4a and 5a). This discrepancy is apparently caused by the function of the two models, and may be used to approximate the ice content in the soil. Thus, the comparison between the two model approaches just provides a way to calculate the ice content. For instance, the SWC simulated by the freezing model drops shortly after 6 th November associated with soil freezing in UG 79 (Fig. 4a). However, the SWC simulated by snow routine keeps constant. From which, an ice content of 0.07 cm 3 cm -3 can be estimated. Similarly, the ice content in WG is 0.05 cm 3 cm -3 (Fig. 5a). This also gives an evidence of grazing effects on soil freezing point and ice content. In late March, coinciding with soil temperature increasing above 0°C, both simulated (freezing model) and measured SWC raise, while simulated SWC by snow routine keeps constant. This again proofs that the freezing model can predict well the increase in SWC by soil thawing. An increase in SWC in the deeper soil layers (20 and 40 cm) accompanied by soil thawing is also clearly predicted (Figs. 4-5). However, there is no indication of vertical water movement since soil water content is low and it can be held by soil. 127
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SCHRIFTENREIHE Institut für Pflanz
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Aus dem Institut für Pflanzenernä
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I Table of contents I Table of cont
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controlling soil moisture are of pa
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Zusammenfassung Überweidung wird a
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Die Beweidung beieinflusst besonder
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II List of figures Fig. 2.1. Locati
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measured soil moisture in time stab
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III List of tables Table 2.1. Descr
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1.1 Background Chapter 1 Introducti
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Chapter 1 Introduction is also unce
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Chapter 1 Introduction water in spr
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Chapter 1 Introduction requires the
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Chapter 1 Introduction Krümmelbein
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Chapter 2 Spatial variability of so
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Chapter 3 Spatio-temporal variabili
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Chapter 3 Factors controlling spati
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Chapter 4 Temporal stability of soi
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Y orientation Chapter 4 Temporal st
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MRD(%) MRD(%) 100 80 60 40 20 0 -20
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Page 173 and 174: Curriculum Vitae M.Sc. Ying Zhao Of
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