Abstract
The influence of dry air entrainment on surface heat fluxes and the convective boundary
layer (CBL) properties is investigated. To address the influence on the surface
fluxes, a simple expression for the Priestley-Taylor parameter is derived, based on
the definition of equilibrium evaporation and the mixed layer equations. To assess
the CBL modifications through the land-atmosphere feedbacks, a mixed layer CBL
model coupled to the Penman-Monteith equation is used. The essential physics and
feedbacks in the coupled land atmosphere system are retained in this model.
It is shown that the moisture content of the free atmosphere largely influences the
surface evaporation. The Priestley - Taylor parameter indicates that especially at low
temperatures, entrainment of dry air can significantly enhance the evaporation and
consequently reduce the sensible heat flux. Under these conditions, the CBL growth
is suppressed significantly. Therefore, the free atmosphere moisture conditions can be
considered as a sensitive parameter for the CBL height.
Original language | English |
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Publication status | Published - 2008 |
Event | Eighth Annual Meeting of the European Meteorological Society - Duration: 29 Sep 2008 → 3 Oct 2008 |
Conference
Conference | Eighth Annual Meeting of the European Meteorological Society |
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Period | 29/09/08 → 3/10/08 |