A simple model for estimating the Bowen ratio from climatic factors for determining latent and sensible heat flux

The energy partitioning or Bowen ratio β at the surface, can be expressed as a function of a climatic factor C (which depends on the climatic characteristics through the climatological resistance ri) and of a surface factor S (which depends on the surface characteristics through the surface resistance rc). This paper explains an approach for estimating S and therefore β as a function of standard meteorological variables. The empirical approach is then validated by estimating the latent (λE) and sensible (H) heat flux. The experimental data were measured over grass at two semiarid locations in the Ebro river valley, NE Spain, with typical Mediterranean climates: at Mas Bove, using a Bowen ratio-energy balance method from 1991 to 1993, and at Zaragoza, using a weighing lysimeter from 1999 to 2000.