 | Xiao H. Factors affecting dewfall, its measurement with lysimeters, and its estimation with micrometeorological equations: Diss. … Dr. rer. nat. - Leipzig: Helmholtz-Centre for Environmental Research, UFZ., 2010. - xix, 144 p.: graph. - (PhD Dissertation; 10). - Incl. bibl. ref.
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Summary ........................................................ VI
Zusammenfassung ................................................ XI
List of variables ............................................ XVII
1 Introduction to the topic .................................... 1
1.1 The significance of dew ................................. 1
1.2 The physical process of dew formation ................... 3
1.3 Methods used in the dew studies ......................... 5
1.4 Objectives of this thesis ............................... 8
1.5 References .............................................. 9
2 Analysis of the effect of meteorological factors on dew
formation ................................................... 17
2.1 Abstract ............................................... 17
2.2 Introduction ........................................... 17
2.3 Materials and methods .................................. 19
2.3.1 Energy balance equation ......................... 19
2.3.2 Computation procedure ........................... 26
2.4 Results ................................................ 27
2.4.1 Air temperature ................................. 27
2.4.2 Cloud cover ..................................... 28
2.4.3 Soil heat flux .................................. 28
2.4.4 Relative humidity ............................... 31
2.4.5 Wind speed ...................................... 34
2.4.6 Importance of the various meteorological
factors ......................................... 34
2.5 Discussion ............................................. 36
2.5.1 Air temperature ................................. 36
2.5.1.1 Vapour pressure gradient in relation
to air temperature ..................... 36
2.5.1.2 Latent heat flux in relation to air
temperature ............................ 38
2.5.2 Cloud cover ..................................... 39
2.5.3 Soil heat flux .................................. 40
2.5.4 Relative humidity ............................... 40
2.5.5 Wind speed ...................................... 43
2.5.5.1 Vapour conductance in relation to
wind speed ............................. 43
2.5.5.2 Vapour pressure gradient in relation
to wind speed .......................... 44
2.5.5.3 Latent heat flux in relation to wind
speed .................................. 45
2.6 Conclusions ............................................ 46
2.7 References ............................................. 47
3 Testing the precision of a weighable gravitation
lysimeter ................................................... 50
3.1 Abstract ............................................... 50
3.2 Introduction ........................................... 50
3.3 Materials and methods .................................. 52
3.3.1 Description of the lysimeter .................... 52
3.3.2 Testing the weighing precision of the
lysimeter ....................................... 54
3.3.2.1 Smallest detectable mass change and
measurement stability .................. 54
3.3.2.2 Effect of load position ................ 54
3.4 Results ................................................ 55
3.4.1 Smallest detectable mass change and
measurement stability ........................... 55
3.4.2 Effect of load position ......................... 57
3.5 Discussion ............................................. 59
3.6 Conclusions ............................................ 60
3.7 References ............................................. 61
4 Effect of vegetation type and growth stage on dewfall,
determined with high precision weighing Iysimeters at
a site in northern Germany .................................. 64
4.1 Abstract ............................................... 64
4.2 Introduction ........................................... 64
4.3 Materials and methods .................................. 66
4.4 Results ................................................ 67
4.1 Number of nights with dewfall .......................... 67
4.4.2 Amount of dewfall ............................... 69
4.5 Discussion ............................................. 71
4.6 Conclusions ............................................ 77
4.7 References ............................................. 77
5 Assessment of four methods to compute dewfall ............... 81
5.1 Abstract ............................................... 81
5.2 Introduction ........................................... 81
5.3 Materials and methods .................................. 82
5.3.1 Data ............................................ 82
5.3.2 Equations ....................................... 84
5.3.2.1 Energy balance equation (EB) ........... 84
5.3.2.2 Equation for turbulent vapour
transport (TVT) ........................ 84
5.3.2.3 Penman-Monteith equation (PM) .......... 84
5.3.2.4 Bowen ratio energy balance equation
(BREB) ................................. 86
5.4 Results ................................................ 87
5.4.1 Plausibility of the meteorological data ......... 87
5.4.2 Performance of the equations .................... 92
5.5 Discussion ............................................ 101
5.6 Conclusions ........................................... 105
5.7 References ............................................ 105
6 Comparison between measured and computed dewfall ........... 109
6.1 Abstract .............................................. 109
6.2 Introduction .......................................... 109
6.3 Materials and methods ................................. 110
6.4 Results ............................................... 112
6.5 Discussion ............................................ 116
6.6 Conclusions ........................................... 118
6.7 References ............................................ 119
7 Concluding Remarks ......................................... 121
7.1 Effect of various meteorological factors on dewfall ... 121
7.2 Precision of a weighable gravitation lysimeter ........ 122
7.3 Effect of vegetation type and growth stage on
dewfall ............................................... 123
7.4 Four methods to compute dewfall ....................... 124
7.5 Comparison between measured and computed dewfall ...... 125
8 References (all chapters) .................................. 128
Darstellung der wissenschaftlichen Entwicklung ................ 140
Erklärung ..................................................... 142
Acknowledgements .............................................. 143
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