PhD Thesis, 2007 - University College Cork

Chapter 6
Water and energy budgets
6.5.2 Dormant season (October to March)
Daily ET between October and March varied considerably from day to day. The
monthly mean ET ranged between a minimum of 0.4 mm in December 2005 and a
maximum of 1.1 mm day -1 in March 2004 (Figure 6.4). In winter, ET appeared to
closely follow the daytime temperature, often exceeding 1.5 mm day -1 during days
warmer than 10 °C. In most years, December had the lowest monthly mean daily
ET (about 0.4 mm day -1 ). The 2004/05 winter was different from the other winters,
with the lowest monthly ET occurring in November, while December had similar
ET as February, and January had a higher ET than March, due to very mild daytime
temperatures.
ET [mm day -1 ]
3
2.5
2
1.5
1
0.5
a)
0
oct 2002 apr 2003 oct 2003 apr 2004 oct 2004 apr 2005 oct 2005 apr 2006 oct 2006
20
b)
15
t air
[°C]
10
5
0
oct 2002 apr 2003 oct 2003 apr 2004 oct 2004 apr 2005 oct 2005 apr 2006 oct 2006
Month of the year
Figure 6.5. a) Daily evapotranspiration (bars) and superimposed monthly mean ET
(heavy black line) for the period 1 st September 2002 to 31 st October 2006. b) Daily
T air (grey line) and superimposed monthly mean T air for the same period.
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